Science.gov

Sample records for magnetic energy conversion

  1. Optimizing Energy Conversion: Magnetic Nano-materials

    NASA Astrophysics Data System (ADS)

    McIntyre, Dylan; Dann, Martin; Ilie, Carolina C.

    2015-03-01

    We present herein the work started at SUNY Oswego as a part of a SUNY 4E grant. The SUNY 4E Network of Excellence has awarded SUNY Oswego and collaborators a grant to carry out extensive studies on magnetic nanoparticles. The focus of the study is to develop cost effective rare-earth-free magnetic materials that will enhance energy transmission performance of various electrical devices (solar cells, electric cars, hard drives, etc.). The SUNY Oswego team has started the preliminary work for the project and graduate students from the rest of the SUNY 4E team (UB, Alfred College, Albany) will continue the project. The preliminary work concentrates on analyzing the properties of magnetic nanoparticle candidates, calculating molecular orbitals and band gap, and the fabrication of thin films. SUNY 4E Network of Excellence Grant.

  2. Magnetic energy storage and conversion in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Spicer, D. S.; Mariska, J. T.; Boris, J. P.

    1986-01-01

    According to the approach employed in this investigation, particularly important simple configurations of magnetic field and plasma are identified, and it is attempted to achieve an understanding of the large-scale dynamic processes and transformations which these systems can undergo. Fundamental concepts are discussed, taking into account aspects of magnetic energy generation, ideal MHD theory, non-MHD properties, the concept of 'anomalous' resistivity, and global electrodynamic coupling. Questions of magnetically controlled energy conversion are examined, giving attention to magnetic modifications of plasma transport, the transition region structure and flows, channeling and acceleration of plasma, channeling and dissipation of MHD waves, and anomalous dissipation of field-aligned currents. A description of the characteristics of magnetohydrodynamic energy conversion is also provided, and outstanding questions are discussed.

  3. Energy Conversion and Particle Acceleration during Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Li, X.; Guo, F.; Daughton, W. S.; Li, H.; Li, S.; Liu, Y. H.; Li, G.

    2014-12-01

    We study energy conversion and particle acceleration during magnetic reconnection starting from a force-free current layer using two-dimensional particle-in-cell (PIC) simulations and high-Lundquist-number MHD simulations. In PIC simulations of collisionless magnetic reconnection, pressure anisotropy develops and is found to be stronger for particles with higher energies. When an external guide field is added, the pressure anisotropy is stronger with the magnitude of guide field. The energy conversion and particle acceleration through particle guiding center drifts, magnetization current, and parallel electric field are quantitatively evaluated and compared for a range of guide fields. The results are then explained using an electric current description associated with pressure anisotropy. This description is further used to study energy conversion during reconnection in high-Lundquist-number MHD simulations, where plasma pressure is assumed to be isotropic, and energy conversion is from compressional and Ohmic heating. These results demonstrate the importance of considering the influence of anisotropic velocity distributions on particle acceleration during magnetic reconnection.

  4. A permanent magnet tubular linear generator for wave energy conversion

    NASA Astrophysics Data System (ADS)

    Yu, Haitao; Liu, Chunyuan; Yuan, Bang; Hu, Minqiang; Huang, Lei; Zhou, Shigui

    2012-04-01

    A novel three-phase permanent magnet tubular linear generator (PMTLG) with Halbach array is proposed for the sea wave energy conversion. Non-linear axi-symmetrical finite element method (FEM) is implemented to calculate the magnetic fields along air-gap for different Halbach arrays of PMTLGs. The PMTLG characteristics are analyzed and the simulation results are validated by the experiment. An assistant tooth is implemented to greatly minimize the end and cogging effects which cause the oscillatory detent force.

  5. Permanent magnet energy conversion machine with magnet mounting arrangement

    DOEpatents

    Hsu, John S. (Oak Ridge, TN); Adams, Donald J. (Knoxville, TN)

    1999-01-01

    A hybrid permanent magnet dc motor includes three sets of permanent magnets supported by the rotor and three sets of corresponding stators fastened to the surrounding frame. One set of magnets operates across a radial gap with a surrounding radial gap stator, and the other two sets of magnets operate off the respective ends of the rotor across respective axial gaps.

  6. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma

    DOE PAGESBeta

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M.; Myers, Clayton E.

    2014-09-10

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first timemore » in a well defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step toward resolving one of the most important problems in plasma physics.« less

  7. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma.

    PubMed

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M; Myers, Clayton E

    2014-01-01

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first time in a well-defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step towards resolving one of the most important problems in plasma physics. PMID:25205135

  8. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma

    SciTech Connect

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M.; Myers, Clayton E.

    2014-09-10

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first time in a well defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step toward resolving one of the most important problems in plasma physics.

  9. Direct fission fragment energy conversion utilizing magnetic collimation

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Pavel Valeryevich

    The objective of this dissertation was to determine the technological feasibility of direct fission fragment energy conversion utilizing magnetic collimation (DFFEC-MC). This objective was accomplished by producing a conceptual design for a DFFEC-MC system and by analysis of the potential DFFEC-MC system performance. Consistent analysis and evaluation of the technological feasibility of the DFFEC-MC concept were achieved using state-of-the-art computer codes that allowed realistic and consistent modeling of the important physical processes governing DFFEC-MC system performance. Unique computational schemes, including three-dimensional modeling, were constructed and applied to obtain the performance characteristics of DFFEC-MC systems. Special effort was made to include all important physical processes. Important simplifications introduced due to modeling limitations were also assessed. The analysis takes into consideration a wide range of operational aspects including fission fragment (FF) escape from the fuel, FF collimation, FF collection, criticality, long-term performance, energy conversion efficiency, heat removal, and safety characteristics. Required engineering conditions are formulated that must be satisfied in order for the DFFEC-MC concept to have a reasonable chance to demonstrate technological feasibility. Specific characteristics of individual system components and the entire DFFEC-MC system are evaluated. To identify which technological improvements are needed, several possible design solutions are provided for some of the components along with analyses of the corresponding DFFEC-MC system performance. As a result of the computational analysis, the conditions for achieving an attractive (high) system efficiency are demonstrated. A technologically feasible DFFEC-MC system layout with promising operational characteristics is presented. The resulting DFFEC-MC system is envisioned as an advanced DFFEC system that combines advantageous design solutions proposed for application in both fission and fusion reactors. The analysis identifies possible application areas where the DFFEC-MC system might be competitive with other advanced direct and indirect energy conversion systems. To bring closer the time when the DFFEC-MC systems might become a reality, design challenges and required experimental studies are indicated.

  10. Scaling the energy conversion rate from magnetic field reconnection to different bodies

    SciTech Connect

    Mozer, F. S.; Hull, A.

    2010-10-15

    Magnetic field reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar coronae, and other astrophysical objects. Because of the huge dynamic range of magnetic fields in these bodies, it is important to understand energy conversion as a function of magnetic field strength and related parameters. It is conjectured theoretically and shown experimentally that the energy conversion rate per unit area in reconnection scales as the cube of an appropriately weighted magnetic field strength divided by the square root of an appropriately weighted density. With this functional dependence, the energy release in flares on the Sun, the large and rapid variation of the magnetic flux in the tail of Mercury, and the apparent absence of reconnection on Jupiter and Saturn, may be understood. Electric fields at the perihelion of the Solar Probe Plus mission may be tens of V/m.

  11. Electro-mechanical energy conversion system having a permanent magnet machine with stator, resonant transfer link and energy converter controls

    DOEpatents

    Skeist, S. Merrill; Baker, Richard H.

    2006-01-10

    An electro-mechanical energy conversion system coupled between an energy source and an energy load comprising an energy converter device including a permanent magnet induction machine coupled between the energy source and the energy load to convert the energy from the energy source and to transfer the converted energy to the energy load and an energy transfer multiplexer to control the flow of power or energy through the permanent magnetic induction machine.

  12. Energy conversion and transfer for plasmas in a magnetic expansion configuration

    SciTech Connect

    Cheng, Jiao; Tang, Hai-Bin; York, Thomas M.

    2014-06-15

    A two-dimensional axisymmetric particle-in-cell code with Monte Carlo collision conditions has been used to study particle energy transfer in plasmas and conversion in applied magnetic and electric fields appropriate to coaxial acceleration. The research incorporates a computation scheme with: a model of single particle magnetic interactions; a model of single particle interactions in electric and magnetic fields; and a model of multi-particle collisional interactions in order to understand the energy transfer processes and conversion mechanisms of charged plasma particles. This approach predicts electron and ion motions along with their energy variations for physical conditions that occur in the related models; the results allow comparison with experimental data for magnetic field strengths of 0.010.05?T and electrode voltages of 22.032.0?V. With the incorporation of magnetic and electric field effects on charged particles, the multi-particle model includes electron-neutral ionization collisions, ion-neutral charge exchange collisions, and electron-ion Coulomb collisions. This research presents a new approach to achieve an underlying understanding of the plasma energy transfer and conversion in the external electric and magnetic fields that is not possible using magnetohydrodynamics continuum representations. Results indicate the following innovative conclusions: (1) Radial and azimuthal energies of magnetized electrons are converted into an axial electron energy component in the diverging magnetic field, and the azimuthal kinetic energy of unmagnetized ions is converted into axial and radial components. (2) In electric and magnetic fields, electric field energy is primarily converted into axial kinetic energy of magnetized electrons by the energy transformation effects of magnetic fields, and for unmagnetized ions, the radial kinetic energy component dominates in the conversion of electric field energy. (3) For the collisional plasma, electron kinetic energy tends to increase (or decrease) to a terminal value since electrons lose energy in collisions then gain energy again from the field. Ions acquire most energy directly from the electric field, although part of the electric field energy arrives to the ions by collisions. Further, the ion axial energy component dominates the total ion energy. The collision processes are found to be integral and essential for the conversion of the plasma non-directed energy gain to be converted into the resultant axial energy, the magnitudes of which are found to be in agreement with experimental results.

  13. Study of energy conversion and partitioning in the magnetic reconnection layer of a laboratory plasma

    SciTech Connect

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M.; Myers, Clayton E.; Daughton, William

    2015-05-15

    While the most important feature of magnetic reconnection is that it energizes plasma particles by converting magnetic energy to particle energy, the exact mechanisms by which this happens are yet to be determined despite a long history of reconnection research. Recently, we have reported our results on the energy conversion and partitioning in a laboratory reconnection layer in a short communication [Yamada et al., Nat. Commun. 5, 4474 (2014)]. The present paper is a detailed elaboration of this report together with an additional dataset with different boundary sizes. Our experimental study of the reconnection layer is carried out in the two-fluid physics regime where ions and electrons move quite differently. We have observed that the conversion of magnetic energy occurs across a region significantly larger than the narrow electron diffusion region. A saddle shaped electrostatic potential profile exists in the reconnection plane, and ions are accelerated by the resulting electric field at the separatrices. These accelerated ions are then thermalized by re-magnetization in the downstream region. A quantitative inventory of the converted energy is presented in a reconnection layer with a well-defined, variable boundary. We have also carried out a systematic study of the effects of boundary conditions on the energy inventory. This study concludes that about 50% of the inflowing magnetic energy is converted to particle energy, 2/3 of which is ultimately transferred to ions and 1/3 to electrons. Assisted by another set of magnetic reconnection experiment data and numerical simulations with different sizes of monitoring box, it is also observed that the observed features of energy conversion and partitioning do not depend on the size of monitoring boundary across the range of sizes tested from 1.5 to 4 ion skin depths.

  14. Energy conversion

    SciTech Connect

    Woodall, J.M.

    1982-02-16

    Energy conversion capable of receiving input energy in thermal or radiant form at a variable rate and releasing energy in thermal, radiant or electrical form independent of rate is accomplished by providing a buffer member of a material that has three criteria: a melting temperature above 1300/sup degree/ K, a thermal conductance greater than 0.1 in calories per square centimeter per centimeter per degree per second and a latent heat of fusion of the order of 1 kilocalorie per mole. The converter can absorb energy of multiple types, store it and then release it in a form compatible with the prospective use. Sunlight of daylight duration and varying intensity is converted to steady 24 hour a day electrical output.

  15. Experiment on direct energy conversion from tandem mirror plasmas by using a slanted cusp magnetic field

    NASA Astrophysics Data System (ADS)

    Yasaka, Y.; Yamamoto, T.; Kurumatani, Y.; Takeno, H.; Nakashima, Y.; Cho, T.; Tomita, Y.; Ishikawa, M.

    2008-03-01

    A direct energy converter (DEC) designed for thermal ions escaping from a linear or near-linear device consists of a cusp magnetic field and decelerating electrodes. The electrons are deflected along the field lines and consequently separated from ions that are not fully magnetized. The ions are led to the decelerating electrodes to produce dc power. This type of DEC, the CUSPDEC, is applied to the GAMMA 10 tandem mirror in order to investigate the capability of separation of charged particles as well as to demonstrate energy conversion from ions. The separation of electrons and ions with energies of the order of kilo-electron Volt is achieved by using a slanted cusp magnetic field for the first time. It is also demonstrated that the separated ions are decelerated by the electric field in front of ion collectors and flow into the collectors at a high potential to produce electricity.

  16. Magnetic flux conversion and relaxation toward a minimum-energy state in S-1 spheromak plasmas

    SciTech Connect

    Janos, A.

    1985-09-01

    S-1 Spheromak currents and magnetic fluxes have been measured with Rogowski coils and flux loops external to the plasma. Toroidal plasma currents up to 350 kA and spheromak configuration lifetimes over 1.0 msec have been achieved at moderate power levels. The plasma formation in the S-1 Spheromak device is based on an inductive transfer of poloidal and toroidal magnetic flux from a toroidal ''flux core'' to the plasma. Formation is programmed to guide the configuration into a force-free, minimum-energy Taylor state. Properly detailed programming of the formation process is found not to be essential since plasmas adjust themselves during formation to a final equilibrium near the Taylor state. After formation, if the plasma evolves away from the stable state, then distinct relaxation oscillation events occur which restore the configuration to that stable state. The relaxation process involves reconnection of magnetic field lines, and conversion of poloidal to toroidal magnetic flux (and vice versa) has been observed and documented. The scaling of toroidal plasma current and toroidal magnetic flux in the plasma with externally applied currents is consistent with the establishment of a Taylor state after formation. In addition, the magnetic helicity is proportional to that injected from the flux core, independent of how that helicity is generated.

  17. Vocational-Technical Physics Project. The Alternator: I. Current Electricity, II. Magnets from Electricity, III. Electricity from Magnets, IV. Energy Conversion. Field Test Edition.

    ERIC Educational Resources Information Center

    Forsyth Technical Inst., Winston-Salem, NC.

    This vocational physics individualized instructional student module on the alternator consists of the four units: Current electricity, magnets from electricity, electricity from magnets, and energy conversion. Designed with a laboratory orientation, the units present explanations of the concepts and experiments. Laboratory data sheets,

  18. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  19. Magnetohydrodynamics of atmospheric transients. IV. Nonplane two-dimensional analyses of energy conversion and magnetic field evolution

    SciTech Connect

    Wu, S.T.; Nakagama, Y.; Han, S.M.; Dryer, M.

    1982-11-01

    The evolution of the magnetic field and the manner of conversion of thermal energy into different forms in the corona following a solar flare are examined by a nonplane magnetohydrodynamic (MHD) analysis. In the analysis all three components of magnetic field and velocity are treated in a physically self-consistent manner, with all physical variables as functions of time (t) and two spatial coordinates (r,theta). The difference due to the initial magnetic field, either twisted (force-free) or nontwisted (potential), is demonstrated. In both cases, of course, the field becomes non-force-free after the energy release, i.e., a flare. As in Papers I and II of this series, two initial field topologies (open vs. closed) are considered. The results show that the conversion of magnetic energy is faster for the case of the initially twisted (force-free) field in comparison with the initially untwisted (potential) field. Also, the twisted field produces a complex structure of the density enhancements. Comparison of the asymmetric topological evolution of the initially twisted magnetic fields with several white-light coronal transients (observed recently during the Solar Maximum year suggests that some preflare, magnetic topologies above the site of the energy release are nonpotential. This suggestion is based on the asymmetrial, somewhat concentric (''tennis racket'' shape), electron density enhancement obtained together with the twisted magnetic field lines in this study.

  20. Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation

    NASA Astrophysics Data System (ADS)

    Lewis, Laura H.; Jimnez-Villacorta, Flix

    2013-01-01

    Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a very large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance.

  1. Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation

    SciTech Connect

    Lewis, LH; Jimenez-Villacorta, F

    2012-07-18

    Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a very large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance. DOI: 10.1007/s11661-012-1278-2 (C) The Minerals, Metals & Materials Society and ASM International 2012

  2. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  3. Evaluating Energy Conversion Efficiency

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

    1983-01-01

    Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

  4. Photochemical Energy Conversion.

    ERIC Educational Resources Information Center

    Batschelet, William H.; George, Arnold

    1986-01-01

    Describes procedures for two demonstrations: (1) photochemical energy conversion using ferric oxalate actinometry and (2) liquification of gases using Freon 114. Safety precautions are given for both demonstrations, as are procedures and material specifications. (JM)

  5. Reconnection and Energy Conversion at the Magnetopause as Influenced by Earth's Dipole Tilt Angle and Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Hoilijoki, S.; Palmroth, M.

    2013-12-01

    We study the effect of Earth's dipole tilt angle and interplanetary magnetic field (IMF) Bx and By components on the location of reconnection and the energy conversion at the magnetopause. We simulate southward IMF satisfying both inward- and outward-type Parker spiral conditions during three different dipole tilt angles using a global magnetohydrodynamic model GUMICS-4. Different combinations of dipole tilt angle and IMF Bx and By components change the magnetopause reconnection morphology and magnitude. This can be studied by comparing the location of the reconnection line and the location and strength of the energy conversion for different parameter combinations. We find that the IMF Bx and the dipole tilt angle modify the reconnection line location and both magnitude and location of the energy conversion. We discuss the relative role of the non-zero Bx and the dipole tilt angle in dayside reconnection first separately and then by letting the parameters change simultaneously. We find that positive (negative) Bx moves the reconnection line northward (southward) and positive (negative) tilt angle moves the line southward (northward). When both tilt angle and Bx are positive or negative they reverse each others effect so that the reconnection line location is almost the same as it is when both Bx and tilt angle are zero. When these two parameters have opposite signs they enhance each other's effects. We find evidence that reconnection-induced processes modify the shape of the magnetopause, which in turn has and effect on the reconnection location. Therefore intrinsic processes within the magnetosphere - the magnetic flux transfer to nightside and the subsequent return of the closed flux - can influence the basic reconnection processes within the dayside magnetopause.

  6. Advanced Control of Permanent Magnet Synchronous Generators for Variable Speed Wind Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    Hostettler, Jacob

    Various environmental and economic factors have lead to increased global investment in alternative energy technologies such as solar and wind power. Although methodologies for synchronous generator control are well researched, wind turbines present control systems challenges not presented by traditional generation. The varying nature of wind makes achieving synchronism with the existing electrical power grid a greater challenge. Departing from early use of induction machines, permanent magnet synchronous generators have become the focus of power systems and control systems research into wind energy systems. This is due to their self excited nature, along with their high power density. The problem of grid synchronism is alleviated through the use of high performance power electronic converters. In achievement of the optimal levels of efficiency, advanced control systems techniques oer promise over more traditional approaches. Research into sliding mode control, and linear matrix inequalities with nite time boundedness and Hinfinity performance criteria, when applied to the dynamical models of the system, demonstrate the potential of these control methodologies as future avenues for achieving higher levels of performance and eciency in wind energy.

  7. Session: Energy Conversion

    SciTech Connect

    Robertson, David; LaSala, Raymond J.; Kukacka, Lawrence E.; Bliem, Carl J.; Premuzic, Eugene T.; Weare, John H.

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hydrothermal Energy Conversion Technology'' by David Robertson and Raymond J. LaSala; ''Materials for Geothermal Production'' by Lawrence E. Kukacka; ''Supersaturated Turbine Expansions for Binary Geothermal Power Plants'' by Carl J. Bliem; ''Geothermal Waster Treatment Biotechnology: Progress and Advantages to the Utilities'' by Eugen T. Premuzic; and ''Geothermal Brine Chemistry Modeling Program'' by John H. Weare.

  8. Laser energy conversion

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1989-01-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  9. Laser energy conversion

    NASA Astrophysics Data System (ADS)

    Jalufka, N. W.

    1989-07-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  10. Magnetic energy conversion; Proceedings of Symposium 13 of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

    NASA Astrophysics Data System (ADS)

    Brueckner, G. E.; Somov, B. V.

    Papers on magnetic energy conversion are presented, covering topics such as the propagation of Alfven waves in a doubly-diffusive atmosphere, solar and stellar coronae, magnetodynamical jets and flows, electron acceleration in extended radio sources, three-dimensional reconnection in astrophysical plasmas, solar flare energy release, and energy conversion in the solar flare plasma. Additional topics include magnetic energy release in interacting loops observed in a solar flare from Skylab, acceleration phases in high-energy solar flares, reconnection and solar terrestrial coupling, extreme energetic particle decreases near geostationary orbit, and magnetic reconnection in the tail of a magnetosphere. Other subjects include the disruption of energy storage in magnetotail-like systems, solar magnetic fields and large-scale electric currents in active regions, magnetic energy conversion in the solar transition zone, heating of the solar transition region in fine-scale structures, the acceleration of periodic tearing modes and the time scale of solar radio spikes, and the corespondence between small-scale coronal structures and the evolving solar magnetic field.

  11. Solar energy conversion.

    SciTech Connect

    Crabtree, G. W.; Lewis, N. S.

    2008-03-01

    If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience. The Sun has the enormous untapped potential to supply our growing energy needs. The barrier to greater use of the solar resource is its high cost relative to the cost of fossil fuels, although the disparity will decrease with the rising prices of fossil fuels and the rising costs of mitigating their impact on the environment and climate. The cost of solar energy is directly related to the low conversion efficiency, the modest energy density of solar radiation, and the costly materials currently required. The development of materials and methods to improve solar energy conversion is primarily a scientific challenge: Breakthroughs in fundamental understanding ought to enable marked progress. There is plenty of room for improvement, since photovoltaic conversion efficiencies for inexpensive organic and dye-sensitized solar cells are currently about 10% or less, the conversion efficiency of photosynthesis is less than 1%, and the best solar thermal efficiency is 30%. The theoretical limits suggest that we can do much better. Solar conversion is a young science. Its major growth began in the 1970s, spurred by the oil crisis that highlighted the pervasive importance of energy to our personal, social, economic, and political lives. In contrast, fossil-fuel science has developed over more than 250 years, stimulated by the Industrial Revolution and the promise of abundant fossil fuels. The science of thermodynamics, for example, is intimately intertwined with the development of the steam engine. The Carnot cycle, the mechanical equivalent of heat, and entropy all played starring roles in the development of thermodynamics and the technology of heat engines. Solar-energy science faces an equally rich future, with nanoscience enabling the discovery of the guiding principles of photonic energy conversion and their use in the development of cost-competitive new technologies.

  12. Electromechanical Energy Conversion.

    ERIC Educational Resources Information Center

    LePage, Wilbur R.

    This programed text on electromechanical energy conversion (motors and generators) was developed under contract with the U.S. Office of Education as Number 12 in a series of materials for use in an electrical engineering sequence. It is intended to be used in conjunction with other materials and with other short texts in the series. (DH)

  13. Mechanochemical Energy Conversion

    ERIC Educational Resources Information Center

    Pines, E.; And Others

    1973-01-01

    Summarizes the thermodynamics of macromolecular systems, including theories and experiments of cyclic energy conversion with rubber and collagen as working substances. Indicates that an early introduction into the concept of chemical potential and solution thermodynamics is made possible through the study of the cyclic processes. (CC)

  14. Electromagnetic energy conversion at reconnection fronts.

    PubMed

    Angelopoulos, V; Runov, A; Zhou, X-Z; Turner, D L; Kiehas, S A; Li, S-S; Shinohara, I

    2013-09-27

    Earth's magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth's auroras, heats the magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1- to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10(15) joules of magnetic energy, consistent with global magnetotail flux reduction. PMID:24072917

  15. Wind energy conversion system

    DOEpatents

    Longrigg, Paul

    1987-01-01

    The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

  16. Energy conversion system

    DOEpatents

    Murphy, L.M.

    1985-09-16

    The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.

  17. Energy conversion system

    DOEpatents

    Murphy, Lawrence M.

    1987-01-01

    The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.

  18. Flare onsets in hard and soft X-rays. [magnetic energy conversion in sun

    NASA Technical Reports Server (NTRS)

    Machado, Marcos E.; Orwig, Larry E.; Antonucci, Ester

    1986-01-01

    It is shown that the onset of solar flares, within about 2 min or less before the impulsive peaks, is characterized by an increase in high-energy emission at E less than 100 keV, and strong broadening of soft X-ray lines characteristic of the 10-million-K plasma already present at this stage. The observations are interpreted in terms of the early signature of energy release, during a phase preceding the instability that leads to strong particle acceleration.

  19. Thermal Energy Conversion Branch

    NASA Technical Reports Server (NTRS)

    Bielozer, Matthew C.; Schreiber, Jeffrey, G.; Wilson, Scott D.

    2004-01-01

    The Thermal Energy Conversion Branch (5490) leads the way in designing, conducting, and implementing research for the newest thermal systems used in space applications at the NASA Glenn Research Center. Specifically some of the most advanced technologies developed in this branch can be broken down into four main areas: Dynamic Power Systems, Primary Solar Concentrators, Secondary Solar Concentrators, and Thermal Management. Work was performed in the Dynamic Power Systems area, specifically the Stirling Engine subdivision. Today, the main focus of the 5490 branch is free-piston Stirling cycle converters, Brayton cycle nuclear reactors, and heat rejection systems for long duration mission spacecraft. All space exploring devices need electricity to operate. In most space applications, heat energy from radioisotopes is converted to electrical power. The Radioisotope Thermoelectric Generator (RTG) already supplies electricity for missions such as the Cassini Spacecraft. The focus of today's Stirling research at GRC is aimed at creating an engine that can replace the RTG. The primary appeal of the Stirling engine is its high system efficiency. Because it is so efficient, the Stirling engine will significantly reduce the plutonium fuel mission requirements compared to the RTG. Stirling is also being considered for missions such as the lunar/Mars bases and rovers. This project has focused largely on Stirling Engines of all types, particularly the fluidyne liquid piston engine. The fluidyne was developed by Colin D. West. This engine uses the same concepts found in any type of Stirling engine, with the exception of missing mechanical components. All the working components are fluid. One goal was to develop and demonstrate a working Stirling Fluidyne Engine at the 2nd Annual International Energy Conversion Engineering Conference in Providence, Rhode Island.

  20. Wind energy conversion system

    SciTech Connect

    Longrigg, P.

    1987-03-17

    This patent describes a wind energy conversion system comprising: a propeller rotatable by force of wind; a generator of electricity mechanically coupled to the propeller for converting power of the wind to electric power for use by an electric load; means coupled between the generator and the electric load for varying the electric power drawn by the electric load to alter the electric loading of the generator; means for electro-optically sensing the speed of the wind at a location upwind from the propeller; and means coupled between the sensing means and the power varying means for operating the power varying means to adjust the electric load of the generator in accordance with a sensed value of wind speed to thereby obtain a desired ratio of wind speed to the speed of a tip of a blade of the propeller.

  1. Energy conversion system

    SciTech Connect

    Murphy, L.M.

    1987-09-01

    This patent describes a light-weight and self-contained solar energy conversion apparatus for converting solar radiation to electrical energy, which consists of: an array of photovoltaic cells mounted on a thin film substrate membrane and connected together to provide an electric power source, the thin film being stretched and mounted on a circular rim; support means connected to the rim for supporting the array of photovoltaic cells in a position adapted to be exposed to solar radiation, the support means being adjustable about two orthogonal axes and having strength design parameters sufficient to support the array, substrate membrane, and rim safely in a still atmosphere without regard to ambient outside wind and hail loads; and a substantially spherical dome positioned over and enclosing a chamber around the array of photovoltaic cells and support means, the dome being comprised of a specularly translucent, flexible, thin film material anchored around the support means and inflated to a pressure in the chamber in the range of about 0.02 to 0.10 pounds per square inch more than the pressure outside the chamber. The thin film material of the dome is also tear-resistant and sufficiently strong to withstand normal wind and hail storm forces and having sufficient resilience to yield without puncturing to hail stones, yet to recover to its spherical surface shape under the urging of the inflation pressure in the chamber.

  2. Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan

    ERIC Educational Resources Information Center

    Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

    2014-01-01

    A simple energy conversion system--particularly, the conversion of mechanical energy into electrical energy by using shaker flashlights--has recently been presented. This system uses hand generators, consisting of a magnet in a tube with a coil wrapped around it, and acts as an ac source when the magnet passes back and forth through the coil.…

  3. Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan

    ERIC Educational Resources Information Center

    Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

    2014-01-01

    A simple energy conversion system--particularly, the conversion of mechanical energy into electrical energy by using shaker flashlights--has recently been presented. This system uses hand generators, consisting of a magnet in a tube with a coil wrapped around it, and acts as an ac source when the magnet passes back and forth through the coil.

  4. On the energy conversion efficiency in magnetic hyperthermia applications: A new perspective to analyze the departure from the linear regime

    NASA Astrophysics Data System (ADS)

    Landi, G. T.; Bakuzis, A. F.

    2012-04-01

    The success of magnetic hyperthermia cancer treatments rely strongly on the magnetic properties of the nanoparticles and their intricate dependence on the externally applied field. This is particularly more so as the response departs from the low field linear regime. In this paper we introduce a new parameter, referred to as the efficiency in converting electromagnetic energy into thermal energy, which is shown to be remarkably useful in the analysis of the system response, especially when the power loss is investigated as a function of the applied field amplitude. Using numerical simulations of dynamic hysteresis, through the stochastic Landau-Lifshitz model, we map in detail the efficiency as a function of all relevant parameters of the system and compare the results with simpleyet powerfulpredictions based on heuristic arguments about the relaxation time.

  5. Energy conversion system

    SciTech Connect

    Wang, F.E.

    1981-06-30

    A thermal-mechanical energy converting device is disclosed that has at least two rotatably supported wheels and with one or more endless transmission elements of a material having a memory effect capable in the bending mode of converting thermal energy into mechanical energy when heated from a temperature below its transition temperature to a temperature above its transition temperature; the transmission elements serve to drive one wheel from the other wheel upon application of thermal energy to the transmission elements, whereby the thermal energy is transferred from the other wheel to the transmission elements over at least a major portion of the circumferential contact of the transmission elements with the other wheel.

  6. Solar energy conversion.

    SciTech Connect

    Crabtree, G. W.; Lewis, N. S.; Materials Science Division; Cal Tech

    2007-03-01

    The Sun provides Earth with a staggering amount of energy - enough to power the great oceanic and atmospheric currents, the cycle of evaporation and condensation that brings fresh water inland and drives river flow, and the typhoons, hurricanes, and tornadoes that so easily destroy the natural and built landscape. The San Francisco earthquake of 1906, with magnitude 7.8, released an estimated 10{sup 17} joules of energy, the amount the Sun delivers to Earth in one second. Earth's ultimate recoverable resource of oil, estimated at 3 trillion barrels, contains 1.7 x 10{sup 22} joules of energy, which the Sun supplies to Earth in 1.5 days. The amount of energy humans use annually, about 4.6 x 10{sup 20} joules, is delivered to Earth by the Sun in one hour. The enormous power that the Sun continuously delivers to Earth, 1.2 x 10{sup 5} terawatts, dwarfs every other energy source, renewable or nonrenewable. It dramatically exceeds the rate at which human civilization produces and uses energy, currently about 13 TW.

  7. Energy Conversion and Storage Program

    SciTech Connect

    Cairns, E.J.

    1992-03-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

  8. Energy conversion in the coronal plasma

    NASA Technical Reports Server (NTRS)

    Martens, P. C. H.

    1986-01-01

    Solar and stellar X-ray emission are the observed waste products of the interplay between magnetic fields and the motion of stellar plasma. Theoretical understanding of the process of coronal heating is of utmost importance, since the high temperature is what defines the corona in the first place. Most of the research described deals with the aspects of the several rivalling theories for coronal heating. The rest of the papers deal with processes of energy conversion related to flares.

  9. Energy conversion apparatus

    SciTech Connect

    Fuchs, F.J.

    1982-04-20

    An apparatus for maintaining the speed of rotation of a windmill rotor at a fixed ratio to the free flow velocity of the driving wind. This arrangement permits the windmill rotor to rotate at the speed at which its power output is maximized. The apparatus includes a plurality of interleaved rotating and stationary friction discs which convert the rotational kinetic energy of the windmill rotor shaft into thermal energy. An anemometer shaft, which rotates with a velocity which is proportional to the ambient wind velocity, drives a gear train which increases or decreases the pressure on the friction discs so that the load on the rotor is increased or decreased, in an offsetting manner, as the wind velocity changes.

  10. Electrochemistry for Energy Conversion

    NASA Astrophysics Data System (ADS)

    O'Hayre, Ryan

    2010-10-01

    Imagine a laptop computer that runs for 30 hours on a single charge. Imagine a world where you plug your house into your car and power lines are a distant memory. These dreams motivate today's fuel cell research. While some dreams (like powering your home with your fuel cell car) may be distant, others (like a 30-hour fuel cell laptop) may be closer than you think. If you are curious about fuel cells---how they work, when you might start seeing them in your daily life--- this talk is for you. Learn about the state-of-the art in fuel cells, and where the technology is likely to be headed in the next 20 years. You'll also be treated to several ``behind-the scenes'' glimpses of cutting-edge research projects under development in the Renewable Energy Materials Center at the Colorado School of Mines--- projects like an ``ionic transistor'' that works with protons instead of electrons, and a special ceramic membrane material that enables the ``uphill'' diffusion of steam. Associate Professor Ryan O'Hayre's laboratory at the Colorado School of Mines develops new materials and devices to enable alternative energy technologies including fuel cells and solar cells. Prof. O'Hayre and his students collaborate with the Colorado Fuel Cell Center, the Colorado Center for Advanced Ceramics, the Renewable Energy Materials Science and Engineering Center, and the National Renewable Energy Laboratory.[4pt] In collaboration with Ann Deml, Jianhua Tong, Svitlana Pylypenko, Archana Subramaniyan, Micahael Sanders, Jason Fish, Annette Bunge, Colorado School of Mines.

  11. Review of betavoltaic energy conversion

    NASA Technical Reports Server (NTRS)

    Olsen, Larry C.

    1993-01-01

    Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.

  12. Review of betavoltaic energy conversion

    NASA Astrophysics Data System (ADS)

    Olsen, Larry C.

    1993-05-01

    Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.

  13. Turbines For Optomechanical Energy Conversion

    NASA Technical Reports Server (NTRS)

    Dick, G. John

    1996-01-01

    Class of proposed optomechanical energy-conversion machines exploit multiple reflections from precise, high-reflectivity mirrors, some of which fixed to turbinelike rotors that spin at high speeds. Basic idea to increase frequencies of photons (and thus energy of light) by repeated Doppler-shifting reflections from moving mirrors. Gain in optical energy in such reflection proportional to speed of mirror, while loss function of imperfections of mirror.

  14. Advanced thermionic energy conversion

    NASA Technical Reports Server (NTRS)

    Britt, E. J.; Fitzpatrick, G. D.; Hansen, L. K.; Rasor, N. S.

    1974-01-01

    Basic analytical and experimental exploration was conducted on several types of advanced thermionic energy converters, and preliminary analysis was performed on systems utilizing advanced converter performance. The Pt--Nb cylindrical diode which exhibited a suppressed arc drop, as described in the preceding report, was reassembled and the existence of the postulated hydrid mode of operation was tentatively confirmed. Initial data obtained on ignited and unignited triode operation in the demountable cesium vapor system essentially confirmed the design principles developed in earlier work, with a few exceptions. Three specific advanced converter concepts were selected as candidates for concentrated basic study and for practical evaluation in fixed-configuration converters. Test vehicles and test stands for these converters and a unique controlled-atmosphere station for converter assembly and processing were designed, and procurement was initiated.

  15. Autonomic Energy Conversion

    PubMed Central

    Caplan, S. R.

    1968-01-01

    All discussions of muscle energetics concern themselves with the Hill force-velocity relation, which is also the general output relation of a class of self-regulated energy converters and as such contains only a single adjustable parameter the degree of coupling. It is therefore important to see whether in principle muscle can be included in this class. One requirement is that the muscle should possess a working element characterized by a dissipation function of two terms: mechanical output and chemical input. This has been established by considering the initial steady phase of isotonic and isometric tetanic contraction to represent a stationary state of the fibrils (a considerable body of evidence supports this). Further requirements, which can be justified for the working element, are linearity and incomplete coupling. Thus the chemical input of the muscle may be expected to follow the inverse Hill equation (see Part I). The relatively large changes in activities of reactants which the equation demands could only be controlled by local operation of the regulator, and a scheme is outlined to show how such control may be achieved. Objections to this view recently raised by Wilkie and Woledge rest on at least two important assumptions, the validity of which is questioned: (a) that heat production by processes other than the immediate driving reaction is negligible, which disregards the regulatory mechanism (possibly this involves the calcium pump), and (b) that the affinity of the immediate driving reaction is determined by over-all concentrations. The division of heat production into shortening heat and maintenance heat or activation heat is found to be arbitrary. PMID:5679394

  16. Turbulence and energy conversion research

    SciTech Connect

    Hutchinson, R.A.

    1985-07-01

    This report examines the role of fluid mechanics research (particularly turbulence research) in improving energy conversion systems. In this report two of the listed application areas are selected as examples: fluidization and cavitation. Research needs in general, and research possibilities for ECUT in particular, are examined.

  17. Photochemical conversion of solar energy.

    PubMed

    Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

    2008-01-01

    Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago. PMID:18605661

  18. Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan

    NASA Astrophysics Data System (ADS)

    Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

    2014-02-01

    A simple energy conversion systemparticularly, the conversion of mechanical energy into electrical energy by using shaker flashlightshas recently been presented. This system uses hand generators, consisting of a magnet in a tube with a coil wrapped around it, and acts as an ac source when the magnet passes back and forth through the coil. Additionally, this system includes an LED, a capacitor, a switch, and a full-wave bridge rectifier. We were inspired by this work to design a simpler demonstrator made for teaching energy conversion concepts to science students using piezoelectric material.

  19. Materials for thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1988-01-01

    The field of thermoelectric energy conversion is reviewed from both a theoretical and an experimental standpoint. The basic theory is introduced and the thermodynamic and solid state views are compared. An overview of the development of thermoelectric materials is presented with particular emphasis being placed on the most recent developments in high-temperature semiconductors. A number of possible device applications are discussed and the successful use and suitability of these devices for space power is manifest.

  20. Pyroelectric energy conversion: optimization principles.

    PubMed

    Sebald, Gael; Lefeuvre, Elie; Guyomar, Daniel

    2008-03-01

    In the framework of microgenerators, we present in this paper the key points for energy harvesting from temperature using ferroelectric materials. Thermoelectric devices profit from temperature spatial gradients, whereas ferroelectric materials require temporal fluctuation of temperature, thus leading to different applications targets. Ferroelectric materials may harvest perfectly the available thermal energy whatever the materials properties (limited by Carnot conversion efficiency) whereas thermoelectric material's efficiency is limited by materials properties (ZT figure of merit). However, it is shown that the necessary electric fields for Carnot cycles are far beyond the breakdown limit of bulk ferroelectric materials. Thin films may be an excellent solution for rising up to ultra-high electric fields and outstanding efficiency. Different thermodynamic cycles are presented in the paper: principles, advantages, and drawbacks. Using the Carnot cycle, the harvested energy would be independent of materials properties. However, using more realistic cycles, the energy conversion effectiveness remains dependent on the materials properties as discussed in the paper. A particular coupling factor is defined to quantify and check the effectiveness of pyroelectric energy harvesting. It is defined similarly to an electromechanical coupling factor as k2=p2theta0/(epsilontheta33cE), where p, theta0, epsilontheta33, cE are pyroelectric coefficient, maximum working temperature, dielectric permittivity, and specific heat, respectively. The importance of the electrothermal coupling factor is shown and discussed as an energy harvesting figure of merit. It gives the effectiveness of all techniques of energy harvesting (except the Carnot cycle). It is finally shown that we could reach very high efficiency using 1110.75Pb(Mg1/3Nb2/3)-0.25PbTiO3 single crystals and synchronized switch harvesting on inductor (almost 50% of Carnot efficiency). Finally, practical implementation key points of pyroelectric energy harvesting are presented showing that the different thermodynamic cycles are feasible and potentially effective, even compared to thermoelectric devices. PMID:18407845

  1. Radiation energy conversion in space

    NASA Technical Reports Server (NTRS)

    Billman, K. W.

    1979-01-01

    Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.

  2. Electrodes for thermionic energy conversion

    NASA Technical Reports Server (NTRS)

    Rufeh, F.; Sommer, A. H.; Huffman, F. N.

    1975-01-01

    Problems concerning an application of thermionic energy conversion methods are related to the high heat source temperatures currently required for practical power densities and efficiencies. A description is given of advances made in the development of improved emitter and collector surfaces as a basis for the reduction of operating temperatures. The controlled addition of oxygen has resulted in a considerable improvement of emitter performance. Improvements in converter performance have been obtained by a reduction of the collector work function. Attention is given to fundamental studies, simulated converter environment tests, and variable spacing converter experiments.

  3. Electrodynamic tethers for energy conversion

    NASA Technical Reports Server (NTRS)

    Nobles, W.

    1986-01-01

    Conductive tethers have been proposed as a new method for converting orbital mechanical energy into electrical power for use on-board a satellite (generator mode) or conversely (motor mode) as a method of providing electric propulsion using electrical energy from the satellite. The operating characteristics of such systems are functionally dependent on orbit altitude and inclination. Effects of these relationships are examined to determine acceptable regions of application. To identify system design considerations, a specific set of system performance goals and requirements are selected. The case selected is for a 25 kW auxiliary power system for use on Space Station. Appropriate system design considerations are developed, and the resulting system is described.

  4. Biomass conversion processes for energy and fuels

    NASA Astrophysics Data System (ADS)

    Sofer, S. S.; Zaborsky, O. R.

    The book treats biomass sources, promising processes for the conversion of biomass into energy and fuels, and the technical and economic considerations in biomass conversion. Sources of biomass examined include crop residues and municipal, animal and industrial wastes, agricultural and forestry residues, aquatic biomass, marine biomass and silvicultural energy farms. Processes for biomass energy and fuel conversion by direct combustion (the Andco-Torrax system), thermochemical conversion (flash pyrolysis, carboxylolysis, pyrolysis, Purox process, gasification and syngas recycling) and biochemical conversion (anaerobic digestion, methanogenesis and ethanol fermentation) are discussed, and mass and energy balances are presented for each system.

  5. Clean Fossil Energy Conversion Processes

    NASA Astrophysics Data System (ADS)

    Fan, L.-S.

    2007-03-01

    Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

  6. The chemistry of energy conversion and storage.

    PubMed

    Su, Dang Sheng

    2014-05-01

    What's in store: The sustainable development of our society requires the conversion and storage of renewable energy, and these should be scaled up to serve the global primary energy consumption. This special issue on "The Chemistry of Energy Conversion and Storage", assembled by guest editor Dangsheng Su, contains papers dealing with these aspects, and highlights important developments in the chemistry of energy conversion and storage during the last two years. PMID:24832535

  7. Magnetic Materials in sustainable energy

    NASA Astrophysics Data System (ADS)

    Gutfleisch, Oliver

    2012-02-01

    A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy efficiency in the total energy lifecycle, has accelerated research in energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the efficiency and performance of devices in electric power generation, conversion and transportation. Magnetic materials are essential components of energy applications (i.e. motors, generators, transformers, actuators, etc.) and improvements in magnetic materials will have significant impact in this area, on par with many ``hot'' energy materials efforts. The talk focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials with an emphasis on their optimization for energy applications. Specifically, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, will be discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure-property relationships, will be examined in the context of their respective markets as well as their potential impact on energy efficiency. Finally, considering future bottle-necks in raw materials and in the supply chain, options for recycling of rare-earth metals will be analyzed.ootnotetextO. Gutfleisch, J.P. Liu, M. Willard, E. Bruck, C. Chen, S.G. Shankar, Magnetic Materials and Devices for the 21st Century: Stronger, Lighter, and More Energy Efficient (review), Adv. Mat. 23 (2011) 821-842.

  8. Solar energy, its conversion and utilization

    NASA Technical Reports Server (NTRS)

    Farber, E. A.

    1972-01-01

    The work being carried out at the University of Florida Solar Energy and Energy Conversion Laboratory in converting solar energy, our only income, into other needed and useful forms of energy is described. A treatment such as this demonstrates, in proper perspective, how solar energy can benefit mankind with its many problems of shortages and pollution. Descriptions were given of the conversion processes, equipment, and performance. The testing of materials, solar water heating, space heating, cooking and baking, solar distillation, refrigeration and air-conditioning, work with the solar furnace, conversion to mechanical power, hot air engines, solar-heated sewage digestion, conversion to electricity, and other devices will be discussed.

  9. Thermophotovoltaic Energy Conversion Development Program

    NASA Technical Reports Server (NTRS)

    Shukla, Kailash; Doyle, Edward; Becker, Frederick

    1998-01-01

    Completely integrated thermophotovoltaic (TPV) power sources in the range of 100 to 500 watts are being developed. The technical approach taken in this project focuses on optimizing the integrated performance of the primary subsystems in order to yield high energy conversion efficiency and cost effectiveness. An important aspect of the approach is the use of a narrow band fibrous emitter radiating to a bandgap matched photovoltaic array to minimize thermal and optical recuperation requirements, as well as the non-recoverable heat losses. For the prototype system, fibrous ytterbia emitters radiating in a narrow band centered at 980 nm are matched with high efficiency silicon photoconverters. The integrated system includes a dielectric stack filter for optical energy recovery and a ceramic recuperator for thermal energy recovery. The prototype TPV system uses a rapid mix distributed fuel delivery system with controlled feeding of the fuel and heated air into a flame at the surface of the emitter. This makes it possible to operate at air preheat temperatures well above the auto-ignition temperature of the fuel thereby substantially increasing the system efficiency. The system has been operated with air preheat temperatures up to 1367 K and has produced a uniform narrow band radiation over the surface of the emitter with this approach. The design of the system is described and test data for the system and some of the key components are presented. The results from a system model, which show the impact of various parameters on system performance, are also discussed.

  10. Electromagnetic energy conversion at dipolarization fronts: Multispacecraft results

    NASA Astrophysics Data System (ADS)

    Huang, S. Y.; Fu, H. S.; Yuan, Z. G.; Zhou, M.; Fu, S.; Deng, X. H.; Sun, W. J.; Pang, Y.; Wang, D. D.; Li, H. M.; Li, H. M.; Yu, X. D.

    2015-06-01

    Dipolarization fronts (DFs) are believed to play important roles in transferring plasmas, magnetic fluxes, and energies in the magnetotail. Using the Cluster observations in 2003, electromagnetic energy conversion at the DFs is investigated by case and statistical studies. The case study indicates strongest energy conversion at the DF. The statistical study shows the similar features that the energy of the fields can be significantly transferred to the plasmas (load, J E > 0) at the DFs. These results are consistent with some recent simulations. Examining the electromagnetic fluctuations at the DFs, we suggest that the wave activities around the lower hybrid frequency may play an important role in the energy dissipation.

  11. Biological Solar Energy Conversion and U.S. Energy Policy

    ERIC Educational Resources Information Center

    Pimentel, David; And Others

    1978-01-01

    Surveys energy consumption in the United States and explores the possibility of increasing the amount of energy obtained from biomass conversion (biologically produced energy). Economic and environmental concerns of biomass conversion processes are discussed. (CP)

  12. Magnetic energy flow in the solar wind.

    NASA Technical Reports Server (NTRS)

    Modisette, J. L.

    1972-01-01

    Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

  13. Energy Conversion Alternatives Study (ECAS)

    NASA Technical Reports Server (NTRS)

    1977-01-01

    ECAS compared various advanced energy conversion systems that can use coal or coal-derived fuels for baseload electric power generation. It was conducted in two phases. Phase 1 consisted of parametric studies. From these results, 11 concepts were selected for further study in Phase 2. For each of the Phase 2 systems and a common set of ground rules, performance, cost, environmental intrusion, and natural resource requirements were estimated. In addition, the contractors defined the state of the associated technology, identified the advances required, prepared preliminary research and development plans, and assessed other factors that would affect the implementation of each type of powerplant. The systems studied in Phase 2 include steam systems with atmospheric- and pressurized-fluidized-bed boilers; combined cycle gas turbine/steam systems with integrated gasifiers or fired by a semiclean, coal derived fuel; a potassium/steam system with a pressurized-fluidized-bed boiler; a closed-cycle gas turbine/organic system with a high-temperature, atmospheric-fluidized-bed furnace; a direct-coal-fired, open- cycle magnetohydrodynamic/steam system; and a molten-carbonate fuel cell/steam system with an integrated gasifier. The sensitivity of the results to changes in the ground rules and the impact of uncertainties in capital cost estimates were also examined.

  14. High temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, Charles

    1987-01-01

    The theory and current status of materials research for high-temperature thermoelectric energy conversion are reviewed. Semiconductors are shown to be the preferred class of materials for this application. Optimization of the figure of merit of both broadband and narrow-band semiconductors is discussed as a function of temperature. Phonon scattering mechanisms are discussed, and basic material guidelines are given for reduction of thermal conductivity. Two general classes of materials show promise for high temperature figure of merit (Z) values, namely the rare earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

  15. Metallurgical technologies, energy conversion, and magnetohydrodynamic flows

    SciTech Connect

    Branover, H.; Unger, Y.

    1993-01-01

    The present volume discusses metallurgical applications of MHD, R D on MHD devices employing liquid working medium for process applications, electromagnetic (EM) modulation of molten metal flow, EM pump performance of superconducting MHD devices, induction EM alkali-metal pumps, a physical model for EM-driven flow in channel-induction furnaces, grain refinement in Al alloys via EM vibrational method, dendrite growth of solidifying metal in dc magnetic field, MHD for mass and heat transfer in single-crystal melt growth, inverse EM shaping, and liquid-metal MHD development in Israel. Also discussed are the embrittlement of steel by lead, an open cycle MHD disk generator, the acceleration of gas-liquid piston flows for molten-metal MHD generators, MHD flow around a cylinder, new MHD drag coefficients, liquid-metal MHD two-phase flow, and two-phase liquid gas mixers for MHD energy conversion.

  16. Photon Splitting and Pair Conversion in Strong Magnetic Fields

    SciTech Connect

    Baring, Matthew G.

    2008-10-17

    The magnetospheres of neutron stars provide a valuable testing ground for as-yet unverified theoretical predictions of quantum electrodynamics (QED) in strong electromagnetic fields. Exhibiting magnetic field strengths well in excess of a TeraGauss, such compact astrophysical environments permit the action of exotic mechanisms that are forbidden by symmetries in field-free regions. Foremost among these processes are single-photon pair creation, where a photon converts to an electron-positron pair, and magnetic photon splitting, where a single photon divides into two of lesser energy via the coupling to the external field. The pair conversion process is exponentially small in weak fields, and provides the leading order contribution to vacuum polarization. In contrast, photon splitting possesses no energy threshold and can operate in kinematic regimes where the lower order pair conversion is energetically forbidden. This paper outlines some of the key physical aspects of these processes, and highlights their manifestation in neutron star magnetospheres. Anticipated observational signatures include profound absorption turnovers in pulsar spectra at gamma-ray wavelengths. The shapes of these turnovers provide diagnostics on the possible action of pair creation and the geometrical locale of the photon emission region. There is real potential for the first confirmation of strong field QED with the new GLAST gamma-ray mission, recently launched by NASA in June 2008. The suppression of pair creation by photon splitting and its implications for pulsars are also discussed.

  17. Energy conversion & storage program. 1994 annual report

    SciTech Connect

    Cairns, E.J.

    1995-04-01

    The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  18. Energy Conversion & Storage Program, 1993 annual report

    SciTech Connect

    Cairns, E.J.

    1994-06-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  19. Energy Conversion in Natural and Artificial Photosynthesis

    PubMed Central

    McConnell, Iain; Li, Gonghu; Brudvig, Gary W.

    2010-01-01

    Summary Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil fuel dependence has severe consequences including energy security issues and greenhouse gas emissions. The consequences of fossil fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices including photoelectrochemical cells for solar energy conversion. PMID:20534342

  20. Figures of Merit for Energy Conversion Processes

    ERIC Educational Resources Information Center

    Rubin, Morton H.

    1978-01-01

    Explores the problem of how to determine standards of performance for energy conversion processes. Argues against infinitely slow reversible processes as standards, and explores simple and faster alternative processes. (Author/GA)

  1. Second NASA Conference on Laser Energy Conversion

    NASA Technical Reports Server (NTRS)

    Billman, K. W. (Editor)

    1976-01-01

    The possible transmission of high power laser beams over long distances and their conversion to thrust, electricity, or other useful forms of energy is considered. Specific topics discussed include: laser induced chemistry; developments in photovoltaics, including modification of the Schottky barrier devices and generation of high voltage emf'sby laser radiation of piezoelectric ceramics; the thermo electronic laser energy converter and the laser plasmadynamics converters; harmonic conversion of infrared laser radiation in molecular gases; and photon engines.

  2. Chemistry of energy conversion and storage.

    PubMed

    Su, Dang Sheng

    2012-03-12

    Energy is a big issue in our society, fueled by growing awareness of the finite resources of liquid fossil fuels and the noticeable changes in our climate resulting from its consumption. The general consensus is that there should be a well-considered roadmap towards a future energy scenario, with the replacement of fossil energy by renewable energies as the final goal. This "Chemistry of Energy Conversion and Storage" issue contains papers dealing with the chemistry behind renewable energies. PMID:22407997

  3. Thermionic energy conversion technology - Present and future

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Morris, J. F.

    1977-01-01

    Aerospace and terrestrial applications of thermionic direct energy conversion and advances in direct energy conversion (DEC) technology are surveyed. Electrode materials, the cesium plasma drop (the difference between the barrier index and the collector work function), DEC voltage/current characteristics, conversion efficiency, and operating temperatures are discussed. Attention is centered on nuclear reactor system thermionic DEC devices, for in-core or out-of-core operation. Thermionic fuel elements, the radiation shield, power conditions, and a waste heat rejection system are considered among the thermionic DEC system components. Terrestrial applications include topping power systems in fossil fuel and solar power generation.

  4. Thermionic Energy Conversion (TEC) topping thermoelectrics

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1981-01-01

    Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

  5. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  6. Photoelectrochemical cells - Conversion of intense optical energy

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Ellis, A. B.; Kaiser, S. W.

    1976-01-01

    Conversion of optical energy to chemical energy and/or electrical energy using wet photoelectrochemical cells is described. Emphasis is on (1) the photoelectrolysis of H2O to H2 and O2 using cells having n-type semiconductor photoelectrodes fabricated from TiO2, SnO2, SrTiO3, KTaO3, and KTa(0.77)Nb(0.23)O3, and (2) the conversion of light to electrical energy using CdSe- and CdS-based cells with polysulfide electrolytes.

  7. SPS Energy Conversion Power Management Workshop

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.

  8. SPS Energy Conversion Power Management Workshop

    NASA Astrophysics Data System (ADS)

    1980-06-01

    Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.

  9. High-Temperature Thermoelectric Energy Conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1987-01-01

    Theory of thermoelectric energy conversion at high temperatures and status of research on conversion materials reviewed in report. Shows highest values of thermoelectric figure of merit, Z, found in semiconductor materials. Semiconductors keep wide choice of elements and compounds. Electrical properties tailored to particular application by impurity doping and control of stoichiometry. Report develops definition of Z useful for comparing materials and uses it to evaluate potentials of different classes of materialsmetals, semiconductors, and insulators.

  10. Magnetic Materials Suitable for Fission Power Conversion in Space Missions

    NASA Technical Reports Server (NTRS)

    Bowman, Cheryl L.

    2012-01-01

    Terrestrial fission reactors use combinations of shielding and distance to protect power conversion components from elevated temperature and radiation. Space mission systems are necessarily compact and must minimize shielding and distance to enhance system level efficiencies. Technology development efforts to support fission power generation scenarios for future space missions include studying the radiation tolerance of component materials. The fundamental principles of material magnetism are reviewed and used to interpret existing material radiation effects data for expected fission power conversion components for target space missions. Suitable materials for the Fission Power System (FPS) Project are available and guidelines are presented for bounding the elevated temperature/radiation tolerance envelope for candidate magnetic materials.

  11. Hydraulic wind energy conversion system

    SciTech Connect

    Not Available

    1981-07-01

    The purpose of this research was to design, build and test a hydraulic wind energy system. This design used a three bladed turbine, which drove a hydraulic pump. The energy is transmitted from the pump through a long hose and into a hydraulic motor, where the energy is used. This wind system was built and tested during the winter of 1980-1981. The power train included a five meter, three bladed wind turbine, a 9.8:1 ratio gearbox, a 1.44 cubic inch displacement pump with a small supercharge gear pump attached. The hydraulic fluid was pumped through a 70', 3/4'' I-D-high pressure flexhose, then through a volume control valve and into a 1.44 cubic inch displacement motor. The fluid was returned through a 70', 1'' I-D-flexhose.

  12. Hydraulic wind energy conversion system

    NASA Astrophysics Data System (ADS)

    1981-07-01

    The purpose of this reseach was to design, build and test a hydraulic wind energy system. This design used a three bladed turbine, which drove a hydraulic pump. The energy is transmitted from the pump through a long hose and into a hydraulic motor, where the energy is used. This wind system was built and tested during the winter of 1980-1981. The power train included a five meter, three bladed wind turbine, a 9.8:1 ratio gearbox, a 1.44 cubic inch displacement pump with a small supercharge gear pump attached. The hydraulic fluid was pumped through a 70 ft, 3/4 in. I-D-high pressure flexhose, then through a volume control valve and into a 1.44 cubic inch displacement motor. The fluid was returned through a 7 ft, 1 in. I-D-flexhose.

  13. Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.

    PubMed

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

  14. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    PubMed Central

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

  15. Energy conversion & storage program. 1995 annual report

    SciTech Connect

    Cairns, E.J.

    1996-06-01

    The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.

  16. Surface Plasmon-Assisted Solar Energy Conversion.

    PubMed

    Dodekatos, Georgios; Schünemann, Stefan; Tüysüz, Harun

    2016-01-01

    The utilization of localized surface plasmon resonance (LSPR) from plasmonic noble metals in combination with semiconductors promises great improvements for visible light-driven photocatalysis, in particular for energy conversion. This review summarizes the basic principles of plasmonic photocatalysis, giving a comprehensive overview about the proposed mechanisms for enhancing the performance of photocatalytically active semiconductors with plasmonic devices and their applications for surface plasmon-assisted solar energy conversion. The main focus is on gold and, to a lesser extent, silver nanoparticles in combination with titania as semiconductor and their usage as active plasmonic photocatalysts. Recent advances in water splitting, hydrogen generation with sacrificial organic compounds, and CO2 reduction to hydrocarbons for solar fuel production are highlighted. Finally, further improvements for plasmonic photocatalysts, regarding performance, stability, and economic feasibility, are discussed for surface plasmon-assisted solar energy conversion. PMID:26092694

  17. Harnessing surface plasmons for solar energy conversion

    NASA Technical Reports Server (NTRS)

    Anderson, L. M.

    1983-01-01

    NASA research on the feasibility of solar-energy conversion using surface plasmons is reviewed, with a focus on inelastic-tunnel-diode techniques for power extraction. The need for more efficient solar converters for planned space missions is indicated, and it is shown that a device with 50-percent efficiency could cost up to 40 times as much per sq cm as current Si cells and still be competitive. The parallel-processing approach using broadband carriers and tunable diodes is explained, and the physics of surface plasmons on metal surfaces is outlined. Technical problems being addressed include phase-matching sunlight to surface plasmons, minimizing ohmic losses and reradiation in energy transport, coupling into the tunnels by mode conversion, and gaining an understanding of the tunnel-diode energy-conversion process. Diagrams illustrating the design concepts are provided.

  18. Energy conversion in natural and artificial photosynthesis.

    PubMed

    McConnell, Iain; Li, Gonghu; Brudvig, Gary W

    2010-05-28

    Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil-fuel dependence has severe consequences, including energy security issues and greenhouse gas emissions. The consequences of fossil-fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and in artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices, including photoelectrochemical cells, for solar energy conversion. PMID:20534342

  19. A new wind energy conversion system

    NASA Technical Reports Server (NTRS)

    Smetana, F. O.

    1975-01-01

    It is presupposed that vertical axis wind energy machines will be superior to horizontal axis machines on a power output/cost basis and the design of a new wind energy machine is presented. The design employs conical cones with sharp lips and smooth surfaces to promote maximum drag and minimize skin friction. The cones are mounted on a vertical axis in such a way as to assist torque development. Storing wind energy as compressed air is thought to be optimal and reasons are: (1) the efficiency of compression is fairly high compared to the conversion of mechanical energy to electrical energy in storage batteries; (2) the release of stored energy through an air motor has high efficiency; and (3) design, construction, and maintenance of an all-mechanical system is usually simpler than for a mechanical to electrical conversion system.

  20. Energy Conversion: Nano Solar Cell

    NASA Astrophysics Data System (ADS)

    Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad

    2009-09-01

    Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics can produce electricity at 20-30 c//kWhr with about 25% efficiency. Nanoparticles have a strong capacity to absorb light and generate more electrons for current as discovered in the recent work of organic and dye-sensitized cell. Using cheap preparation technique such as screen-printing and self-assembly growth, organic cells shows a strong potential for commercialization. Thin Films research group at National University Malaysia has been actively involved in these areas, and in this seminar, we will present a review works on nanomaterials for solar cells and particularly on hybrid organic solar cell based on ZnO nanorod arrays. The organic layer consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) and [6, 6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) was spin-coated on ZnO nanorod arrays. ZnO nanorod arrays were grown on FTO glass substrates which were pre-coated with ZnO nanoparticles using a low temperature chemical solution method. A gold electrode was used as the top contact. The device gave a short circuit current density of 2.49×10-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.

  1. US energy conversion and use characteristics

    SciTech Connect

    Imhoff, C.H.; Liberman, A.; Ashton, W.B.

    1982-02-01

    The long-range goal of the Energy Conversion and Utilization Technology (ECUT) Program is to enhance energy productivity in all energy-use sectors by supporting research on improved efficiency and fuel switching capability in the conversion and utilization of energy. Regardless of the deficiencies of current information, a summary of the best available energy-use information is needed now to support current ECUT program planning. This document is the initial draft of this type of summary and serves as a data book that will present current and periodically updated descriptions of the following aspects of energy use: gross US energy consumption in each major energy-use sector; energy consumption by fuel type in each sector; energy efficiency of major equipment/processes; and inventories, replacement rates, and use patterns for major energy-using capital stocks. These data will help the ECUT program staff perform two vital planning functions: determine areas in which research to improve energy productivity might provide significant energy savings or fuel switching and estimate the actual effect that specific research projects may have on energy productivity and conservation. Descriptions of the data sources and examples of the uses of the different types of data are provided in Section 2. The energy-use information is presented in the last four sections; Section 3 contains general, national consumption data; and Sections 4 through 6 contain residential/commercial, industrial, and transportation consumption data, respectively. (MCW)

  2. Thermal Energy Conversion in Nanofluids

    NASA Astrophysics Data System (ADS)

    Taylor, Robert

    2011-12-01

    A relatively simple subset of nanotechnology---nanofluids---can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.

  3. Wind energy conversion - An introduction

    NASA Astrophysics Data System (ADS)

    Musgrove, P. J.

    1983-12-01

    System integration studies indicate that existing utility grid systems could accept a contribution of about 20 percent of their total power from wind turbines. Similar percentages in fuel savings are envisioned for wind/diesel electricity generation systems in remote areas. An assessment of recent wind turbine development advancements indicates that 20-40 m diameter turbines, with 50-500 kW power ratings, offer the most attractive economics for land-based applications in the near future, yielding energy costs of the order of 2.8-5.6 p/kWh at sites where the annual average wind speed is 5.5 m/sec. In windier locations, the cost will be even lower. Further operational experience is required, however, to demonstrate that reliable operation can be sustained over periods of many years. As experience accumulates and economies of scale associated with mass production become available, the wind turbine market is expected to grow rapidly.

  4. Photochemical energy conversion systems using immobilized chloroplasts

    SciTech Connect

    Kayano, H.; Matsunaga, T.; Karube, I.; Suzuki, S.

    1981-10-01

    Immobilized chloropasts and Clostridium butyricum were employed for a photochemical energy conversion system. Spinach chloroplasts were immobilized in 2% agar gel. The optimum temperature of immobilized chloroplasts was 30 degrees Celcius. The maximum activity was obtained in the phosphate buffer solution (pH 8.0) containing 8 mu meters of ferredoxin under an N2 bubbling condition. Hydrogen was evolved under illumination by immobilized chloroplasts and C. butyricum. Hydrogen produced by this system was applied to a hydrogen-oxygen fuel cell. Photoinduced current was obtained from this photochemical energy conversion system. A photocurrent 0.4-1.5 mA was continuously obtained for 4h. The conversion ratio from hydrogen to current was 80-100%. (Refs. 12).

  5. Lightning energy conversion using lasers

    NASA Astrophysics Data System (ADS)

    Khan, Nasrullah; Mariun, Norman

    2000-01-01

    Potential energy sources are being investigated for the socioeconomic needs and increased power demand. Systems employing nuclear, thermal, hydro, solar, volcano, MHD, tidal and wind power generation techniques already exist. This work describes our attempt to utilize the off-planet lightning charge to store super electrolytic batteries or super capacitors. The electrostatic charge on clouds can be shifted to earth through a conducive air plasma channel created by appropriate high power Q-switched and mode-locked laser. The pulsed laser may create a conducting path consisting of ionized air particles from earth to some upper atmosphere. An antenna connected to anode of super cell or positive terminal of the super capacitor will accumulate and store this charge for future use. The anode of battery or positive terminal of capacitor may be connected to earth to complete the circuit. Due to extremely loud thundering and tropical weather severity a detailed work was done on lightning regarding its temporal and spatial profiles to develop a reasonable model to explore transient charging characteristics. Experimental work in respect of laser inducted plasma wire creation and charging capabilities of super storage batteries or super capacitors is optimized. Latest experimental results are reported.

  6. Solar energy conversion through ligand photodissociation

    SciTech Connect

    Hoffman, B.M.; Sima, P.D.

    1983-04-06

    A new technique for photochemical conversion of solar energy based on ligand photodissociation from metal complexes is examined. The concept is illustrated with a photogalvanic cell in which voltages are generated by photodissociation of CO from carbonylferroheme and with a cell in which the illuminated electrode is coated with an iron tetraphenylporphyrin.

  7. The power of thermionic energy conversion

    SciTech Connect

    Ramalingam, M.L. ); Young, T.J. . Aerospace Power Div.)

    1993-09-01

    This article is a technology assessment of thermionic energy conversion. The topics of the article include current thermionic programs, application to planned military and civilian space missions, USA and former Soviet Union cooperation in thermionic developmental activities, the Topaz program, types of converters, emitter developments, demonstrating readiness, and ionization media developments.

  8. Comments on TEC trends. [Thermionic Energy Conversion

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1979-01-01

    The paper comments on published and projected thermionic-energy-conversion (TEC) performance trends. This commentary includes graphs and an appendix relating TEC performance parameters, plots of predicted and actual TEC trends, a figure relating projected cost of electricity to overall efficiency for TEC topping, and a discussion of the implications of these relationships.

  9. Magnetic skyrmion logic gates: conversion, duplication and merging of skyrmions.

    PubMed

    Zhang, Xichao; Ezawa, Motohiko; Zhou, Yan

    2015-01-01

    Magnetic skyrmions, which are topological particle-like excitations in ferromagnets, have attracted a lot of attention recently. Skyrmionics is an attempt to use magnetic skyrmions as information carriers in next generation spintronic devices. Proposals of manipulations and operations of skyrmions are highly desired. Here, we show that the conversion, duplication and merging of isolated skyrmions with different chirality and topology are possible all in one system. We also demonstrate the conversion of a skyrmion into another form of a skyrmion, i.e., a bimeron. We design spin logic gates such as the AND and OR gates based on manipulations of skyrmions. These results provide important guidelines for utilizing the topology of nanoscale spin textures as information carriers in novel magnetic sensors and spin logic devices. PMID:25802991

  10. Magnetic skyrmion logic gates: conversion, duplication and merging of skyrmions

    PubMed Central

    Zhang, Xichao; Ezawa, Motohiko; Zhou, Yan

    2015-01-01

    Magnetic skyrmions, which are topological particle-like excitations in ferromagnets, have attracted a lot of attention recently. Skyrmionics is an attempt to use magnetic skyrmions as information carriers in next generation spintronic devices. Proposals of manipulations and operations of skyrmions are highly desired. Here, we show that the conversion, duplication and merging of isolated skyrmions with different chirality and topology are possible all in one system. We also demonstrate the conversion of a skyrmion into another form of a skyrmion, i.e., a bimeron. We design spin logic gates such as the AND and OR gates based on manipulations of skyrmions. These results provide important guidelines for utilizing the topology of nanoscale spin textures as information carriers in novel magnetic sensors and spin logic devices. PMID:25802991

  11. Optical Energy Transfer and Conversion System

    NASA Technical Reports Server (NTRS)

    Stone, William C. (Inventor); Hogan, Bartholomew P. (Inventor)

    2015-01-01

    An optical power transfer system comprising a fiber spooler, a fiber optic rotary joint mechanically connected to the fiber spooler, and an electrical power extraction subsystem connected to the fiber optic rotary joint with an optical waveguide. Optical energy is generated at and transferred from a base station through fiber wrapped around the spooler, through the rotary joint, and ultimately to the power extraction system at a remote mobility platform for conversion to another form of energy.

  12. Speed, Acceleration, and Velocity: Level II, Unit 9, Lesson 1; Force, Mass, and Distance: Lesson 2; Types of Motion and Rest: Lesson 3; Electricity and Magnetism: Lesson 4; Electrical, Magnetic, and Gravitational Fields: Lesson 5; The Conservation and Conversion of Matter and Energy: Lesson 6; Simple Machines and Work: Lesson 7; Gas Laws: Lesson 8; Principles of Heat Engines: Lesson 9; Sound and Sound Waves: Lesson 10; Light Waves and Particles: Lesson 11; Program. A High.....

    ERIC Educational Resources Information Center

    Manpower Administration (DOL), Washington, DC. Job Corps.

    This self-study program for high-school level contains lessons on: Speed, Acceleration, and Velocity; Force, Mass, and Distance; Types of Motion and Rest; Electricity and Magnetism; Electrical, Magnetic, and Gravitational Fields; The Conservation and Conversion of Matter and Energy; Simple Machines and Work; Gas Laws; Principles of Heat Engines;…

  13. Semiconducting materials for photoelectrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Sivula, Kevin; van de Krol, Roel

    2016-02-01

    To achieve a sustainable society with an energy mix primarily based on solar energy, we need methods of storing energy from sunlight as chemical fuels. Photoelectrochemical (PEC) devices offer the promise of solar fuel production through artificial photosynthesis. Although the idea of a carbon-neutral energy economy powered by such ‘artificial leaves’ is intriguing, viable PEC energy conversion on a global scale requires the development of devices that are highly efficient, stable and simple in design. In this Review, recently developed semiconductor materials for the direct conversion of light into fuels are scrutinized with respect to their atomic constitution, electronic structure and potential for practical performance as photoelectrodes in PEC cells. The processes of light absorption, charge separation and transport, and suitable energetics for energy conversion in PEC devices are emphasized. Both the advantageous and unfavourable aspects of multinary oxides, oxynitrides, chalcogenides, classic semiconductors and carbon-based semiconductors are critically considered on the basis of their experimentally demonstrated performance and predicted properties.

  14. Approaches for biological and biomimetic energy conversion

    PubMed Central

    LaVan, David A.; Cha, Jennifer N.

    2006-01-01

    This article highlights areas of research at the interface of nanotechnology, the physical sciences, and biology that are related to energy conversion: specifically, those related to photovoltaic applications. Although much ongoing work is seeking to understand basic processes of photosynthesis and chemical conversion, such as light harvesting, electron transfer, and ion transport, application of this knowledge to the development of fully synthetic and/or hybrid devices is still in its infancy. To develop systems that produce energy in an efficient manner, it is important both to understand the biological mechanisms of energy flow for optimization of primary structure and to appreciate the roles of architecture and assembly. Whether devices are completely synthetic and mimic biological processes or devices use natural biomolecules, much of the research for future power systems will happen at the intersection of disciplines. PMID:16567648

  15. Novel Nuclear Powered Photocatalytic Energy Conversion

    SciTech Connect

    White,John R.; Kinsmen,Douglas; Regan,Thomas M.; Bobek,Leo M.

    2005-08-29

    The University of Massachusetts Lowell Radiation Laboratory (UMLRL) is involved in a comprehensive project to investigate a unique radiation sensing and energy conversion technology with applications for in-situ monitoring of spent nuclear fuel (SNF) during cask transport and storage. The technology makes use of the gamma photons emitted from the SNF as an inherent power source for driving a GPS-class transceiver that has the ability to verify the position and contents of the SNF cask. The power conversion process, which converts the gamma photon energy into electrical power, is based on a variation of the successful dye-sensitized solar cell (DSSC) design developed by Konarka Technologies, Inc. (KTI). In particular, the focus of the current research is to make direct use of the high-energy gamma photons emitted from SNF, coupled with a scintillator material to convert some of the incident gamma photons into photons having wavelengths within the visible region of the electromagnetic spectrum. The high-energy gammas from the SNF will generate some power directly via Compton scattering and the photoelectric effect, and the generated visible photons output from the scintillator material can also be converted to electrical power in a manner similar to that of a standard solar cell. Upon successful implementation of an energy conversion device based on this new gammavoltaic principle, this inherent power source could then be utilized within SNF storage casks to drive a tamper-proof, low-power, electronic detection/security monitoring system for the spent fuel. The current project has addressed several aspects associated with this new energy conversion concept, including the development of a base conceptual design for an inherent gamma-induced power conversion unit for SNF monitoring, the characterization of the radiation environment that can be expected within a typical SNF storage system, the initial evaluation of Konarka's base solar cell design, the design and fabrication of a range of new cell materials and geometries at Konarka's manufacturing facilities, and the irradiation testing and evaluation of these new cell designs within the UML Radiation Laboratory. The primary focus of all this work was to establish the proof of concept of the basic gammavoltaic principle using a new class of dye-sensitized photon converter (DSPC) materials based on KTI's original DSSC design. In achieving this goal, this report clearly establishes the viability of the basic gammavoltaic energy conversion concept, yet it also identifies a set of challenges that must be met for practical implementation of this new technology.

  16. Chemistry of Energy Conversion and Storage.

    PubMed

    Su, Dang-Sheng; Schlögl, R

    2016-02-01

    Special Issue: Energy Conversion and Storage. Critical issues in current energy-based societies are its generation through methods utilizing alternatives to fossil fuels as well as its storage. Considering the scope, it is not surprising that the research becomes more and more multidisciplinary. Therefore, it is important to keep focused. The ChemEner symposia, the last one being highlighted in this Special Issue, achieve this by focusing on the state of the art and the newest development of the Chemistry of hydrogen generation, carbon dioxide reduction, and other related topics, exploring new concepts for clean future energy. PMID:26914171

  17. Thermal to electricity conversion using thermal magnetic properties

    DOEpatents

    West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

    2010-04-27

    A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

  18. Stimulation of technologies towards photovoltaic energy conversion

    NASA Astrophysics Data System (ADS)

    Jacobs, K.

    1983-09-01

    The utilization of technologies for photovoltaic energy conversion is discussed. The German Federal Ministry of Research and Technology plans to support industries working in the field of photovoltaic applications, with emphasis on cheaper production of solar cell generators based on crystalline silicon. Development aims include cost reduction in the production of polycrystalline silicon and production techniques for monocrystalline silicon; cheap production methods for solar cells with high reproducibility; and reliable shielding of generator modules against weather effects.

  19. Small scale wind energy conversion programmatic equipment

    NASA Astrophysics Data System (ADS)

    Wegman, S.

    1985-05-01

    The purpose of this project is to provide South Dakota citizens with a case study of the institutional and technical problems encountered in the installation, maintenance and use of a small wind energy system. The project will provide information on wind turbine reliability, maintenance requirements and power production to demonstrate the feasibility of small-scale wind energy conversion projects for South Dakota. The system was installed by vocational students and instructors at Mitchell Vocational School. It has been in operation since the fall of 1983.

  20. Bio-Inspired Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Warncke, Kurt

    2009-11-01

    The areas of solar-powered catalysts for energy rich fuels formation and bio-inspired molecular assemblies for integrating photon-to-fuels pathways have been identified by the Office of Basic Energy Sciences of the U. S. Department of Energy as challenges for the next generation of sustainable, high-efficiency solar energy conversion systems [1]. The light-harvesting, energy-transducing and carbon compound-synthesizing (carbon dioxide-fixing) reactions that are encompassed by natural photosynthesis offer molecular paradigms for efficient free energy capture and storage. We seek to emulate these features in cell-free, protein-based systems. Our goal is to transform the robust (alpha,beta)8-barrel fold of an enzyme that naturally catalyzes radical reactions into a catalytic module for the reduction of carbon dioxide to formate, by using the cobalt-containing cobalamins and other organocobalt centers. The activation of the catalytic center will be driven by photo-reduction, by using soluble and attached organic or semiconductor architectures. Progress on the biochemical, chemical, physical, and molecular biological (including rational design of high binding affinity and reactivity towards carbon dioxide) approaches to the development of the photocatalytic system will be presented.[4pt] [1] Lewis, N.; Crabtree, G. In: Basic Research Needs for Solar Energy Utilization, Basic Energy Sciences Workshop on Solar Energy Utilization, Energy, U.S. Department of Energy, Office of Science: 2005.

  1. Oriented Nanostructures for Energy Conversion and Storage

    SciTech Connect

    Liu, Jun; Cao, Guozhong H.; Yang, Zhenguo; Wang, Donghai; DuBois, Daniel L.; Zhou, Xiao Dong; Graff, Gordon L.; Pederson, Larry R.; Zhang, Jiguang

    2008-08-28

    Recently the role of nanostructured materials in addressing the challenges in energy and natural resources has attracted wide attention. In particular, oriented nanostructures have demonstrated promising properties for energy harvesting, conversion and storage. The purpose of the paper is to review the synthesis and application of oriented nanostructures in a few key areas of energy technologies, namely photovoltaics, batteries, supercapacitors and thermoelectrics. Although the applications differ from field to field, one of the fundamental challenges is to improve the generation and transport of electrons and ions. We will first briefly review the several major approaches to attain oriented nanostructured films that are applicable for energy applications. We will then discuss how such controlled nanostructures can be used in photovoltaics, batteries, capacitors, thermoelectrics, and other unconventional ways of energy conversion. We will highlight the role of high surface area to maximize the surface activity, and the importance of optimum dimension and architecture, controlled pore channels and alignment of the nanocrystalline phase to optimize the electrons and ion transport. Finally, the paper will discuss the challenges in attaining integrated architectures to achieve the desired performance. Brief background information will be provided for the relevant technologies, but the emphasis is focused mainly on the nanoeffects of mostly inorganic based materials and devices.

  2. Innovative oxide materials for electrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Wachsman, Eric D.

    2012-02-01

    Research in functional materials has progressed from those materials exhibiting structural to electronic functionality. The study of ion conducting ceramics ushers in a new era of ``chemically functional materials.'' This chemical functionality arises out of the defect equilibria of these materials, and results in the ability to transport chemical species and actively participate in chemical reactions at their surface. Moreover, this chemical functionality provides a promise for the future whereby the harnessing of our natural hydrocarbon energy resources can shift from inefficient and polluting combustion - mechanical methods to direct electrochemical conversion. The unique properties of these materials and their applications will be described. The focus will be on the application of ion conducting ceramics to energy conversion and storage, chemical sensors, chemical separation and conversion, and life support systems. Results presented will include development of record high power density (3 kW/kg) solid oxide fuel cells, NOx/CO species selective solid-state sensors, high yield membrane reactors, and regenerative life support systems that reduce CO2 to O2 and solid C.

  3. Thermophotovoltaic Energy Conversion for Space Applications

    NASA Astrophysics Data System (ADS)

    Teofilo, V. L.; Choong, P.; Chen, W.; Chang, J.; Tseng, Y.-L.

    2006-01-01

    Thermophotovoltaic (TPV) energy conversion cells have made steady and over the years considerable progress since first evaluated by Lockheed Martin for direct conversion using nuclear power sources in the mid 1980s. The design trades and evaluations for application to the early defensive missile satellites of the Strategic Defense Initiative found the cell technology to be immature with unacceptably low cell efficiencies comparable to thermoelectric of <10%. Rapid advances in the epitaxial growth technology for ternary compound semiconductors, novel double hetero-structure junctions, innovative monolithic integrated cell architecture, and bandpass tandem filter have, in concert, significantly improved cell efficiencies to 25% with the promise of 35% using solar cell like multi-junction approach in the near future. Recent NASA sponsored design and feasibility testing programs have demonstrated the potential for 19% system efficiency for 100 We radioisotopic power sources at an integrated specific power of ~14 We/kg. Current state of TPV cell technology however limits the operating temperature of the converter cells to < 400K due to radiator mass consideration. This limitation imposes no system mass penalty for the low power application for use with radioisotopes power sources because of the high specific power of the TPV cell converters. However, the application of TPV energy conversion for high power sources has been perceived as having a major impediment above 1 kWe due to the relative low waste heat rejection temperature. We explore this limitation and compare the integrated specific power of TPV converters with current and projected TPV cells with other advanced space power conversion technologies. We find that when the redundancy needed required for extended space exploration missions is considered, the TPV converters have a much higher range of applicability then previously understood. Furthermore, we believe that with a relatively modest modifications of the current epitaxial growth in MOCVD, an optimal cell architecture for elevated TPV operation can be found to out-perform the state-of-the-art TPV at an elevated temperature.

  4. Nanoscale Materials and Architectures for Energy Conversion

    SciTech Connect

    Grulke, Eric A.; Sunkara, Mahendra K.

    2011-05-25

    The Kentucky EPSCoR Program supported an inter-university, multidisciplinary energy-related research cluster studying nanomaterials for converting solar radiation and residual thermal energy to electrical energy and hydrogen. It created a collaborative center of excellence based on research expertise in nanomaterials, architectures, and their synthesis. The project strengthened and improved the collaboration between the University of Louisville, the University of Kentucky, and NREL. The cluster hired a new faculty member for ultra-fast transient spectroscopy, and enabled the mentoring of one research scientist, two postdoctoral scholars and ten graduate students. Work was accomplished with three focused cluster projects: organic and photoelectrochemical solar cells, solar fuels, and thermionic energy conversion.

  5. Ocean energy conversion systems annual research report

    SciTech Connect

    Not Available

    1981-03-01

    Alternative power cycle concepts to the closed-cycle Rankine are evaluated and those that show potential for delivering power in a cost-effective and environmentally acceptable fashion are explored. Concepts are classified according to the ocean energy resource: thermal, waves, currents, and salinity gradient. Research projects have been funded and reported in each of these areas. The lift of seawater entrained in a vertical steam flow can provide potential energy for a conventional hydraulic turbine conversion system. Quantification of the process and assessment of potential costs must be completed to support concept evaluation. Exploratory development is being completed in thermoelectricity and 2-phase nozzles for other thermal concepts. Wave energy concepts are being evaluated by analysis and model testing with present emphasis on pneumatic turbines and wave focussing. Likewise, several conversion approaches to ocean current energy are being evaluated. The use of salinity resources requires further research in membranes or the development of membraneless processes. Using the thermal resource in a Claude cycle process as a power converter is promising, and a program of R and D and subsystem development has been initiated to provide confirmation of the preliminary conclusion.

  6. Energy transfer processes in solar energy conversion

    SciTech Connect

    Fayer, M.D.

    1989-11-01

    We have made substantial progress in experimental and theoretical studies in two areas: Photoinduced donor to acceptor electron transfer followed by back transfer in random solutions; and electronic excitation transport in systems with complex inhomogeneous spatial geometries and inhomogeneous energy distributions. Through the development of accurate statistical mechanical theories, we have been able to relate dynamics in complex systems to experimental observables. We have then used the experimental observables, time resolved fluorescence depolarization and transient grating experiments, to examine well defined molecular systems. The agreement between theory and experiment is excellent. 11 refs.

  7. Energy transfer processes in solar energy conversion

    SciTech Connect

    Fayer, M.D.

    1986-11-01

    By combining picosecond optical experiments and detailed statistical mechanics theory we continue to increase our understanding of the complex interplay of structure and dynamics in important energy transfer situations. A number of different types of problems will be focused on experimentally and theoretically. They are excitation transport among chromophores attached to finite size polymer coils; excitation transport among chromophores in monolayers, bilayers, and finite and infinite stacks of layers; excitation transport in large vesicle systems; and photoinduced electron transfer in glasses and liquids, focusing particularly on the back transfer of the electron from the photogenerated radical anion to the radical cation. 33 refs., 13 figs.

  8. Openggcm Simulations of Energy Conversion in Dipolarization Fronts

    NASA Astrophysics Data System (ADS)

    Raeder, J.; Cramer, W. D.; Germaschewski, K.; Ge, Y.

    2014-12-01

    Over the past few years results from the THEMIS mission have shown thatBursty Bulk Flows (BBFs) and the associated Dipolarization Fronts (DFs)are ubiquitous features of the tail plasma sheet. They also play a major rolein the transport of energy, plasma, and magnetic flux. However, their rolein converting energy is not entirely clear. DFs have been implicated as significant electromagnetic energy dissipation sites, thus competing with reconnection as a major energy conversion process.In this presentation we use global OpenGGCM simulations to assess the role that BBFs and DFs play in theenergy and entropy budget of the tail, and the relative importance of dissipationat DFs versus dissipation at reconnection sites.

  9. Energy conversion device with improved seal

    DOEpatents

    Miller, Gerald R. (Salt Lake City, UT); Virkar, Anil V. (Midvale, UT)

    1980-01-01

    An energy conversion device comprising an improved sealing member adapted to seal a cation-permeable casing to the remainder of the device. The sealing member comprises a metal substrate which (i) bears a nonconductive and corrosion resistant coating on the major surface to which said casing is sealed, and (ii) is corrugated so as to render it flexible, thereby allowing said member to move relative to said casing without cracking the seal therebetween. Corrugations may be circumferential, radial, or both radial and circumferential so as to form dimples. The corrugated member may be in form of a bellows or in a substantially flat form, such as a disc.

  10. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

    1997-02-11

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

  11. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  12. Parametric energy conversion of thermoacoustic vibrations

    NASA Astrophysics Data System (ADS)

    Guthy, C.; Van Neste, C. W.; Mitra, S.; Bhattacharjee, S.; Thundat, T.

    2012-05-01

    We demonstrate a parametric energy conversion method of thermoacoustic (TA) vibrations into electrical oscillations of a LC circuit. The inductance modulation necessary to excite the parametric oscillations is achieved by varying the air gap between two halves of a ferrite E-core coil. As a proof-of-concept, the parametric converter was attached to a Sondhauss tube that converts the heat into acoustic vibrations. The maximum total acoustic power output of this thermoacoustic engine was 5.3 mW. A flexible metallic membrane capping the Sondhauss tube connected to the moving half E-core served as a mechanical oscillator. The resonance frequency of the membrane was matched with the operating frequency (130 Hz) of the Sondhauss tube for resonant energy extraction. We have characterized the power output of the complete system as a function of electrical load. The maximum electrical power of 2.3 mW produced by the system corresponds to an acoustic-to-electric conversion efficiency of 44%.

  13. Nanoengineered Surfaces for Thermal Energy Conversion

    NASA Astrophysics Data System (ADS)

    Bhatia, Bikram; Preston, Daniel J.; Bierman, David M.; Miljkovic, Nenad; Lenert, Andrej; Enright, Ryan; Nam, Youngsuk; Lopez, Ken; Dou, Nicholas; Sack, Jean; Chan, Walker R.; Celanović, Ivan; Soljačić, Marin; Wang, Evelyn N.

    2015-12-01

    We provide an overview of the impact of using nanostructured surfaces to improve the performance of solar thermophotovoltaic (STPV) energy conversion and condensation systems. We demonstrated STPV system efficiencies of up to 3.2%, compared to ≤1% reported in the literature, made possible by nanophotonic engineering of the absorber and emitter. For condensation systems, we showed enhanced performance by using scalable superhydrophobic nanostructures via jumping-droplet condensation. Furthermore, we observed that these jumping droplets carry a residual charge which causes the droplets to repel each other mid-flight. Based on this finding of droplet residual charge, we demonstrated electric-field-enhanced condensation and jumping-droplet electrostatic energy harvesting.

  14. OCEAN THERMAL ENERGY CONVERSION PROGRAMMATIC ENVIRONMENTAL ASSESSMENT

    SciTech Connect

    Sands, M.Dale

    1980-08-01

    Significant achievements in Ocean Thermal Energy Conversion (OTEC) technology have increased the probability of producing OTEC-derived power in this decade with subsequent large-scale commercialization to follow by the turn of the century. Under U.S. Department of Energy funding, Interstate Electronics has prepared an OTEC Programmatic Environmental Assessment (EA) that considers tne development, demonstration, and commercialization of OTEC power systems. The EA considers several tecnnological designs (open cycle and closed cycle), plant configurations (land-based, moored, and plantship), and power usages (baseload electricity and production of ammonia and aluminum). Potencial environmental impacts, health and safety issues, and a status update of international, federal, and state plans and policies, as they may influence OTEC deployments, are included.

  15. Black metallurgical silicon for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Li, Xiaopeng; Lee, Jung-Ho; Sprafke, Alexander N.; Wehrspohn, Ralf B.

    2016-01-01

    Metal impurities are known to create deep traps in the silicon (Si) bandgap, significantly reducing the minority carrier lifetime and consequently deteriorating the efficiency of a Si-based solar conversion system. Traditional purification methods via ‘Siemens’ and metallurgical routes involve complex and energy-intensive processes. Therefore, it is highly desirable to develop novel Si treatment technologies. With the radical evolution of nanotechnology in the past decades, new nano-approaches are offering opportunities to diminish the detrimental impacts of metal impurities or upgrade low quality Si in a cost-effective and energy-saving way. Here we review various recently developed dry and wet chemical etching methods including reactive ion etching, electrochemical etching, stain etching and metal assisted chemical etching. The current progress and the application prospects of those methods in nanostructure creation and Si upgrading are given and discussed in detail.

  16. Recycling of Wasted Energy: Thermal to Electrical Energy Conversion

    NASA Astrophysics Data System (ADS)

    Lim, Hyuck

    Harvesting useful electric energy from ambient thermal gradients and/or temperature fluctuations is immensely important. For many years, a number of direct and indirect thermal-to-electrical energy conversion technologies have been developed. Typically, direct energy conversion is achieved by using thermoelectric generators or thermogalvanic cells; indirect energy conversion is achieved by using Organic Rankine Cycle or Sterling Engines. On the one hand, there is a fundamental technical difficulty, thermal shorting, that limits the energy conversion efficiency of direct thermoelectric energy conversion methods. While extensive study has been conducted in this area, currently the portion of thermal energy that can be converted to electricity is still small. On the other hand, the indirect energy conversion systems tend to be complicated and expensive. Thus, existing energy harvesting technologies are less economically competitive compared with the grid power. To develop advanced energy harvesting systems, a novel concept using nanoporous materials is investigated. Nanoporous materials have been widely used as advanced absorbents. Because of their ultra-large surface areas (100--2000 m2/g), they can adsorb a large amount of ions when they are immersed in electrolyte solutions. The ion adsorption capacity is thermally dependent. If two nanoporous electrodes are placed at different temperatures, they adsorb different amounts of ions, generating a net output voltage. The thermally driven ion motion causes a transient current, which can be reactivated through temperature fluctuation or internal grounding. The two electrodes are isolated; that is, the direct heat loss between them is minimized. Our experimental data have shown encouraging results: the output voltage and the energy conversion efficiency are higher than that of conventional thermoelectric materials by orders of magnitude. Our study will not only lead to the development of high-performance thermal energy harvesting systems, but also shed light on fundamentals of electrophysics in nanoenvironment. The thermal effect on surface electrification (i.e. the capacitive effect) in nanopores is a new scientific area. Conventional interface theories have failed in explaining a number of experimental observations. We have carried out a systematic study of the effects of ions, solvent, electrode, cell configuration, etc. to understand the fundamental mechanisms and processes that govern the ion motion and charge transfer in nanopores.

  17. Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion

    NASA Astrophysics Data System (ADS)

    Khan, Farid Ullah; Izhar

    2016-02-01

    This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester.

  18. Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion.

    PubMed

    Khan, Farid Ullah; Izhar

    2016-02-01

    This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester. PMID:26931884

  19. Nanoscale Fluid Mechanics and Energy Conversion

    SciTech Connect

    Chen, X; Xu, BX; Liu, L

    2014-05-29

    Under nanoconfinement, fluid molecules and ions exhibit radically different configurations, properties, and energetics from those of their bulk counterparts. These unique characteristics of nanoconfined fluids, along with the unconventional interactions with solids at the nanoscale, have provided many opportunities for engineering innovation. With properly designed nanoconfinement, several nanofluidic systems have been devised in our group in the past several years to achieve energy conversion functions with high efficiencies. This review is dedicated to elucidating the unique characteristics of nanofluidics, introducing several novel nanofluidic systems combining nanoporous materials with functional fluids, and to unveiling their working mechanisms. In all these systems, the ultra-large surface area available in nanoporous materials provides an ideal platform for seamlessly interfacing with nanoconfined fluids, and efficiently converting energy between the mechanical, thermal, and electrical forms. These systems have been demonstrated to have great potentials for applications including energy dissipation/absorption, energy trapping, actuation, and energy harvesting. Their efficiencies can be further enhanced by designing efforts based upon improved understanding of nanofluidics, which represents an important addition to classical fluid mechanics. Through the few systems exemplified in this review, the emerging research field of nanoscale fluid mechanics may promote more exciting nanofluidic phenomena and mechanisms, with increasing applications by encompassing aspects of mechanics, materials, physics, chemistry, biology, etc.

  20. Technology assessment of wind energy conversion systems

    SciTech Connect

    Meier, B. W.; Merson, T. J.

    1980-09-01

    Environmental data for wind energy conversion systems (WECSs) have been generated in support of the Technology Assessment of Solar Energy (TASE) program. Two candidates have been chosen to characterize the WECS that might be deployed if this technology makes a significant contribution to the national energy requirements. One WECS is a large machine of 1.5-MW-rated capacity that can be used by utilities. The other WECS is a small machine that is characteristic of units that might be used to meet residential or small business energy requirements. Energy storage systems are discussed for each machine to address the intermittent nature of wind power. Many types of WECSs are being studied and a brief review of the technology is included to give background for choosing horizontal axis designs for this study. Cost estimates have been made for both large and small systems as required for input to the Strategic Environmental Assessment Simulation (SEAS) computer program. Material requirements, based on current generation WECSs, are discussed and a general discussion of environmental impacts associated with WECS deployment is presented.

  1. Photothermal energy conversion by plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Cole, Joseph Raymond

    Photothermal energy conversion is important when designing optically active devices based on plasmonic nanoparticles. Many early applications of these nanoparticles, like photothermal tumor ablation, drug delivery, and microfluidic devices, depend on the conversion of light to heat. In this dissertation, we compare three nanoparticle species' theoretical absorption efficiency from electromagnetic calculations with their photothermal transduction efficiency from measurements of temperature in an illuminated system. Several mechanisms that may account for differences between the two efficiencies are suggested. With a view specifically toward clinical applications, our analysis assumes a random orientation of nanorods, as would occur naturally in the tumor vasculature. For the samples studied here, photothermal transduction efficiencies differed only by a factor of two or three, regardless of particle type and concentration. Both experiment and theory show that particle size plays a dominant role in determining transduction efficiency, with smaller particles more efficient for heating and larger particles for combined heating and imaging. Additionally, we evaluate the potential of mixtures of plasmonic nanoparticles for CO 2 scrubbing substrates that could be used in space applications. These measurements indicate possible dynamic nanoscale effects that need to be accounted for when modeling photothermal transduction.

  2. Systems issues in antimatter energy conversion

    NASA Astrophysics Data System (ADS)

    Nordley, Gerald D.

    Use of antimatter as a lightweight and or highly compact energy source may someday be potentially attractive where nuclear energy, for one reason or another, is not a viable option. Propulsive energy storage has received the most attention to date, but other applications may exist. Consideration of the external radiation level results in a set of system trades between safety, efficiency, mass, and power. In 'solid core' converters, exhaust temperature is limited by the converter materials; efficiency decreases slowly and radiation safety decreases sharply with as mass decreases. In systems using magnetic containment of charged annihilation products to further heat the exhaust, there is a trade between efficiency and exhaust velocity. In both cases, lower efficiency implies an increased radiation hazard. Fully shielded converters may be considered for earth to orbit, ground based, and orbital use. Partially shielded converters may be used with care in orbit, having to move further away as exhaust velocity increases.

  3. Engineered nanomaterials for solar energy conversion.

    PubMed

    Mlinar, Vladan

    2013-02-01

    Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for the conversion of solar energy to electricity are those exploiting the particle nature of light in conventional photovoltaic cells, and those using the collective electromagnetic nature, where light is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial components. Examples include arrays of semiconductor nanostructures as an intermediate band (so called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation, or, in antenna-rectifier cells, nanomaterials for effective optical frequency rectification. Here, we discuss the state of the art in p-n junction, intermediate band, multiple exciton generation, and antenna-rectifier solar cells. We provide a summary of how engineered nanomaterials have been used in these systems and a discussion of the open questions. PMID:23298882

  4. Modeling and analysis of energy conversion systems

    SciTech Connect

    Den Braven, K.R. . Dept. of Mechanical Engineering); Stanger, S. )

    1990-10-01

    An investigation was conducted to assess the need for and the feasibility of developing a computer code that could model thermodynamic systems and predict the performance of energy conversion systems. To assess the market need for this code, representatives of a few industrial organizations were contacted, including manufacturers, system and component designers, and research personnel. Researchers and small manufacturers, designers, and installers were very interested in the possibility of using the proposed code. However, large companies were satisfied with the existing codes that they have developed for their own use. Also, a survey was conduced of available codes that could be used or possibly modified for the desired purpose. The codes were evaluated with respect to a list of desirable features, which was prepared as a result of the survey. A few publicly available codes were found that might be suitable. The development, verification, and maintenance of such a code would require a substantial, ongoing effort. 21 refs.

  5. Hierarchically Structured Nanomaterials for Electrochemical Energy Conversion.

    PubMed

    Trogadas, Panagiotis; Ramani, Vijay; Strasser, Peter; Fuller, Thomas F; Coppens, Marc-Olivier

    2016-01-01

    Hierarchical nanomaterials are highly suitable as electrocatalysts and electrocatalyst supports in electrochemical energy conversion devices. The intrinsic kinetics of an electrocatalyst are associated with the nanostructure of the active phase and the support, while the overall properties are also affected by the mesostructure. Therefore, both structures need to be controlled. A comparative state-of-the-art review of catalysts and supports is provided along with detailed synthesis methods. To further improve the design of these hierarchical nanomaterials, in-depth research on the effect of materials architecture on reaction and transport kinetics is necessary. Inspiration can be derived from nature, which is full of very effective hierarchical structures. Developing fundamental understanding of how desired properties of biological systems are related to their hierarchical architecture can guide the development of novel catalytic nanomaterials and nature-inspired electrochemical devices. PMID:26549054

  6. Stretchable energy storage and conversion devices.

    PubMed

    Yan, Chaoyi; Lee, Pooi See

    2014-09-10

    Stretchable electronics are a type of mechanically robust electronics which can be bended, folded, crumpled and stretched and represent the emerging direction towards next-generation wearable and implantable devices. Unlike existing electronics based on rigid Si technologies, stretchable devices can conform to the complex non-coplanar surfaces and provide unique functionalities which are unreachable with simple extension of conventional technologies. Stretchable energy storage and conversion devices are the key components for the fabrication of complete and independent stretchable systems. In this review, we present the recent progresses in the developments of stretchable power sources including supercapacitors, batteries and solar cells. Representative structural and material designs to impart stretchability to the originally rigid devices are discussed. Advantages and drawbacks associated with the fabrication methods are also analysed. Summaries of the research progresses along with future development directions for this exciting field are also presented. PMID:25340184

  7. Stochastic conversions of TeV photons into axion-like particles in extragalactic magnetic fields

    SciTech Connect

    Mirizzi, Alessandro; Montanino, Daniele E-mail: daniele.montanino@le.infn.it

    2009-12-01

    Very-high energy photons emitted by distant cosmic sources are absorbed on the extragalactic background light (EBL) during their propagation. This effect can be characterized in terms of a photon transfer function at Earth. The presence of extragalactic magnetic fields could also induce conversions between very high-energy photons and hypothetical axion-like particles (ALPs). The turbulent structure of the extragalactic magnetic fields would produce a stochastic behaviour in these conversions, leading to a statistical distribution of the photon transfer functions for the different realizations of the random magnetic fields. To characterize this effect, we derive new equations to calculate the mean and the variance of this distribution. We find that, in presence of ALP conversions, the photon transfer functions on different lines of sight could have relevant deviations with respect to the mean value, producing both an enhancement or a suppression in the observable photon flux with respect to the expectations with only absorption. As a consequence, the most striking signature of the mixing with ALPs would be a reconstructed EBL density from TeV photon observations which appears to vary over different directions of the sky: consistent with standard expectations in some regions, but inconsistent in others.

  8. Direct energy conversion using liquid metals

    NASA Astrophysics Data System (ADS)

    Onea, Alexandru; Diez de los Rios Ramos, Nerea; Hering, Wolfgang; Stieglitz, Robert; Moster, Peter

    2014-12-01

    Liquid metals have excellent properties to be used as heat transport fluids due to their high thermal conductivity and their wide applicable temperature range. The latter issue can be used to go beyond limitations of existing thermal solar energy systems. Furthermore, the direct energy converter Alkali Metal Thermo Electric Converter (AMTEC) can be used to make intangible areas of energy conversion suitable for a wide range of applications. One objective is to investigate AMTEC as a complementary cycle for the next generation of concentrating solar power (CSP) systems. The experimental research taking place in the Karlsruhe Institute of Technology (KIT) is focused on the construction of a flexible AMTEC test facility, development, test and improvement of liquid-anode and vapor-anode AMTEC devices as well as the coupling of the AMTEC cold side to the heat storage tank proposed for the CSP system. Within this project, the investigations foreseen will focus on the analyses of BASE-metal interface, electrode materials and deposition techniques, corrosion and erosion of materials brought in contact with high temperature sodium. This prototype demonstrator is planned to be integrated in the KArlsruhe SOdium LAboratory (KASOLA), a flexible closed mid-size sodium loop, completely in-house designed, presently under construction at the Institute for Neutron Physics and Reactor Technology (INR) within KIT.

  9. Progress on PEP-II magnet power conversion system

    SciTech Connect

    Bellomo, P.; Genova, L.; Jackson, T.; Shimer, D.

    1996-06-04

    The various power systems for supplying the PEP-II DC magnets rely exclusively on switchmode conversion, utilizing a variety of means depending on the requirements. All of the larger power supplies, ranging from 10 to 200 kW, are powered from DC sources utilizing rectified 480 V AC. Choppers can be used for the series connected strings, but for smaller groups and individual magnets, inverters driving high-frequency transformers with rectifiers comprise the best approach. All of the various systems use a ``building block`` approach of multiple standard-size units connected in series or parallel to most cost-effectively deal with a great range of voltage and current requirements. Utilization of existing infrastructure from PEP-I has been a cost-effective determinant. Equipment is being purchased either off-the-shelf, through performance specification, or by hardware purchase based on design-through-prototype. The corrector magnet power system, utilizing inexpensive, off-the-shelf, four-quadrant switching motor-controllers, has already proven very reliable: 120 of the total of 900 units have been running on the injection system for four months with no failures.

  10. Axial inlet conversion to a centrifugal compressor with magnetic bearings

    SciTech Connect

    Novecosky, T. )

    1994-01-01

    NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

  11. Theoretical efficiency limits for thermoradiative energy conversion

    SciTech Connect

    Strandberg, Rune

    2015-02-07

    A new method to produce electricity from heat called thermoradiative energy conversion is analyzed. The method is based on sustaining a difference in the chemical potential for electron populations above and below an energy gap and let this difference drive a current through an electric circuit. The difference in chemical potential originates from an imbalance in the excitation and de-excitation of electrons across the energy gap. The method has similarities to thermophotovoltaics and conventional photovoltaics. While photovoltaic cells absorb thermal radiation from a body with higher temperature than the cell itself, thermoradiative cells are hot during operation and emit a net outflow of photons to colder surroundings. A thermoradiative cell with an energy gap of 0.25?eV at a temperature of 500?K in surroundings at 300?K is found to have a theoretical efficiency limit of 33.2%. For a high-temperature thermoradiative cell with an energy gap of 0.4?eV, a theoretical efficiency close to 50% is found while the cell produces 1000?W/m{sup 2} has a temperature of 1000?K and is placed in surroundings with a temperature of 300?K. Some aspects related to the practical implementation of the concept are discussed and some challenges are addressed. It is, for example, obvious that there is an upper boundary for the temperature under which solid state devices can work properly over time. No conclusions are drawn with regard to such practical boundaries, because the work is aimed at establishing upper limits for ideal thermoradiative devices.

  12. Soft Magnetic Materials for Improved Energy Performance

    NASA Astrophysics Data System (ADS)

    Willard, Matthew

    2012-02-01

    A main focus of sustainable energy research has been development of renewable energy technologies (e.g. from wind, solar, hydro, geothermal, etc.) to decrease our dependence on non-renewable energy resources (e.g. fossil fuels). By focusing on renewable energy sources now, we hope to provide enough energy resources for future generations. In parallel with this focus, it is essential to develop technologies that improve the efficiency of energy production, distribution, and consumption, to get the most from these renewable resources. Soft magnetic materials play a central role in power generation, conditioning, and conversion technologies and therefore promoting improvements in the efficiency of these materials is essential for our future energy needs. The losses generated by the magnetic core materials by hysteretic, acoustic, and/or eddy currents have a great impact on efficiency. A survey of soft magnetic materials for energy applications will be discussed with a focus on improvement in performance using novel soft magnetic materials designed for these power applications. A group of premiere soft magnetic materials -- nanocrystalline soft magnetic alloys -- will be highlighted for their potential in addressing energy efficiency. These materials are made up of nanocrystalline magnetic transition metal-rich grains embedded within an intergranular amorphous matrix, obtained by partial devitrification of melt-spun amorphous ribbons. The nanoscale grain size results in a desirable combination of large saturation induction, low coercivity, and moderate resistivity unobtainable in conventional soft magnetic alloys. The random distribution of these fine grains causes a reduction in the net magnetocrystalline anisotropy, contributing to the excellent magnetic properties. Recently developed (Fe,Co,Ni)88Zr7B4Cu1 alloys will be discussed with a focus on the microstructure/magnetic property relationship and their effects on the energy efficiency of these materials for AC applications.

  13. Evidence of the theoretically predicted seismo-magnetic conversion

    NASA Astrophysics Data System (ADS)

    Bordes, Clarisse; Jouniaux, Laurence; Garambois, Stphane; Dietrich, Michel; Pozzi, Jean-Pierre; Gaffet, Stphane

    2008-08-01

    Seismo-electromagnetic phenomena in porous media arise from seismic wave-induced fluid motion in the pore space, which perturbs the equilibrium of the electric double layer. This paper describes with details the original experimental apparatus built within the ultra-shielded chamber of the Low Noise Underground Laboratory of Rustrel (France). We measured seismo-magnetic conversions in moist sand using two induction magnetometers, and a pneumatic seismic source to generate the seismic wave propagation. We ensured to avoid the magnetometer vibrations, which could induce strong disturbances from induction origin. Interpretation of the data is improved by an analytical description of phase velocities for fast (Pf) and slow (Ps) longitudinal modes, transverse mode (S) as well as the extensional mode due to the cylindrical geometry of the sample. The purpose of this paper is to provide elements to measure correctly coseismic seismomagnetic fields and to specify their amplitude. The seismic arrivals recorded in the sample showing a 1200-1300ms-1 velocity have been associated to P and extensional waves. The measured seismo-magnetic arrivals show a velocity of about 800ms-1 close to the calculated phase velocity of S waves. Therefore, we show that the seismo-magnetic field is associated to the transverse part of the propagation, as theoretically predicted by Pride (1994), but never measured up to now. Moreover, the combined experimental and analytical approaches lead us to the conclusion that the measured seismo-magnetic field is probably about 0.035nT for a 1ms-2 seismic source acceleration (0.1g).

  14. Photonic Crystals for Enhancing Thermophotovoltaic Energy Conversion

    SciTech Connect

    LIN, SHAWN-YU; FLEMING, JAMES G.; MORENO, JOSEPH A.

    2003-03-01

    Thermophotovoltaics (TPV) converts the radiant energy of a thermal source into electrical energy using photovoltaic cells. TPV has a number of attractive features, including: fuel versatility (nuclear, fossil, solar, etc.), quiet operation, low maintenance, low emissions, light weight, high power density, modularity, and possibility for cogeneration of heat and electricity. Some of these features are highly attractive for military applications (Navy and Army). TPV could also be used for distributed power and automotive applications wherever fuel cells, microturbines, or cogeneration are presently being considered if the efficiencies could be raised to around 30%. This proposal primarily examine approaches to improving the radiative efficiency. The ideal irradiance for the PV cell is monochromatic illumination at the bandgap. The photonic crystal approach allows for the tailoring of thermal emission spectral bandwidth at specific wavelengths of interest. The experimental realization of metallic photonic crystal structures, the optical transmission, reflection and absorption characterization of it have all been carried out in detail and will be presented next. Additionally, comprehensive models of TPV conversion has been developed and applied to the metallic photonic crystal system.

  15. Status of thermoelectronic laser energy conversion, TELEC

    NASA Technical Reports Server (NTRS)

    Britt, E. J.

    1982-01-01

    A concept known as a thermo-electronic laser energy converter (TELEC), was studied as a method of converting a 10.6 micron CO2 laser beam into electric power. The calculated characteristics of a TELEC seem to be well matched to the requirements of a spacecraft laser energy conversion system. The TELEC is a high power density plasma device which absorbs an intense laser beam by inverse bremsstrahlung with the plasma electrons. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes which are in contact with the plasma at the boundaries. These two electrodes have different areas: the larger one is designated as the collector, the smaller one is designated as the emitter. The smaller electrode functions as an electron emitter provide continuity of the current. Waste heat is rejected from the collector electrode. An experiment was carried out with a high power laser using a cesium vapor TELEC cell with 30 cm active length. Laser supported plasma were produced in the TELEC device during a number of laser runs over a period of several days. Electric power from the TELEC was observed with currents in the range of several amperes and output potentials of less than 1 volt.

  16. Science of Nanofluidics and Energy Conversion

    NASA Astrophysics Data System (ADS)

    Xu, Baoxing

    The emerging subject of nanofluidics, where solids and fluids interact closely at the nanoscale, has exhibited radically different from their macroscopic counterparts (and sometimes counterintuitive), and yet relatively less explored. On the other hand, the resulting unique properties may contribute to a number of innovative functions with fascinating applications. Among various exciting potential applications, an important and ever expanding one is to provide alternative solutions to energy conversion with high efficiency, including energy absorption, actuation and harvesting. In this dissertation, we first report a novel protection mechanism of energy capture through which an intensive impact or blast energy can be effectively mitigated based on a nonwetting liquid-nanoporous material system. The captured energy is stored in nanopores in the form of potential energy of intercalated water molecules for a while, and not necessarily converted to other forms of energy (e.g. heat). At unloading stage, the captured energy will be released gradually due to the hydrophobic inner surfaces of nanopores through the diffusion of water molecules out of nanopores, thus making this system reusable. Several key controlling factors including impacting velocity, nanopore size, nanopore structure, and liquid phase have been investigated on the capacity of energy capture. The molecular mechanism is elucidated through the study of water molecular distributions inside nanpores. These molecular dynamic (MD) findings are quantitatively verified by a parallel blast experiment on a zeolite/water system. During the transport of confined liquid molecules, the friction resistance exerted by solid atoms of nanopores to liquid molecules will dissipate part of energy, and is highly dependent of temperature of liquid molecules and wall morphology of nanopores. Using MD simulations, the effects of temperature and wall roughness on the transport resistance of water molecules inside nanopores are investigated in Chapter 3. The effective shear stress and nominal viscosity that dominate the nanofluidic transport resistance are extracted and coupled with the nanopore size, transport rate, and liquid property. The molecular-level mechanisms are revealed through the study of the density profile and hydrogen bonding of confined liquid molecules. A parallel experiment on a nanoporous carbon-liquid system is carried out and qualitatively verifies MD findings. Motived by the well-known thermo- and electro-capillary effect, Chapter 4 and Chapter 5 present a conceptual design of thermal and electric actuation system by adjusting the relative hydrophobicity of a liquid-nanoporous system through a thermal and electric field, respectively. The thermally and electrically dependent infiltration behaviors of liquids into nanopores are analyzed by using MD simulations. The fundamental molecular characteristics, including the density profile, contact angle, and surface tension of the confined liquid molecules, are examined to reveal underlying mechanisms. The energy density, power density, and efficiency of both thermal and electric actuation systems are explored and their variations with pore size, solid phase, and liquid phase are evaluated. Thermally and electrically controlled infiltration experiments on a zeolite-water /electrolyte solution system are performed accordingly to qualitatively validate these findings. These energy actuation systems can also become high density thermal or electric storage devices with proper designs. Energy harvesting by the flow of a hydrochloric acid-water solution through a nanopore is explored using atomistic simulations in the last chapter. Through ion configurations near the pore wall, an averaged ion drifting velocity is determined, and the induced voltage along the axial direction is obtained as a function of key material parameters, including the applied flow rate, environmental temperature, solution concentration and nanopore size. The molecular mechanism of ion hopping and motion is revealed. This study shed light on harvesting wasted thermal and mechanical energy from ambient environmental sources such as wasted heat in power plants. Nanofluidics is a novel and thriving research area, whose couplings with other disciplines such as material, mechanical, physical, chemical, electrical engineering are open.

  17. Organohalide Perovskites for Solar Energy Conversion.

    PubMed

    Lin, Qianqian; Armin, Ardalan; Burn, Paul L; Meredith, Paul

    2016-03-15

    Lead-based organohalide perovskites have recently emerged as arguably the most promising of all next generation thin film solar cell technologies. Power conversion efficiencies have reached 20% in less than 5 years, and their application to other optoelectronic device platforms such as photodetectors and light emitting diodes is being increasingly reported. Organohalide perovskites can be solution processed or evaporated at low temperatures to form simple thin film photojunctions, thus delivering the potential for the holy grail of high efficiency, low embedded energy, and low cost photovoltaics. The initial device-driven "perovskite fever" has more recently given way to efforts to better understand how these materials work in solar cells, and deeper elucidation of their structure-property relationships. In this Account, we focus on this element of organohalide perovskite chemistry and physics in particular examining critical electro-optical, morphological, and architectural phenomena. We first examine basic crystal and chemical structure, and how this impacts important solar-cell related properties such as the optical gap. We then turn to deeper electronic phenomena such as carrier mobilities, trap densities, and recombination dynamics, as well as examining ionic and dielectric properties and how these two types of physics impact each other. The issue of whether organohalide perovskites are predominantly nonexcitonic at room temperature is currently a matter of some debate, and we summarize the evidence for what appears to be the emerging field consensus: an exciton binding energy of order 10 meV. Having discussed the important basic chemistry and physics we turn to more device-related considerations including processing, morphology, architecture, thin film electro-optics and interfacial energetics. These phenomena directly impact solar cell performance parameters such as open circuit voltage, short circuit current density, internal and external quantum efficiency, fill factor, and ultimately the all-important power conversion efficiency. Finally, we address the key challenges pertinent to actually delivering a new and viable solar cell technology. These include long-term cell stability, scaling to the module level, and the toxicity associated with lead. Organohalide perovskites not only offer exciting possibilities for next generation optoelectronics and photovoltaics, but are an intriguing class of material crossing the boundaries of molecular solids and banded inorganic semiconductors. This is a potential area of rich new chemistry, materials science, and physics. PMID:26863507

  18. Fundamental formulae for wave-energy conversion

    PubMed Central

    Falnes, Johannes; Kurniawan, Adi

    2015-01-01

    The time-average wave power that is absorbed from an incident wave by means of a wave-energy conversion (WEC) unit, or by an array of WEC units—i.e. oscillating immersed bodies and/or oscillating water columns (OWCs)—may be mathematically expressed in terms of the WEC units' complex oscillation amplitudes, or in terms of the generated outgoing (diffracted plus radiated) waves, or alternatively, in terms of the radiated waves alone. Following recent controversy, the corresponding three optional expressions are derived, compared and discussed in this paper. They all provide the correct time-average absorbed power. However, only the first-mentioned expression is applicable to quantify the instantaneous absorbed wave power and the associated reactive power. In this connection, new formulae are derived that relate the ‘added-mass’ matrix, as well as a couple of additional reactive radiation-parameter matrices, to the difference between kinetic energy and potential energy in the water surrounding the immersed oscillating WEC array. Further, a complex collective oscillation amplitude is introduced, which makes it possible to derive, by a very simple algebraic method, various simple expressions for the maximum time-average wave power that may be absorbed by the WEC array. The real-valued time-average absorbed power is illustrated as an axisymmetric paraboloid defined on the complex collective-amplitude plane. This is a simple illustration of the so-called ‘fundamental theorem for wave power’. Finally, the paper also presents a new derivation that extends a recently published result on the direction-average maximum absorbed wave power to cases where the WEC array's radiation damping matrix may be singular and where the WEC array may contain OWCs in addition to oscillating bodies. PMID:26064612

  19. Progress on PEP-II Magnet Power Conversion System?

    SciTech Connect

    Bellomo, P.; Genova, L.; Jackson, T.; Shimer, D.

    1996-06-01

    The various power systems for supplying the PEP-II DCmagnets rely exclusively on switch mode conversion, utilizing a varietyof means depending on the requirements. All of the larger power supplies,ranging from 10 to 200 kW, are powered from DC sources utilizingrectified 480 V AC. Choppers can be used for the series connectedstrings, but for smaller groups and individual magnets, inverters drivinghigh-frequency transformers with secondary rectifiers comprise the bestapproach. All of the various systems use a "building block" approach ofmultiple standard-size units connected in series or parallel to mostcost-effectively deal with a great range of voltage and currentrequirements. Utilization of existing infrastructure from PEP-I has beena cost-effective determinant. Equipment is being purchased eitheroff-the-shelf, through performance specification, or by hardware purchasebased on design-through-prototype. The corrector magnet power system,utilizing inexpensive, off-the-shelf four-quadrant switching motorcontrollers, has already proven very reliable: 120 of the total of 900units have been running on the injection system for four months with nofailures.

  20. Performance of Tornado Wind Energy Conversion Systems

    SciTech Connect

    Volk, T.

    1982-09-01

    The flow characteristics and power production capabilities of the Tornado Wind Energy Conversion System (TWECS) are examined. Experimental results indicate that the confined vortex in the tower of TWECS rotates approximately as a solid body and only supplements total power production, most of which comes from the tower acting as a bluff body. Wrapped tower experiments were performed by fitting a plastic shroud 360 deg around the tower from the top of the bottom inlet to the tower exit level which transformed the TWECS into a hollow, raised cylinder. Coefficient of power is compared for louvered towers vs. wrapped tower. The fact that the wrapped tower performs as well as the louvered tower suggests that it is the pressure difference between the bottom inlet region and the region above the tower (where the pressure of the ambient flow will be somewhat reduced owing to its acceleration over the bluff body of the tower) which determines the vertical force on the fluid within the tower.

  1. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 1: Bottoming cycles and materials of construction

    NASA Technical Reports Server (NTRS)

    Shah, R. P.; Solomon, H. D.

    1976-01-01

    Energy conversion subsystems and components were evaluated in terms of advanced energy conversion systems. Results of the bottoming cycles and materials of construction studies are presented and discussed.

  2. Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation

    SciTech Connect

    Schleyer, F.; Cairns, Iver H.; Kim, E.-H.

    2013-03-15

    Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence {theta} of the Langmuir/z-mode wave, temperature {beta}=T{sub e}/m{sub e}c{sup 2}, adiabatic index {gamma}, and orientation angle {phi} between the ambient density gradient {nabla}N{sub 0} and ambient magnetic field B{sub 0} in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of {theta}, {gamma}, and {beta} with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency {epsilon} is strongly dependent on {gamma}{beta}, {phi} and {theta}, with {epsilon}{proportional_to}({gamma}{beta}){sup 1/2} and {theta}{proportional_to}({gamma}{beta}){sup 1/2}. The power conversion efficiency {epsilon}{sub p}, on the other hand, is independent of {gamma}{beta} but does vary significantly with {theta} and {phi}. The efficiencies are shown to be maximum for approximately perpendicular density gradients ({phi} Almost-Equal-To 90 Degree-Sign ) and minimal for parallel orientation ({phi}=0 Degree-Sign ) and both the energy and power conversion efficiencies peak at the same {theta}.

  3. Conversion of laser energy to gas kinetic energy

    NASA Technical Reports Server (NTRS)

    Caledonia, G. E.

    1977-01-01

    Techniques for the gas-phase absorption of laser energy with ultimate conversion to heat or directed kinetic energy are reviewed. It is shown that the efficiency of resonance absorption by the vibration/rotation bands of the working gas can be enhanced by operating at sufficiently high pressures so that the linewidths of the absorbing transition exceed the line spacing. Within this limit, the gas can absorb continuously over the full spectral region of the band, and bleaching can be minimized since the manifold of molecular vibrational levels can simultaneously absorb the laser radiation.

  4. Superconducting energy storage magnet

    NASA Technical Reports Server (NTRS)

    Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

    1993-01-01

    A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

  5. Open cycle ocean thermal energy conversion system

    DOEpatents

    Wittig, J. Michael

    1980-01-01

    An improved open cycle ocean thermal energy conversion system including a flash evaporator for vaporizing relatively warm ocean surface water and an axial flow, elastic fluid turbine having a vertical shaft and axis of rotation. The warm ocean water is transmitted to the evaporator through a first prestressed concrete skirt-conduit structure circumferentially situated about the axis of rotation. The unflashed warm ocean water exits the evaporator through a second prestressed concrete skirt-conduit structure located circumferentially about and radially within the first skirt-conduit structure. The radially inner surface of the second skirt conduit structure constitutes a cylinder which functions as the turbine's outer casing and obviates the need for a conventional outer housing. The turbine includes a radially enlarged disc element attached to the shaft for supporting at least one axial row of radially directed blades through which the steam is expanded. A prestressed concrete inner casing structure of the turbine has upstream and downstream portions respectively situated upstream and downstream from the disc element. The radially outer surfaces of the inner casing portions and radially outer periphery of the axially interposed disc cooperatively form a downwardly radially inwardly tapered surface. An annular steam flowpath of increasing flow area in the downward axial direction is radially bounded by the inner and outer prestressed concrete casing structures. The inner casing portions each include a transversely situated prestressed concrete circular wall for rotatably supporting the turbine shaft and associated structure. The turbine blades are substantially radially coextensive with the steam flowpath and receive steam from the evaporator through an annular array of prestressed concrete stationary vanes which extend between the inner and outer casings to provide structural support therefor and impart a desired flow direction to the steam.

  6. Broadband down-conversion spectral modification based on energy transfer

    NASA Astrophysics Data System (ADS)

    Zhou, Jiajia; Teng, Yu; Ye, Song; Liu, Xiaofeng; Qiu, Jianrong

    2010-12-01

    Broadband down-conversion spectral modification attracts our attention followed by narrowband down-conversion due to its applicability for solar cells. This article reviews on the recent research development on broadband down-conversion spectral modification based on energy transfer: (1) f-d transition rare earth ions including Eu 2+, Ce 3+ and Yb 2+ to Yb 3+; (2) other sensitizer including heavy metal ions and host lattice absorption to Yb 3+. The mechanisms of energy transfer and the possibilities of efficient near-infrared emission are analyzed. We also point out some problems need further development on broadband down-conversion spectral modification.

  7. Plasmon-assisted radiolytic energy conversion in aqueous solutions

    PubMed Central

    Kim, Baek Hyun; Kwon, Jae W.

    2014-01-01

    The field of conventional energy conversion using radioisotopes has almost exclusively focused on solid-state materials. Herein, we demonstrate that liquids can be an excellent media for effective energy conversion from radioisotopes. We also show that free radicals in liquid, which are continuously generated by beta radiation, can be utilized for electrical energy generation. Under beta radiation, surface plasmon obtained by the metallic nanoporous structures on TiO2 enhanced the radiolytic conversion via the efficient energy transfer between plasmons and free radicals. This work introduces a new route for the development of next-generation power sources. PMID:24918356

  8. A Metric (SI) Energy Scale: Conversions and Comparisons

    ERIC Educational Resources Information Center

    Petrakis, L.

    1974-01-01

    An energy scale, constructed in terms of the Joule, is presented. It provides for the conversion of all traditional units employed in engineering, science, and technology to describe forms of energy; gives the energy associated with physical phenomena; and provides energy equivalents of quantities associated with various energy sources. (DT)

  9. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; DePoy, David Moore; Baldasaro, Paul Francis

    2007-01-23

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  10. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; Baldasaro, Paul F.; DePoy, David M.

    2010-09-07

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  11. Radiative energy receiver for high performance energy conversion cycles

    NASA Technical Reports Server (NTRS)

    Rault, D.; Hertzberg, A.

    1982-01-01

    An analysis of gas dynamic processes pertinent to the functioning of earth-based and space-based solar electric power plants is presented, with attention given to potassium vapor as the working fluid. A device is described which features focused photon absorption by a nontransparent flowing gas. The feed flow is effected around the outside walls of a cavity receiver to raise efficiencies by trapping reemitted energy. A theoretical study of the interaction of a photon flux with a coaxial particle flux was performed, with the receiver flow treated as a Graetz flow. The critical parameters were defined, including a figure of merit as the gas enthalpy increase to absorbable energy ratio. A small-scale laboratory model was tested in comparison with the theoretically obtained values. Less than 15% of the absorbed energy was lost through dissipation while an 80% conversion efficiency was attained.

  12. NASA-OAST program in photovoltaic energy conversion

    NASA Technical Reports Server (NTRS)

    Mullin, J. P.; Flood, D. J.

    1982-01-01

    The NASA program in photovoltaic energy conversion includes research and technology development efforts on solar cells, blankets, and arrays. The overall objectives are to increase conversion efficiency, reduce mass, reduce cost, and increase operating life. The potential growth of space power requirements in the future presents a major challenge to the current state of technology in space photovoltaic systems.

  13. Superconducting magnetic energy storage

    SciTech Connect

    Hassenzahl, W.

    1988-08-01

    Recent programmatic developments in Superconducting Magnetic Energy Storage (SMES) have prompted renewed and widespread interest in this field. In mid 1987 the Defense Nuclear Agency, acting for the Strategic Defense Initiative Office, issued a request for proposals for the design and construction of SMES Engineering Test Model (ETM). Two teams, one led by Bechtel and the other by Ebasco, are now engaged in the first phase of the development of a 10 to 20 MWhr ETM. This report presents the rationale for energy storage on utility systems, describes the general technology of SMES, and explains the chronological development of the technology. The present ETM program is outlined; details of the two projects for ETM development are described in other papers in these proceedings. The impact of high T/sub c/ materials on SMES is discussed. 69 refs., 3 figs., 3 tabs.

  14. Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Dasgupta, Neil P.; Yang, Peidong

    2014-06-01

    Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.

  15. Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion

    SciTech Connect

    Dasgupta, Neil; Yang, Peidong

    2013-01-23

    Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.

  16. Semiconductor Nanowires and Nanotubes for Energy Conversion

    NASA Astrophysics Data System (ADS)

    Fardy, Melissa Anne

    In recent years semiconductor nanowires and nanotubes have garnered increased attention for their unique properties. With their nanoscale dimensions comes high surface area and quantum confinement, promising enhancements in a wide range of applications. 1-dimensional nanostructures are especially attractive for energy conversion applications where photons, phonons, and electrons come into play. Since the bohr exciton radius and phonon and electron mean free paths are on the same length scales as nanowire diameters, optical, thermal, and electrical properties can be tuned by simple nanowire size adjustments. In addition, the high surface area inherent to nanowires and nanotubes lends them towards efficient charge separation and superior catalytic performance. In thermoelectric power generation, the nanoscale wire diameter can effectively scatter phonons, promoting reductions in thermal conductivity and enhancements in the thermoelectric figure of merit. To that end, single-crystalline arrays of PbS, PbSe, and PbTe nanowires have been synthesized by a chemical vapor transport approach. The electrical and thermal transport properties of the nanowires were characterized to investigate their potential as thermoelectric materials. Compared to bulk, the lead chalcogenide nanowires exhibit reduced thermal conductivity below 100 K by up to 3 orders of magnitude, suggesting that they may be promising thermoelectric materials. Smaller diameters and increased surface roughness are expected to give additional enhancements. The solution-phase synthesis of PbSe nanowires via oriented attachment of nanoparticles enables facile surface engineering and diameter control. Branched PbSe nanowires synthesized by this approach showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing of the PbSe nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration or hole mobility. After optimal annealing, single PbSe nanowires exhibited a thermoelectric figure of merit (ZT) of 0.12 at 300 K. In addition, using a field-effect gated device, the Seebeck coefficient of single PbSe nanowires could be tuned from 64 to 193 muV?K-1. This direct electrical field control of the electrical conductivity and Seebeck coefficient suggests a powerful strategy for optimizing ZT in thermoelectric devices and these results represent the first demonstration of field-effect modulation of the thermoelectric figure of merit in a single semiconductor nanowire. This novel strategy for thermoelectric property modulation could prove especially important in optimizing the thermoelectric properties of semiconductors where reproducible doping is difficult to achieve. Recent theoretical work has shown large enhancements in ZT for single-crystal nanowires containing nanoscale interfaces along their lengths. M2O3(ZnO) n ( M = In, Ga, Fe) superlattice nanowires were synthesized via a novel solid-state diffusion approach to investigate this possible enhancement. Using atomic resolution Z-contrast STEM imaging a detailed structural analysis was performed on In2-xGaxO3(ZnO) n nanowires, leading to the discovery that octahedral inclusions within the superlattice structure are likely generated through a defect-assisted process. Single-nanowire thermal and electrical measurements on In2-x GaxO3(ZnO)n reveal a simultaneous improvement in all contributing factors to the thermoelectric figure of merit, giving an order of magnitude enhancement over similar bulk materials at room temperature. This is the first report of enhancement of all three thermoelectric parameters (Seebeck coefficient, electrical conductivity, and thermal resistivity) for a nanowire system. Photoelectrochemical water splitting is another exciting renewable energy application that can benefit from the high surface area of nanomaterials. Recently, (Ga1-xZnx)(N1-xOx) has gained

  17. Nanowires for thermal energy conversion and management

    NASA Astrophysics Data System (ADS)

    Chen, Renkun

    This dissertation presents the application of nanowires in two aspects of thermal energy conversion and management: (i) silicon (Si) nanowires as efficient and scalable thermoelectric materials due to the reduced thermal conductivity (k), and (ii) Si and copper (Cu) nanowire arrays for enhanced phase change heat transfer including boiling and evaporation and their applications in thermal management of microelectronics. In the first half of the thesis (chapter 2 and 3), we describe thermal and thermoelectric measurements of individual Si nanowires for studying phonon transport properties and their potential application in thermoelectrics. A theoretical model based on coherent phonon scattering was developed to explain the experiemental data, which suggests that phonon-boundary scattering is highly frequency dependent. For low frequency (long wavelength) phonons, the transport is nearly ballistic, whereas high frequency or short wavelength phonons scatter diffusively at nanowire boundary. The competition between the two phonon transmission regimes results in the unusual linear behavior of the thermal conductance of thin VLS Si nanowires at low temperature. Next, the thermal conductivity of EE Si nanowires, which have much rougher surface compared to VLS nanowires, was measured and found to be five-eight times lower than that of VLS counterparts with similar diameters. The substantial reduction in k is presumably due to the higher surface roughness, since both types of nanowires have single crystalline cores. In particular, for ˜ 50 nm EE Si nanowires etched from 0.1 O-cm B-doped p-Si <111> (˜2 x 1017 cm-3 dopant concentration), the k is around 1.6 Wm-1K-1 and the kL is ˜1.2 Wm-1 K-1 at room temperature, approaching that of amorphous Si. The single nanowire measurements show the great promise of using Si nanowire arrays as high-performance, scalable thermoelectric materials. As the second focus of the thesis (chapter 4 and 5), nanowire arrays were used for enhanced phase change heat transfer such as evaporation and boiling, owing to the high surface tension offered by liquid confined in the nanowire array, large effective surface area, and etc. In chapter 4, we describe the design of a hot-spot adaptive thermal spreader (HATS) for the thermal management of microprocessors. The HATS is a heat pipe vapor chamber that utilizes a hierarchical wicking structure based on Cu nanowires arrays. A comprehensive thermal and fluid model indicates that the overall thermal resistivities of HATS are 0.016 cm2-K-W-1 and 0.045 cm2-K-W-1 respectively, under uniform and non-uniform heating conditions, at least 10 times smaller than those of state-of-the-art vapor chambers and copper heat spreaders. The capillary limit of HATS was estimated to be about 1000 W/cm2, which is one order of magnitude higher than conventional heat pipes, suggesting that the design of the HATS can increase the capillary and conductance limits simultaneously. Finally, pool boiling experiments were carried out on a 1 cm x 1 cm surface covered by Cu or Si nanowires. The Cu nanowires were synthesized by Cu electroplating using porous anodic alumina (PAA) as templates and the Si nanowires were synthesized by the previously mentioned EE method. Both nanowire arrays show that the critical heat flux and thermal conductance of pool boiling are increased by more than 100 percent with respect to plain surface, which is presumably due to the high capillary forces offered by liquids confined in nanowire arrays, as well as the high number density of microscale cavities formed in the arrays. (Abstract shortened by UMI.)

  18. An Overview of the Progress in Photoelectrochemical Energy Conversion.

    ERIC Educational Resources Information Center

    Parkinson, Bruce

    1983-01-01

    Provides an overview of advances made in the field of photoelectrochemistry. Includes a short historical account of the development of the field, a review of the state-of-the-art of photoelectrochemical energy conversion and future prospects. (JN)

  19. Conversion of laser energy to gas kinetic energy

    NASA Technical Reports Server (NTRS)

    Caledonia, G. E.

    1975-01-01

    Techniques for the gas phase absorption of laser radiation for conversion to gas kinetic energy are discussed. Absorption by inverse Bremsstrahlung, in which laser energy is converted at a gas kinetic rate in a spectrally continuous process, is briefly described, and absorption by molecular vibrational rotation bands is discussed at length. High pressure absorption is proposed as a means of minimizing gas bleaching and dissociation, the major disadvantages of the molecular absorption process. A band model is presented for predicting the molecular absorption spectra in the high pressure absorption region and is applied to the CO molecule. Use of a rare gas seeded with Fe(CO)5 for converting vibrational modes to translation modes is described.

  20. Advanced Thermal Energy Conversion of Temperature under 300°C by Thermoelectric Conversion Method

    NASA Astrophysics Data System (ADS)

    Ueda, Tadashi; Uchida, Yoshiyuki; Shingu, Hiroyasu

    Many approaches have been developing for energy conversion throughout the world. However, it is difficult to achieve the global warming countermeasure based on “The Kyoto protocol”. Until now effective utilization of low temperature thermal energy (under 300°C) is not advancing one. For example, effective utilization method has not been established for waste heat energy which arise from industry machine tools, automobiles, internal combustion engines and thermal energy from natural environment, etc. In this paper, we reported the experiment for effective utilizing of low temperature (under 300°C) thermal energy conversion. The device used for the measurement is a copper thermo device. Thermo electromotive force of 150mW/cm2 was obtained at 200°C. The obtained thermo electromotive force is about 15 times higher in comparison with generally used alumal-chromal thermocouple. Our aim is that utilizes low temperature thermal energy effectively by converting into electricity.

  1. A summary of USSR thermionic energy conversion activity

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.

    1978-01-01

    The paper surveys the research and development associated with thermionic energy conversion in the USSR. Consideration is given to the basic physics of the thermionic converter, the development of thermionic nuclear reactors including the three TOPAZ models, radioisotope-heated generators, and the thermionic topping of fossil-fueled electric-power plants. Comparisons are made between U.S. and USSR capabilities in thermionic energy conversion and potential cooperative programs are noted.

  2. Space electric power design study. [laser energy conversion

    NASA Technical Reports Server (NTRS)

    Martini, W. R.

    1976-01-01

    The conversion of laser energy to electrical energy is discussed. Heat engines in which the laser heats the gas inside the engine through a window as well as heat engines in which the gas is heated by a thermal energy storage reservoir which has been heated by laser radiation are both evaluated, as well as the necessary energy storage, transmission and conversion components needed for a full system. Preliminary system concepts are presented and a recommended development program is outlined. It appears possible that a free displacer Stirling engine operating directly a linear electric generator can convert 65% of the incident laser energy into electricity.

  3. Energy conversion device with support member having pore channels

    DOEpatents

    Routkevitch, Dmitri [Longmont, CO; Wind, Rikard A [Johnstown, CO

    2014-01-07

    Energy devices such as energy conversion devices and energy storage devices and methods for the manufacture of such devices. The devices include a support member having an array of pore channels having a small average pore channel diameter and having a pore channel length. Material layers that may include energy conversion materials and conductive materials are coaxially disposed within the pore channels to form material rods having a relatively small cross-section and a relatively long length. By varying the structure of the materials in the pore channels, various energy devices can be fabricated, such as photovoltaic (PV) devices, radiation detectors, capacitors, batteries and the like.

  4. Push-n-Go: A Dynamic Energy Conversion Lesson.

    ERIC Educational Resources Information Center

    Taylor, Beverly A. P.

    1998-01-01

    Focuses on the use of push and go toys to discuss with students how the toy acquires potential energy when work is done on it and how this energy is stored in the internal mechanism for later conversion into kinetic energy. (DDR)

  5. Advanced thermionic energy conversion: Joint highlights

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A theoretical model was used to study the effects of structured electrodes on converter I-V characteristics and results are given. An auxiliary-ion-source triode operated as a plasmatron was used for studying the enhancement distribution and magnetic effects, and results are reported. Design features of the high current-zero power (ZEPO) converter tests are given.

  6. Energy production from biomass (Part 2): Conversion technologies.

    TOXLINE Toxicology Bibliographic Information

    McKendry P

    2002-05-01

    The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines.

  7. Energy production from biomass (Part 2): Conversion technologies.

    PubMed

    McKendry, Peter

    2002-05-01

    The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines. PMID:12058830

  8. Converse magnetoelectric effect via strain-driven magnetization reorientations in ultrathin ferromagnetic films on ferroelectric substrates

    NASA Astrophysics Data System (ADS)

    Pertsev, N. A.

    2015-07-01

    A phenomenological theory is developed for the strain-driven magnetization reorientations occurring in ultrathin ferromagnetic films coupled to ferroelectric substrates experiencing electric-field-induced piezoelectric deformations. The theory takes into account the surface/interface magnetic anisotropy playing an important role in the energetics of such films and first describes the thickness-driven spin reorientation transitions emerging in the presence of substrate-induced lattice strains. Then the threshold and critical intensities of the electric field created in a ferroelectric substrate are calculated, at which different magnetic states acquire the same energy or become unstable in a strained ferromagnetic overlayer. To demonstrate stability ranges of various possible magnetization orientations, we introduce magnetoelectric orientational diagrams, where the electric-field intensity and film thickness are employed as two variables. Such diagrams are constructed for ultrathin Ni, Fe, and F e60C o40 films coupled to single crystals of classical and relaxor ferroelectrics. The inspection of these diagrams shows that the use of multiferroic hybrids comprising ultrathin ferromagnetic films significantly enlarges the range of ferroic materials suitable for experimental observations of the strain-mediated converse magnetoelectric effect.

  9. Energy Conversion and Storage Program: 1992 Annual report

    SciTech Connect

    Cairns, E.J.

    1993-06-01

    This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.

  10. Photonic Crystal Emitters for Thermophotovoltaic Energy Conversion

    NASA Astrophysics Data System (ADS)

    Stelmakh, Veronika; Chan, Walker R.; Ghebrebrhan, Michael; Soljacic, Marin; Joannopoulos, John D.; Celanovic, Ivan

    2015-12-01

    This paper reports the design, fabrication, and characterization of 2D photonic crystal (PhC) thermal emitters for a millimeter-scale hydrocarbon TPV microgenerator as a possible replacement for batteries in portable microelectronics, robotics, etc. In our TPV system, combustion heats a PhC emitter to incandescence and the resulting radiation is converted by a low-bandgap TPV cell. The PhC tailors the photonic density of states to produce spectrally confined thermal emission that matches the bandgap of the TPV cell, enabling high heat-to-electricity conversion efficiency. The work builds on a previously developed fabrication process to produce a square array of cylindrical cavities in a metal substrate. We will present ongoing incremental improvements in the optical and thermo-mechanical properties, the fabrication process, and the system integration, as recently combined with fabrication using novel materials, such as sputtered coatings, to enable a monolithic system.

  11. High power density thermophotovoltaic energy conversion

    NASA Astrophysics Data System (ADS)

    Noreen, Darryl L.; Du, Honghua

    1995-01-01

    R&D Technologies is developing thermophotovoltaic (TPV) technology based on the use of porous/fibrous ceramic broadband-type emitter designs that utilize recuperative or regenerative techniques to improve thermal efficiency and power density. This paper describes preliminary estimates of what will be required to accomplish sufficient power density to develop a practical, commercially-viable TPV generator. It addresses the needs for improved, thermal shock-resistant, long-life porous/fibrous ceramic emitters and provides information on the photocell technology required to achieve acceptable power density in broadband-type (with selective filter) TPV systems. TPV combustors/systems operating at a temperature of 1500 C with a broadband-type emitter is proposed as a viable starting point for cost-effective TPV conversion. Based on current projections for photocell cost, system power densities of 7.5-10 watts per square centimeter of emitter area will be required for TPV to become a commercially viable technology.

  12. Pin stack array for thermoacoustic energy conversion

    DOEpatents

    Keolian, Robert M.; Swift, Gregory W.

    1995-01-01

    A thermoacoustic stack for connecting two heat exchangers in a thermoacoustic energy converter provides a convex fluid-solid interface in a plane perpendicular to an axis for acoustic oscillation of fluid between the two heat exchangers. The convex surfaces increase the ratio of the fluid volume in the effective thermoacoustic volume that is displaced from the convex surface to the fluid volume that is adjacent the surface within which viscous energy losses occur. Increasing the volume ratio results in an increase in the ratio of transferred thermal energy to viscous energy losses, with a concomitant increase in operating efficiency of the thermoacoustic converter. The convex surfaces may be easily provided by a pin array having elements arranged parallel to the direction of acoustic oscillations and with effective radial dimensions much smaller than the thicknesses of the viscous energy loss and thermoacoustic energy transfer volumes.

  13. Energy balance of wheat conversion to ethanol

    SciTech Connect

    Stumborg, M.A.; Zentner, R.P.; Coxworth, E.

    1996-12-31

    The Western Canadian ethanol industry uses wheat as the preferred feed stock. The net energy balance of an ethanol system based on this starchy feed stock is of interest if Canada utilizes ethanol fuels from wheat as one of its measures to meet international commitments for greenhouse gas reduction and energy conservation under the Green Plan. The wheat to ethanol production systems for the Brown and Thin Black soil zones of the Canadian Prairies were analyzed from soil to processing completion to determine the net energy balance. The data clearly demonstrates the positive net energy balance, with the energy balance ranging from 1.32 to 1.63:1 for the Brown soil zone, and from 1.19 to 1.47:1 for the Thin Black soil zone. The final energy balance depends upon the agronomic practices and wheat variety assumed for the production system.

  14. Status of wind-energy conversion

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Savino, J. M.

    1973-01-01

    The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems; a sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to: (1) fossil fuel systems; (2) hydroelectric systems; or (3) dispersing them throughout a large grid network. Wind energy appears to have the potential to meet a significant amount of our energy needs.

  15. Physical Limits of Solar Energy Conversion in the Earth System.

    PubMed

    Kleidon, Axel; Miller, Lee; Gans, Fabian

    2016-01-01

    Solar energy provides by far the greatest potential for energy generation among all forms of renewable energy. Yet, just as for any form of energy conversion, it is subject to physical limits. Here we review the physical limits that determine how much energy can potentially be generated out of sunlight using a combination of thermodynamics and observed climatic variables. We first explain how the first and second law of thermodynamics constrain energy conversions and thereby the generation of renewable energy, and how this applies to the conversions of solar radiation within the Earth system. These limits are applied to the conversion of direct and diffuse solar radiation - which relates to concentrated solar power (CSP) and photovoltaic (PV) technologies as well as biomass production or any other photochemical conversion - as well as solar radiative heating, which generates atmospheric motion and thus relates to wind power technologies. When these conversion limits are applied to observed data sets of solar radiation at the land surface, it is estimated that direct concentrated solar power has a potential on land of up to 11.6 PW (1 PW=10(15) W), whereas photovoltaic power has a potential of up to 16.3 PW. Both biomass and wind power operate at much lower efficiencies, so their potentials of about 0.3 and 0.1 PW are much lower. These estimates are considerably lower than the incoming flux of solar radiation of 175 PW. When compared to a 2012 primary energy demand of 17 TW, the most direct uses of solar radiation, e.g., by CSP or PV, have thus by far the greatest potential to yield renewable energy requiring the least space to satisfy the human energy demand. Further conversions into solar-based fuels would be reduced by further losses which would lower these potentials. The substantially greater potential of solar-based renewable energy compared to other forms of renewable energy simply reflects much fewer and lower unavoidable conversion losses when solar radiation is directly converted into renewable energy. PMID:26003563

  16. Control of radiative processes for energy conversion and harvesting.

    PubMed

    Bermel, Peter; Boriskina, Svetlana V; Yu, Zongfu; Joulain, Karl

    2015-11-30

    We review recent advances in the fundamental understanding and technological applications of radiative processes for energy harvesting, conversion, efficiency, and sustainability. State-of-the-art and remaining challenges are discussed, together with the latest developments outlined in the papers comprising this focus issue. The topics range from the fundamentals of the thermal emission manipulation in the far and near field, to applications in radiative cooling, thermophotovoltaics, thermal rectification, and novel approaches to photon detection and conversion. PMID:26698801

  17. Cogeneration Technology Alternatives Study (CTAS). Volume 4: Energy conversion systems

    NASA Technical Reports Server (NTRS)

    Brown, D. H.; Gerlaugh, H. E.; Priestley, R. R.

    1980-01-01

    Industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed-cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum-based residual and distillate liquid fuels, and low Btu gas obtained through the on-site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. The advanced and commercially available cogeneration energy conversion systems studied in CTAS are fined together with their performance, capital costs, and the research and developments required to bring them to this level of performance.

  18. Cogeneration Technology Alternatives Study (CTAS). Volume 4: Energy conversion systems

    NASA Astrophysics Data System (ADS)

    Brown, D. H.; Gerlaugh, H. E.; Priestley, R. R.

    1980-04-01

    Industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed-cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum-based residual and distillate liquid fuels, and low Btu gas obtained through the on-site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. The advanced and commercially available cogeneration energy conversion systems studied in CTAS are fined together with their performance, capital costs, and the research and developments required to bring them to this level of performance.

  19. Preliminary results on the conversion of laser energy into electricity

    NASA Technical Reports Server (NTRS)

    Thompson, R. W.; Manista, E. J.; Alger, D. L.

    1978-01-01

    A preliminary experiment was performed to investigate conversion of 10.6 micron laser energy to electrical energy via a laser-sustained argon plasma. Short-circuit currents of 0.7 A were measured between a thoriated-tungsten emitter and collector electrodes immersed in the laser-sustained argon plasma. Open-circuit voltages of about 1.5 V were inferred from the current-voltage load characteristics. The dominant mechanism of laser energy conversion is uncertain at this time. Much higher output powers appear possible.

  20. Status of wind-energy conversion

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Savino, J. M.

    1973-01-01

    The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems. A sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short-term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to fossil fuel systems, hydroelectric systems, or dispersing them throughout a large grid network. The NSF and NASA-Lewis Research Center have sponsored programs for the utilization of wind energy.

  1. Photoelectrochemical conversion of solar energy using semiconductor electrodes

    NASA Astrophysics Data System (ADS)

    Arutiunian, V. M.

    The principles of operation of semiconductor photoelectrochemical converters of solar energy into chemical or electrical energy are discussed. The properties of suitable semiconductor materials are examined, and methods for the protection of the electrodes from photocorrosion are described. Ways to increase the conversion efficiency are considered, and efficiency values obtained for various materials are tabulated. A review of the recent literature is included.

  2. Wind Energy Conversion Systems. A Unit of Instruction.

    ERIC Educational Resources Information Center

    Greenwald, Martin

    The number of secondary schools, colleges, and universities offering courses in wind energy machine construction, repair, and installation, continues to increase. It is the purpose of this unit to include the study of wind energy conversion systems (WECS) as an integral part of related vocational and technical curriculum materials. The unit's

  3. Wind Energy Conversion Systems. A Unit of Instruction.

    ERIC Educational Resources Information Center

    Greenwald, Martin

    The number of secondary schools, colleges, and universities offering courses in wind energy machine construction, repair, and installation, continues to increase. It is the purpose of this unit to include the study of wind energy conversion systems (WECS) as an integral part of related vocational and technical curriculum materials. The unit's…

  4. Wind energy conversion over Ligurian Apennines

    NASA Astrophysics Data System (ADS)

    Flocchini, G.; Pasquale, V.; Sciarrone, V.

    1983-06-01

    A detailed analysis of wind energy availability at Mount Capellino (Genoa, Italy), based on wind data for a twenty year period, shows that wind energy is a promising renewable natural energy source in this part of the Ligurian Apennines. The instantaneous power output of a real aerogenerator has been integrated over the time to determine the energy output per unit area swept by the rotor over a year and a month respectively. Using a realistic capacity of 0.4 kW/m2 for the ideal machine, the annual power density output is 645 kWh/m2 at 30 m above ground level. It is estimated that five medium size wind-powered generators of 20 m in rotor diameter can produce approximately 1 GWh per year.

  5. Supramolecular Structures for Photochemical Energy Conversion

    SciTech Connect

    Gust, Devens; Moore, Thomas A.; Moore, Ana L.

    2003-08-26

    OAK B188 The goal of this project is to mimic the energy transduction processes by which photosynthetic organisms harvest sunlight and convert it to forms of energy that are more easily used and stored. The results may lead to new technologies for solar energy harvesting based on the natural photosynthetic process. They may also enrich our understanding and control of photosynthesis in living organisms, and lead to methods for increasing natural biomass production, carbon dioxide removal, and oxygen generation. In our work to date, we have learned how to make synthetic antenna and reaction center molecules that absorb light and undergo photoinduced electron transfer to generate long-lived, energetic charge-separated states. We have assembled a prototype system in which artificial reaction centers are inserted into liposomes (artificial cell-like constructs), where they carry out light-driven transmembrane translocation of hydrogen ions to generate proton motive force. By insertion of natural ATP synthase into the liposomal bilayer, this proton motive force has been used to power the synthesis of ATP. ATP is a natural biological energy currency. We are carrying out a systematic investigation of these artificial photosynthetic energy harvesting constructs in order to understand better how they operate. In addition, we are exploring strategies for reversing the direction of the light-powered proton pumping. Most recently, we have extended these studies to develop a light-powered transmembrane calcium ion pump that converts sunlight into energy stored as a calcium ion concentration gradient across a lipid bilayer.

  6. Emerging electrochemical energy conversion and storage technologies

    PubMed Central

    Badwal, Sukhvinder P. S.; Giddey, Sarbjit S.; Munnings, Christopher; Bhatt, Anand I.; Hollenkamp, Anthony F.

    2014-01-01

    Electrochemical cells and systems play a key role in a wide range of industry sectors. These devices are critical enabling technologies for renewable energy; energy management, conservation, and storage; pollution control/monitoring; and greenhouse gas reduction. A large number of electrochemical energy technologies have been developed in the past. These systems continue to be optimized in terms of cost, life time, and performance, leading to their continued expansion into existing and emerging market sectors. The more established technologies such as deep-cycle batteries and sensors are being joined by emerging technologies such as fuel cells, large format lithium-ion batteries, electrochemical reactors; ion transport membranes and supercapacitors. This growing demand (multi billion dollars) for electrochemical energy systems along with the increasing maturity of a number of technologies is having a significant effect on the global research and development effort which is increasing in both in size and depth. A number of new technologies, which will have substantial impact on the environment and the way we produce and utilize energy, are under development. This paper presents an overview of several emerging electrochemical energy technologies along with a discussion some of the key technical challenges. PMID:25309898

  7. Emerging electrochemical energy conversion and storage technologies.

    PubMed

    Badwal, Sukhvinder P S; Giddey, Sarbjit S; Munnings, Christopher; Bhatt, Anand I; Hollenkamp, Anthony F

    2014-01-01

    Electrochemical cells and systems play a key role in a wide range of industry sectors. These devices are critical enabling technologies for renewable energy; energy management, conservation, and storage; pollution control/monitoring; and greenhouse gas reduction. A large number of electrochemical energy technologies have been developed in the past. These systems continue to be optimized in terms of cost, life time, and performance, leading to their continued expansion into existing and emerging market sectors. The more established technologies such as deep-cycle batteries and sensors are being joined by emerging technologies such as fuel cells, large format lithium-ion batteries, electrochemical reactors; ion transport membranes and supercapacitors. This growing demand (multi billion dollars) for electrochemical energy systems along with the increasing maturity of a number of technologies is having a significant effect on the global research and development effort which is increasing in both in size and depth. A number of new technologies, which will have substantial impact on the environment and the way we produce and utilize energy, are under development. This paper presents an overview of several emerging electrochemical energy technologies along with a discussion some of the key technical challenges. PMID:25309898

  8. Emerging electrochemical energy conversion and storage technologies

    NASA Astrophysics Data System (ADS)

    Badwal, Sukhvinder; Giddey, Sarbjit; Munnings, Christopher; Bhatt, Anand; Hollenkamp, Tony

    2014-09-01

    Electrochemical cells and systems play a key role in a wide range of industry sectors. These devices are critical enabling technologies for renewable energy; energy management, conservation and storage; pollution control / monitoring; and greenhouse gas reduction. A large number of electrochemical energy technologies have been developed in the past. These systems continue to be optimized in terms of cost, life time and performance, leading to their continued expansion into existing and emerging market sectors. The more established technologies such as deep-cycle batteries and sensors are being joined by emerging technologies such as fuel cells, large format lithium-ion batteries, electrochemical reactors; ion transport membranes and supercapacitors. This growing demand (multi billion dollars) for electrochemical energy systems along with the increasing maturity of a number of technologies is having a significant effect on the global research and development effort which is increasing in both in size and depth. A number of new technologies, which will have substantial impact on the environment and the way we produce and utilize energy, are under development. This paper presents an overview of several emerging electrochemical energy technologies along with a discussion some of the key technical challenges.

  9. Achieving high molecular conversion efficiency via a magnetic field pulse train

    NASA Astrophysics Data System (ADS)

    Dou, F. Q.; Li, S. C.

    2012-06-01

    We investigate the process of production of ultracold molecules in an ultracold bosonic system with particle interaction via designing a magnetic field pulse train near a Feshbach resonance. This technique offers a high conversion efficiency up to 100% by tuning the pulse durations appropriately. The molecular conversion efficiency is related to the duration of each pulse, which can be derived analytically. It is found that the conversion efficiency is insensitive to the first pulse, highly sensitive to the second one, and very insensitive to the third one. The effects of particle interaction on conversion process are discussed as well.

  10. The plasmatron: Advanced mode thermionic energy conversion

    NASA Technical Reports Server (NTRS)

    Hansen, L. K.; Hatch, G. L.; Rasor, N. S.

    1976-01-01

    A theory of the plasmatron was developed. Also, a wide range of measurements were obtained with two versatile, research devices. To gain insight into plasmatron performance, the experimental results are compared with calculations based on the theoretical model of plasmatron operation. Results are presented which show that the plasma arc drop of the conventional arc (ignited) mode converter can be suppressed by use of an auxiliary ion source. The improved performance, however, is presently limited to low current densities because of voltage losses due to plasma resistance. This resistance loss could be suppressed by an increase in the plasma electron temperature or a decrease in spacing. Plasmatron performance characteristics for both argon and cesium are reported. The argon plasmatron has superior performance. Results are also presented for magnetic cutoff effects and for current distributing effects. These are shown to be important factors for the design of practical devices.

  11. Porous media for catalytic renewable energy conversion

    NASA Astrophysics Data System (ADS)

    Hotz, Nico

    2012-05-01

    A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

  12. Low to high temperature energy conversion system

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  13. Energy Conversion and Storage Program. 1990 annual report

    SciTech Connect

    Cairns, E.J.

    1992-03-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

  14. Magnetopause reconnection and energy conversion as influenced by the dipole tilt and the IMF Bx

    NASA Astrophysics Data System (ADS)

    Hoilijoki, Sanni; Souza, Vitor M.; Walsh, Brian M.; Janhunen, Pekka; Palmroth, Minna

    2014-06-01

    We study the effect of Earth's dipole tilt angle and interplanetary magnetic field (IMF) Bx and By components on the location of reconnection and the energy conversion at the magnetopause. We simulate southward IMF satisfying both inward- and outward-type Parker spiral conditions during three different dipole tilt angles using a global magnetohydrodynamic model GUMICS-4. We find that positive (negative) Bx contributes to the magnetopause reconnection line location by moving northward (southward) and positive (negative) dipole tilt angle by moving it southward (northward). The tilt shifts the dayside load region toward the winter hemisphere and the summer cusp toward the equatorial plane. Magnetic flux hence piles effectively in the summer hemisphere leading to increased magnetopause currents that enhance the Poynting flux through the magnetopause. We find that the intensity of the energy conversion in the generators is strongly affected by the dipole tilt angle, whereas intensity in the load region is mainly affected by IMF Bx.

  15. Functionalization of graphene for efficient energy conversion and storage.

    PubMed

    Dai, Liming

    2013-01-15

    As global energy consumption accelerates at an alarming rate, the development of clean and renewable energy conversion and storage systems has become more important than ever. Although the efficiency of energy conversion and storage devices depends on a variety of factors, their overall performance strongly relies on the structure and properties of the component materials. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. As a building block for carbon materials of all other dimensionalities (such as 0D buckyball, 1D nanotube, 3D graphite), the two-dimensional (2D) single atomic carbon sheet of graphene has emerged as an attractive candidate for energy applications due to its unique structure and properties. Like other materials, however, a graphene-based material that possesses desirable bulk properties rarely features the surface characteristics required for certain specific applications. Therefore, surface functionalization is essential, and researchers have devised various covalent and noncovalent chemistries for making graphene materials with the bulk and surface properties needed for efficient energy conversion and storage. In this Account, I summarize some of our new ideas and strategies for the controlled functionalization of graphene for the development of efficient energy conversion and storage devices, such as solar cells, fuel cells, supercapacitors, and batteries. The dangling bonds at the edge of graphene can be used for the covalent attachment of various chemical moieties while the graphene basal plane can be modified via either covalent or noncovalent functionalization. The asymmetric functionalization of the two opposite surfaces of individual graphene sheets with different moieties can lead to the self-assembly of graphene sheets into hierarchically structured materials. Judicious application of these site-selective reactions to graphene sheets has opened up a rich field of graphene-based energy materials with enhanced performance in energy conversion and storage. These results reveal the versatility of surface functionalization for making sophisticated graphene materials for energy applications. Even though many covalent and noncovalent functionalization methods have already been reported, vast opportunities remain for developing novel graphene materials for highly efficient energy conversion and storage systems. PMID:23030244

  16. Photovoltaic and photoelectrochemical conversion of solar energy.

    PubMed

    Grtzel, Michael

    2007-04-15

    The Sun provides approximately 100,000 terawatts to the Earth which is about 10000 times more than the present rate of the world's present energy consumption. Photovoltaic cells are being increasingly used to tap into this huge resource and will play a key role in future sustainable energy systems. So far, solid-state junction devices, usually made of silicon, crystalline or amorphous, and profiting from the experience and material availability resulting from the semiconductor industry, have dominated photovoltaic solar energy converters. These systems have by now attained a mature state serving a rapidly growing market, expected to rise to 300 GW by 2030. However, the cost of photovoltaic electricity production is still too high to be competitive with nuclear or fossil energy. Thin film photovoltaic cells made of CuInSe or CdTe are being increasingly employed along with amorphous silicon. The recently discovered cells based on mesoscopic inorganic or organic semiconductors commonly referred to as 'bulk' junctions due to their three-dimensional structure are very attractive alternatives which offer the prospect of very low cost fabrication. The prototype of this family of devices is the dye-sensitized solar cell (DSC), which accomplishes the optical absorption and the charge separation processes by the association of a sensitizer as light-absorbing material with a wide band gap semiconductor of mesoporous or nanocrystalline morphology. Research is booming also in the area of third generation photovoltaic cells where multi-junction devices and a recent breakthrough concerning multiple carrier generation in quantum dot absorbers offer promising perspectives. PMID:17272237

  17. Efficient electrochemical CO2 conversion powered by renewable energy.

    PubMed

    Kauffman, Douglas R; Thakkar, Jay; Siva, Rajan; Matranga, Christopher; Ohodnicki, Paul R; Zeng, Chenjie; Jin, Rongchao

    2015-07-22

    The catalytic conversion of CO2 into industrially relevant chemicals is one strategy for mitigating greenhouse gas emissions. Along these lines, electrochemical CO2 conversion technologies are attractive because they can operate with high reaction rates at ambient conditions. However, electrochemical systems require electricity, and CO2 conversion processes must integrate with carbon-free, renewable-energy sources to be viable on larger scales. We utilize Au25 nanoclusters as renewably powered CO2 conversion electrocatalysts with CO2 ? CO reaction rates between 400 and 800 L of CO2 per gram of catalytic metal per hour and product selectivities between 80 and 95%. These performance metrics correspond to conversion rates approaching 0.8-1.6 kg of CO2 per gram of catalytic metal per hour. We also present data showing CO2 conversion rates and product selectivity strongly depend on catalyst loading. Optimized systems demonstrate stable operation and reaction turnover numbers (TONs) approaching 6 10(6) molCO2 molcatalyst(-1) during a multiday (36 h total hours) CO2 electrolysis experiment containing multiple start/stop cycles. TONs between 1 10(6) and 4 10(6) molCO2 molcatalyst(-1) were obtained when our system was powered by consumer-grade renewable-energy sources. Daytime photovoltaic-powered CO2 conversion was demonstrated for 12 h and we mimicked low-light or nighttime operation for 24 h with a solar-rechargeable battery. This proof-of-principle study provides some of the initial performance data necessary for assessing the scalability and technical viability of electrochemical CO2 conversion technologies. Specifically, we show the following: (1) all electrochemical CO2 conversion systems will produce a net increase in CO2 emissions if they do not integrate with renewable-energy sources, (2) catalyst loading vs activity trends can be used to tune process rates and product distributions, and (3) state-of-the-art renewable-energy technologies are sufficient to power larger-scale, tonne per day CO2 conversion systems. PMID:26121278

  18. Efficient electrochemical CO2 conversion powered by renewable energy

    DOE PAGESBeta

    Kauffman, Douglas R.; Thakkar, Jay; Siva, Rajan; Matranga, Christopher; Ohodnicki, Paul R.; Zeng, Chenjie; Jin, Rongchao

    2015-06-29

    The catalytic conversion of CO2 into industrially relevant chemicals is one strategy for mitigating greenhouse gas emissions. Along these lines, electrochemical CO2 conversion technologies are attractive because they can operate with high reaction rates at ambient conditions. However, electrochemical systems require electricity, and CO2 conversion processes must integrate with carbon-free, renewable-energy sources to be viable on larger scales. We utilize Au25 nanoclusters as renewably powered CO2 conversion electrocatalysts with CO2 → CO reaction rates between 400 and 800 L of CO2 per gram of catalytic metal per hour and product selectivities between 80 and 95%. These performance metrics correspond tomore » conversion rates approaching 0.8–1.6 kg of CO2 per gram of catalytic metal per hour. We also present data showing CO2 conversion rates and product selectivity strongly depend on catalyst loading. Optimized systems demonstrate stable operation and reaction turnover numbers (TONs) approaching 6 × 106 mol CO2 molcatalyst–1 during a multiday (36 hours total hours) CO2electrolysis experiment containing multiple start/stop cycles. TONs between 1 × 106 and 4 × 106 molCO2 molcatalyst–1 were obtained when our system was powered by consumer-grade renewable-energy sources. Daytime photovoltaic-powered CO2 conversion was demonstrated for 12 h and we mimicked low-light or nighttime operation for 24 h with a solar-rechargeable battery. This proof-of-principle study provides some of the initial performance data necessary for assessing the scalability and technical viability of electrochemical CO2 conversion technologies. Specifically, we show the following: (1) all electrochemical CO2 conversion systems will produce a net increase in CO2 emissions if they do not integrate with renewable-energy sources, (2) catalyst loading vs activity trends can be used to tune process rates and product distributions, and (3) state-of-the-art renewable-energy technologies are sufficient to power larger-scale, tonne per day CO2 conversion systems.« less

  19. Photoassisted electrolysis of water - Conversion of optical to chemical energy

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Bolts, J. M.; Kaiser, S. W.; Ellis, A. B.

    1976-01-01

    A description is given of devices, termed photoelectrochemical cells, which can, in principle, be used to directly convert light to fuels and/or electricity. The fundamental principles on which the photoelectrochemical cell is based are related to the observation that irradiation of a semiconductor electrode in an electrochemical cell can result in the flow of an electric current in the external circuit. Attention is given to the basic mechanisms involved, the energy conversion efficiency, the advantages of photoelectrochemical cells, and the results of investigations related to the study of energy conversion via photoelectrochemical cells.

  20. Solar and laser energy conversion with Schottky barrier solar cells

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y.-C. M.

    1974-01-01

    Photovoltaic devices have been fabricated for solar and short-wavelength laser energy conversion using the thin metal film-semiconductor (Schottky barrier) approach. Studies of the metal film optical characteristics and the voltage outputs were emphasized. Air mass zero efficiencies of 8 to 9% in GaAs and laser conversion efficiencies of 25% at 4880 A in GaAs(0.6)P(0.4) are presently measured, with projected efficiencies of 15 and 45%, respectively. The techniques, if applied successfully to semiconductor thin films, could have an impact in solar energy terrestrial application.

  1. Nonadiabatic chemoelectron energy conversion in heterostructures for hydrogen power engineering

    NASA Astrophysics Data System (ADS)

    Grankin, V. P.; Grankin, D. V.

    2015-12-01

    A relationship describing the probability of electron excitation in a solid crystal by the energy of a chemical reaction on its surface has been found. It is established that the probability of electron excitation in this reaction exponentially increases with decreasing energy of electron transition in the solid. A method of nonadiabatic chemoelectron energy conversion in heterostructures for hydrogen power engineering based on Schottky diodes is proposed and the efficiency of this method is calculated.

  2. Advanced energy conversion concept for beamed-energy propulsion

    NASA Astrophysics Data System (ADS)

    Myrabo, Leik N.

    1987-08-01

    Basic research was performed on an innovative power conversion concept for trans atmospheric, beamed energy propulsion: a new class of External Surface Impulse (ESI) thrusters. This advanced thruster principle could be used for atmospheric VTOL, high acceleration, and lateral flight (e.g., short-term cruise) propulsion of Single-Stage-To-Orbit (SSTO) beam-powered shuttlecraft of the next century. Three classes of ESI thrusters were initially examined: (1) simple thermal, (2) electrostatic, and (3) electromagnetic. Beam power wavelengths from 10 cm (microwave) to 0.3 micron (laser) were considered. The subsequent effort concentrated on the simple thermal repetitively-pulsed ESI thrusters, energized with laser power and using air as the working fluid. Laser frequencies were selected because of the relative wealth of experimental data and theoretical research on laser impulse coupling existing in the literature. The first year analytical effort has proven conclusively that such an engine can deliver high levels of thrust-to-beam-power at liftoff (e.g., at least an order of magnitude greater than beam-powered hydrogen-fueled rockets), with infinite specific impulse (decreased only, perhaps, by ablation of the thruster surface). Later along an orbital trajectory, the primary propulsion function would transition to other modes; upon leaving the atmosphere, the SSTO vehicle would continue in a pure rocket mode.

  3. The NASA program in Space Energy Conversion Research and Technology

    NASA Technical Reports Server (NTRS)

    Mullin, J. P.; Flood, D. J.; Ambrus, J. H.; Hudson, W. R.

    1982-01-01

    The considered Space Energy Conversion Program seeks advancement of basic understanding of energy conversion processes and improvement of component technologies, always in the context of the entire power subsystem. Activities in the program are divided among the traditional disciplines of photovoltaics, electrochemistry, thermoelectrics, and power systems management and distribution. In addition, a broad range of cross-disciplinary explorations of potentially revolutionary new concepts are supported under the advanced energetics program area. Solar cell research and technology are discussed, taking into account the enhancement of the efficiency of Si solar cells, GaAs liquid phase epitaxy and vapor phase epitaxy solar cells, the use of GaAs solar cells in concentrator systems, and the efficiency of a three junction cascade solar cell. Attention is also given to blanket and array technology, the alkali metal thermoelectric converter, a fuel cell/electrolysis system, and thermal to electric conversion.

  4. Proceedings of the 25th intersociety energy conversion engineering conference

    SciTech Connect

    Nelson, P.A.; Schertz, W.W.; Till, R.H.

    1990-01-01

    This book contains the proceedings of the 25th Intersociety Energy Conversion Engineering Conference. Volume 5 is organized under the following headings: Photovoltaics I, Photovoltaics II, Geothermal power, Thermochemical conversion of biomass, Energy from waste and biomass, Solar thermal systems for environmental applications, Solar thermal low temperature systems and components, Solar thermal high temperature systems and components, Wind systems, Space power sterling technology Stirling cooler developments, Stirling solar terrestrial I, Stirling solar terrestrial II, Stirling engine generator sets, Stirling models and simulations, Stirling engine analysis, Stirling models and simulations, Stirling engine analysis, Stirling engine loss understanding, Novel engine concepts, Coal conversion and utilization, Power cycles, MHD water propulsion I, Underwater vehicle powerplants - performance, MHD underwater propulsion II, Nuclear power, Update of advanced nuclear power reactor concepts.

  5. Nanostructured semiconductors for thermoelectric energy conversion: Synthesis and transport properties

    NASA Astrophysics Data System (ADS)

    Sahoo, Pranati

    Increasing energy demands and decreasing natural energy resources have sparked search for alternative clean and renewable energy sources. For instance, currently there is a tremendous interest in thermoelectric and photovoltaic solar energy production technologies. Half-Heusler (HH) alloys are among the most popular material systems presently under widespread investigations for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties (thermal conductivity, electrical conductivity, magnetic) of various oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in a HH matrix to reduce the thermal conductivity. Detailed reviews of the past efforts along with the current effort to optimize synthetic routes are presented. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are also discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions and structures coherently embedded inside the half-Heusler matrix. The role of the nanostructures in the regulation of phonon and charge carrier transports within the half-heusler matrix is extensively discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered heterojunctions with a valence band (VB) offset energy at the HH/FH phase boundaries. The resulting energy barrier discriminates existing holes with respect to their energy by trapping low energy holes, while promoting the transport of high energy holes through the VB of the FH-quantum dots. This "carrier culling" results in surprisingly large increase in the mobility and the effective mass of high energy holes contributing to electronic conduction. The simultaneous reduction in the density and the increase in the effective mass of holes resulted in large enhancements of the thermopower, whereas the increase in the mobility minimizes the drop in the electrical conductivity. In the third part, the application of this concept of nanostructuring on the Copper Selenide material system is described. Various synthetic approaches such as liquid assisted solid-state reaction and mechanical alloying are utilized for the fabrication of copper selenide compositions. We found that the mechanical alloying clearly decreases the thermal conductivity of the composition as well increases the Seebeck due to decrease in carrier concentrations.

  6. SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOFC

    SciTech Connect

    Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; H. Skip Mieney

    2003-06-09

    The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with piped-in water (Demonstration System A); and Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from July through December 2002 under Department of Energy Cooperative Agreement DE-FC-02NT41246 for the 5 kW mass-market automotive (gasoline) auxiliary power unit. This report highlights technical results of the work performed under the following tasks for the automotive 5 kW system: Task 1--System Design and Integration; Task 2--Solid Oxide Fuel Cell Stack Developments; Task 3--Reformer Developments; Task 4--Development of Balance of Plant (BOP) Components; Task 5--Manufacturing Development (Privately Funded); Task 6--System Fabrication; and Task 7--System Testing.

  7. A high-efficiency energy conversion system

    SciTech Connect

    Belcher, A.E.

    1996-12-31

    A fundamentally new method for converting pressure into rotative motion is introduced. A historical background is given and an idealized non-turbine Brayton cycle engine and associated equations are described. Salient features are explained, together with suggested applications. Concerns over global warming, unacceptable levels of air pollution, and the need for more efficient utilization of nonrenewable energy resources, are issues which continue to plague us. The situation is further exacerbated by the possibility that underdeveloped countries, under pressure to expand their economies, might adopt power generating systems which could produce high levels of emissions. This scenario could easily develop if equipment, which once complied with stringent standards, failed to be adequately maintained through the absence of a reliable technical infrastructure. The Brayton cycle manometric engine has the potential for eliminating, or at least mitigating, many of the above issues. It is therefore of considerable importance to all populations, irrespective of demographic or economic considerations. This engine is inherently simple--the engine proper has only one moving part. It has no pistons, vanes, or other such conventional occlusive devices, yet it is a positive displacement machine. Sealing is achieved by what can best be described as a series of traveling U-tube manometers. Its construction does not require precision engineering nor the use of exotic materials, making it easy to maintain with the most rudimentary resources. Rotational velocity is low, and its normal life cycle is expected to extend to several decades. These advantages more than offset the machine`s large size. It is suited only to large and medium-scale stationary applications.

  8. Solar Program Assessment: Environmental Factors - Ocean Thermal Energy Conversion.

    ERIC Educational Resources Information Center

    Energy Research and Development Administration, Washington, DC. Div. of Solar Energy.

    This report presents the environmental problems which may arise with the further development of Ocean Thermal Energy Conversion, one of the eight Federally-funded solar technologies. To provide a background for this environmental analysis, the history and basic concepts of the technology are reviewed, as are its economic and resource requirements.…

  9. Experiments to Determine the Efficiency of Various Energy Conversions.

    ERIC Educational Resources Information Center

    Curtis, D.; Goodwin, R. D.

    1980-01-01

    Described are experiments used in the "Physical Science and Man" course at Hartley CAE which enable determinations of efficiencies of two energy conversion processes, namely, electricity into heat and burning gas to produce heat. Activities for comparing the processes are suggested. (DS)

  10. Piezoelectric ribbons printed onto rubber for flexible energy conversion.

    PubMed

    Qi, Yi; Jafferis, Noah T; Lyons, Kenneth; Lee, Christine M; Ahmad, Habib; McAlpine, Michael C

    2010-02-10

    The development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers could yield breakthroughs in implantable or wearable energy harvesting systems. Being electromechanically coupled, piezoelectric crystals represent a particularly interesting subset of smart materials that function as sensors/actuators, bioMEMS devices, and energy converters. Yet, the crystallization of these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers. Here, we overcome these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric nanothick ribbons of lead zirconate titanate from host substrates onto flexible rubbers over macroscopic areas. Fundamental characterization of the ribbons by piezo-force microscopy indicates that their electromechanical energy conversion metrics are among the highest reported on a flexible medium. The excellent performance of the piezo-ribbon assemblies coupled with stretchable, biocompatible rubber may enable a host of exciting avenues in fundamental research and novel applications. PMID:20102189

  11. Research and development on ocean thermal energy conversion in Japan

    SciTech Connect

    Uehara, H.

    1982-08-01

    The study of Ocean Thermal Energy Conversion (OTEC) in Japan has been conducted under the leadership of a team of the ''Sunshine Project'', a national new energy development project promoted by the Ministry of International Trade and Industries (MITI) since 1974. At present, two experimental OTEC power plants -Nauru's OTEC plant and Imari's OTEC plant are operating. In this paper, the review of research and development activity of these two OTEC plants in Japan is made.

  12. Saturation and energy-conversion efficiency of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Tsai, S. T.; Xu, M. J.; Shen, J. W.

    1981-01-01

    A quasi-linear theory is used to study the saturation level of the auroral kilometric radiation. The investigation is based on the assumption that the emission is due to a cyclotron maser instability as suggested by Wu and Lee and Lee et al. The thermodynamic bound on the radiation energy is also estimated separately. The energy-conversion efficiency of the radiation process is discussed. The results are consistent with observations.

  13. Efficient Energy Conversion of the 14 MeV Neutrons in DT Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2013-02-01

    In DT fusion 80 % of the energy released goes into 14 MeV neutrons, and only the remaining 20 % into charged particles. Unlike the charged particles, the uncharged neutrons cannot be confined by a magnetic field, and for this reason cannot be used for a direct conversion into electric energy. Instead, the neutrons have to be slowed down in some medium, heating this medium to a temperature of less than 103 K, with the heat removed from this medium to drive a turbo-generator. This conversion of nuclear into electric energy has a Carnot efficiency of about 30 %. For the 80 % of the energy released into neutrons, the efficiency is therefore no more than 24 %. While this low conversion efficiency cannot be overcome in magnetic confinement concepts, it can be overcome in inertial confinement concepts, by surrounding the inertial confinement fusion target with a sufficiently thick layer of liquid hydrogen and a thin outer layer of boron, to create a hot plasma fire ball. The hydrogen layer must be chosen just thick and dense enough to be heated by the neutrons to 100,000 K. The thusly generated, fully ionized, and rapidly expanding fire ball can drive a pulsed magnetohydrodynamic generator at an almost 100 % Carnot efficiency, or possibly be used to generate hydrocarbons.

  14. Proceedings of the 22nd intersociety energy conversion engineering conference

    SciTech Connect

    Not Available

    1987-01-01

    This book contains 29 sections, each consisting of several papers. Some of the titles are: Advanced Concepts; Aerospace Power Space Requirements and Issues; Space Solar Dynamic Systems I - Energy Conversion; Space Solar Dynamic Systems II - Receivers/Thermal Storage; Space Thermal Systems; Unmanned Space Power Systems; High Power Devices for Space Power Systems; High Power Conversion for Space Power Systems; Large Space Power Systems and Modeling; SP-100 Space Nuclear Power Program; 100 kW Class Nuclear Power Technology; Space Reactor Safety Multimegawatt Space Nuclear Power Systems; Space Power Systems Automation II; Space Power Electronics - Computer Analysis I; Space Power Systems Automation V; and Space Power Electronics.

  15. Advanced materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Vining, Cronin B.; Vandersande, Jan W.; Wood, Charles

    1992-01-01

    A number of refractory semiconductors are under study at the Jet Propulsion Laboratory for application in thermal to electric energy conversion for space power. The main thrust of the program is to improve or develop materials of high figure of merit and, therefore, high conversion efficiencies over a broad temperature range. Materials currently under investigation are represented by silicon-germanium alloys, lanthanum telluride, and boron carbide. The thermoelectric properties of each of these materials, and prospects for their further improvements, are discussed. Continued progress in thermoelectric materials technology can be expected to yield reliable space power systems with double to triple the efficiency of current state of the art systems.

  16. Future of photovoltaic energy conversion in developing countries

    SciTech Connect

    Hogan, S.

    1980-04-01

    Recent studies reveal that photovoltaic energy conversion will be economically viable for usage in developing countries. An overview of programs designed to lower the costs of such conversion systems is presented. Government goals are reviewed, as well as application projects relative to rural usage. A summary of the state-of-the-art in both advanced research and commercially available technology is presented. It is concluded that with the range of the work being done, such systems will be viable for many rural applications within 5 years.

  17. SPS energy conversion and power management workshop. Final report

    SciTech Connect

    Not Available

    1980-06-01

    In 1977 a four year study, the concept Development and Evaluation Program, was initiated by the US Department of Energy and the National Aeronautics and Space Administration. As part of this program, a series of peer reviews were carried out within the technical community to allow available information on SPS to be sifted, examined and, if need be, challenged. The SPS Energy Conversion and Power Management Workshop, held in Huntsville, Alabama, February 5 to 7, 1980, was one of these reviews. The results of studies in this particular field were presented to an audience of carefully selected scientists and engineers. This first report summarizes the results of that peer review. It is not intended to be an exhaustive treatment of the subject. Rather, it is designed to look at the SPS energy conversion and power management options in breadth, not depth, to try to foresee any troublesome and/or potentially unresolvable problems and to identify the most promising areas for future research and development. Topics include photovoltaic conversion, solar thermal conversion, and electric power distribution processing and power management. (WHK)

  18. Thermally driven electrokinetic energy conversion with liquid water microjets

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

    2015-11-01

    A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

  19. Compact magnetic energy storage module

    DOEpatents

    Prueitt, M.L.

    1994-12-20

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.

  20. Compact magnetic energy storage module

    DOEpatents

    Prueitt, Melvin L.

    1994-01-01

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.

  1. Accuracy of magnetic energy computations

    NASA Astrophysics Data System (ADS)

    Valori, G.; Dmoulin, P.; Pariat, E.; Masson, S.

    2013-05-01

    Context. For magnetically driven events, the magnetic energy of the system is the prime energy reservoir that fuels the dynamical evolution. In the solar context, the free energy (i.e., the energy in excess of the potential field energy) is one of the main indicators used in space weather forecasts to predict the eruptivity of active regions. A trustworthy estimation of the magnetic energy is therefore needed in three-dimensional (3D) models of the solar atmosphere, e.g., in coronal fields reconstructions or numerical simulations. Aims: The expression of the energy of a system as the sum of its potential energy and its free energy (Thomson's theorem) is strictly valid when the magnetic field is exactly solenoidal. For numerical realizations on a discrete grid, this property may be only approximately fulfilled. We show that the imperfect solenoidality induces terms in the energy that can lead to misinterpreting the amount of free energy present in a magnetic configuration. Methods: We consider a decomposition of the energy in solenoidal and nonsolenoidal parts which allows the unambiguous estimation of the nonsolenoidal contribution to the energy. We apply this decomposition to six typical cases broadly used in solar physics. We quantify to what extent the Thomson theorem is not satisfied when approximately solenoidal fields are used. Results: The quantified errors on energy vary from negligible to significant errors, depending on the extent of the nonsolenoidal component of the field. We identify the main source of errors and analyze the implications of adding a variable amount of divergence to various solenoidal fields. Finally, we present pathological unphysical situations where the estimated free energy would appear to be negative, as found in some previous works, and we identify the source of this error to be the presence of a finite divergence. Conclusions: We provide a method of quantifying the effect of a finite divergence in numerical fields, together with detailed diagnostics of its sources. We also compare the efficiency of two divergence-cleaning techniques. These results are applicable to a broad range of numerical realizations of magnetic fields. Appendices are available in electronic form at http://www.aanda.org

  2. Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength

    SciTech Connect

    Kim, Eun-Hwa; Johnson, Jay R.; Cairns, Iver H.

    2013-12-15

    Linear mode conversion of Langmuir/z waves to electromagnetic radiation near the plasma and upper hybrid frequency in the presence of density gradients is potentially relevant to type II and III solar radio bursts, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here, we study mode conversion in warm, magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angle, ?, to the ambient magnetic field, B{sub 0}, for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced in various ranges of ? for ?{sub 0} = (?L/c){sup 1/3}(?{sub ce}/?) < 1.5, where ?{sub ce} is the (angular) electron cyclotron frequency, ? is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light; (2) the xR mode is produced most strongly in the range, 40 < ? < 60, for intermediately magnetized plasmas with ?{sub 0} = 1.0 and 1.5, while it is produced over a wider range, 0 ? ? ? 90, for weakly magnetized plasmas with ?{sub 0} = 0.1 and 0.7; (3) the maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%99% and the corresponding energy conversion efficiencies are 5%14% (depending on the adiabatic index ? and ? = T{sub e}/m{sub e}c{sup 2}, where T{sub e} is the electron temperature and m{sub e} is the electron) for various ?{sub 0}; (4) the mode conversion window becomes wider as ?{sub 0} and ? increase. Hence, the results in this paper confirm that linear mode conversion under these conditions can explain the weak total circular polarization of interplanetary type II and III solar radio bursts because a strong xR mode can be generated via linear mode conversion near ? ? 45.

  3. Photon energy conversion efficiency in gamma-ray spectrometry.

    PubMed

    vec, Anton

    2016-01-01

    Photon energy conversion efficiency coefficient is presented as the ratio of total energy registered in the collected spectrum to the emitted photon energy. This parameter is calculated from the conventional gamma-ray histogram and in principle is not affected by coincidence phenomena. This feature makes it particularly useful for calibration and measurement of radionuclide samples at close geometries. It complements the number of efficiency parameters used in gamma-ray spectrometry and can partly change the view as to how the gamma-ray spectra are displayed and processed. PMID:26474210

  4. Energy: A continuing bibliography with indexes, February 1975. [solar energy, energy conversion

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1974 through September 30, 1974 are cited. Regional, national, and international energy systems; research and development on fuels and other sources of energy; energy conversion, transport, transmission, distribution, and storage, with emphasis on the use of hydrogen and solar energy are included along with methods of locating or using new energy resources. Emphasis is placed on energy for heating, lighting, and powering aircraft, surface vehicles, or other machinery.

  5. Wave energy conversion systems:optimal localization offshore Italian coastlines

    NASA Astrophysics Data System (ADS)

    Benassai, Guido; Morucci, Sara

    2010-05-01

    A method for evaluating renewable energy technologies in terms of costs and engineering solutions has been implemented on the Italian coastlines, in order to achieve the optimal localization and choose the best wave energy conversion technology avoiding the transfer of systems suitable for more energetic seas. The Italian coastal wave climate was studied in detail. The study used four years of wave data from 14 sites offshore the Italian coastlines, of which six offshore the coastlines of Sicily and Sardinia, four offshore the Thyrrenian Sea and four offshore the Adriatic Sea. The study resulted in scatter diagrams, and a mapping of the energy flux in each coastal area. The average energy flux was higher for the coastlines of Sardinia and Sicily, lower for the coastlines of the Thyrrenian Sea and even lower for the coastlines of the Adriatic Sea. A comparison between wave energy and offshore wind energy conversion systems was performed in terms of initial cost, maintainance cost and performance, resulting in pay back time between 4 and 8 years depending on the systems. The wave energy farms exhibit a higher load factor than the offshore wind farms (although higher than the land wind plants). Besides, in a number of Italian regions (like Sardinia) offshore wind plants have been banned for their visual impact. On the other hand, the costs of wave power plants are higher and have not yet reached a mature stage, so that they have not yet shown all possible inconveniences. More comprehensive studies have to be performed in order to optimize the mooring technology, the energy transfer on the main land and/or conservation on site, which is an important feature for isles, for which the wave conversion systems seem to be particularly attractive.

  6. Thermoelectric Energy Conversion: Future Directions and Technology Development Needs

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre

    2007-01-01

    This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.

  7. Magnetohydrodynamic energy conversion by using convexly divergent channel

    SciTech Connect

    Murakami, Tomoyuki; Okuno, Yoshihiro

    2009-12-21

    We describe a magnetohydrodynamic (MHD) electrical power generator equipped with a convexly divergent channel, as determined through shock-tunnel-based experiments. The quality of MHD power-generating plasma and the energy conversion efficiency in the convexly divergent channel are compared with those from previous linearly divergent channel. The divergence enhancement in the channel upstream is effective for suppressing an excessive increase in static pressure, whereby notably high isentropic efficiency is achieved.

  8. Thermophotovoltaic energy conversion using photonic bandgap selective emitters

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-06-24

    A method for thermophotovoltaic generation of electricity comprises heating a metallic photonic crystal to provide selective emission of radiation that is matched to the peak spectral response of a photovoltaic cell that converts the radiation to electricity. The use of a refractory metal, such as tungsten, for the photonic crystal enables high temperature operation for high radiant flux and high dielectric contrast for a full 3D photonic bandgap, preferable for efficient thermophotovoltaic energy conversion.

  9. DIRECT ENERGY CONVERSION (DEC) FISSION REACTORS - A U.S. NERI PROJECT

    SciTech Connect

    D. BELLER; G. POLANSKY; ET AL

    2000-11-01

    The direct conversion of the electrical energy of charged fission fragments was examined early in the nuclear reactor era, and the first theoretical treatment appeared in the literature in 1957. Most of the experiments conducted during the next ten years to investigate fission fragment direct energy conversion (DEC) were for understanding the nature and control of the charged particles. These experiments verified fundamental physics and identified a number of specific problem areas, but also demonstrated a number of technical challenges that limited DEC performance. Because DEC was insufficient for practical applications, by the late 1960s most R&D ceased in the US. Sporadic interest in the concept appears in the literature until this day, but there have been no recent programs to develop the technology. This has changed with the Nuclear Energy Research Initiative that was funded by the U.S. Congress in 1999. Most of the previous concepts were based on a fission electric cell known as a triode, where a central cathode is coated with a thin layer of nuclear fuel. A fission fragment that leaves the cathode with high kinetic energy and a large positive charge is decelerated as it approaches the anode by a charge differential of several million volts, it then deposits its charge in the anode after its kinetic energy is exhausted. Large numbers of low energy electrons leave the cathode with each fission fragment; they are suppressed by negatively biased on grid wires or by magnetic fields. Other concepts include magnetic collimators and quasi-direct magnetohydrodynamic generation (steady flow or pulsed). We present the basic principles of DEC fission reactors, review the previous research, discuss problem areas in detail and identify technological developments of the last 30 years relevant to overcoming these obstacles. A prognosis for future development of direct energy conversion fission reactors will be presented.

  10. Energy of magnetic moment of superconducting current in magnetic field

    NASA Astrophysics Data System (ADS)

    Gurtovoi, V. L.; Nikulov, A. V.

    2015-09-01

    The energy of magnetic moment of the persistent current circulating in superconducting loop in an externally produced magnetic field is not taken into account in the theory of quantization effects because of identification of the Hamiltonian with the energy. This identification misleads if, in accordance with the conservation law, the energy of a state is the energy expended for its creation. The energy of magnetic moment is deduced from a creation history of the current state in magnetic field both in the classical and quantum case. But taking this energy into account demolishes the agreement between theory and experiment. Impartial consideration of this problem discovers the contradiction both in theory and experiment.

  11. Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA

    NASA Astrophysics Data System (ADS)

    Liangping, Wang; Mo, Li; Juanjuan, Han; Jian, Wu; Ning, Guo; Aici, Qiu

    2014-06-01

    The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6-1.0 ? in about 10-20 ns.

  12. Numerical Experiments on the Detailed Energy Conversion and Spectrum Studies in a Corona Current Sheet

    NASA Astrophysics Data System (ADS)

    Ni, Lei; Lin, Jun; Mei, Zhixing; Li, Yan

    2015-10-01

    In this paper, we study the energy conversion and spectra in a corona current sheet (CS) by 2.5 dimensional MHD numerical simulations. Numerical results show that many Petschek-like fine structures with slow-mode shocks mediated by plasmoid instabilities develop during the magnetic reconnection process. The termination shocks can also be formed above the primary magnetic island and at the head of secondary islands. These shocks play important roles in generating thermal energy in a corona CS. For a numerical simulation with initial conditions close to the solar corona environment, the ratio of the generated thermal energy to the total dissipated magnetic energy is around 1/5 before secondary islands appear. After secondary islands appear, the generated thermal energy starts to increase sharply and this ratio can reach a value of about 3/5. In an environment with a relatively lower plasma density and plasma ?, the plasma can be heated to a much higher temperature. After secondary islands appear, the one-dimensional energy spectra along the CS do not behave as a simple power law and the spectrum index increases with the wave number. The average spectrum index for the magnetic energy spectrum along the CS is about 1.8. The two-dimensional spectra intuitively show that part of the high energy is cascaded to large kx and ky space after secondary islands appear. The plasmoid distribution function calculated from numerical simulations behaves as a power law closer to f(\\psi ) {\\psi }-1 in the intermediate ? regime. By using {? }{eff}={v}{inflow}\\cdot L, the effective magnetic diffusivity is estimated to be about 1011 1012 m2 s-1.

  13. Transmission and conversion of magnetoacoustic waves on the magnetic canopy in a quiet Sun region

    NASA Astrophysics Data System (ADS)

    Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

    2014-07-01

    Context. We present evidence for the conversion and transmission of wave modes on the magnetic flux tubes that constitute mottles and form the magnetic canopy in a quiet Sun region. Aims: Our aim is to highlight the details and the key parameters of the mechanism that produces power halos and magnetic shadows around the magnetic network observed in H?. Methods: We use our previous calculations of the magnetic field vector and the height of the magnetic canopy, and based on simple assumptions, we determine the turning height, i.e., the height at which the fast magnetoacoustic waves reflect at the chromosphere. We compare the variation of 3, 5, and 7 min power in the magnetic shadow and the power halo with the results of a two-dimensional model on mode conversion and transmission. The key parameter of the model is the attack angle, which is related to the inclination of the magnetic field vector at the canopy height. Our analysis takes also into account that 1) there are projection effects on the propagation of waves; 2) the magnetic canopy and the turning height are curved layers; 3) waves with periods longer than 3 min only reach the chromosphere in the presence of inclined magnetic fields (ramp effect); 4) mottles in H? are canopy structures; and 5) the wings of H? contain mixed signal from low- and high-? plasma. Results: The dependence of the measured power on the attack angle follows the anticipated by the two-dimensional model very well. Long-period slow waves are channeled to the upper chromospheric layers following the magnetic field lines of mottles, while short-period fast waves penetrate the magnetic canopy and are reflected back higher, at the turning height. Conclusions: Although both magnetoacoustic modes contribute to velocity signals, making the interpretation of observations a challenging task, we conclude that conversion and transmission of the acoustic waves into fast and slow magnetoacoustic waves are responsible for forming power halos and magnetic shadows in the quiet Sun region.

  14. Investigation of direct solar-to-microwave energy conversion techniques

    NASA Technical Reports Server (NTRS)

    Chatterton, N. E.; Mookherji, T. K.; Wunsch, P. K.

    1978-01-01

    Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.

  15. Nanostructured transition metal oxides for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Li, Qiang

    Lithium-ion batteries, supercapacitors and photovoltaic devices have been widely considered as the three major promising alternatives of fossil fuels facing upcoming depletion to power the 21th century. The conventional film configuration of electrochemical electrodes hardly fulfills the high energy and efficiency requirements because heavy electroactive material deposition restricts ion diffusion path, and lowers power density and fault tolerance. In this thesis, I demonstrate that novel nanoarchitectured transition metal oxides (TMOs), e.g. MnO2, V2O 5, and ZnO, and their relevant nanocomposites were designed, fabricated and assembled into devices to deliver superior electrochemical performances such as high energy and power densities, and rate capacity. These improvements could be attributed to the significant enhancement of surface area, shortened ion diffusion distances and facile penetration of electrolyte solution into open structures of networks as well as to the pseudocapacitance domination. The utilization of ForcespinningRTM, a newly developed nanofiber processing technology, for large-scale energy storage and conversion applications is emphasized. This process simplifies the tedious multi-step hybridization synthesis and facilitates the contradiction between the micro-batch production and the ease of large-scale manufacturing. Key Words: Transition metal oxides, energy storage and conversion, ForcespinningRTM, pseudocapacitance domination, high rate capacity

  16. Surface conversion techniques for low energy neutral atom imagers

    NASA Technical Reports Server (NTRS)

    Quinn, J. M.

    1995-01-01

    This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

  17. Explorations of Novel Energy Conversion and Storage Systems

    NASA Astrophysics Data System (ADS)

    Duffin, Andrew Mark

    At present, the majority of the world's energy demand is met by the consumption of exhaustible fuel supplies. Consequently, it is urgent to research and develop viable alternatives. In this dissertation, I present research that addresses fundamental questions concerning how water interacts with surfaces and solutes, with the goal of identifying novel systems for energy production and storage. Electrokinetic currents are created when moving fluid entrains charge from the diffuse portion of an electric double layer and carries that charge downstream. The potential difference that develops on either end of the channel is known as the streaming potential. Chapter 2 of this dissertation focuses on electrokinetic energy production and conversion efficiency of liquid microjets. Section 1 of Chapter 2 presents proof-of-principle research demonstrating that molecular hydrogen is generated from electrokinetic currents in liquid water microjets. Hydrogen is generated when hydrated protons are preferentially carried downstream and recombine with electrons at a grounded target electrode. Both the current and hydrogen production scale nearly quadratically with flow rate, as predicted by equations derived from simple double layer theory and fluid mechanics. The efficiency is currently very low (ca 10-6) and is limited by the low electrokinetic current (nA). Designs to improve this efficiency are considered. Rather than chemical conversion efficiency, Section 2 of Chapter 2 investigates the electrical conversion efficiency of liquid water microjets. Typical electrokinetic energy conversion schemes measure current or voltage via electrodes in the fluid reservoirs on either side of a channel. With this design, the streaming potential drives a current against the flow of the fluid and, consequently, limits the conversion efficiency. In contrast, liquid microjets break up into droplets before reaching the downstream electrode and this eliminates the possibility for back conduction. As a result, liquid microjets yield conversion efficiencies exceeding 10%, much larger than channel-dependent measurements (3%). It is the large potentials obtainable with electrokinetic currents (tens of kilovolts) that drive up the electrical conversion efficiency. Unfortunately, low currents with high voltages are inconvenient for application. Section 3 of Chapter 2 describes efforts to utilize the high voltage of electrokinetic currents by coupling light into the process. More specifically, the streaming potential is used to modify the space charge layer in a semiconductor and, consequently, the light harvesting characteristics of that semiconductor. To this end, microchannel jets fabricated out of glass and silicon were built to allow light to impinge on the current generating surface. Although plagued with inconsistent results, streaming currents were found to increase upon illumination and some channels even gave measurable responses to ambient room lights. Chapter 3 of this dissertation addresses the details of hydration of boron-oxides and sodium borohydride as studied by near edge x-ray absorption fine structure spectroscopy (NEXAFS) and associated theory. Boron-oxides and molecular hydrogen are products of borohydride hydrolysis which has been intensely studied for hydrogen storage purposes. In spite of their hydroxide moieties, boron-oxides turn out to not be strongly hydrated by water. The experimental spectra, as well as attending calculations, show no evidence for electronic coupling that would indicate strong hydrogen bonding between the boron-oxides and water. On the other hand, the NEXAFS spectrum of sodium borohydride is significantly altered by water. The experiment and calculations show strong evidence for short dihydrogen bonds between water hydrogens and borohydride hydrogens. Molecular dynamics simulations indicate that borohydride is hydrated at the tetrahedral corners and edge.

  18. Renewable energy from corn residues by thermochemical conversion

    NASA Astrophysics Data System (ADS)

    Yu, Fei

    Declining fossil oil reserve, skyrocket price, unsecured supplies, and environment pollution are among the many energy problems we are facing today. It is our conviction that renewable energy is a solution to these problems. The long term goal of the proposed research is to develop commercially practical technologies to produce energy from renewable resources. The overall objective of my research is to study and develop thermochemical processes for converting bulky and low-energy-density biomass materials into bio-fuels and value-added bio-products. The rationale for the proposed research is that, once such processes are developed, processing facility can be set up on or near biomass product sites, reducing the costs associated with transport of bulky biomass which is a key technical barrier to biomass conversion. In my preliminary research, several conversion technologies including atmospheric pressure liquefaction, high pressure liquefaction, and microwave pyrolysis have been evaluated. Our data indicated that microwave pyrolysis had the potential to become a simple and economically viable biomass conversion technology. Microwave pyrolysis is an innovative process that provides efficient and uniform heating, and are robust to type, size and uniformity of feedstock and therefore suitable for almost any waste materials without needing to reduce the particle size. The proposed thesis focused on in-depth investigations of microwave pyrolysis of corn residues. My first specific aim was to examine the effects of processing parameters on product yields. The second specific research aim was to characterize the products (gases, bio-oils, and solid residues), which was critical to process optimization and product developments. Other research tasks included conducting kinetic modeling and preliminary mass and energy balance. This study demonstrated that microwave pyrolysis could be optimized to produce high value syngas, liquid fuels and pyrolytic carbons, and had a great potential to become a commercial process according to the mass and energy balance. One-step global model and two-step consecutive-reaction kinetic model offered a clue to the key mechanistic steps in the overall pyrolysis of corn residues. These results should have a positive impact on advancing renewable energy technologies and establishing the University's leadership status in the area of renewable energy development.

  19. Quantum coherence in photosynthesis for efficient solar-energy conversion

    NASA Astrophysics Data System (ADS)

    Romero, Elisabet; Augulis, Ramunas; Novoderezhkin, Vladimir I.; Ferretti, Marco; Thieme, Jos; Zigmantas, Donatas; van Grondelle, Rienk

    2014-09-01

    The crucial step in the conversion of solar to chemical energy in photosynthesis takes place in the reaction centre, where the absorbed excitation energy is converted into a stable charge-separated state by ultrafast electron transfer events. However, the fundamental mechanism responsible for the near-unity quantum efficiency of this process is unknown. Here we elucidate the role of coherence in determining the efficiency of charge separation in the plant photosystem II reaction centre by comprehensively combining experiment (two-dimensional electronic spectroscopy) and theory (Redfield theory). We reveal the presence of electronic coherence between excitons as well as between exciton and charge-transfer states that we argue to be maintained by vibrational modes. Furthermore, we present evidence for the strong correlation between the degree of electronic coherence and efficient and ultrafast charge separation. We propose that this coherent mechanism will inspire the development of new energy technologies.

  20. Solar energy conversion by dye-sensitized photovoltaic cells.

    PubMed

    Grtzel, Michael

    2005-10-01

    The quality of human life depends to a large degree on the availability of energy. This is threatened unless renewable energy resources can be developed in the near future. Chemistry is expected to make important contributions to identify environmentally friendly solutions of the energy problem. One attractive strategy discussed in this Forum Article is the development of solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots. These systems have already reached conversion efficiencies exceeding 11%. The underlying fundamental processes of light harvesting by the sensitizer, heterogeneous electron transfer from the electronically excited chromophore into the conduction band of the semiconductor oxide, and percolative migration of the injected electrons through the mesoporous film to the collector electrode will be described below in detail. A number of research topics will also be discussed, and the examples for the first outdoor application of such solar cells will be provided. PMID:16180840

  1. Quantum Coherence in Photosynthesis for Efficient Solar Energy Conversion

    PubMed Central

    Romero, Elisabet; Augulis, Ramunas; Novoderezhkin, Vladimir I.; Ferretti, Marco; Thieme, Jos; Zigmantas, Donatas; van Grondelle, Rienk

    2014-01-01

    The crucial step in the conversion of solar to chemical energy in Photosynthesis takes place in the reaction center where the absorbed excitation energy is converted into a stable charge separated state by ultrafast electron transfer events. However, the fundamental mechanism responsible for the near unity quantum efficiency of this process is unknown. Here we elucidate the role of coherence in determining the efficiency of charge separation in the plant photosystem II reaction centre (PSII RC) by comprehensively combining experiment (two-dimensional electronic spectroscopy) and theory (Redfield theory). We reveal the presence of electronic coherence between excitons as well as between exciton and charge transfer states which we argue to be maintained by vibrational modes. Furthermore, we present evidence for the strong correlation between the degree of electronic coherence and efficient and ultrafast charge separation. We propose that this coherent mechanism will inspire the development of new energy technologies.

  2. ALD for Clean Energy Conversion, Utilization, and Storage

    SciTech Connect

    Elam, Jeffrey W.; Dasgupta, Neil P.; Prinz, Fritz B.

    2011-11-18

    Atomic layer deposition (ALD) uses self-limiting chemical reactions between gaseous precursors and a solid surface to deposit materials in a layer-by-layer fashion. This process results in a unique combination of attributes, including sub-nm precision, the capability to engineer surfaces and interfaces, and unparalleled conformality over high-aspect ratio and nanoporous structures. Given these capabilities, ALD could play a central role in achieving the technological advances necessary to redirect our economy from fossil-based energy to clean, renewable energy. This article will survey some of the recent work applying ALD to clean energy conversion, utilization, and storage, including research in solid oxide fuel cells, thin-film photovoltaics, lithium-ion batteries, and heterogenous catalysts. Throughout the manuscript, we will emphasize how the unique qualities of ALD can enhance device performance and enable radical new designs.

  3. Progress and Perspectives of Plasmon-Enhanced Solar Energy Conversion.

    PubMed

    Cushing, Scott K; Wu, Nianqiang

    2016-02-18

    Plasmonics allows extraordinary control of light, making it attractive for application in solar energy harvesting. In metal-semiconductor heterojunctions, plasmons can enhance photoconversion in the semiconductor via three mechanisms, including light trapping, hot electron/hole transfer, and plasmon-induced resonance energy transfer (PIRET). To understand the plasmonic enhancement, the metal's geometry, constituent metal, and interface must be viewed in terms of the effects on the plasmon's dephasing and decay route. To simplify design of plasmonic metal-semiconductor heterojunctions for high-efficiency solar energy conversion, the parameters controlling the plasmonic enhancement can be distilled to the dephasing time. The plasmonic geometry can then be further refined to optimize hot carrier transfer, PIRET, or light trapping. PMID:26817500

  4. Transition Metal Nitrides for Electrocatalytic Energy Conversion: Opportunities and Challenges.

    PubMed

    Xie, Junfeng; Xie, Yi

    2016-03-01

    Electrocatalytic energy conversion has been considered as one of the most efficient and promising pathways for realizing energy storage and energy utilization in modern society. To improve electrocatalytic reactions, specific catalysts are needed to lower the overpotential. In the search for efficient alternatives to noble metal catalysts, transition metal nitrides have attracted considerable interest due to their high catalytic activity and unique electronic structure. Over the past few decades, numerous nitride-based catalysts have been explored with respect to their ability to drive various electrocatalytic reactions, such as the hydrogen evolution reaction and the oxygen evolution reaction to achieve water splitting and the oxygen reduction reaction coupled with the methanol oxidation reaction to construct fuel cells or rechargeable Li-O2 batteries. This Minireview provides a brief overview of recent progress on electrocatalysts based on transition metal nitrides, and outlines the current challenges and future opportunities. PMID:26494184

  5. Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage.

    PubMed

    Kalyanasundaram, K; Graetzel, M

    2010-06-01

    Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO(2) in the form of sugars. These are achieved through a series of light-induced multi-electron-transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO(2) in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H(2) and O(2), photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO(2) to fuels such as methanol and methane are reviewed here. PMID:20439158

  6. Electrical System for Home Conversion and Storage of Solar Energy.

    PubMed

    Giacoletto, L J

    1959-10-01

    Energy storage has long been a problem in connection with home utilization of solar energy. A solution which utilizes solar semiconductor cells for conversion to d-c power is proposed. The d-c power is used to drive an alternator which is connected directly across the residential power lines. Thus a-c power is delivered to the power lines when a surplus of power is available in the home and is used in other parts of the power distribution system. At latitude 42 degrees N there is 3 times more yearly energy recoverable than is used by an average residence on the basis of a 10-by-10-m collection area. At the present state of technical development the cost of such a large-area semiconductor solar cell would be prohibitive. PMID:17732892

  7. Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

    NASA Technical Reports Server (NTRS)

    Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.

    2012-01-01

    Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

  8. Nanostructured solar irradiation control materials for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Kang, Jin Ho; Marshall, Iseley A.; Torrico, Mattew N.; Taylor, Chase R.; Ely, Jeffry; Henderson, Angel; Sauti, Godfrey; Gibbons, Luke J.; Kim, Jae-Woo; Park, Cheol; Lowther, Sharon E.; Lillehei, Peter T.; Bryant, Robert G.

    2012-10-01

    Tailoring the solar absorptivity (?s) and thermal emissivity (?T) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The ?s and ?T were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the ?s and ?T by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

  9. Visible light to electrical energy conversion using photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, Mark S. (Inventor); Ellis, Arthur B. (Inventor); Kaiser, Steven W. (Inventor)

    1983-01-01

    Sustained conversion of low energy visible or near i.r. light (>1.25 eV) to electrical energy has been obtained using wet photoelectrochemical cells where there are no net chemical changes in the system. Stabilization of n-type semi-conductor anodes of CdS, CdSe, CdTe, GaP, GaAs and InP to photoanodic dissolution is achieved by employing selected alkaline solutions of Na.sub.2 S, Na.sub.2 S/S, Na.sub.2 Se, Na.sub.2 Se/Se, Na.sub.2 Te and Na.sub.2 Te/Te as the electrolyte. The oxidation of (poly) sulfide, (poly)selenide or (poly)telluride species occurs at the irradiated anode, and reduction of polysulfide, polyselenide or polytelluride species occurs at the dark Pt cathode of the photoelectrochemical cell. Optical to electrical energy conversion efficiencies approaching 15% at selected frequencies have been observed in some cells. The wavelength for the onset of photocurrent corresponds to the band gap of the particular anode material used in the cell.

  10. Carbon dioxide release from ocean thermal energy conversion (OTEC) cycles

    SciTech Connect

    Green, H.J. ); Guenther, P.R. )

    1990-09-01

    This paper presents the results of recent measurements of CO{sub 2} release from an open-cycle ocean thermal energy conversion (OTEC) experiment. Based on these data, the rate of short-term CO{sub 2} release from future open-cycle OTEC plants is projected to be 15 to 25 times smaller than that from fossil-fueled electric power plants. OTEC system that incorporate subsurface mixed discharge are expected to result in no long-term release. OTEC plants can significantly reduce CO{sub 2} emissions when substituted for fossil-fueled power generation. 12 refs., 4 figs., 3 tabs.

  11. Quantitative analysis of a wind energy conversion model

    NASA Astrophysics Data System (ADS)

    Zucker, Florian; Gräbner, Anna; Strunz, Andreas; Meyn, Jan-Peter

    2015-03-01

    A rotor of 12 cm diameter is attached to a precision electric motor, used as a generator, to make a model wind turbine. Output power of the generator is measured in a wind tunnel with up to 15 m s-1 air velocity. The maximum power is 3.4 W, the power conversion factor from kinetic to electric energy is cp = 0.15. The v3 power law is confirmed. The model illustrates several technically important features of industrial wind turbines quantitatively.

  12. Advanced solar energy conversion. [solar pumped gas lasers

    NASA Technical Reports Server (NTRS)

    Lee, J. H.

    1981-01-01

    An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.

  13. Low cost composite materials for wind energy conversion systems

    NASA Astrophysics Data System (ADS)

    Weingart, O.

    1980-06-01

    A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).

  14. Photovoltaic and thermal energy conversion for solar powered satellites

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    A summary is provided concerning the most important aspects of present investigations related to a use of solar power satellites (SPS) as a future source of terrestrial energy. General SPS characteristics are briefly considered, early work is reviewed, and a description of current investigations is presented. System options presently under study include a photovoltaic array, a thermionic system, and a closed Brayton cycle. Attention is given to system reference options, basic building blocks, questions of system analysis and engineering, photovoltaic conversion, and the utility interface. It is concluded that an SPS may be cost effective compared to terrestrial systems by 1995.

  15. Analysis of dynamic effects in solar thermal energy conversion systems

    NASA Technical Reports Server (NTRS)

    Hamilton, C. L.

    1978-01-01

    The paper examines a study the purpose of which is to assess the performance of solar thermal power systems insofar as it depends on the dynamic character of system components and the solar radiation which drives them. Using a dynamic model, the daily operation of two conceptual solar conversion systems was simulated under varying operating strategies and several different time-dependent radiation intensity functions. These curves ranged from smoothly varying input of several magnitudes to input of constant total energy whose intensity oscillated with periods from 1/4 hour to 6 hours.

  16. Method and apparatus for testing electrochemical energy conversion devices

    NASA Technical Reports Server (NTRS)

    Cisar, Alan J. (Inventor); Murphy, Oliver J. (Inventor)

    1996-01-01

    A system for testing electrochemical energy conversion and storage devices includes means for sensing the current from the storage device and varying the load across the storage device in response to the current sensed. The system is equally adaptable to batteries and fuel cells. Means is also provided to sense system parameters from a plurality of locations within the system. Certain parameters are then stored in digital form for archive purposes and certain other parameters are used to develop control signals in a host processor.

  17. Low cost composite materials for wind energy conversion systems

    NASA Technical Reports Server (NTRS)

    Weingart, O.

    1980-01-01

    A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).

  18. Environmental programs for Ocean Thermal Energy Conversion (OTEC)

    NASA Astrophysics Data System (ADS)

    Wilde, P.

    1981-07-01

    The ocean thermal energy conversion (OTEC) which provides documented information on the effect of proposed operations on the ocean and the effect of oceanic conditions on the plant is discussed. The associated environment program consists of archival studies in potential areas serial oceanographic cruises to sites or regions of interest, studies from various fixed platforms at sites, and compilation of such information for appropriate legal compliance and permit requirements and for use in progressive design of OTEC plants. Four classes of environmental concerns are identified: (1) redistribution of oceanic properties; (2) chemical pollution; (3) structural effects and (4) socio-legal economic.

  19. Conversion of magnetic anisotropy in electrodeposited Co-Ni alloy nanowires

    NASA Astrophysics Data System (ADS)

    Samardak, A. S.; Nasirpouri, F.; Nadi, M.; Sukovatitsina, E. V.; Ognev, A. V.; Chebotkevich, L. A.; Komogortsev, S. V.

    2015-06-01

    In this paper, the influence of alternating current (ac) electrodeposition frequency and waveform is reported on chemical composition, microstructure and consequently magnetic properties of Co-Ni binary alloy nanowire arrays embedded in an alumina template. For sinusoidal and square electrodeposition waveforms the easy axis of magnetization rotates from being parallel to perpendicular orientation to nanowire long axis as the deposition frequency increases from 200 to 800 Hz. The reason for the drastic change of magnetic anisotropy in nanowires is attributed to the increase of cobalt content and the crystal structure phase transformation from fcc-hcp mixture at high Ni content to hcp at high Co content. We explain the conversion of magnetic behavior of nanowire arrays in terms of a competition between the shape and magnetocrystalline anisotropies.

  20. Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance

    SciTech Connect

    Mamone, Salvatore Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H.; Lei, Xuegong; Li, Yongjun; Goh, Kelvin; Horsewill, Anthony J.

    2014-05-21

    The water-endofullerene H{sub 2}O@C{sub 60} provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H{sub 2}O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H{sub 2}O molecules is catalysed by {sup 13}C nuclei present in the cages.

  1. Kinetic simulation of the O-X conversion process in dense magnetized plasmas

    SciTech Connect

    Ali Asgarian, M.; Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 ; Verboncoeur, J. P.; Parvazian, A.; Trines, R.

    2013-10-15

    One scheme for heating a dense magnetized plasma core, such as in a tokamak, involves launching an ordinary (O) electromagnetic wave at the low density edge. It is converted to a reflected extraordinary (X) electromagnetic wave under certain conditions, and then transformed into an electron Bernstein wave able to reach high density regions inaccessible to most other waves. The O-X mode conversion is important in heating and diagnostic processes in different devices such as tokamaks, stellarators, and some types of pinches. The goal of this study has been to demonstrate that the kinetic particle-in-cell (PIC) scheme is suitable for modeling the O-X conversion process as the first step toward a more complete simulation of O-X-B heating. The O-X process is considered and simulated with a kinetic particle model for parameters of the TJ-II stellarator using the PIC code, XOOPIC. This code is able to model the non-monotonic density and the magnetic profile of the TJ-II stellarator. It can also statistically represent the self-consistent distribution function of the plasma, which has not been possible in previous fluid models. By considering the electric and magnetic components of launched and reflected waves, the O-mode and X-mode waves can be detected, and the O-X conversion can be demonstrated. In this work, the optimum angle for conversion efficiency, as predicted by the previous theory and experimentally confirmed, is used. Via considering the power of the launched O-mode wave and the converted X-mode wave, the efficiency of 63% for O-X conversion for the optimum theoretical launch angle of 47{sup ?} is obtained, which is in good agreement with efficiencies computed via full-wave simulations.

  2. Conversion of relic gravitational waves into photons in cosmological magnetic fields

    SciTech Connect

    Dolgov, Alexander D.; Ejlli, Damian E-mail: ejlli@fe.infn.it

    2012-12-01

    Conversion of gravitational waves into electromagnetic radiation is discussed. The probability of transformations of gravitons into photons in presence of cosmological background magnetic field is calculated at the recombination epoch and during subsequent cosmological stages. The produced electromagnetic radiation is concentrated in the X-ray part of the spectrum. It is shown that if the early Universe was dominated by primordial black holes (PBHs) prior to Big Bang Nucleosynthesis (BBN), the relic gravitons emitted by PBHs would transform to an almost isotropic background of electromagnetic radiation due to conversion of gravitons into photons in cosmological magnetic fields. Such extragalactic radiation could be noticeable or even dominant component of Cosmic X-ray Background.

  3. Protection of NdFeB magnets by corrosion resistance phytic acid conversion film

    NASA Astrophysics Data System (ADS)

    Nan, Haiyang; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2015-11-01

    Phytic acid conversion film was prepared on NdFeB magnets by dipping the NdFeB into phytic acid solution. The morphology, composition, structure and corrosion resistance of the film were systematically investigated. The results showed that the phytic acid film was effective in improving the corrosion resistance of NdFeB magnets. XRD, TEM and FT-IR analyses revealed that the film was amorphous and had a strong peak of phosphate radical (PO43-). The formation mechanism of the film was also explored by XPS and the potential of zero charge (Epzc) measurement at the solution-metal interface.

  4. Excitation of kinetic Alfven waves by resonant mode conversion and longitudinal heating of magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Tanaka, Motohiko; Sato, Tetsuya; Hasegawa, A.

    1989-01-01

    The excitation of the kinetic Alfven wave by resonant mode conversion and longitudinal heating of the plasma by the kinetic Alfven wave were demonstrated on the basis of a macroscale particle simulation. The longitudinal electron current was shown to be cancelled by the ions. The kinetic Alfven wave produced an ordered motion of the plasma particles in the wave propagation direction. The electrons were pushed forward along the ambient magnetic field by absorbing the kinetic Alfven wave through the Landau resonance.

  5. Energy and data conversion circuits for low power sensory systems

    NASA Astrophysics Data System (ADS)

    Ghosh, Suvradip

    This dissertation focuses on the problem of increasing the lifetime of wireless sensors. This problem is addressed from two different angles: energy harvesting and data compression. Energy harvesting enables a sensor to extract energy from its environment and use it to power itself or recharge its batteries. Data compression, on the other hand, allows a sensor to save energy by reducing the radio transmission bandwidth. This dissertation proposes a fractal-based photodiode fabricated on standard CMOS process as an energy harvesting device with increased efficiency. Experiments show that, the fractal based photodiodes are 6% more efficient compared to the conventional square shaped photodiode. The fractal shape photodiode has more perimeter-to-area ratio which increases the lateral response, improving its efficiency. With increased efficiency, more current is generated but the open-circuit voltage still remains low (0.3V--0.45V depending on illumination condition). These voltages have to be boosted up to higher values if they are going to be used to power up any sensory circuit or recharge a battery. We propose a switched-inductor DC-DC converter to boost the low voltage of the photodiodes to higher voltages. The proposed circuit uses two on-chip switches and two off-chip Components: an inductor and a capacitor. Experiments show a voltage up to 2.81V can be generated from a single photodiode of 1mm2 area. The voltage booster circuit achieved a conversion efficiency of 59%. Data compression was also explored in an effort to reduce energy consumption during radio transmission. An analog-to-digital converter (ADC), which can jointly perform the tasks of digital conversion and entropy encoding, has also been proposed in this dissertation. The joint data conversion/compression help savings in area and power resources, making it suitable for on-sensor compression. The proposed converter combines a cyclic converter architecture and Golomb-Rice entropy encoder. The converter hardware design is based on current-mode circuits and it was fabricated on a 0.5 mum CMOS process and tested. Experiment results show a lossless compression ratio of 1.52 and a near-lossless compression of 5.2 can be achieved for 32 x 32 pixel image.

  6. Plasmon-induced resonance energy transfer for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Li, Jiangtian; Cushing, Scott K.; Meng, Fanke; Senty, Tess R.; Bristow, Alan D.; Wu, Nianqiang

    2015-09-01

    In Frster resonance energy transfer (FRET), energy non-radiatively transfers from a blue-shifted emitter to a red-shifted absorber by dipole-dipole coupling. This study shows that plasmonics enables the opposite transfer direction, transferring the plasmonic energy towards the short-wavelength direction to induce charge separation in a semiconductor. Plasmon-induced resonance energy transfer (PIRET) differs from FRET because of the lack of a Stoke's shift, non-local absorption effects and a strong dependence on the plasmon's dephasing rate and dipole moment. PIRET non-radiatively transfers energy through an insulating spacer layer, which prevents interfacial charge recombination losses and dephasing of the plasmon from hot-electron transfer. The distance dependence of dipole-dipole coupling is mapped out for a range of detuning across the plasmon resonance. PIRET can efficiently harvest visible and near-infrared sunlight with energy below the semiconductor band edge to help overcome the constraints of band-edge energetics for single semiconductors in photoelectrochemical cells, photocatalysts and photovoltaics.

  7. Nitride metal - semiconductor superlattices for solid state thermionic energy conversion

    NASA Astrophysics Data System (ADS)

    Wortman, Robert David

    With the current energy crisis, efficiency of thermal systems is becoming ever more important. Furthermore, as the cost of energy goes up, methods to increase efficiencies of these systems become more and more cost-effective. Waste heat from engines and power plants is a readily available source of energy that, for the most part, is not being used. Using this waste heat therefore represents the easiest method for energy recovery and generation and can result in a higher overall system efficiency. The research is focused on the direct conversion of waste heat (and in some niche applications, non-waste heat) into electricity. The method for conversion, however, differs from that of standard thermoelectric generators. Thermoelectrics tend to be homogenous materials, typically semiconductors. In contrast, the non-homogenous solid state thermionic emission device uses a layered structure of metals and semiconductors with nanometer-scale layer thicknesses. By using this structure, thermal conductivity is greatly reduced as compared to the constituent materials by means of interface scattering. In addition, if ballistic transport across the semiconductor layer can be realized, the energy in the electrons is preserved, resulting in an increased Seebeck Coecient. By these methods, the figure of merit of our devices (ZT) has been shown in theory to be much higher than currently reported devices at the temperature of interest (900 K). To this end, superlattices of ZrN/ScN and HfN/ScN have been grown via reactive D.C. magnetron sputtering. Characterization of the grown lms has been carried out using X-ray diffraction, SEM and TEM. In addition, the initial development of testing structures has been carried out. The creation of these structures using photolithography as well as wet and dry etching techniques is in the preliminary stages.

  8. Development of a high-energy distributed energy source electromagnetic railgun with improved energy conversion efficiency

    SciTech Connect

    Tower, M.M.; Haight, C.H.

    1984-03-01

    Vought Corporation in cooperation with the Center for Electromechanics at the University of Texas (CEM-UT) has developed under sponsorship by the Defense Advanced Research Projects Agency (DARPA) and the Army Armament, Munitions, and Chemical Command (AMCCOM) a high-energy distributed energy source (DES) electromagnetic (EM) railgun accelerator. This paper discusses the development and current status of the DES railgun which has the design capability to launch projectile masses up to 60 grams to the 3-4 km/sec velocity regime with energy conversion efficiencies above 35 percent. These goals are being accomplished through utilization of scaled-energy CEM-UT railgun experiments for sequenced timing/staging and a full energy (575 kJ) design at Vought for high efficiency capability. The operational Vought single-pulse railgun forms the baseline for the full energy testing.

  9. Lagrangian description of energy conversion in the Taconis oscillations

    NASA Astrophysics Data System (ADS)

    Ishii, K.; Adachi, S.; Hayashi, H.; Menshov, I.

    2015-10-01

    Energy conversion in the Taconis oscillations is studied from the Lagrangian point of view. Numerical simulations are performed for the spontaneous thermoacoustic oscillations of helium gas which are observed in a tube with a strong temperature gradient along the tube axis. Flow fields in a closed straight cylindrical tube are obtained by solving the axisymmetric compressible Navier-Stokes equations. The amount of net work done by each fluid particle during one period is estimated for the fundamental mode as well as the second mode. In the second mode, moving fluid particles in the region of finite temperature gradient perform work, and those near the tube end walls absorb work. Almost no net work is done by fluid particles in the region of the tube center. Displacement of fluid particles is large in the fundamental mode, while fluid particles move in the vicinity of their starting points in the second mode. In the fundamental mode, pressure amplitudes are larger than other cases and the oscillation of the temperature in the tube is large. Both in the region of finite temperature gradient and in the region of the tube center, fluid particles are concerned with energy conversion in the fundamental mode oscillation.

  10. Naval facility energy conversion plants as resource recovery system components

    NASA Astrophysics Data System (ADS)

    Capps, A. G.

    1980-01-01

    This interim report addresses concepts for recovering energy from solid waste by using Naval facilities steam plants as principle building blocks of candidate solid waste/resource recovery systems at Navy installations. The major conclusions of this portion of the project are: although it is technically feasible to adapt Navy energy conversion systems to fire Waste Derived Fuels (WDF) in one or more of its forms, the optimal form selected should be a site-specific total system; near- to intermediate-term programs should probably continue to give first consideration to waterwall incinerators and to the cofiring of solid WDF in coal-capable plants; package incinerators and conversions of oil burning plants to fire a fluff form of solid waste fuel may be the options with the greatest potential for the intermediate term because waterwalls would be uneconomical in many small plants and because the majority of medium-sized oil-burning plants will not be converted to burn coal; and pyrolytic processes to produce gaseous and liquid fuels have not been sufficiently developed as yet to be specified for commerical operation.

  11. Wind energy conversion system analysis model (WECSAM) computer program documentation

    SciTech Connect

    Downey, W T; Hendrick, P L

    1982-07-01

    Described is a computer-based wind energy conversion system analysis model (WECSAM) developed to predict the technical and economic performance of wind energy conversion systems (WECS). The model is written in CDC FORTRAN V. The version described accesses a data base containing wind resource data, application loads, WECS performance characteristics, utility rates, state taxes, and state subsidies for a six state region (Minnesota, Michigan, Wisconsin, Illinois, Ohio, and Indiana). The model is designed for analysis at the county level. The computer model includes a technical performance module and an economic evaluation module. The modules can be run separately or together. The model can be run for any single user-selected county within the region or looped automatically through all counties within the region. In addition, the model has a restart capability that allows the user to modify any data-base value written to a scratch file prior to the technical or economic evaluation. Thus, any user-supplied data for WECS performance, application load, utility rates, or wind resource may be entered into the scratch file to override the default data-base value. After the model and the inputs required from the user and derived from the data base are described, the model output and the various output options that can be exercised by the user are detailed. The general operation is set forth and suggestions are made for efficient modes of operation. Sample listings of various input, output, and data-base files are appended. (LEW)

  12. Proceedings of the Chornobyl phytoremediation and biomass energy conversion workshop

    SciTech Connect

    Hartley, J.; Tokarevsky, V.

    1998-06-01

    Many concepts, systems, technical approaches, technologies, ideas, agreements, and disagreements were vigorously discussed during the course of the 2-day workshop. The workshop was successful in generating intensive discussions on the merits of the proposed concept that includes removal of radionuclides by plants and trees (phytoremediation) to clean up soil in the Chornobyl Exclusion Zone (CEZ), use of the resultant biomass (plants and trees) to generate electrical power, and incorporation of ash in concrete casks to be used as storage containers in a licensed repository for low-level waste. Twelve years after the Chornobyl Nuclear Power Plant (ChNPP) Unit 4 accident, which occurred on April 26, 1986, the primary 4radioactive contamination of concern is from radioactive cesium ({sup 137}Cs) and strontium ({sup 90}Sr). The {sup 137}Cs and {sup 90}Sr were widely distributed throughout the CEZ. The attendees from Ukraine, Russia, Belarus, Denmark and the US provided information, discussed and debated the following issues considerably: distribution and characteristics of radionuclides in CEZ; efficacy of using trees and plants to extract radioactive cesium (Cs) and strontium (Sr) from contaminated soil; selection of energy conversion systems and technologies; necessary infrastructure for biomass harvesting, handling, transportation, and energy conversion; radioactive ash and emission management; occupational health and safety concerns for the personnel involved in this work; and economics. The attendees concluded that the overall concept has technical and possibly economic merits. However, many issues (technical, economic, risk) remain to be resolved before a viable commercial-scale implementation could take place.

  13. Flexible ZnO-cellulose nanocomposite for multisource energy conversion.

    PubMed

    Kumar, Ashavani; Gullapalli, Hemtej; Balakrishnan, Kaushik; Botello-Mendez, Andres; Vajtai, Robert; Terrones, Mauricio; Ajayan, Pulickel M

    2011-08-01

    Materials with the ability to harness multiple sources of energy from the ambient environment could lead to new types of energy-harvesting systems. It is demonstrated that nanocomposite films consisting of zinc oxide nanostructures embedded in a common paper matrix can be directly used as energy-conversion devices to transform mechanical and thermal energies to electric power. These mechanically robust and flexible devices can be fabricated over large areas and are capable of producing an output voltage and power up to 80 mV and 50 nW cm(-2) , respectively. Furthermore, it is shown that by integrating a certain number of devices (in series and parallel) the output voltage and the concomitant output power can be significantly increased. Also, the output voltage and power can be enhanced by scaling the size of the device. This multisource energy-harvesting system based on ZnO nanostructures embedded in a flexible paper matrix provides a simplified and cost-effective platform for capturing trace amounts of energy for practical applications. PMID:21626690

  14. Current developments in small wind energy conversion systems

    NASA Astrophysics Data System (ADS)

    Hansen, A. C.; Butterfield, C. P.

    1980-05-01

    The development of Small Wind Energy Conversion Systems (SWECS) with capacities under 100 kW and rotor diameters of approximately 30 meters is surveyed with a view to current prototypes, design programs, cost factors and wind systems testing. The characteristics of development SWECS and the projected cost of energy from the new prototypes are given. A primary objective of the Rocky Flats Test Center is the determination of the SWECS power output as a function of average wind speed. One-second average values of wind speed and power output are continuously recorded for each wind turbine and the data are analyzed using the Method of Bins. Areas of research discussed include rotor/wind dynamic interaction, and measurements of power output and blade root bending moments. It is noted that a reliable method of load spectrum prediction would be invaluable in designing for fatigue.

  15. Silicon nanowires for biosensing, energy storage, and conversion.

    PubMed

    Wang, Yanli; Wang, Tianyu; Da, Peimei; Xu, Ming; Wu, Hao; Zheng, Gengfeng

    2013-10-01

    Semiconducting silicon nanowires (SiNWs) represent one of the most interesting research directions in nanoscience and nanotechnology, with capabilities of realizing structural and functional complexity through rational design and synthesis. The exquisite control of chemical composition, structure, morphology, doping, and assembly of SiNWs, in both individual and array format, as well as incorporation with other materials, offers a nanoscale building block with unique electronic, optoelectronic, and catalytic properties, thus allowing for a variety of exciting opportunities in the fields of life sciences and renewable energy. This review provides a brief summary of SiNW research in the past decade, from the SiNW synthesis by both the top-down approaches and the bottom-up approaches, to several important biological and energy applications including biomolecule sensing, interfacing with cells and tissues, lithium-ion batteries, solar cells, and photoelectrochemical conversion. PMID:23828226

  16. ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.

  17. All silicon electrode photocapacitor for integrated energy storage and conversion.

    PubMed

    Cohn, Adam P; Erwin, William R; Share, Keith; Oakes, Landon; Westover, Andrew S; Carter, Rachel E; Bardhan, Rizia; Pint, Cary L

    2015-04-01

    We demonstrate a simple wafer-scale process by which an individual silicon wafer can be processed into a multifunctional platform where one side is adapted to replace platinum and enable triiodide reduction in a dye-sensitized solar cell and the other side provides on-board charge storage as an electrochemical supercapacitor. This builds upon electrochemical fabrication of dual-sided porous silicon and subsequent carbon surface passivation for silicon electrochemical stability. The utilization of this silicon multifunctional platform as a combined energy storage and conversion system yields a total device efficiency of 2.1%, where the high frequency discharge capability of the integrated supercapacitor gives promise for dynamic load-leveling operations to overcome current and voltage fluctuations during solar energy harvesting. PMID:25806838

  18. Solid State Energy Conversion Alliance 2nd Annual Workshop Proceedings

    SciTech Connect

    National Energy Technology Laboratory

    2001-03-30

    The National Energy Technology Laboratory (NETL) and the Pacific Northwest National Laboratory (PNNL) are pleased to provide the proceedings of the second annual Solid State Energy Conversion Alliance (SECA) Workshop held on March 29-30, 2001 in Arlington. The package includes the presentations made during the workshop, a list of participants, and the results of the breakout sessions. Those sessions covered stack materials and processes, power electronics, balance of plant and thermal integration, fuel processing technologies, and stack and system performance modeling. The breakout sessions have been reported as accurately as possible; however, due to the recording and transcription process errors may have occurred. If you note any significant omissions or wish to provide additional information, we welcome your comments and hope that all stakeholder groups will use the enclosed information in their planning endeavors.

  19. Energy Conversion and Utilization Technologies program: 1981 work element appraisal

    SciTech Connect

    Not Available

    1981-09-01

    The Division of Energy Conversion and Utilization Technologies (ECUT) has employed a work element appraisal methodology that enables a systematic comparison of various research and development (R and D) work elements within its program. The work element analysis is dependent upon the potential of the R and D to affect future energy savings, critical fuel substitution, and other public benefits such as environmental impacts. This report summarizes the process and results of the application of this appraisal methodology to the ECUT work elements proposed for FY 1983 funding. The context of the appraisal is outlined to clarify its role and purpose in the planning and budgeting cycle. Implementation of the process, including the data development and the appraisal review session, is also discussed, along with the impact of the appraisal results on ECUT's total planning system and on the preparation of the FY 1983 budget.

  20. Controlled cellular energy conversion in brown adipose tissue thermogenesis

    NASA Technical Reports Server (NTRS)

    Horowitz, J. M.; Plant, R. E.

    1978-01-01

    Brown adipose tissue serves as a model system for nonshivering thermogenesis (NST) since a) it has as a primary physiological function the conversion of chemical energy to heat; and b) preliminary data from other tissues involved in NST (e.g., muscle) indicate that parallel mechanisms may be involved. Now that biochemical pathways have been proposed for brown fat thermogenesis, cellular models consistent with a thermodynamic representation can be formulated. Stated concisely, the thermogenic mechanism in a brown fat cell can be considered as an energy converter involving a sequence of cellular events controlled by signals over the autonomic nervous system. A thermodynamic description for NST is developed in terms of a nonisothermal system under steady-state conditions using network thermodynamics. Pathways simulated include mitochondrial ATP synthesis, a Na+/K+ membrane pump, and ionic diffusion through the adipocyte membrane.

  1. ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project

    NASA Astrophysics Data System (ADS)

    1988-03-01

    Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.

  2. On the stator slot geometry of a cable wound generator for hydrokinetic energy conversion.

    PubMed

    Grabbe, Mrten; Eriksson, Sandra; Leijon, Mats

    2015-01-01

    The stator slot geometry of a cable wound permanent magnet synchronous generator for hydrokinetic energy conversion is evaluated. Practical experience from winding two cable wound generators is used to propose optimized dimensions of different parts in the stator slot geometry. A thorough investigation is performed through simulations of how small geometrical changes alter the generator performance. The finite element method (FEM) is used to model the generator and the simulations show that small changes in the geometry can have large effect on the performance of the generator. Furthermore, it is concluded that the load angle is especially sensitive to small geometrical changes. A new generator design is proposed which shows improved efficiency, reduced weight, and a possibility to decrease the expensive permanent magnet material by almost one-fifth. PMID:25879072

  3. On the Stator Slot Geometry of a Cable Wound Generator for Hydrokinetic Energy Conversion

    PubMed Central

    Grabbe, Mårten; Leijon, Mats

    2015-01-01

    The stator slot geometry of a cable wound permanent magnet synchronous generator for hydrokinetic energy conversion is evaluated. Practical experience from winding two cable wound generators is used to propose optimized dimensions of different parts in the stator slot geometry. A thorough investigation is performed through simulations of how small geometrical changes alter the generator performance. The finite element method (FEM) is used to model the generator and the simulations show that small changes in the geometry can have large effect on the performance of the generator. Furthermore, it is concluded that the load angle is especially sensitive to small geometrical changes. A new generator design is proposed which shows improved efficiency, reduced weight, and a possibility to decrease the expensive permanent magnet material by almost one-fifth. PMID:25879072

  4. Conversion of concentrated solar thermal energy into chemical energy.

    PubMed

    Tamaura, Yutaka

    2012-01-01

    When a concentrated solar beam is irradiated to the ceramics such as Ni-ferrite, the high-energy flux in the range of 1500-2500 kW/m(2) is absorbed by an excess Frenkel defect formation. This non-equilibrium state defect is generated not by heating at a low heating-rate (30 K/min), but by irradiating high flux energy of concentrated solar beam rapidly at a high heating rate (200 K/min). The defect can be spontaneously converted to chemical energy of a cation-excess spinel structure (reduced-oxide form) at the temperature around 1773 K. Thus, the O(2) releasing reaction (?-O(2) releasing reaction) proceeds in two-steps; (1) high flux energy of concentrated solar beam absorption by formation of the non-equilibrium Frenkel defect and (2) the O(2) gas formation from the O(2-) in the Frenkel defect even in air atmosphere. The 2nd step proceeds without the solar radiation. We may say that the 1st step is light reaction, and 2nd step, dark reaction, just like in photosynthesis process. PMID:22434435

  5. Energy transfer processes in solar energy conversion. Final report

    SciTech Connect

    Fayer, M.D.

    1984-01-01

    The following were studied experimentally and/or theoretically: dynamics of energy transport and trapping in two-component systems (using rhodamine 6G and malachite green as traps), electronic excited state transport among molecules randomly distributed in a finite volume, electronic excitation transport in polymer systems, and excitation transport in synthetic Zn-chlorophyllide substituted hemoglobin. (DLC)

  6. High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion

    NASA Astrophysics Data System (ADS)

    Juhasz, Albert J.; Sawicki, Jerzy T.

    2004-02-01

    For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a ``partial energy conversion'' system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the reactor thermal energy for conversion to electric power. Most of the fusion reactor's output is in the form of charged plasma which is expanded through a magnetic nozzle of the interplanetary propulsion system. Reactor heat energy is ducted to the high temperature series radiator utilizing the electric power generated to drive a helium gas circulation fan. In addition to discussing the thermodynamic aspects of the system design the authors include a brief overview of the gas turbine and fan rotor-dynamics and proposed bearing support technology along with performance characteristics of the three phase AC electric power generator and fan drive motor.

  7. High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; Sawicki, Jerzy T.

    2003-01-01

    For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a partial energy conversion system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the reactor thermal energy for conversion to electric power. Most of the fusion reactor's output is in the form of charged plasma which is expanded through a magnetic nozzle of the interplanetary propulsion system. Reactor heat energy is ducted to the high temperature series radiator utilizing the electric power generated to drive a helium gas circulation fan. In addition to discussing the thermodynamic aspects of the system design the authors include a brief overview of the gas turbine and fan rotor-dynamics and proposed bearing support technology along with performance characteristics of the three phase AC electric power generator and fan drive motor.

  8. PRELIMINARY ENVIRONMENTAL ASSESSMENT OF ENERGY CONVERSION PROCESSES FOR AGRICULTURAL AND FOREST PRODUCT RESIDUES. VOLUME 1

    EPA Science Inventory

    A preliminary assessment was made of the environmental impacts of several types of conversion processes for producing energy or fuels from agricultural and forestry residues. Fifteen examples were selected to represent various combinations of agricultural residues and conversion ...

  9. Experimental and Analytical Studies on Pyroelectric Waste Heat Energy Conversion

    NASA Astrophysics Data System (ADS)

    Lee, Felix

    This study is concerned with direct conversion of thermal energy into electrical energy by subjecting pyroelectric materials to the Olsen cycle. The Olsen cycle consists of two isoelectric field and two isothermal process on the electric displacement versus electric field diagram. The energy and power generation capabilities of copolymer poly(vinylidene fluoridetrifluorethylene) [P(VDF-TrFE)] films and lead lanthanum zirconate titanate (PLZT) ceramics were evaluated by executing the Olsen cycle via so-called "stamping experiments" and "dipping experiments". The stamping experiments consisted of alternatively pressing a pyroelectric material in thermal contact with hot and cold aluminum blocks under specified electric fields. It was performed to assess the pyroelectric energy conversion performance using heat conduction. The largest energy density generated in the stamping experiments was 155 J/L/cycle with 60/40 P(VDF-TrFE) thin film at 0.066 Hz between 25 and 110°C and electric fields cycled between 20 and 35 MV/m. This energy density exceeded the 130 J/L/cycle achieved by our previous prototypical device using oscillatory laminar convective heat transfer. However, the performance was limited by poor thermal contact between the aluminum blocks and pyroelectric material and also by excessive leakage current inherent to P(VDF-TrFE) at high temperatures and/or large electric fields. On the other hand, dipping experiments consisted of successively immersing a pyroelectric material into isothermal hot and cold thermal reservoirs at different temperatures while simultaneously cycling the electric fields. It was performed on relaxor ferroelectric x/65/35 PLZT ceramics with x between 5 and 10 mol.%. The operating temperature, applied electric field, sample thickness, cycle frequency, and electrode material were systematically varied to explore their respective effects on the energy and power densities produced. A maximum energy density of 1014 J/L/cycle was obtained with a 190μm thick 7/65/35 PLZT sample at 0.0256 Hz at temperatures between 30 and 200°C and electric field from 0.2 to 7.0 MV/m. To the best of our knowledge, this energy density is the largest achieved among pyroelectric single crystals, ceramics, and polymers using the Olsen cycle. Meanwhile, a maximum power density of 55.3 ± 8.0 W/L obtained with a 190μm thick 9.5/65/35 PLZT sample at 0.125 Hz. Additionally, the temperature-dependent dielectric behavior of PLZT ceramics were characterized. The polarization transition temperature of lanthanum-doped x /65/35 PLZT ceramics decreased from 240 to 10°C for increasing lanthanum dopant concentration x from 5 to 10 mol.%. This establishes that the different compositions should be operated at different temperatures for maximum pyroelectric energy conversion. Finally, a physical thermo-electrical model for estimating the energy harvested by ferroelectric relaxors was further validated against experimental data for a wide range of electric fields and temperatures.

  10. Understanding and tuning nanostructured materials for chemical energy conversion

    NASA Astrophysics Data System (ADS)

    Jian, Guoqiang

    The conversion of energy that employs chemical reaction is termed chemical energy conversion. In my dissertation, I have focused on chemical energy conversion systems involving energetic materials and lithium ion batteries, where performance is strongly dependent on the properties of materials and their architecture. The objective of this study is to enhance our understanding and tuning of nanostructured materials that might find application toward energetic materials and electrode materials in lithium ion batteries. Rapid heating diagnostics tools, i.e. temperature-jump techniques, have been used to study the ignition of aluminum nanoparticles, nanothermite reaction mechanism and metal oxides nanoparticles decomposition under rapid heating conditions (105-106 K/s). Time-resolved mass spectra results support the hypothesis that Al containing species diffuse outwards through the oxide shell. Low effective activation energies were found for metal oxides nanoparticles decomposition at high heating rates, implying the mass transfer control at high heating rates. The role of oxygen release from oxidizer in nanothermite reactions have been examined for several different systems, including some using microsized oxidizer (i.e., nano-Al/micro-I 2O5). In particular, for periodate based nanothermites, direct evidence from high heating rate SEM and mass spectrometry results support that direct gas phase oxygen release from oxidizer decomposition is critical in its ignition and combustion. Efforts have also been made to synthesize nanostructured materials for nanoenergetic materials and lithium ion batteries applications. Hollow CuO spheres were synthesized by aerosol spray pyrolysis, employing a gas blowing mechanism for the formation of hollow structure during aerosol synthesis. The materials synthesized as oxidizers in nanothermite demonstrated superior performance, and of particular note, periodate salts based nanothermite demonstrated the best gas generating performance for nanothermite materials. Energetic composite nanofibrous mats (NC/Al-CuO, NC/Al-Fe2O3, and NC/Al-Bi2O3) were also prepared by an electrospinning method and evaluated for their combustion performance. Aerosol spray pyrolysis was employed to produce carbon coated CuO hollow spheres, Mn3O4 hollow spheres, and Fe2O 3 mesoporous spheres. These hollow/mesoporous spheres demonstrated superior electrochemical performance when used as anode materials in lithium ion batteries. The effects of the amorphous and crystal structures on the electrochemical performance and the structure evolution during electrochemical tests were also investigated.

  11. Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Brown, E.J.; Baldasaro, P.F.; Dziendziel, R.J.

    1997-12-23

    A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength {lambda}{sub IF} approximately equal to the bandgap wavelength {lambda}{sub g} of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5{lambda}{sub IF} to {lambda}{sub IF} and reflect from {lambda}{sub IF} to about 2{lambda}{sub IF}; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5{lambda}{sub IF}. 10 figs.

  12. Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Brown, Edward J. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY); Dziendziel, Randolph J. (Middlegrove, NY)

    1997-01-01

    A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength .lambda..sub.IF approximately equal to the bandgap wavelength .lambda..sub.g of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5.lambda..sub.IF to .lambda..sub.IF and reflect from .lambda..sub.IF to about 2.lambda..sub.IF ; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5.lambda..sub.IF.

  13. Energy transfer processes in solar energy conversion. Progress report

    SciTech Connect

    Fayer, M.D.

    1989-11-01

    We have made substantial progress in experimental and theoretical studies in two areas: Photoinduced donor to acceptor electron transfer followed by back transfer in random solutions; and electronic excitation transport in systems with complex inhomogeneous spatial geometries and inhomogeneous energy distributions. Through the development of accurate statistical mechanical theories, we have been able to relate dynamics in complex systems to experimental observables. We have then used the experimental observables, time resolved fluorescence depolarization and transient grating experiments, to examine well defined molecular systems. The agreement between theory and experiment is excellent. 11 refs.

  14. An investigation of the effect of a magnetic field on the phosphate conversion coating formed on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; Li, Jianguo; He, Guangping; Xie, Honglan; Fu, Yanan

    2013-10-01

    In this paper, the influence of the magnetic field on the phosphate conversion coating formed on magnesium alloy has been studied by scanning ion selective electrode technique (SIET), X-rays phase-contrast radiography, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that the superposition of a magnetic field during the phosphate conversion coating process can promote the generation of small hydrogen gas bubbles and accelerate their desorption. In addition, irrespective of the microstructure of the AZ91D magnesium alloy, it was found that the Mg2+ cations were distributed comparatively uniformly. A uniform smooth phosphate conversion coating could be obtained by immersion in the treatment solution when a magnetic field was applied perpendicular to the magnesium alloy. It may be expected to use magnetic field to control the formation of phosphate conversion coating on magnesium alloy.

  15. Nonlinear energy dissipation of magnetic nanoparticles in oscillating magnetic fields

    NASA Astrophysics Data System (ADS)

    Soto-Aquino, D.; Rinaldi, C.

    2015-11-01

    The heating of magnetic nanoparticle suspensions subjected to alternating magnetic fields enables a variety of emerging applications such as magnetic fluid hyperthermia and triggered drug release. Rosensweig (2002) [25] obtained a model for the heat dissipation rate of a collection of non-interacting particles. However, the assumptions made in this analysis make it rigorously valid only in the limit of small applied magnetic field amplitude and frequency (i.e., values of the Langevin parameter that are much less than unity and frequencies below the inverse relaxation time). In this contribution we approach the problem from an alternative point of view by solving the phenomenological magnetization relaxation equation exactly for the case of arbitrary magnetic field amplitude and frequency and by solving a more accurate magnetization relaxation equation numerically. We also use rotational Brownian dynamics simulations of non-interacting magnetic nanoparticles subjected to an alternating magnetic field to estimate the rate of energy dissipation and compare the results of the phenomenological theories to the particle-scale simulations. The results are summarized in terms of a normalized energy dissipation rate and show that Rosensweig's expression provides an upper bound on the energy dissipation rate achieved at high field frequency and amplitude. Estimates of the predicted dependence of energy dissipation rate, quantified as specific absorption rate (SAR), on magnetic field amplitude and frequency, and particle core and hydrodynamic diameter, are also given.

  16. Numerical analysis of magnetic field in superconducting magnetic energy storage

    SciTech Connect

    Kanamaru, Y. ); Amemiya, Y. )

    1991-09-01

    This paper reports that the superconducting magnetic energy storage (SMES) is more useful than the other systems of electric energy storage because of larger stored energy and higher efficiency. The other systems are the battery, the flywheel, the pumped-storage power station. Some models of solenoid type SMES are designed in U.S.A. and Japan. But a high magnetic field happens by the large scale SMES in the living environment, and makes the erroneous operations of the computer display, the pacemaker of the heart and the electronic equipments. We study some fit designs of magnetic shielding of the solenoidal type SMES for reduction of the magnetic field in living environment. When some superconducting shielding coils are over the main storage coil, magnetic field reduces remarkably than the case of non shielding coil. The calculated results of the magnetic field are obtained y the finite element method.

  17. Refractory materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.

    1983-01-01

    Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

  18. Refractory materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.

    1984-01-01

    Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimaiation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

  19. ECUT (Energy Conversion and Utilization Technologies Program). Biocatalysis Project

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Presented are the FY 1985 accomplishments, activities, and planned research efforts of the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Program. The Project's technical activities were organized as follows: In the Molecular Modeling and Applied Genetics work element, research focused on (1) modeling and simulation studies to establish the physiological basis of high temperature tolerance in a selected enzyme and the catalytic mechanisms of three species of another enzyme, and (2) determining the degree of plasmid amplification and stability of several DNA bacterial strains. In the Bioprocess Engineering work element, research focused on (1) studies of plasmid propagation and the generation of models, (2) developing methods for preparing immobilized biocatalyst beads, and (3) developing an enzyme encapsulation method. In the Process Design and Analysis work element, research focused on (1) further refinement of a test case simulation of the economics and energy efficiency of alternative biocatalyzed production processes, (2) developing a candidate bioprocess to determine the potential for reduced energy consumption and facility/operating costs, and (3) a techno-economic assessment of potential advancements in microbial ammonia production.

  20. ECUT (Energy Conversion and Utilization Technologies Program). Biocatalysis Project

    NASA Astrophysics Data System (ADS)

    1986-07-01

    Presented are the FY 1985 accomplishments, activities, and planned research efforts of the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Program. The Project's technical activities were organized as follows: In the Molecular Modeling and Applied Genetics work element, research focused on (1) modeling and simulation studies to establish the physiological basis of high temperature tolerance in a selected enzyme and the catalytic mechanisms of three species of another enzyme, and (2) determining the degree of plasmid amplification and stability of several DNA bacterial strains. In the Bioprocess Engineering work element, research focused on (1) studies of plasmid propagation and the generation of models, (2) developing methods for preparing immobilized biocatalyst beads, and (3) developing an enzyme encapsulation method. In the Process Design and Analysis work element, research focused on (1) further refinement of a test case simulation of the economics and energy efficiency of alternative biocatalyzed production processes, (2) developing a candidate bioprocess to determine the potential for reduced energy consumption and facility/operating costs, and (3) a techno-economic assessment of potential advancements in microbial ammonia production.

  1. Alkali layered compounds interfaces for energy conversion and energy storage

    NASA Technical Reports Server (NTRS)

    Papageorgopoulos, Chris A.

    1996-01-01

    During year one a new ultra-high vacuum, an Ar(+) ion sputterer, a low energy electron diffraction (LEED) system, an Auger electron spectrometer (AES), a work function measurement device with a Kelvin probe, and related accessories were used. The study found a focus in the adsorption of chalcogenides on Si and III-V compound semiconductors. In the second year, a scanning tunneling microscope was obtained along with a quadrapole mass spectrometer, power supplies, a computer, a chart recorder, etc. We started the systematic study on the adsorption of chalcogenides on the compound semiconductor surfaces. The third year saw the mounting of the scanning tunneling microscope (STM) on the existing UHV system. The investigation continued with the adsorption of Cs (alkali) on S-covered Si(100)2x1 surfaces. Then the adsorption of S on Cs-covered Si(100) surfaces was studied.

  2. Experimental and theoretical studies on solar energy for energy conversion

    NASA Technical Reports Server (NTRS)

    Thomas, A. P.; Thekaekara, M. P.

    1976-01-01

    This paper presents the results of investigations made experimentally and theoretically to evaluate the various parameters that affect the amount of solar energy received on a collector surface. Measurements were made over a long period of time using both pyranometer and pyrheliometer. Computation of spectral and total irradiance at ground level have been made for a large variety of combinations of atmospheric parameters for ozone density, precipitable water vapor, turbidity-coefficients and air mass. A study of the air mass as a function of irradiance measured at GSFC, and comparison of the data with the computed values of total direct solar irradiance for various parameters indicate that turbidity changes with time of the day; atmospheric opacity is less in the afternoon than in the morning.

  3. Siting handbook for small wind energy conversion systems

    SciTech Connect

    Wegley, H.L.; Ramsdell, J.V.; Orgill, M.M.; Drake, R.L.

    1980-03-01

    This handbook was written to serve as a siting guide for individuals wishing to install small wind energy conversion systems (WECS); that is, machines having a rated capacity of less than 100 kilowatts. It incorporates half a century of siting experience gained by WECS owners and manufacturers, as well as recently developed siting techniques. The user needs no technical background in meteorology or engineering to understand and apply the siting principles discussed; he needs only a knowledge of basic arithmetic and the ability to understand simple graphs and tables. By properly using the siting techniques, an owner can select a site that will yield the most power at the least installation cost, the least maintenance cost, and the least risk of damage or accidental injury.

  4. Power conversion system utilizing reversible energy of liquefied natural gas

    SciTech Connect

    Hoskinson, R.L.

    1982-05-18

    A power conversion system comprising a combination of a liquefied natural gas vaporizing plant and a fuel burning power generating facility is disclosed. The liquefied natural gas vaporizing plant utilizes the cryogenic capacity of the liquefied natural gas to produce liquid air which is pumped to a high pressure by a liquid air pump. The liquid air is then brought into a heat exchanging relationship with air drawn into the vaporizing plant so that the high pressure liquid air is converted to high pressure gaseous air. The high pressure gaseous air which represents recovered reversible energy of the liquefied natural gas is fed into a combustion chamber of the fuel burning power generating plant. Since the power generating facility requires no significant output of power to drive a compressor to compress ambient air prior to its entry into the combustion chamber, the power generating facility is operated at a high efficiency.

  5. Land-use implications of wind-energy-conversion systems

    SciTech Connect

    Noun, R.J.

    1981-02-01

    An estimated 20 utilities in the United States are now investigating potential wind machine sites in their areas. Identifying sites for wind machine clusters (wind farms) involves more than just finding a location with a suitable wind resource. Consideration must also be given to the proximity of sites to existing transmission lines, environmental impacts, aesthetics, and legal concerns as well as the availability of and alternative uses for the land. These issues have made it increasingly difficult for utilities to bring conventional power plants on-line quickly. Utilities are now required, however, to give careful consideration to specific legal, social, and environmental questions raised by the siting of wind energy conversion systems (WECS).

  6. Photochemical energy conversion by membrane-bound photoredox systems

    SciTech Connect

    Tollin, G.

    1992-03-01

    Most of our effort during the past grant period has been directed towards investigating electron transfer processes involving redox proteins at lipid bilayer/aqueous interfaces. This theme, as was noted in our previous three year renewal proposal, is consistent with our goal of developing biomimetic solar energy conversion systems which utilize the unique properties of biological electron transfer molecules. Thus, small redox proteins such as cytochrome c, plastocyanin and ferredoxin function is biological photosynthesis as mediators of electron flow between the photochemical systems localized in the membrane, and more complex soluble or membrane-bound redox proteins which are designed to carry out specific biological tasks such as transbilayer proton gradient formation, dinitrogen fixation, ATP synthesis, dihydrogen synthesis, generation of strong reductants, etc. In these studies, we have utilized two principal experimental techniques, laser flash photolysis and cyclic voltammetry, both of which permit direct measurements of electron transfer processes.

  7. Comparison of performances of turbines for wave energy conversion

    NASA Astrophysics Data System (ADS)

    Kinoue, Yoichi; Setoguchi, Toshiaki; Kuroda, Tomohiko; Kaneko, Kenji; Takao, Manabu; Thakker, Ajit

    2003-11-01

    The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.

  8. Carbon-based electrocatalysts for advanced energy conversion and storage.

    PubMed

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-08-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

  9. Tandem photovoltaic solar cells and increased solar energy conversion efficiency

    NASA Technical Reports Server (NTRS)

    Loferski, J. J.

    1976-01-01

    Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

  10. Standards for photovoltaic energy conversion systems. Final report

    SciTech Connect

    Schafft, H. A.

    1980-04-01

    This report provides the results of a search for existing domestic standards and related documents for possible application in the development of a standards base for photovoltaic energy conversion systems. The search resulted in locating about 150 test methods, recommended practices, standards, solar-thermal performance criteria, and other standards-related documents. They are listed by topic areas in the appendix. The listing was prepared to assist those involved in developing performance criteria for photovoltaic systems and in identifying methods to test system performance against these criteria. It is clear from the results of the search that few standards are directly applicable to terrestrial solar photovoltaic systems and that much standards development is required to support the commercialization of such systems.

  11. Monolithic Interconnected Modules (MIMs) for Thermophotovoltaic Energy Conversion

    NASA Technical Reports Server (NTRS)

    Wilt, David; Wehrer, Rebecca; Palmisiano, Marc; Wanlass, Mark; Murray, Christopher

    2003-01-01

    Monolithic Interconnected Modules (MIM) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include rear-surface infrared (IR) reflectors. The MIM architecture is being implemented in InGaAsSb materials without semi-insulating substrates through the development of alternative isolation methodologies. Motivations for developing the MIM structure include: reduced resistive losses, higher output power density than for systems utilizing front surface spectral control, improved thermal coupling and ultimately higher system efficiency. Numerous design and material changes have been investigated since the introduction of the MIM concept in 1994. These developments as well as the current design strategies are addressed.

  12. Carbon-based electrocatalysts for advanced energy conversion and storage

    PubMed Central

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

  13. Sea-water bioufouling problems in thermal energy conversion

    SciTech Connect

    Sasscer, D.S.; Morgan, T.O.; Tosteson, T.R.

    1982-09-01

    Between 29 January 1980 and 10 March 1981, a continuous flow of ocean surface water was passed through simulated Ocean Thermal Energy Conversion (OTEC) evaporator tubes in order to determine, in situ, the effects of microbiofouling on heat-exchanger efficiency. This study was conducted in two phases. The first phase, the initiation of microfouling, consisted of relating the fouling resistance (R/sub f/) to the biological analysis of aluminum and titanium sacrificial tube samples on eleven occasions during the first 143 days. The second phase consisted of the long-term determination of microfouling. This was accomplished by correlating fouling resistance, (R/sub f/), and fouling rate, (dR/sub f/dt), with the bioanalysis of the microbiofouling which occurred in tubes which were periodically cleaned. (JMT)

  14. Holey tungsten oxynitride nanowires: novel anodes efficiently integrate microbial chemical energy conversion and electrochemical energy storage.

    PubMed

    Yu, Minghao; Han, Yi; Cheng, Xinyu; Hu, Le; Zeng, Yinxiang; Chen, Meiqiong; Cheng, Faliang; Lu, Xihong; Tong, Yexiang

    2015-05-20

    Holey tungsten oxynitride nanowires with superior conductivity, good biocompatibility, and good stability achieve excellent performance as anodes for both asymmetric supercapacitors and microbial fuel cells. Moreover, an innovative system is devised based on these as-prepared tungsten oxynitride anodes, which can simultaneously realize both energy conversion from chemical to electric energy and its storage. PMID:25854325

  15. Review of pyroelectric thermal energy harvesting and new MEMs based resonant energy conversion techniques

    SciTech Connect

    Hunter, Scott Robert; Lavrik, Nickolay V; Mostafa, Salwa; Rajic, Slobodan; Datskos, Panos G

    2012-01-01

    Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.

  16. Review of pyroelectric thermal energy harvesting and new MEMs-based resonant energy conversion techniques

    NASA Astrophysics Data System (ADS)

    Hunter, Scott R.; Lavrik, Nickolay V.; Mostafa, Salwa; Rajic, Slo; Datskos, Panos G.

    2012-06-01

    Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-toelectrical energy conversion devices.

  17. Thermal energy conversion by coupled shape memory and piezoelectric effects

    NASA Astrophysics Data System (ADS)

    Zakharov, Dmitry; Lebedev, Gor; Cugat, Orphee; Delamare, Jerome; Viala, Bernard; Lafont, Thomas; Gimeno, Leticia; Shelyakov, Alexander

    2012-09-01

    This work gives experimental evidence of a promising method of thermal-to-electric energy conversion by coupling shape memory effect (SME) and direct piezoelectric effect (DPE) for harvesting quasi-static ambient temperature variations. Two original prototypes of thermal energy harvesters have been fabricated and tested experimentally. The first is a hybrid laminated composite consisting of TiNiCu shape memory alloy (SMA) and macro fiber composite piezoelectric. This composite comprises 0.1 cm3 of active materials and harvests 75 J of energy for each temperature variation of 60 C. The second prototype is a SME/DPE machine which uses the thermally induced linear strains of the SMA to bend a bulk PZT ceramic plate through a specially designed mechanical structure. The SME/DPE machine with 0.2 cm3 of active material harvests 90 J over a temperature increase of 35 C (60 J when cooling). In contrast to pyroelectric materials, such harvesters are also compatible with both small and slow temperature variations.

  18. Functional Nanostructures for Magnetic and Energy Application

    NASA Astrophysics Data System (ADS)

    Zhou, Minjie

    Functional nanostructures serve as the basic building blocks for nanodevices and significant efforts have been devoted to their morphology control and properties optimization. In present study, four functional nanostructures, i.e., FePt/B4C multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite film, Ga-doped ZnO nanowire arrays, and CdSe nanotube arrays are designed, synthesized and characterized in detail, in which the first two are expected to be prominent candidates for ultrahigh-density magnetic storage media while the later two have potential applications in solar energy conversion. FePt/B4C multilayer thin films are deposited on silicon substrates using magnetron sputtering with different B4C layer thickness. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to be incorporated into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the properties of the composite film. Based on the experimental results of multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite thin films on Si substrate are synthesized, in which a record coercivity of 2200 Oe is achieved compared to similar system. The size uniformity of the FePt nanoparticles, the well-defined particle-particle separation, together with the good magnetic property and high temperature thermal stability of the overall composite film, make it a very promising candidate for the ultrahigh density magnetic storage media. Semiconductor based one-dimensional nanostructures are investigated as promising building blocks for solar energy conversion devices. Two aspects are explored, aiming at increasing the energy conversion efficiency, i.e., facilitating electron transport and enhancing photon absorbing. In the first case, large area Ga-doped ZnO nanowire arrays are grown on transparent conducting substrate. Experimental results reveal the well-aligned array morphology and the uniform Ga concentration in these nanowires. In particular, direct I-V measurements performed on single nanowire-on-ITO substrate disclose its Ohmic contact with the conducting substrate and the significant conductivity improvement compared to undoped ZnO nanowire, In the second case, a novel synthesis strategy for nanotube arrays is developed and CdSe is used for demonstration, which material possessing more appropriate band gap as effective light harvester compared to that of materials for existing semiconductor nanotube arrays. The controllable tube wall thickness that can be increased until continuous CdSe porous network is obtained. The experimental results suggest a nanotube array formation mechanism that can be generally applied to a wide range of materials.

  19. Concept to Employ Magnetohydrodynamic (MHD) Conversion in a 2 GW Direct Drive Inertial Fusion Energy (IFE) Power Reactor

    NASA Astrophysics Data System (ADS)

    Anderson, Brett; Burstein, Alison; Gentile, Charles

    2007-11-01

    The conceptual design of a 2 GW direct drive IFE power reactor may provide an opportunity to directly harness the power in the post detonation ion fields. Conceptually, this can be accomplished by utilizing a magnetic cusp field to guide the ions into equatorial and polar ion dumps. The ion fields resulting from this magnetic intervention configuration pose a distinct challenge, as their intensity may have the potential to damage the ion dumps. One method of addressing this challenge is by employing MHD conversion to transform the internal energy of the fields directly into electrical energy, a process which would also reduce the fields' strength. In order to analyze the potential of MHD conversion in IFE, results of previous work in other applications are examined in the context of this project. Preliminary assessment reveals that MHD conversion is a promising solution to this issue, although a number of engineering and practical concerns will need to be addressed. This paper concentrates on the primary issues associated with MHD conversion. Support for this research was provided by the U.S. Department of Energy's Science Undergraduate Laboratory Internship (SULI) Program.

  20. Methods for locating ground faults and insulation degradation condition in energy conversion systems

    DOEpatents

    Agamy, Mohamed; Elasser, Ahmed; Galbraith, Anthony William; Harfman Todorovic, Maja

    2015-08-11

    Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

  1. Power conversion and control methods for renewable energy sources

    NASA Astrophysics Data System (ADS)

    Yu, Dachuan

    2005-07-01

    In recent years, there has been an increase in the use of renewable energy due to the growing concern over the pollution caused by fossil-fuel-based energy. Renewable energy sources, such as photovoltaic (PV) and fuel cell, can be used to enhance the safety, reliability, sustainability, and transmission efficiency of a power system. This dissertation focuses on the power conversion and control for two major renewable-energy sources: PV and fuel cell. Firstly, a current-based, maximum power-point tracking (MPPT) algorithm is proposed for PV energy. An economical converter system using the above scheme for converting the output from PV panels into 60 Hz AC voltage is developed and built. Secondly, a novel circuit model for the Proton Exchange Membrane (PEM) fuel-cell stack that is useful in the design and analysis of fuel-cell-based power systems is proposed. This Pspice-based model uses elements available in the Pspice library with some modifications to represent both the static and dynamic responses of a PEM fuel-cell module. The accuracy of the model is verified by comparing the simulation and experimental results. Thirdly, a DSP-controlled three-phase induction-motor drive using constant voltage over frequency is built and can be used in a fuel-cell automobile. A hydrogen sensor is used in the drive to both sound an alarm and shut down the inverter trigger pulses through the DSP. Finally, a hybrid power system consisting of PV panels and fuel cell is proposed and built. In the proposed system, PV panels can supply most of the power when the sunlight is available, and the excess power required by the load is supplied by a fuel cell. Load sharing between a fuel cell (FC) and the PV panel is investigated by both simulation and experiments.

  2. Sodium as Coupling Cation in Respiratory Energy Conversion.

    PubMed

    Fritz, Gnter; Steuber, Julia

    2016-01-01

    Among the alkali cations, Na(+) has an extraordinary role in living cells since it is used to charge the battery of life. To this end, sophisticated protein complexes in biological membranes convert chemical energy obtained from oxidation of NADH, or hydrolysis of ATP, into an electrochemical gradient of sodium ions. Cells use this so-called sodium-motive force stored in energy-converting membranes for important processes like uptake of nutrients, motility, or expulsion of toxic compounds. The Na(+) pumps act in concert with other enzymes embedded in the lipid membrane, and together they form the respiratory chain which achieves the oxidation of NADH derived from nutrients under formation of an electrochemical sodium (or proton) gradient. We explain why Na(+) pumps are important model systems for the homologous, proton-translocating complexes, and hope to convince the reader that studying the Na(+)-translocating ATP synthase from the unimpressive bacterium Ilyobacter tartaricus had a big impact on our understanding of energy conversion by human ATP synthase. The Na(+)-translocating systems described here are either driven by the oxidation of NADH, the carrier of redox equivalents of cells, or by the hydrolysis of adenosine 5'-triphosphate, the universal high-energy compound of cells. The electrochemical energy provided by these respiratory Na(+) pumps, the NADH dehydrogenase or the ATPase, drives other Na(+) transport systems like the bacterial flagellum discussed in the last part of this chapter. The flagellar motor does not represent a Na(+) pump, but like ATPase, it operates by a rotational mechanism. By comparing these two Na(+) -translocating, rotary machines, we obtain new insight into the possible mechanisms of Na(+) transport through the stator proteins of the flagellar motor. Na(+) pumps are widespread in pathogenic bacteria where they play an important role in metabolism, making them novel targets for antibiotics. PMID:26860307

  3. Flywheel energy-storage-and-conversion system for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Jarvinen, P. O.

    1982-03-01

    Efforts to develop a magnetically suspended solar photovoltaic flywheel energy storage unit for residential applications are discussed. A 1/10-scale prototype flywheel unit, which stores 1 kWh of energy in a 400-pound, 15-inch-diameter steel rotor at a maximum of 15,000 RPM, was designed, constructed and tested. The 1/10-scale prototype unit was based on a full-scale, 40-kWh residential flywheel design and was a total system in that it included all the electrical features needed for a complete interface between a photovoltaic array and a residential or utility load. Design features of the unit, such as its magnetic bearing, motor-generator, rotor and output power-conditioning equipment, are described and test results are presented. Manufacturing cost studies of the full-scale, 40-kWh residential flywheel system are reported along with user worth studies of flywheel systems in the Northeast and Southwest. The 1/10-scale prototype test setup was modified into an advanced prototype flywheel test unit.

  4. Advanced Energy Conversion Technologies and Architectures for Earth and Beyond

    NASA Technical Reports Server (NTRS)

    Howell, Joe T.; Fikes, John C.; Phillips, Dane J.; Laycock, Rustin L.; ONeill, Mark; Henley, Mark W.; Fork, Richard L.

    2006-01-01

    Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. There is a need to produce "proof-ofconcept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space surface sites. Space surface receiving sites of particular interest include the areas of permanent shadow near the moon s North and South poles, where WPT technologies could enable access to ice and other useful resources for human exploration. This paper discusses work addressing a promising approach to solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) applied to both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars. Strategies for developing energy infrastructures in space which utilize this technology are presented. This dual use system produces electrical energy efficiently from either coherent light, such as from a highly coherent laser, or from conventional solar illumination. This allows, for example, supplementing solar energy with energy provided by highly coherent laser illumination during periods of low solar illumination or no illumination. This reduces the need for batteries and alternate sources of power. The capability of using laser illumination in a lowest order Gaussian laser mode provides means for transmitting power optically with maximum efficiency and precision over the long distances characteristic of space. A preliminary receiving system similar to that described here, has been produced and tested under solar and laser illumination. A summary of results is given.

  5. Internal Conversion and Vibrational Energy Redistribution in Chlorophyll A.

    PubMed

    Shenai, Prathamesh M; Fernandez-Alberti, Sebastian; Bricker, William P; Tretiak, Sergei; Zhao, Yang

    2016-01-14

    We have computationally investigated the role of intramolecular vibrational modes in determining nonradiative relaxation pathways of photoexcited electronic states in isolated chlorophyll A (ChlA) molecules. To simulate the excited state relaxation from the initially excited Soret state to the lowest excited state Qy, the approach of nonadiabatic excited state molecular dynamics has been adopted. The intramolecular vibrational energy relaxation and redistribution that accompany the electronic internal conversion process is followed by analyzing the excited state trajectories in terms of the ground state equilibrium normal modes. The time dependence of the normal mode velocities is determined by projecting instantaneous Cartesian velocities onto the normal mode vectors. Our analysis of the time evolution of the average mode energies uncovers that only a small subset of the medium-to-high frequency normal modes actively participate in the electronic relaxation processes. These active modes are characterized by the highest overlap with the nonadiabatic coupling vectors (NACRs) during the electronic transitions. Further statistical analysis of the nonadiabatic transitions reveals that the electronic and vibrational energy relaxation occurs via two distinct pathways with significantly different time scales on which the hopping from Soret to Qx occurs thereby dictating the overall dynamics. Furthermore, the NACRs corresponding to each of the transitions have been consistently found to be predominantly similar to a set of normal modes that vary depending upon the transition and the identified categories. Each pathway exhibits a differential time scale of energy transfer and also a differential set of predominant active modes. Our present analysis can be considered as a general approach allowing identification of a reduced subset of specific vibrational coordinates associated with nonradiative relaxation pathways. Therefore, it represents an adequate prior strategy that can particularly facilitates mixed quantum-classical approaches. PMID:26651494

  6. Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013

    SciTech Connect

    Lian, Tianquan

    2013-09-20

    The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

  7. Optimized vacuum thermionic energy conversion using diamond materials

    NASA Astrophysics Data System (ADS)

    Smith, Joshua; Bilbro, Griff; Nemanich, Robert

    2009-03-01

    The vacuum thermionic energy conversion device (TEC) has been an attractive alternative to other means of energy production for some time due to its potentially high efficiency operation, but practical devices have been difficult to develop as a result of the negative space charge effect. It is well known that a hydrogen termination layer on a diamond material induces a negative electron affinity (NEA). In this study we present a theoretical analysis showing it is possible to tune the parameters of a thermionic device featuring a doped diamond material as the emitter electrode to maximize the output power produced. For example, a TEC operating between 950K and 300K with an emitter negative electron affinity of 0.5eV, a collector barrier height of 0.6eV, Richardson's constant of both electrodes equal to 10A cm-2 K-2, emissivity of both electrode of 0.5, and interelectrode spacing of 10?m will have a maximum output power of 1.5W cm-2 and efficiency of 20% occurring at an emitter barrier height of 1.2eV. The efficiency calculation includes electronic and blackbody heat transport across the device. The analysis establishes approaches to increase the efficiency to values greater than 20%. This work was funded by the Office of Naval Research through the TEC MURI Program.

  8. Ocean thermal energy conversion: Historical highlights, status, and forecast

    SciTech Connect

    Dugger, G.L.; Avery, W.H.; Francis, E.J.; Richards, D.

    1983-07-01

    In 1881, d'Arsonval conceived the closed-Rankine-cycle ocean thermal energy conversion (OTEC) system in which a working fluid is vaporized by heat exchange with cold water drawn from a 700-1200 m depth. In 1930, Claude demonstrated an open-cycle process in Cuba. Surface water was flash-vaporized at 3 kPa to drive a turbine directly (no secondary working fluid) and then was condensed by direct contact with water drawn from a 700-m depth through a 1.6m-diam, 1.75-km-long cold-water pipe (CWP). From a delta T of 14/sup 0/C his undersized turbine generated 22 kW. In 1956 a French team designed a 3.5-MW (net) open-cycle plant for installation off Abidjan on the Ivory Coast of Africa and demonstrated the necessary CWP deployment. The at-sea demonstrations by Mini-OTEC and OTEC-1 and other recent advances in OTEC technology summarized herein represent great progress. All of the types of plants proposed for the DOE's PON program may be worthy of development; certainly work on a grazing plant is needed. Our estimates indicate that the U.S. goals established by Public Law 96-310 leading to 10 GW of OTEC power and energy product equivalents by 1999 are achievable, provided that adequate federal financial incentives are retained to assure the building of the first few plants.

  9. Environmental programs for ocean thermal energy conversion (OTEC)

    SciTech Connect

    Wilde, P.

    1981-07-01

    The environmental research effort in support of the US Department of Energy's Ocean Thermal Energy Conversion (OTEC) program has the goal of providing documented information on the effect of proposed operations on the ocean and the effect of oceanic conditions on the plant. The associated environment program consists of archival studies in potential areas serial oceanographic cruises to sites or regions of interest, studies from various fixed platforms at sites, and compilation of such information for appropriate legal compliance and permit requirements and for use in progressive design of OTEC plants. Site/regions investigated are south of Mobile and west of Tampa, Gulf of Mexico; Punta Tuna, Puerto Rico; St. Croix, Virgin Islands; Kahe Point, Oahu and Keahole Point, Hawaii, Hawaiian Islands; and off the Brazilian south Equatorial Coast. Four classes of environmental concerns identified are: redistribution of oceanic properties (ocean water mixing, impingement/entrainment etc.); chemical pollution (biocides, working fluid leaks, etc.); structural effects (artificial reef, aggregation, nesting/migration, etc.); socio-legal-economic (worker safety, enviromaritime law, etc.).

  10. Energy Conversion Advanced Heat Transport Loop and Power Cycle

    SciTech Connect

    Oh, C. H.

    2006-08-01

    The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various operating conditions as well as trade offs between efficiency and capital cost. Prametric studies were carried out on reactor outlet temperature, mass flow, pressure, and turbine cooling. Recommendations on the optimal working fluid for each configuration were made. A steady state model comparison was made with a Closed Brayton Cycle (CBC) power conversion system developed at Sandia National Laboratory (SNL). A preliminary model of the CBC was developed in HYSYS for comparison. Temperature and pressure ratio curves for the Capstone turbine and compressor developed at SNL were implemented into the HYSYS model. A comparison between the HYSYS model and SNL loop demonstrated power output predicted by HYSYS was much larger than that in the experiment. This was due to a lack of a model for the electrical alternator which was used to measure the power from the SNL loop. Further comparisons of the HYSYS model and the CBC data are recommended. Engineering analyses were performed for several configurations of the intermediate heat transport loop that transfers heat from the nuclear reactor to the hydrogen production plant. The analyses evaluated parallel and concentric piping arrangements and two different working fluids, including helium and a liquid salt. The thermal-hydraulic analyses determined the size and insulation requirements for the hot and cold leg pipes in the different configurations. Economic analyses were performed to estimate the cost of the va

  11. Investigation and development of new materials for electrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Ivanovskaya, Anna

    Performance of next generation electrochemical energy conversion devices relies on optimization of both ion selective membranes that retain conductivity at elevated temperatures, and electrode materials active and stable in corrosive environment. The work presented focuses on (1) improving energy conversion in fuel cells by designing novel ion conductive membrane materials optimized by an original optical high-throughput screening technique and (2) development of new stable mixed transition metal sulfide electrocatalysts for industrial bromine recovery. A functionalized fullerene derivative was used to fabricate mechanically strong, flexible organic-inorganic membranes via cooperative sol-gel synthesis. Amorphous materials with nanometer range wormlike structures were obtained. The dependence of conductivity on the concentration of triflic acid was quantitatively described by percolation theory. Fullerene derivatives with arbitrarily attached chains increased disorder of the structure, but before the wormlike network collapsed conductivity 40 times higher than that of the sample with no fullerenes was recorded. This enhancement was attributed to the additional inter-channel connections for proton transport facilitated by the fullerene derivatives. Optimization of the structure by an optical high-throughput screening made possible proton conductivity of 3.2x10-3 S/cm at 130C and 5% humidity conditions. A series of doped Ru, Fe, Mo, W sulfide catalysts was synthesized, and their hydrogen evolution and oxygen reduction activity in HBr were studied as a function of dopant. RuS2 compounds showed the highest rates of hydrogen evolution and oxygen reduction reactions in HBr. Among all dopants, Co was the most active for hydrogen evolution reaction with overpotentials 100 mV lower than that of Pt at current density of 80 mA/cm2 in 0.5 M HBr. Oxygen reduction activity of RuS2 catalysts was found to change consistently as a function of periodic position of a dopant. Cr, Mn and Fe dopants inhibited oxygen reduction activity of RuS2, while Co, Ni and Cu promoted the activity. Inexpensive Ni-W sulfide was identified as active catalyst for oxygen reduction reaction in HBr. The activity increased with the addition of Ni up to 50%. Although Co-doped RuS2 is unstable in 6 M HBr, it was found to be stable under applied potential during 5 hour hydrogen evolution reaction test.

  12. Direct Energy Conversion for Nuclear Propulsion at Low Specific Mass

    NASA Technical Reports Server (NTRS)

    Scott, John H.

    2014-01-01

    The project will continue the FY13 JSC IR&D (October-2012 to September-2013) effort in Travelling Wave Direct Energy Conversion (TWDEC) in order to demonstrate its potential as the core of a high potential, game-changing, in-space propulsion technology. The TWDEC concept converts particle beam energy into radio frequency (RF) alternating current electrical power, such as can be used to heat the propellant in a plasma thruster. In a more advanced concept (explored in the Phase 1 NIAC project), the TWDEC could also be utilized to condition the particle beam such that it may transfer directed kinetic energy to a target propellant plasma for the purpose of increasing thrust and optimizing the specific impulse. The overall scope of the FY13 first-year effort was to build on both the 2012 Phase 1 NIAC research and the analysis and test results produced by Japanese researchers over the past twenty years to assess the potential for spacecraft propulsion applications. The primary objective of the FY13 effort was to create particle-in-cell computer simulations of a TWDEC. Other objectives included construction of a breadboard TWDEC test article, preliminary test calibration of the simulations, and construction of first order power system models to feed into mission architecture analyses with COPERNICUS tools. Due to funding cuts resulting from the FY13 sequestration, only the computer simulations and assembly of the breadboard test article were completed. The simulations, however, are of unprecedented flexibility and precision and were presented at the 2013 AIAA Joint Propulsion Conference. Also, the assembled test article will provide an ion current density two orders of magnitude above that available in previous Japanese experiments, thus enabling the first direct measurements of power generation from a TWDEC for FY14. The proposed FY14 effort will use the test article for experimental validation of the computer simulations and thus complete to a greater fidelity the mission analysis products originally conceived for FY13.

  13. ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis project

    NASA Technical Reports Server (NTRS)

    Baresi, Larry

    1989-01-01

    The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is managed by the Jet Propulsion Laboratory, California Institute of Technology. The Biocatalysis Project is a mission-oriented, applied research and exploratory development activity directed toward resolution of the major generic technical barriers that impede the development of biologically catalyzed commercial chemical production. The approach toward achieving project objectives involves an integrated participation of universities, industrial companies and government research laboratories. The Project's technical activities were organized into three work elements: (1) The Molecular Modeling and Applied Genetics work element includes research on modeling of biological systems, developing rigorous methods for the prediction of three-dimensional (tertiary) protein structure from the amino acid sequence (primary structure) for designing new biocatalysis, defining kinetic models of biocatalyst reactivity, and developing genetically engineered solutions to the generic technical barriers that preclude widespread application of biocatalysis. (2) The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields and lower separation energetics. Results of work within this work element will be used to establish the technical feasibility of critical bioprocess monitoring and control subsystems. (3) The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the energy-economics of biocatalyzed chemical production processes, and initiation of technology transfer for advanced bioprocesses.

  14. ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis project

    NASA Astrophysics Data System (ADS)

    Baresi, Larry

    1989-03-01

    The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is managed by the Jet Propulsion Laboratory, California Institute of Technology. The Biocatalysis Project is a mission-oriented, applied research and exploratory development activity directed toward resolution of the major generic technical barriers that impede the development of biologically catalyzed commercial chemical production. The approach toward achieving project objectives involves an integrated participation of universities, industrial companies and government research laboratories. The Project's technical activities were organized into three work elements: (1) The Molecular Modeling and Applied Genetics work element includes research on modeling of biological systems, developing rigorous methods for the prediction of three-dimensional (tertiary) protein structure from the amino acid sequence (primary structure) for designing new biocatalysis, defining kinetic models of biocatalyst reactivity, and developing genetically engineered solutions to the generic technical barriers that preclude widespread application of biocatalysis. (2) The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields and lower separation energetics. Results of work within this work element will be used to establish the technical feasibility of critical bioprocess monitoring and control subsystems. (3) The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the energy-economics of biocatalyzed chemical production processes, and initiation of technology transfer for advanced bioprocesses.

  15. Direct energy conversion in fission reactors: A U.S. NERI project

    SciTech Connect

    SLUTZ,STEPHEN A.; SEIDEL,DAVID B.; POLANSKY,GARY F.; ROCHAU,GARY E.; LIPINSKI,RONALD J.; BESENBRUCH,G.; BROWN,L.C.; PARISH,T.A.; ANGHAIE,S.; BELLER,D.E.

    2000-05-30

    In principle, the energy released by a fission can be converted directly into electricity by using the charged fission fragments. The first theoretical treatment of direct energy conversion (DEC) appeared in the literature in 1957. Experiments were conducted over the next ten years, which identified a number of problem areas. Research declined by the late 1960's due to technical challenges that limited performance. Under the Nuclear Energy Research Initiative the authors are determining if these technical challenges can be overcome with todays technology. The authors present the basic principles of DEC reactors, review previous research, discuss problem areas in detail, and identify technological developments of the last 30 years that can overcome these obstacles. As an example, the fission electric cell must be insulated to avoid electrons crossing the cell. This insulation could be provided by a magnetic field as attempted in the early experiments. However, from work on magnetically insulated ion diodes they know how to significantly improve the field geometry. Finally, a prognosis for future development of DEC reactors will be presented .

  16. Forced Reconnection in the Near Magnetotail: Onset and Energy Conversion in PIC and MHD Simulations

    NASA Technical Reports Server (NTRS)

    Birn, J.; Hesse, Michael

    2014-01-01

    Using two-dimensional particle-in-cell (PIC) together with magnetohydrodynamic (MHD) Q1 simulations of magnetotail dynamics, we investigate the evolution toward onset of reconnection and the subsequent energy transfer and conversion. In either case, reconnection onset is preceded by a driven phase, during which magnetic flux is added to the tail at the high-latitude boundaries, followed by a relaxation phase, during which the configuration continues to respond to the driving. The boundary deformation leads to the formation of thin embedded current sheets, which are bifurcated in the near tail, converging to a single sheet farther out in the MHD simulations. The thin current sheets in the PIC simulation are carried by electrons and are associated with a strong perpendicular electrostatic field, which may provide a connection to parallel potentials and auroral arcs and an ionospheric signal even prior to the onset of reconnection. The PIC simulation very well satisfies integral entropy conservation (intrinsic to ideal MHD) during this phase, supporting ideal ballooning stability. Eventually, the current intensification leads to the onset of reconnection, the formation and ejection of a plasmoid, and a collapse of the inner tail. The earthward flow shows the characteristics of a dipolarization front: enhancement of Bz, associated with a thin vertical electron current sheet in the PIC simulation. Both MHD and PIC simulations show a dominance of energy conversion from incoming Poynting flux to outgoing enthalpy flux, resulting in heating of the inner tail. Localized Joule dissipation plays only a minor role.

  17. Photochemical conversion of solar energy in the environment. Book chapter

    SciTech Connect

    Zepp, R.G.

    1991-01-01

    Past research on photochemistry in the environment has focused on gas phase reactions in the atmosphere. Recently, however, environmentally significant photoreactions have been discovered in natural waters (i.e., the sea, lakes, and rivers), on soil surfaces, and in atmospheric condensed phases. These new investigations have been stimulated in part by interest in developing a scientific understanding of the role of photochemical processes in the biogeochemical cycles of various elements. In addition, other studies have explored the role of natural photochemical processes in cleansing the environemnt of various waste materials or, in some cases, in converting the wastes to more toxic substances. In the paper, current research results on the photochemical conversion of solar energy in aquatic environments and on soil and metal oxide surfaces are presented. Rate equations and products for selected homogeneous and heterogeneous photoreactions that occur in these systems are described. Data are presented for direct and sensitized photoreactions and for sunlight-initiated free radical reactions. (Copyright (c) 1991 Kluwer Academic Publishers.)

  18. Photovoltaic solar energy conversion in the '80s

    NASA Astrophysics Data System (ADS)

    Chevalier, I.

    1981-04-01

    The potential for photovoltaic solar energy conversion in the generation of electricity to meet the needs of industrial and developing nations in the 1980s is discussed. The current technology of photovoltaic cells and modules, which are for the most part based on single crystal silicon and can deliver peak powers of 2 to 40 W at 6 to 12 V, is reviewed and prospects for cost reduction in the short- and medium-term by the development of new materials and production methods and increased cell efficiency and in the long term by the development of thin film cells, alternative compounds and mass production are indicated. Possible applications of photovoltaic-derived electricity are pointed out, including educational television receivers, rural telephones, refrigerators, water pumping and hospitals in developing nations and telecommunications, cathodic protection, signaling, telemetry and low-power pumping applications in industrial nations. Predictions of a photovoltaic peak Watt installed costing less than 10 francs by 1990 and a market above 100 MW in 1985 are pointed out.

  19. Enhanced photo-bioelectrochemical energy conversion by genetically engineered cyanobacteria.

    PubMed

    Sekar, Narendran; Jain, Rachit; Yan, Yajun; Ramasamy, Ramaraja P

    2016-03-01

    Photosynthetic energy conversion using natural systems is increasingly being investigated in the recent years. Photosynthetic microorganisms, such as cyanobacteria, exhibit light-dependent electrogenic characteristics in photo-bioelectrochemical cells (PBEC) that generate substantial photocurrents, yet the current densities are lower than their photovoltaic counterparts. Recently, we demonstrated that a cyanobacterium named Nostoc sp. employed in PBEC could generate up to 35 mW m(-2) even in a non-engineered PBEC. With the insights obtained from our previous research, a novel and successful attempt has been made in the current study to genetically engineer the cyanobacteria to further enhance its extracellular electron transfer. The cyanobacterium Synechococcus elongatus PCC 7942 was genetically engineered to express a non-native redox protein called outer membrane cytochrome S (OmcS). OmcS is predominantly responsible for metal reducing abilities of exoelectrogens such as Geobacter sp. The engineered S. elongatus exhibited higher extracellular electron transfer ability resulting in approximately ninefold higher photocurrent generation on the anode of a PBEC than the corresponding wild-type cyanobacterium. This work highlights the scope for enhancing photocurrent generation in cyanobacteria, thereby benefiting faster advancement of the photosynthetic microbial fuel cell technology. Biotechnol. Bioeng. 2016;113: 675-679. © 2015 Wiley Periodicals, Inc. PMID:26348367

  20. Exciton fission and solar energy conversion beyond the limit

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoyang

    2014-03-01

    The absorption of one photon by a semiconductor material usually creates one electron-hole pair, but this general rule breaks down in a few organic semiconductors, such as pentacene and tetracene, where one photon absorption may result in two electron-hole pairs in a process called singlet exciton. Recent measurements in our group by time-resolved two-photon photoemission (TR-2PPE) spectroscopy in crystalline pentacene and tetracene provided the first spectroscopic signatures in singlet fission of a critical intermediate known as the multiexciton state. More importantly, population of the multiexciton state is found to rise concurrently with that of the singlet state on the ultrafast time scale upon photo excitation. This observation provides an experimental foundation for a quantum coherent mechanism in which the electronic coupling creates a quantum superposition of the singlet and the multiexciton state immediately following optical excitation. We demonstrate the feasibility of harvesting the multiexciton state for multiple charge carriers and the implementation of singlet fission for solar energy conversion beyond the Shockley-Queisser limit.

  1. Ocean Thermal Energy Conversion (OTEC) Programmatic Environmental Analysis--Appendices

    SciTech Connect

    Authors, Various

    1980-01-01

    The programmatic environmental analysis is an initial assessment of Ocean Thermal Energy Conversion (OTEC) technology considering development, demonstration and commercialization. It is concluded that the OTEC development program should continue because the development, demonstration, and commercialization on a single-plant deployment basis should not present significant environmental impacts. However, several areas within the OTEC program require further investigation in order to assess the potential for environmental impacts from OTEC operation, particularly in large-scale deployments and in defining alternatives to closed-cycle biofouling control: (1) Larger-scale deployments of OTEC clusters or parks require further investigations in order to assess optimal platform siting distances necessary to minimize adverse environmental impacts. (2) The deployment and operation of the preoperational platform (OTEC-1) and future demonstration platforms must be carefully monitored to refine environmental assessment predictions, and to provide design modifications which may mitigate or reduce environmental impacts for larger-scale operations. These platforms will provide a valuable opportunity to fully evaluate the intake and discharge configurations, biofouling control methods, and both short-term and long-term environmental effects associated with platform operations. (3) Successful development of OTEC technology to use the maximal resource capabilities and to minimize environmental effects will require a concerted environmental management program, encompassing many different disciplines and environmental specialties. This volume contains these appendices: Appendix A -- Deployment Scenario; Appendix B -- OTEC Regional Characterization; and Appendix C -- Impact and Related Calculations.

  2. Draft environmental assessment: Ocean Thermal Energy Conversion (OTEC) Pilot Plants

    SciTech Connect

    Sullivan, S.M.; Sands, M.D.; Donat, J.R.; Jepsen, P.; Smookler, M.; Villa, J.F.

    1981-02-01

    This Environmental Assessment (EA) has been prepared, in accordance with the National Environmental Policy Act of 1969, for the deployment and operation of a commercial 40-Megawatt (MW) Ocean Thermal Energy Conversion (OTEC) Pilot Plant (hereafter called the Pilot Plant). A description of the proposed action is presented, and a generic environment typical of the candidate Pilot Plant siting regions is described. An assessment of the potential environmental impacts associated with the proposed action is given, and the risk of credible accidents and mitigating measures to reduce these risks are considered. The Federal and State plans and policies the proposed action will encompass are described. Alternatives to the proposed action are presented. Appendix A presents the navigation and environmental information contained in the US Coast Pilot for each of the candidate sites; Appendix B provides a brief description of the methods and calculations used in the EA. It is concluded that environmental disturbances associated with Pilot Plant activities could potentially cause significant environmental impacts; however, the magnitude of these potential impacts cannot presently be assessed, due to insufficient engineering and environmental information. A site- and design-specific OTEC Pilot Plant Environmental Impact Statement (EIS) is required to resolve the potentially significant environmental effects associated with Pilot Plant deployment and operation. (WHK)

  3. Magnetic properties and energy-mapping analysis.

    PubMed

    Xiang, Hongjun; Lee, Changhoon; Koo, Hyun-Joo; Gong, Xingao; Whangbo, Myung-Hwan

    2013-01-28

    The magnetic energy levels of a given magnetic solid are closely packed in energy because the interactions between magnetic ions are weak. Thus, in describing its magnetic properties, one needs to generate its magnetic energy spectrum by employing an appropriate spin Hamiltonian. In this review article we discuss how to determine and specify a necessary spin Hamiltonian in terms of first principles electronic structure calculations on the basis of energy-mapping analysis and briefly survey important concepts and phenomena that one encounters in reading the current literature on magnetic solids. Our discussion is given on a qualitative level from the perspective of magnetic energy levels and electronic structures. The spin Hamiltonian appropriate for a magnetic system should be based on its spin lattice, i.e., the repeat pattern of its strong magnetic bonds (strong spin exchange paths), which requires one to evaluate its Heisenberg spin exchanges on the basis of energy-mapping analysis. Other weaker energy terms such as Dzyaloshinskii-Moriya (DM) spin exchange and magnetocrystalline anisotropy energies, which a spin Hamiltonian must include in certain cases, can also be evaluated by performing energy-mapping analysis. We show that the spin orientation of a transition-metal magnetic ion can be easily explained by considering its split d-block levels as unperturbed states with the spin-orbit coupling (SOC) as perturbation, that the DM exchange between adjacent spin sites can become comparable in strength to the Heisenberg spin exchange when the two spin sites are not chemically equivalent, and that the DM interaction between rare-earth and transition-metal cations is governed largely by the magnetic orbitals of the rare-earth cation. PMID:23128376

  4. Linear mode conversion of Langmuir and ordinary waves in unmagnetized and magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Keller, S.; Kim, E.; Johnson, J.; Cairns, I. H.; Labelle, J. W.

    2012-12-01

    Linear mode conversion (LMC) between Langmuir waves and EM radiation that occurs in inhomogeneous density profiles at frequencies close to the local electron plasma frequency ?pe is relevant to various ionospheric, solar, and heliospheric radio emissions. In this study, we investigate LMC in warm unmagnetized plasmas using a full wave model and wave simulation code including a density gradient. We calculate the power (?s) and energy (?) conversion efficiencies for various wave frequencies (?), incidence angles (?), density scale lengths, and ? = vth2/c2, where vth is the electron thermal speed. We also investigate the effects of various different electron density profiles on LMC, e.g. various E and F region ionospheric density profiles. For unmagnetized plasmas, we show that (a) both ?s and ? are almost a constant as a function of ? for constant ?pe. However, for ?/ ?pe ? 1, the angular mode conversion window (??) is clearly reduced and the maximum conversion efficiency (?max and ?smax ) increases; (b) When ? increases from 0.01 to 0.2, ?max linearly increases from 5 to 20% and ?? of ? also becomes wider, while ?smax and ?? ( ?s= ?smax) are not changed and ?? for ?s slightly increases.

  5. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 1, Overview

    SciTech Connect

    Butner, R.S.; Elliott, D.C.; Sealock, L.J. Jr.; Pyne, J.W.

    1988-12-01

    Pacific Northwest Laboratory has completed an initial investigation of the effects of physical and chemical properties of biomass feedstocks relative to their performance in biomass energy conversion systems. Both biochemical conversion routes (anaerobic digestion and ethanol fermentation) and thermochemical routes (combustion, pyrolysis, and gasification) were included in the study. Related processes including chemical and physical pretreatment to improve digestibility, and size and density modification processes such as milling and pelletizing were also examined. This overview report provides background and discussion of feedstock and conversion relationships, along with recommendations for future research. The recommendations include (1) coordinate production and conversion research programs; (2) quantify the relationship between feedstock properties and conversion priorities; (3) develop a common framework for evaluating and characterizing biomass feedstocks; (4) include conversion effects as part of the criteria for selecting feedstock breeding programs; and (5) continue emphasis on multiple feedstock/conversion options for biomass energy systems. 9 refs., 3 figs., 2 tabs.

  6. Resonant high energy graviton to photon conversion at the post-recombination epoch

    NASA Astrophysics Data System (ADS)

    Dolgov, Alexander D.; Ejlli, Damian

    2013-05-01

    Resonant conversion of high energy gravitons into photons in large scale cosmological magnetic fields at the post-recombination epoch is considered. It is shown that the probability of the resonance photon production is much higher than the nonresonant one. As a result, an observable isotropic background of cosmic gamma rays might be created. As shown in our previous paper, an early population of primordial black holes prior to big bang nucleosynthesis could be an efficient source of high frequency gravitational waves. For the primordial black hole mass, about 108g, the produced photons would be the dominant component of the soft to hard cosmic x-ray background and for lower masses the spectrum is shifted down to the ultraviolet and optic.

  7. Electrolyte- and Transport-Enhanced Thermogalvanic Energy Conversion

    NASA Astrophysics Data System (ADS)

    Gunawan, Andrey

    Waste heat energy conversion remains an inviting subject for research, given the renewed emphasis on energy efficiency and carbon emissions reduction. Solid-state thermoelectric devices have been widely investigated, but their practical application remains challenging because of cost and the inability to fabricate them in geometries that are easily compatible with heat sources. An intriguing alternative to solid-state thermoelectric devices is thermogalvanic cells, which include a generally liquid electrolyte that permits the transport of ions. Thermogalvanic cells have long been known in the electrochemistry community, but have not received much attention from the thermal transport community. This is surprising given that their performance is highly dependent on controlling both thermal and mass (ionic) transport. This research will focus on a research project, which is an interdisciplinary collaboration between mechanical engineering (i.e. thermal transport) and chemistry, and is a largely experimental effort aimed at improving fundamental understanding of thermogalvanic systems. The first part will discuss how a simple utilization of natural convection within the cell doubles the maximum power output of the cell. In the second part of the research, some of the results from the previous part will be applied in a feasibility study of incorporating thermogalvanic waste heat recovery systems into automobiles. Finally, a new approach to enhance Seebeck coefficient by tuning the configurational entropy of a mixed-ligand complex formation of copper sulfate aqueous electrolytes will be presented. Ultimately, a summary of these results as well as possible future work that can be formed from these efforts is discussed.

  8. Efficiency evaluation of oxygen enrichment in energy conversion processes

    SciTech Connect

    Bomelburg, H.J.

    1983-12-01

    The extent to which energy conversion efficiencies can be increased by using oxygen or oxygen-enriched air for combustion was studied. Combustion of most fuels with oxygen instead of air was found to have five advantages: increases combustion temperature and efficiency, improves heat transfer at high temperatures, reduces nitrous oxide emissions, permits a high ration of exhaust gas recirculation and allows combustion of certain materials not combustible in air. The same advantages, although to a lesser degree, are apparent with oxygen-enriched air. The cost-effectiveness of the process must necessarily be improved by about 10% when using oxygen instead of air before such use could become justifiable on purely economic terms. Although such a modest increase appears to be attainable in real situations, this study ascertained that it is not possible to generally assess the economic gains. Rather, each case requires its own evaluation. For certain processes industry has already proven that the use of oxygen leads to more efficient plant operation. Several ideas for essentially new applications are described. Specifically, when oxygen is used with exhaust gas recirculation in external or internal combustion engines. It appears also that the advantages of pulse combustion can be amplified further if oxygen is used. When burning wet fuels with oxygen, direct steam generation becomes possible. Oxygen combustion could also improve processes for in situ gasification of coals, oil shales, peats, and other wet fuels. Enhanced oil recovery by fire flooding methods might also become more effective if oxygen is used. The cold energy contained in liquid oxygen can be substantially recovered in the low end of certain thermodynamic cycles. Further efforts to develop certain schemes for using oxygen for combustion appear to be justified from both the technical and economic viewpoints.

  9. Hierarchically structured carbon nanotubes for energy conversion and storage

    NASA Astrophysics Data System (ADS)

    Du, Feng

    As the world population continues to increase, large amounts of energy are consumed. Reality pushes us to find new energy or use our current energy more efficiently. Researches on energy conversion and storage have become increasingly important and essential. This grand challenge research has led to a recent focus on nanostructured materials. Carbon nanomaterials such as carbon nanotubes (CNTs) play a critical role in all of these nanotechnology challenges. CNTs have a very large surface area, a high electrochemical accessibility, high electronic conductivity and strong mechanical properties. This combination of properties makes them promising materials for energy device applications, such as FETs, supercapacitors, fuel cells, and lithium batteries. This study focuses on exploring the possibility of using vertically aligned carbon nanotubes (VA-CNTs) as the electrode materials in these energy applications. For the application of electrode materials, electrical conductive, vertically aligned CNTs with controllable length and diameter were synthesized. Several CVD methods for VA-CNT growth have been explored, although the iron / aluminum pre-coated catalyst CVD system was the main focus. A systematic study of several factors, including growth time, temperature, gas ratio, catalyst coating was conducted. The mechanism of VA-CNTs was discussed and a model for VA-CNT length / time was proposed to explain the CNT growth rate. Furthermore, the preferential growth of semiconducting (up to 96 atom% carbon) VA-SWNTs by using a plasma enhanced CVD process combined with fast heating was also explored, and these semiconducting materials have been directly used for making FETs using simple dispersion in organic solvent, without any separation and purification. Also, by inserting electron-accepting nitrogen atoms into the conjugated VA-CNT structure during the growth process, we synthesized vertically aligned nitrogen containing carbon nanotubes (VA-NCNTs). After purification of the metal catalyst, these metal-free VA-NCNTs have shown even better oxidation reduction reaction (ORR) performance than commercially available platinum based electrodes in many aspects, including electrocatalytic activity, long-term operation stability, and tolerance to fuel-molecule crossover. Quantum mechanics calculations and electrochemical experimental results indicate that the charge-deficient carbon atoms around the electron-rich nitrogen atoms improve the ORR reaction and the action of the electrochemical cycling. Finally, by growing vertically aligned carbon nanotubes between graphitic layers in thermally-expanded HOPG, we developed a novel, controlled orientation 3D VA-CNT-graphene architecture, which could allow free transport of electrons and ions. These 3D architectures with a tunable pillar length were demonstrated to be excellent electrode materials for energy related devices. Further, these 3D structures were functionalized with nickel hydroxide by electrodeposition, and the resultant hybrid materials could deliver a high energy density (e.g., ~35 Wh/kg) at a high power density (e.g., ~8 kW/kg), which would significantly outperform many currently available electrode materials.

  10. Recovery Act: Integrated DC-DC Conversion for Energy-Efficient Multicore Processors

    SciTech Connect

    Shepard, Kenneth L

    2013-03-31

    In this project, we have developed the use of thin-film magnetic materials to improve in energy efficiency of digital computing applications by enabling integrated dc-dc power conversion and management with on-chip power inductors. Integrated voltage regulators also enables fine-grained power management, by providing dynamic scaling of the supply voltage in concert with the clock frequency of synchronous logic to throttle power consumption at periods of low computational demand. The voltage converter generates lower output voltages during periods of low computational performance requirements and higher output voltages during periods of high computational performance requirements. Implementation of integrated power conversion requires high-capacity energy storage devices, which are generally not available in traditional semiconductor processes. We achieve this with integration of thin-film magnetic materials into a conventional complementary metal-oxide-semiconductor (CMOS) process for high-quality on-chip power inductors. This project includes a body of work conducted to develop integrated switch-mode voltage regulators with thin-film magnetic power inductors. Soft-magnetic materials and inductor topologies are selected and optimized, with intent to maximize efficiency and current density of the integrated regulators. A custom integrated circuit (IC) is designed and fabricated in 45-nm CMOS silicon-on-insulator (SOI) to provide the control system and power-train necessary to drive the power inductors, in addition to providing a digital load for the converter. A silicon interposer is designed and fabricated in collaboration with IBM Research to integrate custom power inductors by chip stacking with the 45-nm CMOS integrated circuit, enabling power conversion with current density greater than 10A/mm2. The concepts and designs developed from this work enable significant improvements in performance-per-watt of future microprocessors in servers, desktops, and mobile devices. These new approaches to scaled voltage regulation for computing devices also promise significant impact on electricity consumption in the United States and abroad by improving the efficiency of all computational platforms. In 2006, servers and datacenters in the United States consumed an estimated 61 billion kWh or about 1.5% of the nation's total energy consumption. Federal Government servers and data centers alone accounted for about 10 billion kWh, for a total annual energy cost of about $450 million. Based upon market growth and efficiency trends, estimates place current server and datacenter power consumption at nearly 85 billion kWh in the US and at almost 280 billion kWh worldwide. Similar estimates place national desktop, mobile and portable computing at 80 billion kWh combined. While national electricity utilization for computation amounts to only 4% of current usage, it is growing at a rate of about 10% a year with volume servers representing one of the largest growth segments due to the increasing utilization of cloud-based services. The percentage of power that is consumed by the processor in a server varies but can be as much as 30% of the total power utilization, with an additional 50% associated with heat removal. The approaches considered here should allow energy efficiency gains as high as 30% in processors for all computing platforms, from high-end servers to smart phones, resulting in a direct annual energy savings of almost 15 billion kWh nationally, and 50 billion kWh globally. The work developed here is being commercialized by the start-up venture, Ferric Semiconductor, which has already secured two Phase I SBIR grants to bring these technologies to the marketplace.

  11. Basic and applied research related to the technology of space energy conversion systems, 1982 - 1983

    NASA Technical Reports Server (NTRS)

    Hertzberg, A.

    1983-01-01

    Topics on solar energy conversion concepts and applications are discussed. An overview of the current status and future utilization of radiation receivers for electrical energy generation, liquid droplet radiation systems, and liquid droplet heat exchangers is presented.

  12. Green farming systems for the Southeast USA using manure-to-energy conversion platforms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Livestock operations in the Southeastern USA are faced with implementing holistic solutions to address effective manure treatment through efficient energy management and safeguarding of supporting natural resources. By integrating waste-to-energy conversion platforms, future green farming systems ca...

  13. A Review of Previous Research in Direct Energy Conversion Fission Reactors

    SciTech Connect

    DUONG,HENRY; POLANSKY,GARY F.; SANDERS,THOMAS L.; SIEGEL,MALCOLM D.

    1999-09-22

    From the earliest days of power reactor development, direct energy conversion was an obvious choice to produce high efficiency electric power generation. Directly capturing the energy of the fission fragments produced during nuclear fission avoids the intermediate conversion to thermal energy and the efficiency limitations of classical thermodynamics. Efficiencies of more than 80% are possible, independent of operational temperature. Direct energy conversion fission reactors would possess a number of unique characteristics that would make them very attractive for commercial power generation. These reactors would be modular in design with integral power conversion and operate at low pressures and temperatures. They would operate at high efficiency and produce power well suited for long distance transmission. They would feature large safety margins and passively safe design. Ideally suited to production by advanced manufacturing techniques, direct energy conversion fission reactors could be produced more economically than conventional reactor designs. The history of direct energy conversion can be considered as dating back to 1913 when Moseleyl demonstrated that charged particle emission could be used to buildup a voltage. Soon after the successful operation of a nuclear reactor, E.P. Wigner suggested the use of fission fragments for direct energy conversion. Over a decade after Wigner's suggestion, the first theoretical treatment of the conversion of fission fragment kinetic energy into electrical potential appeared in the literature. Over the ten years that followed, a number of researchers investigated various aspects of fission fragment direct energy conversion. Experiments were performed that validated the basic physics of the concept, but a variety of technical challenges limited the efficiencies that were achieved. Most research in direct energy conversion ceased in the US by the late 1960s. Sporadic interest in the concept appears in the literature until this day, but there have been no recent significant programs to develop the technology.

  14. The Magnetic Free Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

    2001-01-01

    The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

  15. Magnetic bearings for inertial energy storage

    NASA Technical Reports Server (NTRS)

    Rodriguez, G. Ernest; Eakin, Vickie

    1987-01-01

    Advanced flywheels utilizing high strength fibers must operate at high rotational speeds and as such must operate in vacuum to reduce windage losses. The utilization of magnetic bearings in the flywheels overcome lubrication and seal problems, resulting in an energy storage system offering potential improvements over conventional electrochemical energy storage. Magnetic bearings evolved in the 1950s from the simple application of permanent magnets positioned to exert repulsive forces to the present where permanent magnets and electromagnets have been combined to provide axial and radial suspension. Further development of magnetic suspension has led to the design of a shaftless flywheel system for aerospace application. Despite the lack of proof of concept, integrated magnetic suspension in inertial storage systems can provide significant performance improvements to warrant development and tests.

  16. Mode conversion and absorption of fast waves at high ion cyclotron harmonics in inhomogeneous magnetic fields

    SciTech Connect

    Cho, Suwon; Kwak, Jong-Gu

    2014-04-15

    The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where ?{sub i}=k{sub ?}{sup 2}?{sub i}{sup 2}/2?1 (where k{sub ?} is the perpendicular wave number and ?{sub i} is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.

  17. Summary of State-of-the-Art Power Conversion Systems for Energy Storage Applications

    SciTech Connect

    Atcitty, S.; Gray-Fenner, A.; Ranade, S.

    1998-09-01

    The power conversion system (PCS) is a vital part of many energy storage systems. It serves as the interface between the storage device, an energy source, and an AC load. This report summarizes the results of an extensive study of state-of-the-art power conversion systems used for energy storage applications. The purpose of the study was to investigate the potential for cost reduction and performance improvement in these power conversion systems and to provide recommendations for fiture research and development. This report provides an overview of PCS technology, a description of several state-of-the-art power conversion systems and how they are used in specific applications, a summary of four basic configurations for l:he power conversion systems used in energy storage applications, a discussion of PCS costs and potential cost reductions, a summary of the stancku-ds and codes relevant to the technology, and recommendations for future research and development.

  18. Magnetic Bearings for Inertial Energy Storage

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1983-01-01

    The selection of a noncontacting bearing technique with no wear out phenomena and which is vacuum compatible which is the decisive factor in selecting magnetic bearings for kinetic energy storage was investigated. Unlimited cycle life without degradation is a primary goal. Storage efficiency is a key parameter which is defined as the ratio of the energy remaining to energy stored after a fixed time interval at no load conditions. Magnetic bearings, although noncontacting, are not perfectly frictionless in that magnetic losses due to eddy currents and hysteresis can occur. Practical magnetic bearings, however, deviate from perfect symmetry and have discontinuities and asymmetric flux paths either by design or when controlled in the presence of disturbances, which cause losses. These losses can be kept smaller in the bearings than in a high power motor/generator, however, are a significant factor in selecting the magnetic bearing type.

  19. Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA

    SciTech Connect

    Liangping, Wang; Mo, Li; Juanjuan, Han; Ning, Guo; Jian, Wu; Aici, Qiu

    2014-06-15

    The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6–1.0 Ω in about 10–20 ns.

  20. Optimized Helium-Brayton Power Conversion for Fusion Energy Systems

    SciTech Connect

    Zhao Haihua; Fukuda, Grant; Abbott, Ryan P.; Peterson, Per F.

    2005-04-15

    This paper presents an overview and a few point designs for multiple-reheat helium Brayton cycle power conversion systems using molten salts (or liquid metals or direct helium cooling). All designs are derived from the General Atomics GT-MHR power conversion unit (PCU). The important role of compact, offset fin heat exchangers for heat transfer to the power cycle helium, and the potential for these to be fabricated from carbon-coated composite materials that would have lower potential for fouling, are discussed. Specific links are made to the ITER TBM and laser IFE blanket design, and to Z-Pinch/HIF thick-liquid IFE.

  1. The efficiency of thermal energy conversion into electricity by means of the thermovoltaic effect

    NASA Astrophysics Data System (ADS)

    Egorov, V. M.; Kaminskii, V. V.; Kazanin, M. M.; Solov'ev, S. M.; Golubkov, A. V.

    2015-04-01

    The efficiency of thermal energy conversion into electricity based on the thermovoltaic effect has been studied. Experiments were performed on samarium sulfide (SmS) samples containing a region doped with excess samarium up to Sm1.04S. The conversion efficiency increases with time from 17 to 36% due to a decrease in the amount of absorbed thermal energy at unchanged power of the generated electric energy.

  2. Biomass Conversion Task IV 1987 program of work: International Energy Agency Bioenergy Agreement

    SciTech Connect

    Stevens, D.J.

    1986-12-01

    Biomass is a major, renewable energy resource through out the world, and extensive research is being conducted by many countries on bioenergy technologies. In an effort to improve communications and cooperation in the area of biomass energy, several nations have agreed to a cooperative program of work under the International Energy Agency's Bioenergy Agreement (IEA/BA). Three areas of major importance have been identified including Short Rotation Forestry, Conventional Forestry, and Biomass Conversion. This document describes the 1987 Program of Work for cooperative activities in the area of Biomass Conversion. The background of the cooperation and descriptions of specific conversion projects are presented. Details of activity funding are also provided. 3 tabs.

  3. Challenges and opportunities for photochemists on the verge of solar energy conversion.

    PubMed

    Chu, Cheng-Che; Bassani, Dario M

    2008-05-01

    Has photochemistry missed the boat on solar energy conversion? Certainly not, but it is time to reach out and make a difference if we do not want to have to choose between feeding our families or our thirst for fuel. Compared to other initiatives, such as biofuels or nuclear fusion, direct conversion of solar energy into electricity or fuels is lagging behind in terms of funding, and this is slowing progress on overcoming critical bottlenecks. This perspective outlines some of the key fundamental issues in solar energy conversion based on organic photovoltaic devices or artificial photosynthesis where being a photochemist can make a difference. PMID:18465006

  4. Thermionic emission energy distribution from nanocrystalline diamond films for direct thermal-electrical energy conversion applications

    NASA Astrophysics Data System (ADS)

    Uppireddi, Kishore; Westover, Tyler L.; Fisher, Timothy S.; Weiner, Brad R.; Morell, Gerardo

    2009-08-01

    In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions (TEEDs) from nanocrystalline diamond (NCD) films in the temperature range from 700 to 900 C that reveal a consistent effective work function of 3.3 eV. The NCD films also exhibit emission peaks corresponding to higher work functions as indicated by shifts in their energy position and relative intensity as a function of temperature. These shifts thus appear to be related to instabilities in the NCD's surface chemistry. The analysis of these data yields information on the origin of the low effective work function of NCD.

  5. High energy product in Battenberg structured magnets

    NASA Astrophysics Data System (ADS)

    Bance, S.; Oezelt, H.; Schrefl, T.; Winklhofer, M.; Hrkac, G.; Zimanyi, G.; Gutfleisch, O.; Evans, R. F. L.; Chantrell, R. W.; Shoji, T.; Yano, M.; Sakuma, N.; Kato, A.; Manabe, A.

    2014-11-01

    Multiphase nano-structured permanent magnets show a high thermal stability of remanence and a high energy product while the amount of rare-earth elements is reduced. Non-zero temperature micromagnetic simulations show that a temperature coefficient of remanence of -0.073%/K and that an energy product greater than 400 kJ/m3 can be achieved at a temperature of 450 K in a magnet containing around 40 volume percent Fe65Co35 embedded in a hard magnetic matrix.

  6. Optimization of HTS superconducting magnetic energy storage magnet volume

    NASA Astrophysics Data System (ADS)

    Korpela, Aki; Lehtonen, Jorma; Mikkonen, Risto

    2003-08-01

    Nonlinear optimization problems in the field of electromagnetics have been successfully solved by means of sequential quadratic programming (SQP) and the finite element method (FEM). For example, the combination of SQP and FEM has been proven to be an efficient tool in the optimization of low temperature superconductors (LTS) superconducting magnetic energy storage (SMES) magnets. The procedure can also be applied for the optimization of HTS magnets. However, due to a strongly anisotropic material and a slanted electric field, current density characteristic high temperature superconductors HTS optimization is quite different from that of the LTS. In this paper the volumes of solenoidal conduction-cooled Bi-2223/Ag SMES magnets have been optimized at the operation temperature of 20 K. In addition to the electromagnetic constraints the stress caused by the tape bending has also been taken into account. Several optimization runs with different initial geometries were performed in order to find the best possible solution for a certain energy requirement. The optimization constraints describe the steady-state operation, thus the presented coil geometries are designed for slow ramping rates. Different energy requirements were investigated in order to find the energy dependence of the design parameters of optimized solenoidal HTS coils. According to the results, these dependences can be described with polynomial expressions.

  7. Permanent Magnet Spiral Motor for Magnetic Gradient Energy Utilization: Axial Magnetic Field

    NASA Astrophysics Data System (ADS)

    Valone, Thomas F.

    2010-01-01

    The Spiral Magnetic Motor, which can accelerate a magnetized rotor through 90% of its cycle with only permanent magnets, was an energy milestone for the 20th century patents by Kure Tekkosho in the 1970's. However, the Japanese company used old ferrite magnets which are relatively weak and an electrically-powered coil to jump start every cycle, which defeated the primary benefit of the permanent magnet motor design. The principle of applying an inhomogeneous, anisotropic magnetic field gradient force Fz = ? cos ? dB/dz, with permanent magnets is well-known in physics, e.g., Stern-Gerlach experiment, which exploits the interaction of a magnetic moment with the aligned electron spins of magnetic domains. In this case, it is applied to dB/d? in polar coordinates, where the force F? depends equally on the magnetic moment, the cosine of the angle between the magnetic moment and the field gradient. The radial magnetic field increases in strength (in the attractive mode) or decreases in strength (in the repulsive mode) as the rotor turns through one complete cycle. An electromagnetic pulsed switching has been historically used to help the rotor traverse the gap (detent) between the end of the magnetic stator arc and the beginning (Kure Tekko, 1980). However, alternative magnetic pulse and switching designs have been developed, as well as strategic eddy current creation. This work focuses on the switching mechanism, novel magnetic pulse methods and advantageous angular momentum improvements. For example, a collaborative effort has begun with Toshiyuki Ueno (University of Tokyo) who has invented an extremely low power, combination magnetostrictive-piezoelectric (MS-PZT) device for generating low frequency magnetic fields and consumes "zero power" for static magnetic field production (Ueno, 2004 and 2007a). Utilizing a pickup coil such as an ultra-miniature millihenry inductor with a piezoelectric actuator or simply Wiegand wire geometry, it is shown that the necessary power for magnetic field switching device can be achieved in order to deflect the rotor magnet in transit. The Wiegand effect itself (bistable FeCoV wire called "Vicalloy") invented by John Wiegand (Switchable Magnetic Device, US Patent ?4,247,601), utilizing Barkhausen jumps of magnetic domains, is also applied for a similar achievement (Dilatush, 1977). Conventional approaches for spiral magnetic gradient force production have not been adequate for magnetostatic motors to perform useful work. It is proposed that integrating a magnetic force control device with a spiral stator inhomogeneous axial magnetic field motor is a viable approach to add a sufficient nonlinear boundary shift to apply the angular momentum and potential energy gained in 315 degrees of the motor cycle.

  8. Relationship between thermoelectric figure of merit and energy conversion efficiency

    PubMed Central

    Kim, Hee Seok; Liu, Weishu; Chen, Gang; Chu, Ching-Wu; Ren, Zhifeng

    2015-01-01

    The formula for maximum efficiency (ηmax) of heat conversion into electricity by a thermoelectric device in terms of the dimensionless figure of merit (ZT) has been widely used to assess the desirability of thermoelectric materials for devices. Unfortunately, the ηmax values vary greatly depending on how the average ZT values are used, raising questions about the applicability of ZT in the case of a large temperature difference between the hot and cold sides due to the neglect of the temperature dependences of the material properties that affect ZT. To avoid the complex numerical simulation that gives accurate efficiency, we have defined an engineering dimensionless figure of merit (ZT)eng and an engineering power factor (PF)eng as functions of the temperature difference between the cold and hot sides to predict reliably and accurately the practical conversion efficiency and output power, respectively, overcoming the reporting of unrealistic efficiency using average ZT values. PMID:26100905

  9. Relationship between thermoelectric figure of merit and energy conversion efficiency.

    PubMed

    Kim, Hee Seok; Liu, Weishu; Chen, Gang; Chu, Ching-Wu; Ren, Zhifeng

    2015-07-01

    The formula for maximum efficiency (?max) of heat conversion into electricity by a thermoelectric device in terms of the dimensionless figure of merit (ZT) has been widely used to assess the desirability of thermoelectric materials for devices. Unfortunately, the ?max values vary greatly depending on how the average ZT values are used, raising questions about the applicability of ZT in the case of a large temperature difference between the hot and cold sides due to the neglect of the temperature dependences of the material properties that affect ZT. To avoid the complex numerical simulation that gives accurate efficiency, we have defined an engineering dimensionless figure of merit (ZT)eng and an engineering power factor (PF)eng as functions of the temperature difference between the cold and hot sides to predict reliably and accurately the practical conversion efficiency and output power, respectively, overcoming the reporting of unrealistic efficiency using average ZT values. PMID:26100905

  10. Mimicking enzymatic active sites on surfaces for energy conversion chemistry.

    PubMed

    Gutzler, Rico; Stepanow, Sebastian; Grumelli, Doris; Lingenfelder, Magalí; Kern, Klaus

    2015-07-21

    Metal-organic supramolecular chemistry on surfaces has matured to a point where its underlying growth mechanisms are well understood and structures of defined coordination environments of metal atoms can be synthesized in a controlled and reproducible procedure. With surface-confined molecular self-assembly, scientists have a tool box at hand which can be used to prepare structures with desired properties, as for example a defined oxidation number and spin state of the transition metal atoms within the organic matrix. From a structural point of view, these coordination sites in the supramolecular structure resemble the catalytically active sites of metallo-enzymes, both characterized by metal centers coordinated to organic ligands. Several chemical reactions take place at these embedded metal ions in enzymes and the question arises whether these reactions also take place using metal-organic networks as catalysts. Mimicking the active site of metal atoms and organic ligands of enzymes in artificial systems is the key to understanding the selectivity and efficiency of enzymatic reactions. Their catalytic activity depends on various parameters including the charge and spin configuration in the metal ion, but also on the organic environment, which can stabilize intermediate reaction products, inhibits catalytic deactivation, and serves mostly as a transport channel for the reactants and products and therefore ensures the selectivity of the enzyme. Charge and spin on the transition metal in enzymes depend on the one hand on the specific metal element, and on the other hand on its organic coordination environment. These two parameters can carefully be adjusted in surface confined metal-organic networks, which can be synthesized by virtue of combinatorial mixing of building synthons. Different organic ligands with varying functional groups can be combined with several transition metals and spontaneously assemble into ordered networks. The catalytically active metal centers are adequately separated by the linking molecules and constitute promising candiates for heterogeneous catalysts. Recent advances in synthesis, characterization, and catalytic performance of metal-organic networks are highlighted in this Account. Experimental results like structure determination of the networks, charge and spin distribution in the metal centers, and catalytic mechanisms for electrochemical reactions are presented. In particular, we describe the activity of two networks for the oxygen reduction reaction in a combined scanning tunneling microscopy and electrochemical study. The similarities and differences of the networks compared to metallo-enzymes will be discussed, such as the metal surface that operates as a geometric template and concomitantly functions as an electron reservoir, and how this leads to a new class of bioinspired catalysts. The possibility to create functional two-dimensional coordination complexes at surfaces taking inspiration from nature opens up a new route for the design of potent nanocatalyst materials for energy conversion. PMID:26121410

  11. Status and summary of laser energy conversion. [for space power transmission systems

    NASA Technical Reports Server (NTRS)

    Lee, G.

    1978-01-01

    This paper presents a survey of the status of laser energy converters. Since the inception of these devices in the early 1970's, significant advances have been made in understanding the basic conversion processes. Numerous theoretical and experimental studies have indicated that laser energy can be converted at wavelengths from the ultraviolet to the far-infrared. These converters can be classified into five general categories: photovoltaics, heat engines, thermoelectronic, optical diode, and photochemical. The conversion can be directly into electricity (such as the photovoltaic, thermoelectronic, and optical diode) or it can go through an intermediate stage of conversion to mechanical energy, as in the heat engines. The photochemical converters result in storable energy such as hydrogen. Projected conversion efficiencies range from about 30% for the photochemical to nearly 75% for the heat engines.

  12. IRON-INDUCED CHANGES IN LIGHT HARVESTING AND PHOTOCHEMICAL ENERGY CONVERSION IN EUKARYOTIC MARINE ALGAE

    EPA Science Inventory

    The role of iron in regulating light harvesting and photochemical energy conversion process was examined in the marine unicellular chlorophyte Dunaliella tertiolecta and the marine diatom Phaeodactylum tricornutum. In both species, iron limitation led to a reduction in cellular c...

  13. Role of thermochemical conversion in livestock waste-to-energy treatments: Obstacles and opportunities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Integrating thermochemical conversion (TCC) technologies with current animal waste treatment practices can treat and reduce quantities of manure from consolidated animal feeding operations. Additionally, TCC technologies can produce value-added, renewable energy products. These products can meet hea...

  14. Efficiency calculations for the direct energy conversion system of the Cadarache neutral beam injectors

    SciTech Connect

    White, R.C.

    1988-06-08

    A prototype energy conversion system is presently in operation at Cadarache, France. Such a device is planned for installation on each six neutral beam injectors for use in the Tore Supra experiment in 1989. We present calculations of beam performance that may influence design considerations. The calculations are performed with the DART charged particle beam code. We investigate the effects of cold plasma, direct energy conversion and neutral beam production. 4 refs., 6 figs., 4 tabs.

  15. Control Strategies for Smoothing of Output Power of Wind Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    Pratap, Alok; Urasaki, Naomitsu; Senju, Tomonobu

    2013-10-01

    This article presents a control method for output power smoothing of a wind energy conversion system (WECS) with a permanent magnet synchronous generator (PMSG) using the inertia of wind turbine and the pitch control. The WECS used in this article adopts an AC-DC-AC converter system. The generator-side converter controls the torque of the PMSG, while the grid-side inverter controls the DC-link and grid voltages. For the generator-side converter, the torque command is determined by using the fuzzy logic. The inputs of the fuzzy logic are the operating point of the rotational speed of the PMSG and the difference between the wind turbine torque and the generator torque. By means of the proposed method, the generator torque is smoothed, and the kinetic energy stored by the inertia of the wind turbine can be utilized to smooth the output power fluctuations of the PMSG. In addition, the wind turbines shaft stress is mitigated compared to a conventional maximum power point tracking control. Effectiveness of the proposed method is verified by the numerical simulations.

  16. Thermophotovoltaic energy conversion system having a heavily doped n-type region

    DOEpatents

    DePoy, David M. (Clifton Park, NY); Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY)

    2000-01-01

    A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

  17. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 1: Open-cycle gas turbines

    NASA Technical Reports Server (NTRS)

    Brown, D. H.; Corman, J. C.

    1976-01-01

    Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle; open-cycle MHD; closed-cycle inert gas MHD; closed-cycle liquid metal MHD; and fuel cells. Results are presented.

  18. Application of Nuclear Energy to Bitumen Upgrading and Biomass Conversion

    SciTech Connect

    Mamoru Numata; Yasushi Fujimura; Takayuki Amaya; Masao Hori

    2006-07-01

    Key drivers for the increasing use of nuclear energy are the need to mitigate global warming and the requirement for energy security. Nuclear energy can be applied not only to generate electricity but also as a heat source. Moreover, nuclear energy can be applied for hydrogen as well as water production. The application of nuclear energy to oil processing and biomass production is studied in this paper. (authors)

  19. MAGNETIC ENERGY PRODUCTION BY TURBULENCE IN BINARY NEUTRON STAR MERGERS

    SciTech Connect

    Zrake, Jonathan; MacFadyen, Andrew I.

    2013-06-01

    The simultaneous detection of electromagnetic and gravitational wave emission from merging neutron star binaries would greatly aid in their discovery and interpretation. By studying turbulent amplification of magnetic fields in local high-resolution simulations of neutron star merger conditions, we demonstrate that magnetar-level ({approx}> 10{sup 16} G) fields are present throughout the merger duration. We find that the small-scale turbulent dynamo converts 60% of the randomized kinetic energy into magnetic fields on a merger timescale. Since turbulent magnetic energy dissipates through reconnection events that accelerate relativistic electrons, turbulence may facilitate the conversion of orbital kinetic energy into radiation. If 10{sup -4} of the {approx}10{sup 53} erg of orbital kinetic available gets processed through reconnection and creates radiation in the 15-150 keV band, then the fluence at 200 Mpc would be 10{sup -7} erg cm{sup -2}, potentially rendering most merging neutron stars in the advanced LIGO and Virgo detection volumes detectable by Swift BAT.

  20. Enhanced performance of magnetoelectric energy harvester based on compound magnetic coupling effect

    NASA Astrophysics Data System (ADS)

    Han, Jinchi; Hu, Jun; Wang, Zhongxu; Wang, Shan X.; He, Jinliang

    2015-04-01

    We have theoretically and experimentally demonstrated the greatly enhanced energy harvesting property of the specific magnetoelectric (ME) device, comprising a piezoelectric bimorph cantilever with a permanent magnet tip mass based on a compound interaction between the remanent magnetic moment of the magnet and a nonuniform alternating magnetic field. With appropriate positioning of the device, the coexistence of torque-mode and force-mode excitations leads to reinforced magneto-mechanical coupling, which subsequently yields improvements in both ME response and power conversion. In the experiments, a piezoelectric bimorph/magnet energy harvester was placed at a distance of 10 mm from a power line that was conducting a 50 Hz, 10 A current, and a maximum power of 2.136 mW was achieved via the optimal cooperative magnetic coupling mode. This output power is 7.8× larger than that produced using the conventional torque mode.

  1. Hot electron detectors and energy conversion in the UV and IR

    NASA Astrophysics Data System (ADS)

    Gong, Tao; Krayer, Lisa; Munday, Jeremy N.

    2015-09-01

    Semiconductor materials are well suited for power conversion when the incident photon energy is slightly larger than the bandgap energy of the semiconductor. However, for photons with energy significantly greater than the bandgap energy, power conversion efficiencies are low. Further, for photons with energy below the bandgap energy, the absence of absorption results in no power conversion. Here we describe photon detection and power conversion of both high energy and sub-bandgap photons using hot carrier effects. For the absorption of high-energy photons, excited electrons and holes have excess kinetic energy, which results in the generation of hot electrons and holes. Energy is typically lost through a thermalization process between the carriers and the lattice. However, collection of carriers before thermalization allows for reduced power loss. Devices consisting of a three-layer stack (transparent conductor - insulator - metal) can be used to generate and collect these hot carriers. Alternatively, when a semiconductor is used, photons with energy below the semiconductor bandgap energy generally do not generate electrons and holes; however, hot carrier collection is still possible in semiconductor devices with a metal layer when a Schottky junction is formed at the semiconductor-metal interface. Such structures enable IR detection based on sub-bandgap photon absorption. Combining these concepts, hot carrier generation and collection and be exploited over a large range of incident wavelengths spanning the UV, visible, and IR.

  2. Mode conversion of Langmuir to electromagnetic waves at magnetic field-aligned density inhomogeneities: Simulations, theory, and applications to the solar wind and the corona

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Hwa; Cairns, Iver H.; Robinson, Peter A.

    2008-10-01

    Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) both o- and x-mode waves are produced for ?=(?L/c)1/3(?c/?)<~1, contrary to previous ideas. Only the o mode is produced for ?>~1.5. Here ?c is the (angular) electron cyclotron frequency, ? is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light. A WKB-style analysis accounts semiquantitatively for the production and relative conversion efficiencies of the o and x modes in the simulations. (2) In the unmagnetized limit, equal amounts of o- and x-mode radiation are produced. (3) The mode conversion window narrows as ? increases. (4) As ? increases the total electromagnetic field changes from linear to circular polarization, with the o- and x-mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as ? increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%-70%. They depend strongly on the wave frequency when close to the background plasma frequency but weakly on the electron temperature T0 and ?=T0/mc2. The corresponding energy conversion efficiencies are favored since they allow separation into o and x modes, use directly measured experimental quantities, and generalize easily for wave packets. The total energy conversion efficiency differs from the power conversion efficiency by the ratio of the group speeds for each mode, is less than 10% for the value of ?=0.01 simulated, and decreases linearly with ?. Since ?~10-5-10-4 in the solar wind and corona, this ? dependence is important in applications. (7) The interference effect and the disappearance of the x mode at ?>~1 can be accounted for semiquantitatively using a WKB-type analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o- and x-mode radiation for solar and interplanetary radio bursts. It is therefore possible that linear mode conversion under these conditions might explain the weak total circular polarizations of type II and III solar radio bursts.

  3. Polyoxometalate-conductive polymer composites for energy conversion, energy storage and nanostructured sensors.

    PubMed

    Herrmann, Sven; Ritchie, Chris; Streb, Carsten

    2015-04-28

    The exchange of electric charges between a chemical reaction centre and an external electrical circuit is critical for many real-life technologies. This perspective explores the "wiring" of highly redox-active molecular metal oxide anions, so-called polyoxometalates (POMs) to conductive organic polymers (CPs). The major synthetic approaches to these organic-inorganic hybrid materials are reviewed. Typical applications are highlighted, emphasizing the current bottlenecks in materials development. Utilization of the composites in the fields of energy conversion, electrochemical energy storage, sensors and nanoparticle "wiring" into conductive materials are discussed. The outlook section presents the authors' views on emerging fields of research where the combination of POMs and CPs can be expected to provide novel materials for groundbreaking new technologies. These include light-weight energy storage, high-sensitivity toxin sensors, artificial muscles, photoelectrochemical devices and components for fuel cells. PMID:25787774

  4. Direct conversion of infrared radiant energy for space power applications

    NASA Technical Reports Server (NTRS)

    Finke, R. C.

    1982-01-01

    A proposed technology to convert the earth radiant energy (infrared albedo) for spacecraft power is presented. The resultant system would eliminate energy storage requirements and simplify the spacecraft design. The design and performance of a infrared rectenna is discussed.

  5. DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JULY 1, 2002 THROUGH SEPTEMBER 30, 2002

    SciTech Connect

    L.C. BROWN

    2002-09-30

    Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation.

  6. DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD APRIL 1, 2002 THROUGH JUNE 30, 2002

    SciTech Connect

    L.C. BROWN

    2002-06-30

    Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation.

  7. Thermodynamic Inefficiency of Conversion of Solar Energy to Work.

    ERIC Educational Resources Information Center

    Adamson, Arthur W.; And Others

    1984-01-01

    Considers the thermodynamic limitation to the efficiency with which light energy can be converted into work, indicating that no single chemical system converting solar energy into useful work can be very efficient. Also indicates that if solar energy is absorbed as heat for heating purposes, it is almost completely used. (JN)

  8. Nanobiocomposite from Collagen Waste Using Iron Oxide Nanoparticles and Its Conversion Into Magnetic Nanocarbon.

    PubMed

    Thanikaivelan, P; Narayanan, T N; Gupta, B K; Reddy, A L M; Ajayan, P M

    2015-06-01

    Collagenous wastes discarded from leather industry were stabilized using superparamagnetic iron oxide nanoparticles and further converted into a magnetic nanocarbon. Stabilization of collagen using iron oxide nanoparticles treatment (25% offer) was confirmed through differential scanning calorimetric analysis and further evidenced through scanning electron microscopic analysis. A simple high temperature treatment of the collagen-iron oxide nanoparticle composite at 850 degrees C for 2 h under Ar atmosphere yielded a bi-functional, magnetic and conducting, nanocarbon. The X-ray diffraction and Raman spectroscopic analysis reveal the partial graphitation and X-ray photoelectron spectroscopic results show the presence of trace-iron containing carbon, naturally doped with nitrogen and oxygen. Transmission electron microscopic analysis show the presence of larger iron oxide nanocrystals embedded in graphitic carbon layers while superconducting quantum interference device based analysis reveals a perfect ferrimagnetic property with saturation magnetization. Thus, we have stabilized the collagen waste fibers using iron oxide nanoparticles and converted them into a bi-functional nanocarbon, which has potential for various applications including energy, leather making and environmental remediation. PMID:26369072

  9. Solar energy conversion via hot electron internal photoemission in metallic nanostructures: Efficiency estimates

    SciTech Connect

    Leenheer, Andrew J.; Narang, Prineha; Atwater, Harry A.; Lewis, Nathan S.

    2014-04-07

    Collection of hot electrons generated by the efficient absorption of light in metallic nanostructures, in contact with semiconductor substrates can provide a basis for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion efficiency of systems that rely on internal photoemission processes at metal-semiconductor Schottky-barrier diodes. In this theory, the current-voltage characteristics are given by the internal photoemission yield as well as by the thermionic dark current over a varied-energy barrier height. The Fowler model, in all cases, predicts solar energy-conversion efficiencies of <1% for such systems. However, relaxation of the assumptions regarding constraints on the escape cone and momentum conservation at the interface yields solar energy-conversion efficiencies as high as 1%10%, under some assumed (albeit optimistic) operating conditions. Under these conditions, the energy-conversion efficiency is mainly limited by the thermionic dark current, the distribution of hot electron energies, and hot-electron momentum considerations.

  10. Directed Magnetic Particle Transport above Artificial Magnetic Domains Due to Dynamic Magnetic Potential Energy Landscape Transformation.

    PubMed

    Holzinger, Dennis; Koch, Iris; Burgard, Stefan; Ehresmann, Arno

    2015-07-28

    An approach for a remotely controllable transport of magnetic micro- and/or nanoparticles above a topographically flat exchange-bias (EB) thin film system, magnetically patterned into parallel stripe domains, is presented where the particle manipulation is achieved by sub-mT external magnetic field pulses. Superparamagnetic core-shell particles are moved stepwise by the dynamic transformation of the particles' magnetic potential energy landscape due to the external magnetic field pulses without affecting the magnetic state of the thin film system. The magnetic particle velocity is adjustable in the range of 1-100 ?m/s by the design of the substrate's magnetic field landscape (MFL), the particle-substrate distance, and the magnitude of the applied external magnetic field pulses. The agglomeration of magnetic particles is avoided by the intrinsic magnetostatic repulsion of particles due to the parallel alignment of the particles' magnetic moments perpendicular to the transport direction and parallel to the surface normal of the substrate during the particle motion. The transport mechanism is modeled by a quantitative theory based on the precise knowledge of the sample's MFL and the particle-substrate distance. PMID:26134922

  11. Current challenges in organic photovoltaic solar energy conversion.

    PubMed

    Schlenker, Cody W; Thompson, Mark E

    2012-01-01

    Over the last 10 years, significant interest in utilizing conjugated organic molecules for solid-state solar to electric conversion has produced rapid improvement in device efficiencies. Organic photovoltaic (OPV) devices are attractive for their compatibility with low-cost processing techniques and thin-film applicability to flexible and conformal applications. However, many of the processes that lead to power losses in these systems still remain poorly understood, posing a significant challenge for the future efficiency improvements required to make these devices an attractive solar technology. While semiconductor band models have been employed to describe OPV operation, a more appropriate molecular picture of the pertinent processes is beginning to emerge. This chapter presents mechanisms of OPV device operation, based on the bound molecular nature of the involved transient species. With the intention to underscore the importance of considering both thermodynamic and kinetic factors, recent progress in elucidating molecular characteristics that dictate photovoltage losses in heterojunction organic photovoltaics is also discussed. PMID:21837556

  12. Direct energy converter for open magnetic traps

    SciTech Connect

    Dimitrov, S.K.; Makhin, S.V.; Morozov, A.S.

    1986-08-01

    The authors explore the possibility of using a new form of magnetic expander that converts a cylindrical beam of charged particles into a tubular beam. The presented expander performs the following functions: when particles move along the adiabatically decreasing magnetic field the energy of rotational motion is converted into the energy of translational motion, the influence of the space charge decreases and the penetration of the electric field into the beam improves, and the heat removal from the collector system is improved. The operating principle of the expander in a reactor scheme is shown.

  13. The potential impact of ZT=4 thermoelectric materials on solar thermal energy conversion technologies.

    SciTech Connect

    Xie, M.; Gruen, D. M.; Materials Science Division; Michigan Technological Univ.

    2010-03-02

    State-of-the-art methodologies for the conversion of solar thermal power to electricity are based on conventional electromagnetic induction techniques. If appropriate ZT = 4 thermoelectric materials were available, it is likely that conversion efficiencies of 30-40% could be achieved. The availability of all solid state electricity generation would be a long awaited development in part because of the elimination of moving parts. This paper presents a preliminary examination of the potential performance of ZT = 4 power generators in comparison with Stirling engines taking into account specific mass, volume and cost as well as system reliability. High-performance thermoelectrics appear to have distinct advantages over magnetic induction technologies.

  14. Efficient conversion of solar energy to biomass and electricity.

    PubMed

    Parlevliet, David; Moheimani, Navid Reza

    2014-01-01

    The Earth receives around 1000W.m(-2) of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture. PMID:24976951

  15. Efficient conversion of solar energy to biomass and electricity

    PubMed Central

    2014-01-01

    The Earth receives around 1000W.m?2 of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture. PMID:24976951

  16. High-temperature inert gas plasma magnetohydrodynamic energy conversion by using linear-shaped Faraday-type channel

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Zhuang, Yunqin; Okuno, Yoshihiro

    2013-02-01

    We describe high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a compact linear-shaped Faraday-type MHD electrical power generator is used. Short-time-duration single-pulse shock-tunnel-based experiments demonstrate the MHD energy conversion with varying total inflow temperature up to 9000 K and applied magnetic-flux density up to 4.0 T. The high-temperature plasma is transformed from the thermal-equilibrium state at the entrance to the weak-nonequilibrium state in the supersonic MHD channel. The discharge structure is reasonably homogeneous without suffering from serious streamer development. The power generation performance is monotonically improved by increasing total inflow temperature and strength of magnetic field. The enthalpy extraction efficiency of 13.1% and overall power density of 0.16 GW/m3 are attained. The local power density at the middle of the channel reaches 0.24 GW/m3.

  17. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 2, Appendices

    SciTech Connect

    Butner, R.S.; Elliott, D.C.; Sealock, L.J., Jr.; Pyne, J.W.

    1988-12-01

    This report presents an exploration of the relationships between biomass feedstocks and the conversion processes that utilize them. Specifically, it discusses the effect of the physical and chemical structure of biomass on conversion yields, rates, and efficiencies in a wide variety of available or experimental conversion processes. A greater understanding of the complex relationships between these conversion systems and the production of biomass for energy uses is required to help optimize the complex network of biomass production, collection, transportation, and conversion to useful energy products. The review of the literature confirmed the scarcity of research aimed specifically at identifying the effect of feedstock properties on conversion. In most cases, any mention of feedstock-related effects was limited to a few brief remarks (usually in qualitative terms) in the conclusions, or as a topic for further research. Attempts to determine the importance of feedstock parameters from published data were further hampered by the lack of consistent feedstock characterization and the difficulty of comparing results between different experimental systems. Further research will be required to establish quantitative relationships between feedstocks and performance criteria in conversion. 127 refs., 4 figs., 7 tabs.

  18. Gravity of magnetic stresses and energy

    SciTech Connect

    Bimonte, Giuseppe; Calloni, Enrico; Rosa, Luigi

    2008-02-15

    In the framework of designing laboratory tests of relativistic gravity, we investigate the gravitational field produced by the magnetic field of a solenoid. Observing this field might provide a means of testing whether stresses gravitate as predicted by Einstein's theory. A previous study of this problem by Braginsky, Caves, and Thorne predicted that the contribution to the gravitational field resulting from the stresses of the magnetic field and of the solenoid walls would cancel the gravitational field produced by the mass-energy of the magnetic field, resulting in a null magnetically generated gravitational force outside the solenoid. They claim that this null result, once proved experimentally, would demonstrate the stress contribution to gravity. We show that this result is incorrect, as it arises from an incomplete analysis of the stresses, which neglects the axial stresses in the walls. Once the stresses are properly evaluated, we find that the gravitational field outside a long solenoid is in fact independent of Maxwell and material stresses, and it coincides with the Newtonian field produced by the linear mass distribution equivalent to the density of magnetic energy stored in a unit length of the solenoid. We argue that the gravity of Maxwell stress can be directly measured in the vacuum region inside the solenoid, where the Newtonian noise is absent in principle, and the gravity generated by Maxwell stresses is not screened by the negative gravity of magnetic-induced stresses in the solenoid walls.

  19. Full-wave feasibility study of magnetic diagnostic based on O-X mode conversion and oblique reflectometry imaging

    SciTech Connect

    Meneghini, Orso; Choi, Myunghee; Volpe, Francesco

    2014-02-12

    An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and the edge current as a function of the minor radius in the pedestal region. The idea behind such diagnostic is to localize and characterize a direction of reduced reflectivity at the O-mode cutoff layer. We modeled the wave scattering and mode-conversion processes by means of the finite-element COMSOL Multiphysics code in two dimensions (2D). Sensitivity studies were performed for parameters mocking up DIII-D plasmas. Simulations confirmed the presence of a minimum in reflectivity of an externally injected O-mode beam, and confirmed that this minimum depends on the magnetic field at the cutoff, as expected from the OX mode conversion physics. This study gives confidence in the feasibility of the diagnostic.

  20. High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1992-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

  1. Investigation of current university research concerning energy conversion and conservation in small single-family dwellings

    NASA Technical Reports Server (NTRS)

    Grossman, G. R.; Roberts, A. S., Jr.

    1975-01-01

    An investigation was made of university research concerning energy conversion and conservation techniques which may be applied in small single-family residences. Information was accumulated through published papers, progress reports, telephone conversations, and personal interviews. A synopsis of each pertinent investigation is given. Finally, a discussion of the synopses is presented and recommendations are made concerning the applicability of concepts for the design and construction of NASA-Langley Research Center's proposed Technology Utilization House in Hampton, Virginia.

  2. A universal electromagnetic energy conversion adapter based on a metamaterial absorber.

    PubMed

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D; Simons, Rainee N; Chen, Yunpeng; Xiao, John Q

    2014-01-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

  3. A universal electromagnetic energy conversion adapter based on a metamaterial absorber

    PubMed Central

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

    2014-01-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

  4. Seismo-electric exploration; Expected signal amplitudes. [Conversion of seismic to electromagnetic signal in geological media and detection of electric or magnetic signals

    SciTech Connect

    Russell, R.D. . Dept. of Geophysics and Astronomy); Barker, A.S. Jr. )

    1991-01-01

    For more than 20 years, Soviet scientists have published papers and registered patents describing the conversion of seismic to electromagnetic energy in geological environments and the detection of the electric or magnetic signals as a method of geophysical exploration. Because of the potential importance of a reliable geophysical technique for locating quartz veins, the authors have been conducting extensive laboratory and field tests of the phenomena. For the purposes of designing appropriate field tests the approximate signal magnitudes must be known, but little has been published on them. The paper describes a simplified model from which order-of-magnitude estimates of expected electric and magnetic signal strengths can be made with sufficient accuracy for such purposes. For mathematical convenience the target is modeled as a homogeneous sphere in which the seismic input induces uniform, time-varying electric polarization. More realistic configurations can be described by linear superposition of the potentials of appropriate sub-elements.

  5. Potential environmental consequences of ocean thermal energy conversion (OTEC) plants. A workshop

    SciTech Connect

    Walsh, J.J.

    1981-05-01

    The concept of generating electrical power from the temperature difference between surface and deep ocean waters was advanced over a century ago. A pilot plant was constructed in the Caribbean during the 1920's but commercialization did not follow. The US Department of Energy (DOE) earlier planned to construct a single operational 10MWe Ocean Thermal Energy Conversion (OTEC) plant by 1986. However, Public Law P.L.-96-310, the Ocean Thermal Energy Conversion Research, Development and Demonstration Act, and P.L.-96-320, the Ocean Thermal Energy Conversion Act of 1980, now call for acceleration of the development of OTEC plants, with capacities of 100 MWe in 1986, 500 MWe in 1989, and 10,000 MWe by 1999 and provide for licensing and permitting and loan guarantees after the technology has been demonstrated.

  6. High electrokinetic energy conversion efficiency in charged nanoporous nitrocellulose/sulfonated polystyrene membranes.

    PubMed

    Haldrup, Sofie; Catalano, Jacopo; Hansen, Michael Ryan; Wagner, Manfred; Jensen, Grethe Vestergaard; Pedersen, Jan Skov; Bentien, Anders

    2015-02-11

    The synthesis, characterization, and electrokinetic energy conversion performance have been investigated experimentally in a charged polymeric membrane based on a blend of nitrocellulose and sulfonated polystyrene. The membrane is characterized by a moderate ion exchange capacity and a relatively porous structure with average pore diameter of 11 nm. With electrokinetic energy conversion, pressure can be converted directly into electric energy and vice versa. From the electrokinetic transport properties, a remarkably large intrinsic maximum efficiency of 46% is found. It is anticipated that the results are an experimental verification of theoretical models that predict high electrokinetic energy conversion efficiency in pores with high permselectivity and hydrodynamic slip flow. Furthermore, the result is a promising step for obtaining efficient low-cost electrokinetic generators and pumps for small or microscale applications. PMID:25555128

  7. Electrokinetic energy conversion in nanofluidic channels: addressing the loose ends in nanodevice efficiency.

    PubMed

    Bakli, Chirodeep; Chakraborty, Suman

    2015-03-01

    We bring out a nontrivial coupling of the intrinsic wettability, surface charge, and electrokinetic energy conversion characteristics of nanofluidic devices. Our analyses demonstrate that nanofluidic energy conversion efficiencies may get amplified with increase in surface charge density, not perpetually, but only over a narrow regime of low surface charges, and may get significantly arrested to reach a plateau beyond a threshold surface charging condition, as attributed to a complex interplay between fluid structuration and ionic transport within a charged interfacial layer. We explain the corresponding findings from our molecular dynamics simulations with the aid of a simple modified continuum based theory. We attribute our findings to hitherto-unexplored four-way integration of surface charge, interfacial slip, ionic transport, and the water molecule structuration. The consequent complex nonlinear nature of the energy transfer characteristics may bear far-ranging scientific and technological implications toward design, synthesis, and operation of futuristic energy conversion devices of molecular length scales. PMID:25258090

  8. Research on energy conversion mechanism of a screw centrifugal pump under the water

    NASA Astrophysics Data System (ADS)

    Quan, H.; Li, R. N.; Su, Q. M.; Han, W.; Cheng, X. R.; Shen, Z. J.

    2013-12-01

    In order to research screw centrifugal pump impeller power capability and energy conversion mechanism, we used Navier-Stokes equation and standard k-? equation turbulence model on the basis of the Euler equations to carry out screw centrifugal pump internal flow numerical simulation. This was explored by simulating specific design conditions; the medium is water, variation of speed and pressure of flow filed under the action of the impeller, and the screw centrifugal impeller shroud line and wheel line segment take monitoring sites. The monitoring points are between dynamic head and static head change to analyze the energy conversion capability along the impeller corners of screw centrifugal pump. The results show that the energy of fluid of the screw centrifugal pump is provided by spiral segment, the spiral segment in front of the impeller has played a multi-level role, it has significant reference value to research the energy conversion mechanism of screw centrifugal pump under solid-liquid two phase.

  9. Engineering of Carbon-Based Electrocatalysts for Emerging Energy Conversion: From Fundamentality to Functionality.

    PubMed

    Zheng, Yao; Jiao, Yan; Qiao, Shi Zhang

    2015-09-23

    Over the past decade, developing advanced catalysts for clean and sustainable energy conversion has been subject to extensive study. Driven by great advances achieved in computational quantum chemistry, synthetic chemistry, and material characterization techniques, the preferential design of a most-appropriate catalyst for a specific electrochemical reaction is possible. Here a universal process for the design of high-performance carbon-based electrocatalysts, by engineering their intrinsic electronic structures and physical structures to promote their extrinsic activities for different energy conversion reactions, is presented and summarized. How such a powerful strategy may aid the discovery of more electrocatalysts for a sustainable and clean energy infrastructure is discussed. PMID:26174510

  10. Bio-inspired constructs for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Moore, Thomas

    2006-03-01

    Solar energy input to the biosphere is about 10^24 joules/year. This makes human needs of even a projected 10^21 joules/year a deceptively achievable goal. One key to global-scale use of solar energy is the synthesis of energy-rich fuel materials such as hydrogen and reduced carbon compounds. The latter have the almost inestimable advantage that the energy infrastructure for distribution and use is in place. The photosynthetic and respiratory enzymes provide paradigms for all of the important energy converting processes humans would need to achieve sustainable energy production and use. These include water oxidation, O2 reduction and oxidation of energy dense organics at room temperature. These processes are carried out by biological catalysts at near thermodynamic efficiency without the use of precious metals. Copper, manganese, iron and nickel are typically used at their active sites. Energy rich organics such as ethanol and larger reduced-carbon compounds offer energy densities comparable to that of fossil fuels yet technology has not produced a low temperature catalyst for breaking carbon-carbon bonds. Biology offers myriad examples of such catalysts. Electroreductive synthesis of organics from CO2 is also templated by Nature's catalysts. The challenge is clear: we must understand the structures and chemical reactivity of these catalytic sites and co-opt their essential features for human use. A number of parameters are involved and will be discussed. Even considering an artificial catalysts comprising only the atoms necessary for catalysis, the footprint is relatively large and, since biological turnover rates are often low, achieving current flows adequate for human needs in industry and transportation is problematic. A detailed understanding of efficiently coupling electromotive force to the active sites of redox enzymes will be one key to designing efficient hybrid catalytic devices. A model system for solar-driven reforming of biomass to H2 will be presented.

  11. Magnetic force of piezoelectric cantilever energy harvesters with external magnetic field

    NASA Astrophysics Data System (ADS)

    Tan, D.; Leng, Y. G.; Gao, Y. J.

    2015-11-01

    In piezoelectric cantilever energy harvesters with external magnetic field, one of the difficulties is the impact of the external magnetic field or magnetic force on vibration response and energy harvesting efficiency. Here we use the magnetizing current and magnetic dipoles approaches to analyze the magnetic force. The two calculation models are proposed for the energy harvesters. The calculation results of the two methods are compared with a set of experimental data. It has been proved that errors are produced with both methods while the magnet interval is sufficiently small. However, the calculation result achieved from magnetic dipoles approach is closer to experimental measurements than the one of magnetizing current approach. Consequently, the magnetic dipoles approach can be chosen preferably to calculate the magnetic force of piezoelectric cantilever energy harvesters with external magnetic field.

  12. Relativistic fireballs - Energy conversion and time-scales

    NASA Technical Reports Server (NTRS)

    Rees, M. J.; Meszaros, P.

    1992-01-01

    The expansion energy of a relativistic fireball can be reconverted into radiation when it interacts with an external medium. For expansion with Lorentz factors greater than or approximately equal to 1000 into a typical galactic environment, the corresponding time-scale in the frame of the observer is of the order of seconds. This mechanism would operate in any cosmological scenario of gamma-ray bursts involving initial energies of order a percent of a stellar rest mass, and implies photon energies and time-scales compatible with those observed in gamma-ray bursts.

  13. Flywheel energy storage. II - Magnetically suspended superflywheel

    NASA Technical Reports Server (NTRS)

    Kirk, J. A.; Studer, P. A.

    1977-01-01

    This article, the second of a two part paper, describes the general design requirements for a flywheel energy storage system. A new superflywheel energy storage system, using a spokeless, magnetically suspended, composite material pierced disk rotor is proposed. The new system is configured around a permanent magnet ('flux biased') magnetic suspension system with active control in the radial direction and passive control in the axial direction. The storage ring is used as a moving rotor and electronic commutation of stationary armature coils is proposed. There is no mechanical contact with the rotating ring and long life and low run down losses are projected. A discussion of major components for a 10 kwh system is presented.

  14. Electromagnetic energy transport in RFP magnetic relaxation

    NASA Astrophysics Data System (ADS)

    McCollam, K. J.; Thuecks, D. J.; Stone, D. R.; Anderson, J. K.; den Hartog, D. J.; Duff, J.; Ko, J.; Kumar, S.; Parke, E.; Lin, L.; Brower, D. L.; Ding, W. X.

    2014-10-01

    In an RFP driven by steady toroidal induction, tearing modes responsible for magnetic relaxation redistribute electromagnetic energy throughout the plasma, generating the net EMF that regulates the equilibrium profile. In MST experiments, insertable edge probes measure local fluctuations in electric and magnetic fields, from which flux-surface-average Poynting flux is derived. This outwardly directed flux is maximum during discrete ``sawtooth'' magnetic relaxation events and is a significant fraction (a few 10s of percent) of the total input inductive power when averaged over time. Spatially, the flux is maximum at the reversal surface and decreases outside, indicating that transported energy is deposited at the plasma edge. These results are similar to expectations from a simple model of an incompressible fluid plasma with a resistive boundary and consistent with estimates of global power balance from time-resolved equilibrium reconstructions. This work was supported by the US DOE and NSF.

  15. Assessment of dynamic energy conversion systems for radioisotope heat sources

    SciTech Connect

    Thayer, G.R.; Mangeng, C.A.

    1985-06-01

    The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were Stirling; Brayton Cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos Multiattribute Decision Theory code. Three different heat source designs were used: case I with a beginning of life (BOL) source temperature of 640 C, case II with a BOL source temperature of 745/sup 0/C, and case III with a BOL source temperature of 945/sup 0/C. The Stirling engine system was the top-ranked system of cases I and II, closely followed by the ORC systems in case I and ORC plus thermoelectrics in case II. The Brayton cycle system was top-ranked for case III, with the Stirling engine system a close second. The use of /sup 238/Pu in heat source sizes of 7500 W(t) was examined and found to be questionable because of cost and material availability and because of additional requirements for analysis of safeguards and critical mass.

  16. Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses

    ERIC Educational Resources Information Center

    Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

    2013-01-01

    Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

  17. Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses

    ERIC Educational Resources Information Center

    Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

    2013-01-01

    Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching

  18. Light-harvesting materials: Soft support for energy conversion

    SciTech Connect

    Stolley, Ryan M.; Helm, Monte L.

    2014-11-10

    To convert solar energy into viable fuel sources, coupling light-harvesting materials to catalysts is a critical challenge. Now, coupling between an organic supramolecular hydrogel and a non precious metal catalyst has been demonstrated to be effective for photocatalytic H2 production. Ryan M. Stolley and Monte L. Helm are at Pacific Northwest National Laboratory (PNNL), Richland, WA, USA 99352. PNNL is operated by Battelle for the US Department of Energy. e-mail: Monte.Helm@pnnl.gov

  19. Optimization of Reaction Plates for Wave Energy Conversion

    NASA Astrophysics Data System (ADS)

    Brown, A. C.

    2014-12-01

    Reaction forces are generated as energy is extracted from the motion of ocean waves relative to a wave energy converter (WEC). The reaction forces effect the momentum of the WEC, and in most cases it is beneficial to transfer the loads to a relatively stationary external body. It has become common for WECs to include reaction plates that use hydrodynamic damping to transfer the loads developed during energy extraction to the relatively stationary water below the surface of the ocean. Reaction plates allow WECs to use compliant moorings, which reduce mooring loads and are more easily deployed than taut moorings. Heave plates are commonly used on offshore platforms, but the design of reaction plates for wave energy converters has received little attention. This work presents an initial optimization of reaction plate form to improve the heave and surge performance of the WEC reference models developed for the US Department of Energy. The benefits and drawbacks of various reaction plate geometries are compared, and the impacts on WEC stability, peak loading, and energy production are considered.

  20. Magnetic domain wall energy in Ni/Co superlattices

    NASA Astrophysics Data System (ADS)

    Toyoki, Kentaro; Nishimura, Takashi; Harimoto, Shotaro; Shiratsuchi, Yu; Nakatani, Ryoichi

    2014-12-01

    The magnetic domain wall energy density ?W of a Ni/Co superlattice possessing perpendicular magnetic anisotropy was determined using the magnetic domain theory derived by Kooy and Enz (1960). To determine ?W, we obtained the saturation magnetization, magnetic domain period, and perpendicular magnetic anisotropy energy by individual measurements. Using the magnetic domain period and the ferromagnetic layer thickness, we first determined the dipolar length. The estimated dipolar length was about 15-25 nm, which is in good agreement with the change in the magnetization curve with the ferromagnetic layer thickness. By using the dipolar length and saturation magnetization, the ?W was calculated to be 4-7 erg/cm2.

  1. Ionosphere/microwave beam interaction study. [satellite solar energy conversion

    NASA Technical Reports Server (NTRS)

    Duncan, L. M.; Gordon, W. E.

    1977-01-01

    A solar power satellite microwave power density of 20mw sq cm was confirmed as the level where nonlinear interactions may occur in the ionosphere, particularly at 100 km altitude. Radio wave heating at this altitude, produced at the Arecibo Observatory, yielded negative results for radio wave heating of an underdense ionosphere. Overdense heating produced striations in the ionosphere which may cause severe radio frequency interference problems under certain conditions. The effects of thermal self-focusing are shown to be limited severely geographically. The aspect sensitivity of field-aligned striations makes interference-free regions above magnetic latitude about 60 deg. A test program is proposed to simulate the interaction of the SPS beam with the ionosphere, to measure the effects of the interaction on the ionosphere and on communication and navigation systems, and to interpret the results.

  2. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 1: Introduction and summary and general assumptions. [energy conversion systems for electric power plants using coal - feasibility

    NASA Technical Reports Server (NTRS)

    Beecher, D. T.

    1976-01-01

    Nine advanced energy conversion concepts using coal or coal-derived fuels are summarized. They are; (1) open-cycle gas turbines, (2) combined gas-steam turbine cycles, (3) closed-cycle gas turbines, (4) metal vapor Rankine topping, (5) open-cycle MHD; (6) closed-cycle MHD; (7) liquid-metal MHD; (8) advanced steam; and (9) fuel cell systems. The economics, natural resource requirements, and performance criteria for the nine concepts are discussed.

  3. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 3: Gasification, process fuels, and balance of plant

    NASA Technical Reports Server (NTRS)

    Boothe, W. A.; Corman, J. C.; Johnson, G. G.; Cassel, T. A. V.

    1976-01-01

    Results are presented of an investigation of gasification and clean fuels from coal. Factors discussed include: coal and coal transportation costs; clean liquid and gas fuel process efficiencies and costs; and cost, performance, and environmental intrusion elements of the integrated low-Btu coal gasification system. Cost estimates for the balance-of-plant requirements associated with advanced energy conversion systems utilizing coal or coal-derived fuels are included.

  4. Isothermal separation processes update. Energy Conversion and Utilization Technologies Program

    SciTech Connect

    England, C.

    1984-08-01

    The isothermal processes of membrane separation, supercritical extraction and condensed-phase chromatography were examined using availability analysis, a method which addresses the thermodynamic value of energy as well as its amount. The general approach was to derive equations that identified where energy, expressed in terms of thermodynamic work, is consumed in these processes and how they compare with conventional separation methods. These separation methods are characterized by pure work inputs, chiefly in the form of a pressure drop which supplies the required energy. Equations were derived for the energy requirement in terms of the theories of ideal and regular solutions. This approach is believed to accurately predict the work of separation in terms of the heat of solution and the entropy of mixing. It can form the basis of a convenient calculation method for optimizing membrane and solvent properties for particular applications. Close examination of supercritical extraction found a relatively simple thermodynamic relationship among the thermodynamic properties of the solvent, the entropy of mixing, and the heat of solution. This allows a direct estimate of the work requirements. The actual work, however, is largely due to the requirement to cycle pressure at high levels in this method. Still, the energy requirements are very low, making up for usually high capital costs for equipment. 12 references, 9 figures, 2 tables.

  5. Heat to electricity conversion by cold carrier emissive energy harvesters

    NASA Astrophysics Data System (ADS)

    Strandberg, Rune

    2015-12-01

    This paper suggests a method to convert heat to electricity by the use of devices called cold carrier emissive energy harvesters (cold carrier EEHs). The working principle of such converters is explained and theoretical power densities and efficiencies are calculated for ideal devices. Cold carrier EEHs are based on the same device structure as hot carrier solar cells, but works in an opposite way. Whereas a hot carrier solar cell receives net radiation from the sun and converts some of this radiative heat flow into electricity, a cold carrier EEH sustains a net outflux of radiation to the surroundings while converting some of the energy supplied to it into electricity. It is shown that the most basic type of cold carrier EEHs have the same theoretical efficiency as the ideal emissive energy harvesters described earlier by Byrnes et al. In the present work, it is also shown that if the emission from the cold carrier EEH originates from electron transitions across an energy gap where a difference in the chemical potential of the electrons above and below the energy gap is sustained, power densities slightly higher than those given by Byrnes et al. can be achieved.

  6. Offshore Hydrokinetic Energy Conversion for Onshore Power Generation

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Chao, Yi

    2009-01-01

    Design comparisons have been performed for a number of different tidal energy systems, including a fully submerged, horizontal-axis electro-turbine system, similar to Verdant Tidal Turbines in New York's East River, a platform-based Marine Current Turbine, now operating in Northern Ireland's Strangford Narrows, and the Rotech Lunar Energy system, to be installed off the South Korean Coast. A fourth type of tidal energy system studied is a novel JPL/Caltech hydraulic energy transfer system that uses submerged turbine blades which are mechanically attached to adjacent high-pressure pumps, instead of to adjacent electrical turbines. The generated highpressure water streams are combined and transferred to an onshore hydroelectric plant by means of a closed-cycle pipeline. The hydraulic energy transfer system was found to be cost competitive, and it allows all electronics to be placed onshore, thus greatly reducing maintenance costs and corrosion problems. It also eliminates the expenses of conditioning and transferring multiple offshore power lines and of building offshore platforms embedded in the sea floor.

  7. Toroidal constant-tension superconducting magnetic energy storage units

    DOEpatents

    Herring, J. Stephen

    1992-01-01

    A superconducting magnetic energy storage unit is provided in which the magnet is wound in a toroidal fashion such that the magnetic field produced is contained only within the bore of the magnet, and thus producing a very low external field. The superconducting magnet includes a coolant channel disposed through the wire. The bore of the magnet comprises a storage volume in which cryogenic coolant is stored, and this volume supplies the coolant to be delivered to the coolant channel in the magnet.

  8. Solar-to-Chemical Energy Conversion with Photoelectrochemical Tandem Cells.

    PubMed

    Sivula, Kevin

    2013-01-01

    Efficiently and inexpensively converting solar energy into chemical fuels is an important goal towards a sustainable energy economy. An integrated tandem cell approach could reasonably convert over 20% of the sun's energy directly into chemical fuels like H2 via water splitting. Many different systems have been investigated using various combinations of photovoltaic cells and photoelectrodes, but in order to be economically competitive with the production of H2 from fossil fuels, a practical water splitting tandem cell must optimize cost, longevity and performance. In this short review, the practical aspects of solar fuel production are considered from the perspective of a semiconductor-based tandem cell and the latest advances with a very promising technology - metal oxide photoelectrochemical tandem cells - are presented. PMID:23574955

  9. Radiant energy collection and conversion apparatus and method

    DOEpatents

    Hunt, Arlon J.

    1982-01-01

    The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

  10. Radiant energy collection and conversion apparatus and method

    DOEpatents

    Hunt, A.J.

    The apparatus for collecting radiant energy and converting to alternate energy forms includes a housing having an interior space and a radiation transparent window allowing solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past the window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

  11. Role of energy metabolism in conversion of nonmucoid Pseudomonas aeruginosa to the mucoid phenotype.

    PubMed Central

    Terry, J M; Piña, S E; Mattingly, S J

    1992-01-01

    Phosphatidylcholine, the major component of lung surfactant, when supplied as the sole source of phosphate for Pseudomonas aeruginosa PAO1, resulted in conversion of as much as 2% of the population to the mucoid phenotype under continuous culture conditions over a 24-day culture period. In addition, growth in phosphatidylcholine resulted in the highest yields of extracellular alginate compared with other environmental conditions. Iron limitation, another environmental condition relevant to the lungs of patients with cystic fibrosis, also resulted in conversion to mucoid. Since both conditions suggested the likelihood of an energy-deprived growth environment as a common variable, the effect of direct inhibition of energy generation by N,N'-dicyclohexylcarbodiimide or gramicidin on the conversion of nonmucoid P. aeruginosa to the mucoid phenotype was examined. Both inhibitors resulted in mucoid subpopulations (0.5 and 0.8%, respectively). Severe energy stress imposed by the combination of phosphate limitation and N,N'-dicyclohexylcarbodiimide treatment resulted in conversion of 55% of the population to mucoidy during a 7-day growth period. A growth advantage of the mucoid over the nonmucoid phenotype was observed under severe nutrient deprivation by growth on unsupplemented Noble agar or in a 1/2,500 dilution of a chemically defined medium. These results clearly demonstrate a significant role for the energy state of the cell in conversion to mucoid and in selection for the mucoid phenotype. PMID:1372292

  12. Rankine cycle condenser pressure control using an energy conversion device bypass valve

    DOEpatents

    Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

    2014-04-01

    The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

  13. Resolving Anomalies in Predicting Electrokinetic Energy Conversion Efficiencies of Nanofluidic Devices.

    PubMed

    Majumder, Sagardip; Dhar, Jayabrata; Chakraborty, Suman

    2015-01-01

    We devise a new approach for capturing complex interfacial interactions over reduced length scales, towards predicting electrokinetic energy conversion efficiencies of nanofluidic devices. By embedding several aspects of intermolecular interactions in continuum based formalism, we show that our simple theory becomes capable of representing complex interconnections between electro-mechanics and hydrodynamics over reduced length scales. The predictions from our model are supported by reported experimental data, and are in excellent quantitative agreement with molecular dynamics simulations. The present model, thus, may be employed to rationalize the discrepancies between low energy conversion efficiencies of nanofluidic channels that have been realized from experiments, and the impractically high energy conversion efficiencies that have been routinely predicted by the existing theories. PMID:26437925

  14. Resolving Anomalies in Predicting Electrokinetic Energy Conversion Efficiencies of Nanofluidic Devices

    PubMed Central

    Majumder, Sagardip; Dhar, Jayabrata; Chakraborty, Suman

    2015-01-01

    We devise a new approach for capturing complex interfacial interactions over reduced length scales, towards predicting electrokinetic energy conversion efficiencies of nanofluidic devices. By embedding several aspects of intermolecular interactions in continuum based formalism, we show that our simple theory becomes capable of representing complex interconnections between electro-mechanics and hydrodynamics over reduced length scales. The predictions from our model are supported by reported experimental data, and are in excellent quantitative agreement with molecular dynamics simulations. The present model, thus, may be employed to rationalize the discrepancies between low energy conversion efficiencies of nanofluidic channels that have been realized from experiments, and the impractically high energy conversion efficiencies that have been routinely predicted by the existing theories. PMID:26437925

  15. New bimetallic EMF cell shows promise in direct energy conversion

    NASA Technical Reports Server (NTRS)

    Hesson, J. C.; Shimotake, H.

    1968-01-01

    Concentration cell, based upon a thermally regenerative cell principle, produces electrical energy from any large heat source. This experimental bimetallic EMF cell uses a sodium-bismuth alloy cathode and a pure liquid sodium anode. The cell exhibits reliability, corrosion resistance, and high current density performance.

  16. Parametric design studies of toroidal magnetic energy storage units

    NASA Astrophysics Data System (ADS)

    Herring, J. Stephen

    Superconducting magnetic energy storage (SMES) units have a number of advantages as storage devices. Electrical current is the input, output and stored medium, allowing for completely solid-state energy conversion. The magnets themselves have no moving parts. The round trip efficiency is higher than those for batteries, compressed air or pumped hydro. Output power can be very high, allowing complete discharge of the unit within a few seconds. Finally, the unit can be designed for a very large number of cycles, limited basically by fatigue in the structural components. A small systems code was written to produce and evaluate self-consistent designs for toroidal superconducting energy storage units. The units can use either low temperature or high temperature superconductors. The coils have D shape where the conductor and its stabilizer/structure is loaded only in tension and the centering forces are borne by a bucking cylinder. The coils are convectively cooled from a cryogenic reservoir in the bore of the coils. The coils are suspended in a cylindrical metal shell which protects the magnet during rail, automotive or shipboard use. It is important to note that the storage unit does not rely on its surroundings for structural support, other than normal gravity and inertial loads. Designs are presented for toroidal energy storage units produced by the systems code. A wide range of several parameters have been considered, resulting in units storing from 1 MJ to 72 GJ. Maximum fields range from 5 T to 20 T. The masses and volumes of the coils, bucking cylinder, coolant, insulation and outer shell are calculated. For unattended use, the allowable operating time using only the boiloff of the cryogenic fluid for refrigeration is calculated. For larger units, the coils were divided into modules suitable for normal truck or rail transport.

  17. Chemical Expansion: Implications for Electrochemical Energy Storage and Conversion Devices

    NASA Astrophysics Data System (ADS)

    Bishop, S. R.; Marrocchelli, D.; Chatzichristodoulou, C.; Perry, N. H.; Mogensen, M. B.; Tuller, H. L.; Wachsman, E. D.

    2014-07-01

    Many energy-related materials rely on the uptake and release of large quantities of ions, for example, Li+ in batteries, H+ in hydrogen storage materials, and O2- in solid-oxide fuel cell and related materials. These compositional changes often result in large volumetric dilation of the material, commonly referred to as chemical expansion. This article reviews the current knowledge of chemical expansion and aspires to facilitate and promote future research in this field by providing a taxonomy for its sources, along with recent atomistic insights of its origin, aided by recent computational modeling and an overview of factors impacting chemical expansion. We discuss the implications of chemical expansion for mechanical stability and functionality in the energy applications above, as well as in other oxide-based systems. The use of chemical expansion as a new means to probe other materials properties, as well as its contribution to recently investigated electromechanical coupling, is also highlighted.

  18. Thermoelectric Energy Conversion Technology for High-Altitude Airships

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Elliott, James R.; King, Glen C.; Park, Yeonjoon; Kim, Jae-Woo; Chu, Sang-Hyon

    2011-01-01

    The High Altitude Airship (HAA) has various application potential and mission scenarios that require onboard energy harvesting and power distribution systems. The power technology for HAA maneuverability and mission-oriented applications must come from its surroundings, e.g. solar power. The energy harvesting system considered for HAA is based on the advanced thermoelectric (ATE) materials being developed at NASA Langley Research Center. The materials selected for ATE are silicon germanium (SiGe) and bismuth telluride (Bi2Te3), in multiple layers. The layered structure of the advanced TE materials is specifically engineered to provide maximum efficiency for the corresponding range of operational temperatures. For three layers of the advanced TE materials that operate at high, medium, and low temperatures, correspondingly in a tandem mode, the cascaded efficiency is estimated to be greater than 60 percent.

  19. Free energy conversion in the LUCA: Quo vadis?

    PubMed

    Ducluzeau, Anne-Lise; Schoepp-Cothenet, Barbara; Baymann, Frauke; Russell, Michael J; Nitschke, Wolfgang

    2014-07-01

    Living entities are unimaginable without means to harvest free energy from the environment, that is, without bioenergetics. The quest to understand the bioenergetic ways of early life therefore is one of the crucial elements to understand the emergence of life on our planet. Over the last few years, several mutually exclusive scenarios for primordial bioenergetics have been put forward, all of which are based on some sort of empirical observation, a remarkable step forward from the previous, essentially untestable, ab initio models. We here try to present and compare these scenarios while at the same time discuss their respective empirical weaknesses. The goal of this article is to harness crucial new expertise from the entire field by stimulating a larger part of the bioenergetics community to become involved in "origin-of-energy-metabolism" research. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. PMID:24361840

  20. The phototron: A light to RF energy conversion device

    NASA Technical Reports Server (NTRS)

    Freeman, J. W.; Simons, S.

    1982-01-01

    The phototron, a photoelectric device that converts light to radio frequency energy, is described. It is a vacuum tube, free electron, device that is mechanically similar to a reflex klystron with the hot filament cathode replaced by a large area photocathode. The device can operate either with an external voltage source used to accelerate the photoelectrons or with zero bias voltage; in which case the photokinetic energy of the electrons sustains the R.F. oscillations in the tuned R.F. circuit. One basic design of the phototron was tested. Frequencies as high as about 1 GHz and an overall efficiency of about 1% in the biased mode were obtained. In the unbiased mode, the frequencies of operation and efficiences are considerably lower. Success with test model suggests that considerable improvements are possible through design refinements. One such design refinement is the reduction of the length of the electron flight path.

  1. Conversion of municipal solid waste to energy, Jacksonville, Florida

    NASA Astrophysics Data System (ADS)

    Frounfelker, R.; Belencan, H.

    1982-02-01

    A 227 megagram per day prototype auger combustor system is described and performance tests are discussed. The system is a two chamber, starved-air incinerator so named because of the auger located within the primary chamber which tumbles and moves the waste through the system. The feasibility evaluation of resource recovery in the city of Jacksonville, Florida, involved the determination of the following: (1) the amount and characteristics of the solid waste; (2) the location and requirement of candidate energy customers and materials markets; (3) the applicable incineration/heat recovery and resource recovery technologies; and (4) the institutional, legal, and environmental requirements for constructing a facility. The marketing plan developd to define the specific steps required to employ a waste-to-energy technology in the Jacksonville area is also discussed.

  2. Cogeneration Technology Alternatives Study (CTAS). Volume 3: Energy conversion system characteristics

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Six current and thirty-six advanced energy conversion systems were defined and combined with appropriate balance of plant equipment. Twenty-six industrial processes were selected from among the high energy consuming industries to serve as a frame work for the study. Each conversion system was analyzed as a cogenerator with each industrial plant. Fuel consumption, costs, and environmental intrusion were evaluated and compared to corresponding traditional values. The advanced energy conversion technologies indicated reduced fuel consumption, costs, and emissions. Fuel energy savings of 10 to 25 percent were predicted compared to traditional on site furnaces and utility electricity. With the variety of industrial requirements, each advanced technology had attractive applications. Fuel cells indicated the greatest fuel energy savings and emission reductions. Gas turbines and combined cycles indicated high overall annual savings. Steam turbines and gas turbines produced high estimated returns. In some applications, diesels were most efficient. The advanced technologies used coal derived fuels, or coal with advanced fluid bed combustion or on site gasifications. Data and information for both current and advanced energy conversion technology are presented. Schematic and physical descriptions, performance data, equipment cost estimates, and predicted emissions are included. Technical developments which are needed to achieve commercialization in the 1985-2000 period are identified.

  3. Open cycle ocean thermal energy conversion system structure

    DOEpatents

    Wittig, J. Michael

    1980-01-01

    A generally mushroom-shaped, open cycle OTEC system and distilled water producer which has a skirt-conduit structure extending from the enlarged portion of the mushroom to the ocean. The enlarged part of the mushroom houses a toroidal casing flash evaporator which produces steam which expands through a vertical rotor turbine, partially situated in the center of the blossom portion and partially situated in the mushroom's stem portion. Upon expansion through the turbine, the motive steam enters a shell and tube condenser annularly disposed about the rotor axis and axially situated beneath the turbine in the stem portion. Relatively warm ocean water is circulated up through the radially outer skirt-conduit structure entering the evaporator through a radially outer portion thereof, flashing a portion thereof into motive steam, and draining the unflashed portion from the evaporator through a radially inner skirt-conduit structure. Relatively cold cooling water enters the annular condenser through the radially inner edge and travels radially outwardly into a channel situated along the radially outer edge of the condenser. The channel is also included in the radially inner skirt-conduit structure. The cooling water is segregated from the potable, motive steam condensate which can be used for human consumption or other processes requiring high purity water. The expansion energy of the motive steam is partially converted into rotational mechanical energy of the turbine rotor when the steam is expanded through the shaft attached blades. Such mechanical energy drives a generator also included in the enlarged mushroom portion for producing electrical energy. Such power generation equipment arrangement provides a compact power system from which additional benefits may be obtained by fabricating the enclosing equipment, housings and component casings from low density materials, such as prestressed concrete, to permit those casings and housings to also function as a floating support vessel.

  4. Efficient electrochemical CO2 conversion powered by renewable energy

    SciTech Connect

    Kauffman, Douglas R.; Thakkar, Jay; Siva, Rajan; Matranga, Christopher; Ohodnicki, Paul R.; Zeng, Chenjie; Jin, Rongchao

    2015-06-29

    The catalytic conversion of CO2 into industrially relevant chemicals is one strategy for mitigating greenhouse gas emissions. Along these lines, electrochemical CO2 conversion technologies are attractive because they can operate with high reaction rates at ambient conditions. However, electrochemical systems require electricity, and CO2 conversion processes must integrate with carbon-free, renewable-energy sources to be viable on larger scales. We utilize Au25 nanoclusters as renewably powered CO2 conversion electrocatalysts with CO2 → CO reaction rates between 400 and 800 L of CO2 per gram of catalytic metal per hour and product selectivities between 80 and 95%. These performance metrics correspond to conversion rates approaching 0.8–1.6 kg of CO2 per gram of catalytic metal per hour. We also present data showing CO2 conversion rates and product selectivity strongly depend on catalyst loading. Optimized systems demonstrate stable operation and reaction turnover numbers (TONs) approaching 6 × 106 mol CO2 molcatalyst–1 during a multiday (36 hours total hours) CO2electrolysis experiment containing multiple start/stop cycles. TONs between 1 × 106 and 4 × 106 molCO2 molcatalyst–1 were obtained when our system was powered by consumer-grade renewable-energy sources. Daytime photovoltaic-powered CO2 conversion was demonstrated for 12 h and we mimicked low-light or nighttime operation for 24 h with a solar-rechargeable battery. This proof-of-principle study provides some of the initial performance data necessary for assessing the scalability and technical viability of electrochemical CO2 conversion technologies. Specifically, we show the following: (1) all electrochemical CO2 conversion systems will produce a net increase in CO2 emissions if they do not integrate with renewable-energy sources, (2) catalyst loading vs activity trends can be used to tune process rates and product distributions, and (3) state-of-the-art renewable-energy technologies are sufficient to power larger-scale, tonne per day CO2 conversion systems.

  5. Parametric investigation of nano-gap thermophotovoltaic energy conversion

    NASA Astrophysics Data System (ADS)

    Lau, Japheth Z.-J.; Bong, Victor N.-S.; Wong, Basil T.

    2016-03-01

    Nano-gap thermophotovoltaic energy converters have the potential to be excellent generators of electrical power due to the near-field radiative effect which enhances the transfer of energy from one medium to another. However, there is still much to learn about this new form of energy converter. This paper seeks to investigate three parameters that affect the performance of nano-gap thermophotovoltaic devices: the emitter material, the thermophotovoltaic cell material, and the cell thickness. Furthermore, the temperature profiles in insulated thin films (cells exposed to below-band gap near-field radiation) are analysed. It was discovered that an effective emitter material is one that has a high generalised emissivity value and is also able to couple with the TPV cell material through surface polaritons while a cell material's electrical properties and its thickness has heavy bearing on its internal quantum efficiency. In regards to the temperature profile, the heat-flux absorbed causes a rise in temperature across the thin film, but is insufficient to generate a temperature gradient across the film.

  6. Solar Photoelectrochemical Energy Conversion using Earth-Abundant Nanomaterials

    NASA Astrophysics Data System (ADS)

    Lukowski, Mark A.

    Although the vast majority of energy consumed worldwide is derived from fossil fuels, the growing interest in making cleaner alternative energies more economically viable has motivated recent research efforts aimed to improve photovoltaic, wind, and biomass power generation. Clean power generation also requires clean burning fuels, such as H2 and O2, so that energy can still be provided on demand at all times, despite the intermittent nature inherent to solar or wind power. My research has focused on the rational approach to synthesizing earth-abundant nanomaterials with applications in the generation of clean alternative fuels and understanding the structure-property relationships which directly influence their performance. Herein, we describe the development of low-cost, earth-abundant layered metal chalcogenides as high-performance electrocatalysts for hydrogen evolution, and hematite photoanodes for photoelectrochemical oxygen evolution. This work has revealed a particularly interesting concept where catalytic performance can be enhanced by controlling the phase behavior of the material and taking advantage of previously unexploited properties to overcome the challenges traditionally limiting the performance of these layered materials for hydrogen evolution catalysis.

  7. Thermal-to-electric energy conversion using ferroelectric film capacitors

    SciTech Connect

    Kozyrev, A. B.; Platonov, R. A.; Soldatenkov, O. I.

    2014-10-28

    The capacitive ferroelectric thermoelectric converter harvesting electrical energy through non-linear capacitance variation caused by changes in temperature is analyzed. The ferroelectric material used was the thin (0.5 μm) Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} film. On the basis of experimental dependencies of the ferroelectric film permittivity on temperature ranging from 100 K to 350 K under different electric fields up to 80 V/μm, the optimum values of operating temperatures and electric field for the energy harvesting optimization were determined. For the temperature oscillations of ±15 K around room temperature and electric field about 40 V/μm, the harvested energy was estimated as 30 mJ/cm{sup 3}. It is shown that the use of thin ferroelectric films for rapid capacitance variation versus temperature and microelectromechanical systems for fast temperature modulations may be a relevant solution for creation of small power scale generators for portable electronics.

  8. Advanced, High Power, Next Scale, Wave Energy Conversion Device

    SciTech Connect

    Mekhiche, Mike; Dufera, Hiz; Montagna, Deb

    2012-10-29

    The project conducted under DOE contract DE‐EE0002649 is defined as the Advanced, High Power, Next Scale, Wave Energy Converter. The overall project is split into a seven‐stage, gated development program. The work conducted under the DOE contract is OPT Stage Gate III work and a portion of Stage Gate IV work of the seven stage product development process. The project effort includes Full Concept Design & Prototype Assembly Testing building on our existing PowerBuoy� technology to deliver a device with much increased power delivery. Scaling‐up from 150kW to 500kW power generating capacity required changes in the PowerBuoy design that addressed cost reduction and mass manufacturing by implementing a Design for Manufacturing (DFM) approach. The design changes also focused on reducing PowerBuoy Installation, Operation and Maintenance (IO&M) costs which are essential to reducing the overall cost of energy. In this design, changes to the core PowerBuoy technology were implemented to increase capability and reduce both CAPEX and OPEX costs. OPT conceptually envisaged moving from a floating structure to a seabed structure. The design change from a floating structure to seabed structure would provide the implementation of stroke‐ unlimited Power Take‐Off (PTO) which has a potential to provide significant power delivery improvement and transform the wave energy industry if proven feasible.

  9. Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

    SciTech Connect

    Charache, G.W.; Baldasaro, P.F.; Nichols, G.J.

    1996-12-31

    A thermophotovoltaic energy conversion device and a method for making the device are disclosed. The device includes a substrate formed from a bulk single crystal material having a bandgap (E{sub g}) of 0.4 eV < E{sub g} < 0.7 eV and an emitter fabricated on the substrate formed from one of a p-type and an n-type material. Another thermophotovoltaic energy conversion device includes a host substrate formed from a bulk single crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers.

  10. Advances in graphene-based semiconductor photocatalysts for solar energy conversion: fundamentals and materials engineering

    NASA Astrophysics Data System (ADS)

    Xie, Xiuqiang; Kretschmer, Katja; Wang, Guoxiu

    2015-08-01

    Graphene-based semiconductor photocatalysis has been regarded as a promising technology for solar energy storage and conversion. In this review, we summarized recent developments of graphene-based photocatalysts, including preparation of graphene-based photocatalysts, typical key advances in the understanding of graphene functions for photocatalytic activity enhancement and methodologies to regulate the electron transfer efficiency in graphene-based composite photocatalysts, by which we hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene-based composite photocatalysts for solar-to-energy conversion.

  11. Advances in graphene-based semiconductor photocatalysts for solar energy conversion: fundamentals and materials engineering.

    PubMed

    Xie, Xiuqiang; Kretschmer, Katja; Wang, Guoxiu

    2015-08-28

    Graphene-based semiconductor photocatalysis has been regarded as a promising technology for solar energy storage and conversion. In this review, we summarized recent developments of graphene-based photocatalysts, including preparation of graphene-based photocatalysts, typical key advances in the understanding of graphene functions for photocatalytic activity enhancement and methodologies to regulate the electron transfer efficiency in graphene-based composite photocatalysts, by which we hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene-based composite photocatalysts for solar-to-energy conversion. PMID:26204442

  12. Bulk single crystal ternary substrates for a thermophotovoltaic energy conversion system

    DOEpatents

    Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY); Nichols, Greg J. (Burnt Hills, NY)

    1998-01-01

    A thermophotovoltaic energy conversion device and a method for making the device. The device includes a substrate formed from a bulk single crystal material having a bandgap (E.sub.g) of 0.4 eVenergy conversion device includes a host substrate formed from a bulk single crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers.

  13. Giant Electro-Mechanical Energy Conversion in [011] cut Relaxor Ferroelectric Single Crystals

    NASA Astrophysics Data System (ADS)

    Finkel, Peter; Dong, Wen; Lynch, Chris; Amin, Ahmed

    2012-02-01

    Giant electro-mechanical energy conversion is demonstrated under a ferroelectric/ferroelectric phase transformation in [011] cut and poled lead titanate-based relaxor perovskite morphotropic single crystals. It is found that under mechanical pre-stress, a relatively small oscillatory stress drives the material reversibly between rhombohedral and orthorhombic phases with a remarkably high polarization and strain jumps induced at zero bias electric field and room temperature. The measured electrical output per cycle is more than an order of magnitude larger than that reported for linear piezoelectric materials. Ideal thermodynamic cycles are presented for this electro-mechanical energy conversion followed by a presentation and discussion of the experimental data.

  14. Giant electro-mechanical energy conversion in [011] cut ferroelectric single crystals

    NASA Astrophysics Data System (ADS)

    Dong, Wen D.; Finkel, Peter; Amin, Ahmed; Lynch, Christopher S.

    2012-01-01

    Giant electro-mechanical energy conversion is demonstrated under a ferroelectric/ferroelectric phase transformation in [011] cut and poled lead titanate-based relaxor perovskite morphotropic single crystals. It is found that under mechanical pre-stress, a relatively small oscillatory stress drives the material reversibly between rhombohedral and orthorhombic phases with a remarkably high polarization and strain jump induced at zero bias electric field and room temperature. The measured electrical output per cycle is more than an order of magnitude larger than that reported for linear piezoelectric materials. Ideal thermodynamic cycles are presented for this electro-mechanical energy conversion followed by a presentation and discussion of the experimental data.

  15. Frequency up conversion approach to scavenge mechanical energy from an electromagnetic digital actuator

    NASA Astrophysics Data System (ADS)

    Yan, Linjuan; Badel, Adrien; Petit, Laurent; Formosa, Fabien

    2015-12-01

    This paper reports the practical design and experimental testing of a piezoelectric energy reclamation system. The presented system aims at scavenging energy from a miniaturized electromagnetic digital actuator for additional function such as obtains the discrete position information for enhanced reliability. Based on frequency up conversion technique, and the considered actuator dynamical responses, a piezoelectric energy harvester has been experimentally evaluated. In plane integration is the next step.

  16. Numerical models analysis of energy conversion process in air-breathing laser propulsion

    NASA Astrophysics Data System (ADS)

    Hong, Yanji; Song, Junling; Cui, Cunyan; Li, Qian

    2011-11-01

    Energy source was considered as a key essential in this paper to describe energy conversion process in air-breathing laser propulsion. Some secondary factors were ignored when three independent modules, ray transmission module, energy source term module and fluid dynamic module, were established by simultaneous laser radiation transportation equation and fluid mechanics equation. The incidence laser beam was simulated based on ray tracing method. The calculated results were in good agreement with those of theoretical analysis and experiments.

  17. Numerical models analysis of energy conversion process in air-breathing laser propulsion

    SciTech Connect

    Hong Yanji; Song Junling; Cui Cunyan; Li Qian

    2011-11-10

    Energy source was considered as a key essential in this paper to describe energy conversion process in air-breathing laser propulsion. Some secondary factors were ignored when three independent modules, ray transmission module, energy source term module and fluid dynamic module, were established by simultaneous laser radiation transportation equation and fluid mechanics equation. The incidence laser beam was simulated based on ray tracing method. The calculated results were in good agreement with those of theoretical analysis and experiments.

  18. Free Magnetic Energy and Coronal Heating

    NASA Technical Reports Server (NTRS)

    Winebarger, Amy; Moore, Ron; Falconer, David

    2012-01-01

    Previous work has shown that the coronal X-ray luminosity of an active region increases roughly in direct proportion to the total photospheric flux of the active region's magnetic field (Fisher et al. 1998). It is also observed, however, that the coronal luminosity of active regions of nearly the same flux content can differ by an order of magnitude. In this presentation, we analyze 10 active regions with roughly the same total magnetic flux. We first determine several coronal properties, such as X-ray luminosity (calculated using Hinode XRT), peak temperature (calculated using Hinode EIS), and total Fe XVIII emission (calculated using SDO AIA). We present the dependence of these properties on a proxy of the free magnetic energy of the active region

  19. Ultra-low-power conversion and management techniques for thermoelectric energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Fleming, Jerry W.

    2010-04-01

    Thermoelectric energy harvesting has increasingly gained acceptance as a potential power source that can be used for numerous commercial and military applications. However, power electronic designers have struggled to incorporate energy harvesting methods into their designs due to the relatively small voltage levels available from many harvesting device technologies. In order to bridge this gap, an ultra-low input voltage power conversion method is needed to convert small amounts of scavenged energy into a usable form of electricity. Such a method would be an enabler for new and improved medical devices, sensor systems, and other portable electronic products. This paper addresses the technical challenges involved in ultra-low-voltage power conversion by providing a solution utilizing novel power conversion techniques and applied technologies. Our solution utilizes intelligent power management techniques to control unknown startup conditions. The load and supply management functionality is also controlled in a deterministic manner. The DC to DC converter input operating voltage is 20mV with a conversion efficiency of 90% or more. The output voltage is stored into a storage device such as an ultra-capacitor or lithium-ion battery for use during brown-out or unfavorable harvesting conditions. Applications requiring modular, low power, extended maintenance cycles, such as wireless instrumentation would significantly benefit from the novel power conversion and harvesting techniques outlined in this paper.

  20. Energy conversion and fuel production from electrochemical interfaces

    NASA Astrophysics Data System (ADS)

    Markovic, Nenad

    2012-02-01

    Design and synthesis of energy efficient and stable electrochemical interfaces (materials and double layer components) with tailor properties for accelerating and directing chemical transformations is the key to developing new alternative energy systems -- fuel cells, electrolizers and batteries. In aqueous electrolytes, depending on the nature of the reacting species, the supporting electrolyte, and the metal electrodes, two types of interactions have traditionally been considered: (i) direct -- covalent - bond formation between adsorbates and electrodes, involving chemisorption, electron transfer, and release of the ion hydration shell; and (ii) relatively weak non-covalent metal-ion forces that may affect the concentration of ions in the vicinity of the electrode but do not involve direct metal-adsorbate bonding. The range of physical phenomena associated with these two classes of bonds is unusually broad, and are of paramount importance to understand activity of both metal-electrolyte two phase interfaces and metal-Nafion-electrolyte three phase interfaces. Furthermore, in the past, researcher working in the field of fuel cells (converting hydrogen and oxygen into water) and electrolyzers (splitting water back to H2 and O2) ) seldom focused on understanding the electrochemical compliments of these reactions in battery systems, e.g., the lithium-air system. In this lecture, we address the importance of both covalent and non-covalent interactions in controlling catalytic activity at the two-phase and three-phase interfaces. Although the field is still in its infancy, a great deal has already been learned and trends are beginning to emerge that give new insight into the relationship between the nature of bonding interactions and catalytic activity/stability of electrochemical interfaces. In addition, to bridge the gap between the ``water battery'' (fuel cell <-> electrolyzer) and the Li-air battery systems we demonstrate that this would require fundamentally new knowledge in several critical areas. We conclude that understanding the complexity (simplicity) of electrochemical interfaces would open new avenues for design and deployment of alternative energy systems.

  1. New energy conversion techniques in space, applicable to propulsion

    NASA Technical Reports Server (NTRS)

    Hertzberg, A.; Sun, K. C.

    1989-01-01

    The powering of aircraft with laser energy from a solar power satellite may be a promising new approach to the critical problem of the rising cost of fuel for aircraft transportation systems. The result is a nearly fuelless, pollution-free flight transportation system which is cost-competitive with the fuel-conservative airplane of the future. The major components of this flight system include a laser power satellite, relay satellites, laser-powered turbofans and a conventional airframe. The relay satellites are orbiting optical systems which intercept the beam from a power satellite and refocus and redirect the beam to its next target.

  2. Low Cost Solar Energy Conversion (Carbon Cycle 2.0)

    ScienceCinema

    Ramesh, Ramamoorthy

    2011-06-08

    Ramamoorthy Ramesh from LBNL's Materials Science Division speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

  3. Low Cost Solar Energy Conversion (Carbon Cycle 2.0)

    SciTech Connect

    Ramesh, Ramamoorthy

    2010-02-04

    Ramamoorthy Ramesh from LBNL's Materials Science Division speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 2, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

  4. Energy balance of biofuel production from biological conversion of crude glycerol.

    PubMed

    Zhang, Xiaolei; Yan, Song; Tyagi, Rajeshwar D; Surampalli, Rao Y; Valéro, Jose R

    2016-04-01

    Crude glycerol, a by-product of biodiesel production, has gained significant attention as a carbon source for biofuel production. This study evaluated the energy balance of biodiesel, hydrogen, biogas, and ethanol production from 3.48 million L of crude glycerol (80% w/v). The conversion efficiency (energy output divided by energy invested) was 1.16, 0.22, 0.27, and 0.40 for the production of biodiesel, hydrogen, biogas, and ethanol respectively. It was found that the use of crude glycerol for biodiesel production was an energy gain process, with a positive energy balance and conversion efficiency of greater than 1. The energy balance revealed a net energy gain of 5226 GJ per 1 million kg biodiesel produced. Production of hydrogen, biogas and ethanol from crude glycerol were energy loss processes. Therefore, the conversion of crude glycerol to lipids and subsequently to biodiesel is suggested to be a better option compared to hydrogen, biogas, or ethanol production with respect to energy balance. PMID:26829450

  5. Mode conversion in magneto-optic rib waveguide made by silica matrix doped with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bouras, Mounir; Hocini, Abdessalem

    2016-03-01

    The TE-TM mode conversion is an important requirement for magneto-optical waveguide devices. It has been analyzed by means of a full-vectorial beam propagation method. The present work is based on the study of the influence of diagonal and off-diagonal elements of the complex dielectric tensor on the conversion efficiency in magneto-optical rib waveguide. We have found that in the presence of the absorption (taking into account the imaginary part of diagonal tensor) the conversion efficiency is affected by the absorption and these latter increases as the volume fraction of nanoparticles increases.

  6. MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Abramenko, Valentyna; Yurchyshyn, Vasyl

    2010-09-01

    Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph were used. The turbulence regime was probed via magnetic energy spectra and magnetic dissipation spectra. We found steeper energy spectra for ARs with higher flare productivity. We also report that both the power index, {alpha}, of the energy spectrum, E(k) {approx} k{sup -}{alpha}, and the total spectral energy, W = {integral}E(k)dk, are comparably correlated with the flare index, A, of an AR. The correlations are found to be stronger than those found between the flare index and the total unsigned flux. The flare index for an AR can be estimated based on measurements of {alpha} and W as A = 10{sup b}({alpha}W){sup c}, with b = -7.92 {+-} 0.58 and c = 1.85 {+-} 0.13. We found that the regime of the fully developed turbulence occurs in decaying ARs and in emerging ARs (at the very early stage of emergence). Well-developed ARs display underdeveloped turbulence with strong magnetic dissipation at all scales.

  7. Thermoelectronic laser energy conversion for power transmission in space

    NASA Technical Reports Server (NTRS)

    Britt, E. J.; Yuen, C.

    1977-01-01

    Long distance transmission of power in space by means of laser beams is an attractive concept because of the very narrow beam divergence. Such a system requires efficient means to both generate the laser beam and to convert the light energy in the beam into useful electric output at the receiver. A plasma-type device known as a Thermo-Electronic Laser Energy Converter (TELEC) has been studied as a method of converting a 10.6 micron CO2 laser beam into electric power. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes with different areas. Since more electrons are collected by the larger electrode there is a net transport of current, and an EMF is generated in the external circuit. The smaller electrode functions as an electron emitter to provide continuity of the current. Waste heat is rejected from the large electrode. A design for a TELEC system with an input 1 MW laser beam was developed as part of the study. The calculated performance of the system showed an overall efficiency of about 42%.

  8. Twisted Savonius turbine based marine current energy conversion system

    NASA Astrophysics Data System (ADS)

    Hassan, Md. Imtiaj

    The Ocean Network Seafloor Instrumentation (ONSFI) Project is a multidisciplinary research and development project that aims to design, fabricate and validate a proof-of-concept seafloor array of wireless marine sensors for use in monitoring seabed processes. The sensor pods, known as Seaformatics, will be powered by ocean bottom currents and will be able to communicate with each other and to the Internet through surface master units to facilitate observation of the ocean floor from the shore. This thesis explores the use of the twisted Savonius turbine as a means of converting the kinetic energy of the free flowing water into electrical energy for the pods. This will eliminate the need for battery replacement. A physical model of the turbine was constructed and tested in the Water Flume at the Marine Institute of Memorial University and in the Wind Tunnel in the Engineering Building at Memorial University. A mathematical model of the turbine was constructed in SolidWorks. This was tested in the Computational Fluid Dynamics or CFD software FLOW-3D. Experimental results were compared with CFD results and the agreement was reasonable. A twisted Savonius turbine emulator was developed to test a dc-dc boost converter. A low cost microcontroller based MPPT algorithm was developed to obtain maximum power from the turbine. Overall the thesis shows that the twisted Savonius turbine can provide the power needed by the sensor pods. It also shows that CFD is a viable way to study the performance of the Savonius type of turbine.

  9. Dynamic breakwater and wave energy recovery and conversion system

    SciTech Connect

    Boros, L.J.

    1983-05-24

    A dynamic breakwater system includes at least one and preferably a plurality of dynamic breakwater assemblies, each of which includes a baffle wall member which is pivotally mounted in a body of water about an axis which extends substantially transverse to the direction of wave motion and so that a lower portion thereof is submerged below the water surface while an upper portion thereof extends above the water surface, each baffle wall member being biased such that it has a tendency to move in a direction opposite to the direction of wave motion and wherein apparatus for damping the movement of the baffle wall member when the same moves in the direction of wave motion under the force of waves impinging thereon are provided. Apparatus is provided for recovering at least a portion of the energy imparted to the baffle wall member by the waves impinging thereon and for converting the same to useful energy and generally comprises a fluid circuit supported on a stationary platform assembly and a device operatively interconnecting the baffle wall member and fluid circuit for elevating the pressure of the fluid circulating therein in response to movement of the baffle wall member caused by the waves impinging thereon.

  10. Combined chemical looping for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Galvita, Vladimir V.; Poelman, Hilde; Marin, Guy B.

    2015-07-01

    Combined chemical looping was demonstrated as novel concept of energy storage in a laboratory scale test. The proposed technology is able to store and release energy from redox chemical looping reactions combined with calcium looping. This process uses Fe3O4 and CaO, two low cost and environmentally friendly materials, while CH4 + CO2 serve as feed. During the reduction of Fe3O4 by CH4, both formation of carbon and metallic iron occur. CO2 acts as mediation gas to facilitate the metal/metal oxide redox reaction and carbon gasification into CO. CaO, on the other hand, is used for storage of CO2. Upon temperature rise, CaCO3 releases CO2, which re-oxidizes the carbon deposits and reduced Fe, thus producing carbon monoxide. The amount of produced CO is higher than the theoretical amount for Fe3O4, because carbon deposits from CH4 equally contribute to the CO yield. After each redox cycle, the material is regenerated, so that it can be used repeatedly, providing a stable process.

  11. Biomass accumulation and energy conversion efficiency in aromatic rice genotypes.

    PubMed

    Shahidullah, S M; Hanafi, M M; Ashrafuzzaman, M; Razi Ismail, M; Salam, M A; Khair, A

    2010-01-01

    A field experiment was conducted to evaluate photosynthetic efficiency along with different growth parameters of aromatic rice genotypes. Forty genotypes including three non-aromatic checks exhibited enormous variations for leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), grain yield, total dry matter, harvest index and photosynthetic efficiency or energy use efficiency (Emu) at panicle initiation and heading stages. Minimum LAI-value was 0.52 in Khazar at PI stage and maximum was 4.91 in Sakkor khora at heading stage. The CGR-value was in the range of 4.80-24.11 g m(-2) per day. The best yielder BR39 produced grain of 4.21 t ha(-1) and the worst yielder Khazar gave 1.42 t ha(-1). Total dry matter (TDM) yield varied from 4.04 to 12.26 t ha(-1) where genotypes proved their energy use efficiency a range between 0.58 to 1.65%. Emu showed a significant positive relation with TDM (r=0.80(**)), CGR (r=0.72(**)) and grain yield (r=0.66(**)). A negative correlation was established between TDM and harvest index and LAI and RGR. Path analysis result showed that NAR at heading stage exerted highest positive direct effect (0.70) on Emu. PMID:20176338

  12. Reappraisal of solid selective emitters. [for thermovoltaic energy conversion

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1990-01-01

    New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus, low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied, Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

  13. Magnetic Energy Storage System: Superconducting Magnet Energy Storage System with Direct Power Electronics Interface

    SciTech Connect

    2010-10-01

    GRIDS Project: ABB is developing an advanced energy storage system using superconducting magnets that could store significantly more energy than todays best magnetic storage technologies at a fraction of the cost. This system could provide enough storage capacity to encourage more widespread use of renewable power like wind and solar. Superconducting magnetic energy storage systems have been in development for almost 3 decades; however, past devices were designed to supply power only for short durationsgenerally less than a few minutes. ABBs system would deliver the stored energy at very low cost, making it ideal for eventual use in the electricity grid as a costeffective competitor to batteries and other energy storage technologies. The device could potentially cost even less, on a per kilowatt basis, than traditional lead-acid batteries.

  14. One-dimension-based spatially ordered architectures for solar energy conversion.

    PubMed

    Liu, Siqi; Tang, Zi-Rong; Sun, Yugang; Colmenares, Juan Carlos; Xu, Yi-Jun

    2015-08-01

    The severe consequences of fossil fuel consumption have resulted in a need for alternative sustainable sources of energy. Conversion and storage of solar energy via a renewable method, such as photocatalysis, holds great promise as such an alternative. One-dimensional (1D) nanostructures have gained attention in solar energy conversion because they have a long axis to absorb incident sunlight yet a short radial distance for separation of photogenerated charge carriers. In particular, well-ordered spatially high dimensional architectures based on 1D nanostructures with well-defined facets or anisotropic shapes offer an exciting opportunity for bridging the gap between 1D nanostructures and the micro and macro world, providing a platform for integration of nanostructures on a larger and more manageable scale into high-performance solar energy conversion applications. In this review, we focus on the progress of photocatalytic solar energy conversion over controlled one-dimension-based spatially ordered architecture hybrids. Assembly and classification of these novel architectures are summarized, and we discuss the opportunity and future direction of integration of 1D materials into high-dimensional, spatially organized architectures, with a perspective toward improved collective performance in various artificial photoredox applications. PMID:25856797

  15. A History of Geothermal Energy Research and Development in the United States. Energy Conversion 1976-2006

    SciTech Connect

    Mines, Gregory L.

    2010-09-01

    This report, the last in a four-part series, summarizes significant research projects performed by the U.S. Department of Energy (DOE) over 30 years to overcome challenges in energy conversion and to make generation of electricity from geothermal resources more cost-competitive.

  16. The role of latent heat in kinetic energy conversions of South Pacific cyclones

    NASA Technical Reports Server (NTRS)

    Kann, Deirdre M.; Vincent, Dayton G.

    1986-01-01

    The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.

  17. Theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions.

    PubMed

    Cushing, Scott K; Bristow, Alan D; Wu, Nianqiang

    2015-11-28

    Plasmonics can enhance solar energy conversion in semiconductors by light trapping, hot electron transfer, and plasmon-induced resonance energy transfer (PIRET). The multifaceted response of the plasmon and multiple interaction pathways with the semiconductor makes optimization challenging, hindering design of efficient plasmonic architectures. Therefore, in this paper we use a density matrix model to capture the interplay between scattering, hot electrons, and dipole-dipole coupling through the plasmon's dephasing, including both the coherent and incoherent dynamics necessary for interactions on the plasmon's timescale. The model is extended to Shockley-Queisser limit calculations for both photovoltaics and solar-to-chemical conversion, revealing the optimal application of each enhancement mechanism based on plasmon energy, semiconductor energy, and plasmon dephasing. The results guide application of plasmonic solar-energy harvesting, showing which enhancement mechanism is most appropriate for a given semiconductor's weakness, and what nanostructures can achieve the maximum enhancement. PMID:26497739

  18. Aluminum as anode for energy storage and conversion: a review

    NASA Astrophysics Data System (ADS)

    Li, Qingfeng; Bjerrum, Niels J.

    Aluminum has long attracted attention as a potential battery anode because of its high theoretical voltage and specific energy. The protective oxide layer on the aluminum surface is however detrimental to the battery performance, contributing to failure to achieve the reversible potential and causing the delayed activation of the anode. By developing aluminum alloys as anodes and solution additives to electrolytes, a variety of aluminum batteries have been extensively investigated for various applications. From molten salt and other non-aqueous electrolytes, aluminum can be electrodeposited and therefore be suitable for developing rechargable batteries. Considerable efforts have been made to develop secondary aluminum batteries of high power density. In the present paper, these research activities are reviewed, including aqueous electrolyte primary batteries, aluminum-air batteries and molten salt secondary batteries.

  19. Synchrotron-based spectroscopy for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Himpsel, F. J.; Cook, P. L.; Zegkinoglou, I.; Boukahil, Idris; Qiao, R.; Yang, W.; Pemmaraju, S. C.; Prendergast, D.; Kronawitter, C. X.; Kibria, M. G.; Mi, Zetian; Vayssieres, L.

    2015-09-01

    X-rays from synchrotron radiation enable incisive spectroscopic techniques which speed up the discovery of new materials for photovoltaics and photoelectrochemistry. A particularly useful method is X-ray absorption spectroscopy (XAS), which probes empty electronic states. XAS is element- and bond-specific, with the additional capability of determining the bond orientation. Close feedback from density functional calculations makes it possible to discover and exploit systematic trends in the electronic properties. Case studies are presented, such as solar cells that combine an absorber with an electron donor and an acceptor in one molecular complex and nanowire arrays serving as photoanodes for water splitting. In addition to the energy levels the lifetimes of the charge carriers play an essential role in device performance. A new generation of laser-like X-ray sources will make it possible to follow the fate of excited charge carriers traveling across a molecular complex or through a device structure in real time.

  20. Photochemical energy conversion in a helical oligoproline assembly.

    PubMed Central

    McCafferty, D G; Friesen, D A; Danielson, E; Wall, C G; Saderholm, M J; Erickson, B W; Meyer, T J

    1996-01-01

    A general method is described for constructing a helical oligoproline assembly having a spatially ordered array of functional sites protruding from a proline-II helix. Three different redox-active carboxylic acids were coupled to the side chain of cis-4-amino-L-proline. These redox modules were incorporated through solid-phase peptide synthesis into a 13-residue helical oligoproline assembly bearing in linear array a phenothiazine electron donor, a tris(bipyridine)ruthenium(II) chromophore, and an anthraquinone electron acceptor. Upon transient 460-nm irradiation in acetonitrile, this peptide triad formed with 53% efficiency an excited state containing a phenothiazine radical cation and an anthraquinone radical anion. This light-induced redox-separated state had a lifetime of 175 ns and stored 1.65 eV of energy. Images Fig. 3 Fig. 5 PMID:8710847