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1

Magnetic Energy Conversion From Whistlers to Electrons  

Microsoft Academic Search

The most important aspect of magnetic reconnection is the fast conversion of magnetic energy into particle energy. Fast reconnection is facilitated by two-fluid effects. In the Electron MHD regime (EMHD), magnetic energy is converted into electrons on whistler time scales. In the absence of collisions and inertial effects the heating mechanism is not obvious. Laboratory experiments observing efficient electron heating

R. L. Stenzel; M. J. Urrutia

2008-01-01

2

Magnetic Energy Conversion From Whistlers to Electrons  

NASA Astrophysics Data System (ADS)

The most important aspect of magnetic reconnection is the fast conversion of magnetic energy into particle energy. Fast reconnection is facilitated by two-fluid effects. In the Electron MHD regime (EMHD), magnetic energy is converted into electrons on whistler time scales. In the absence of collisions and inertial effects the heating mechanism is not obvious. Laboratory experiments observing efficient electron heating by nonlinear whistler modes will be presented. Electron energization occurs in magnetic null lines by inductive electric fields along the separator, irrespective of the null point topology (X or O type). A finite electron transit time through the null line provides an inertial "resistivity" which allows dissipation and electron heating. Note that simple electron acceleration (jetting) does not convert magnetic energy in EMHD. The heating is strongest (from 3eV to 30eV) and fastest in field topologies called "whistler spheromaks" [Phys. Rev. Lett. 99, 265005 (2007)]. The energized electrons have anisotropic distributions since secondary whistler instabilities are observed. Thus, intense whistlers with magnetic null lines efficiently heat electrons even on scales larger than the electron inertial length. Such phenomena may arise in strong whistler turbulence near the center of neutral sheets. exp/research/PropertiesNonlinearWhistlers/index.html

Stenzel, R. L.; Urrutia, M. J.

2008-12-01

3

Permanent magnet synchronous generators for regenerative energy conversion - a survey  

Microsoft Academic Search

A survey on recently installed or developed permanent magnet (PM) synchronous generators for energy conversion in regenerative and alternative power supply systems is given. Its focus is for low speed machines on geared and gearless PM generator systems for wind power plants and small PM hydro generators in gearless coupling. For distributed co-generation of heat and electrical power by micro

Andreas Binder; Tobias Schneider

2005-01-01

4

Permanent magnet energy conversion machine with magnet mounting arrangement  

DOEpatents

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.

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

1999-01-01

5

Multiphysics simulation of wave energy to electric energy conversion by permanent magnet linear generator  

Microsoft Academic Search

The possibility to use three-phase permanent magnet linear generators to convert sea wave energy into electric energy is investigated by multiphysics simulations. The results show a possibility, which needs to be further verified by experimental tests, for a future step toward a sustainable electric power production from ocean waves by using direct conversion. The results suggest that wave energy can

Mats Leijon; Hans Bernhoff; Olov gren; Jan Isberg; Jan Sundberg; Marcus Berg; Karl Erik Karlsson; Arne Wolfbrandt

2005-01-01

6

Transverse Flux Permanent Magnet Generator for Ocean Wave Energy Conversion  

Microsoft Academic Search

\\u000a Modern energy demands led the scientific community to renewable energy sources, such as ocean wave energy. The present work\\u000a describes a model for a cost efficient rotary electrical generator, optimized for ocean wave energy conversion. The electrical\\u000a power, supplied by low speed mechanical movement, requires the use of electrical machinery capable of generating high amounts\\u000a of torque. Among the analyzed

Jos Lima; Anabela Pronto; Mrio Ventim Neves

2011-01-01

7

Hydroelectrical energy conversion in narrow confinements in the presence of transverse magnetic fields with electrokinetic effects  

Microsoft Academic Search

In this work, we investigate the combined influences of externally applied axial pressure gradients and transverse magnetic fields on hydroelectrical energy conversion mechanisms in narrow fluidic confinements. This energy conversion is achieved through an exploitation of the electromagnetohydrodynamic effects as a result of electrical double layer formation and the consequent interfacial phenomena. Although no electrical field is externally applied, a

Farooque Munshi; Suman Chakraborty

2009-01-01

8

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

SciTech Connect

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.

Mozer, F. S.; Hull, A. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)

2010-10-15

9

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

DOEpatents

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.

Skeist, S. Merrill; Baker, Richard H.

2006-01-10

10

Energy conversion and transfer for plasmas in a magnetic expansion configuration  

NASA Astrophysics Data System (ADS)

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 0.01-0.05 T and electrode voltages of 22.0-32.0 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.

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

2014-06-01

11

Energy Conversions  

NSDL National Science Digital Library

Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device. They also identify the forms of energy that are useful and the desired output of the device as well as the forms that are not useful for the intended use of the item. This can be used to lead into the law of conservation of energy and efficiency. The student activity is preceded by a demonstration of a more complicated system to convert chemical energy to heat energy to mechanical energy. Drawing the block energy conversion diagram for this system models the activity that the students then do themselves for other simpler systems.

Office of Educational Partnerships,

12

Design of a novel air-cored permanent magnet linear generator for wave energy conversion  

Microsoft Academic Search

An analytical design optimisation model of a novel air-cored permanent magnet linear generator is developed for wave energy conversion. The aim is to reach a design with dimensions optimised for minimum cost of the active material. The analytical results are verified with finite element analysis and compared to previous studies. The optimised machine shows considerable improvement over previous designs.

Rieghard Vermaak; Maarten J. Kamper

2010-01-01

13

Improved wind power conversion system using magnetic energy recovery switch (MERS)  

Microsoft Academic Search

This paper presents experimental results on an innovative power conversion technology using magnetic energy recovery switch (MERS) of a wind turbine system with a synchronous generator to improve the output power and the efficiency. An output voltage of the synchronous generator decreases with the increase of current because of synchronous reactance. The MERS, which consists of four MOSFET or IGBT

T. Takaku; G. Homma; T. Isober; S. Igarashi; Y. Uchida; R. Shimada

2005-01-01

14

Energy conversion and particle acceleration during magnetic reconnection in solar flare plasma  

NASA Astrophysics Data System (ADS)

Recent solar flare observations have inferred that a large fraction of the electrons in the acceleration site are accelerated into non-thermal energies, and the accelerated electrons form power-law energy spectra. Magnetic reconnection is widely accepted to be the energy source of solar flares and may serve as one of the particle acceleration mechanisms. Here, we use two-dimensional PIC simulations to study energy conversion and particle acceleration during reconnection in a low-beta (~0.01) plasma. In the end of the simulations, up to 50% of the electrons can be accelerated into non-thermal energies, which contains about 90% of the total electron kinetic energy. Power-law energy spectra of electrons develop for sufficiently large simulation domain. We then investigate the detailed particle acceleration process using a drift approximation. Fermi mechanism is found dominant for no/low guide field cases, while parallel heating is dominant for high guide field cases. The energy conversion and particle acceleration process is consistent with that inferred in solar flares.

Li, Xiaocan; Guo, Fan; Li, Hui; Li, Gang

2015-04-01

15

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

SciTech Connect

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.

Janos, A.

1985-09-01

16

Energy Conversion  

NSDL National Science Digital Library

In this activity, students devise ways to demonstrate that energy can change from one form to another in accord with the law of conservation of energy. Small appliances, toys, marbles, vinegar and baking soda, simple electrical supplies available from a hardware store, and thermometers are needed to complete this activity. A student worksheet and an assessment rubric are included with the resource. The investigation supports material presented in chapter 1, "What is energy? in the textbook Energy flow, part of Global System Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

17

Direct Conversion of Energy.  

ERIC Educational Resources Information Center

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

Corliss, William R.

18

Design of a double-sided tubular permanent-magnet linear synchronous generator for wave-energy conversion  

Microsoft Academic Search

Purpose The purpose of this paper is to present a double-sided tubular linear machine layout direct-drive applications, with particular focus on wave-energy conversion. The paper documents both the computational and mathematical analysis of this novel machine layout. Design\\/methodology\\/approach The selection and finite-element optimisation of the permanent-magnet array is presented. The machine is then modelled using magnetic circuit theory.

Danson M. Joseph; Willem A. Cronje

2008-01-01

19

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

SciTech Connect

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.

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

1982-11-01

20

Energy conversion alternatives study  

NASA Technical Reports Server (NTRS)

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.

Shure, L. T.

1979-01-01

21

A Permanent-Magnet Tubular Linear Generator for Ocean Wave Energy Conversion  

Microsoft Academic Search

This paper presents a novel permanent-magnet tubular linear generator (PMTLG) buoy system designed to convert the linear motion of ocean waves into electrical energy. The design incorporates no working seals and a saltwater air-gap bearing surface integration between the PMTLG buoy components. The internal generator design will be discussed, in addition to the system integration with the buoy structure. The

Joseph Prudell; Martin Stoddard; Ean Amon; Ted K. A. Brekken; Annette von Jouanne

2010-01-01

22

Evaluating Energy Conversion Efficiency  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

23

Photochemical Energy Conversion.  

ERIC Educational Resources Information Center

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)

Batschelet, William H.; George, Arnold

1986-01-01

24

Algae Harvest Energy Conversion  

Microsoft Academic Search

\\u000a Algae harvest energy conversion to biofuel technology is a promising alternative to fossil fuel that has inherent pollution\\u000a attachment. With present resources available for the microalgae mass production and hence, high oil yield, microalgal can\\u000a sufficiently be a new source of renewable energy to replace the fossil fuels. In this chapter, algae description, composition,\\u000a cultivation, its conversion to biofuel, and

Yung-Tse Hung; O. Sarafadeen Amuda; A. Olanrewaju Alade; I. Adekunle Amoo; Stephen Tiong-Lee Tay; Kathleen Hung Li

25

Observed signatures of magnetic energy conversion in solar flares and microflares  

NASA Astrophysics Data System (ADS)

A study of the evolution of X-ray output in different bipolar structures (Machado et al., 1988) is extended to weaker microflare activity in active regions. It is shown that, in solar flares and in weak flare-like transient brightenings, the energy release is triggered by the interaction of impacted bipolar regions. The results suggest that transient microflares may be responsible for a large fraction of the coronal heating in active regions. It is proposed that reconnection may act as a catalyst for the release of stored magnetic energy.

Mandrini, C. H.; Hernandez, A. M.; Rovira, M. G.; Machado, M. E.

26

BECON, Biomass Energy CONversion  

NSDL National Science Digital Library

How is biomass transformed into a usable fuel? This article, part of a series about the future of energy, discusses the BECON (Biomass Energy CONversion) facility, located in the state of Iowa. Here students read about methods used to produce alternative fuels from biomass. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

27

Hydroelectric Solar Energy Conversion  

Microsoft Academic Search

A means of direct conversion of solar energy to hydroelectric energy is discussed. The mechanism is appropriate to low-lying coastal desert regions with high potential evaporation rates. Formulas for output power are obtained. Climate and related data appropriate to suitable locations are included.

RICHARD L. LIBOFF

1978-01-01

28

Hydroelectric solar energy conversion  

Microsoft Academic Search

A means of direct conversion of solar energy to hydroelectric energy is discussed. The mechanism is appropriate to low-lying coastal desert regions with high potential evaporation rates. Formulas for output power are obtained. Climate and related data appropriate to suitable locations are included. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors

R. L. Liboff

1978-01-01

29

Solar energy conversion apparatus  

Microsoft Academic Search

Solar energy conversion apparatus is disclosed including a housing portion, an energy absorbing portion, a fluid directing portion and a cover portion; the housing portion including a molded plastic pan member including a base section with upwardly extending spaced spacer sections, the pan member including outwardly inclined sidewall sections having spaced inner and outer wall sections with a top section

1983-01-01

30

Solar energy conversion apparatus  

Microsoft Academic Search

Solar energy conversion apparatus including a housing portion, an energy absorbing portion, a fluid directing portion and a cover portion; the housing portion including a molded plastic pan member including a base section with upwardly extending spaced spacer sections, insulation covering the exposed surface of the base section to a depth less than the height of the spacer sections; the

1983-01-01

31

Light energy conversion system  

SciTech Connect

A semiconductor photoelectric conversion structure having a PIN junction is assembled as a unitary structure with a redox reaction chamber, with the P (or N) type semiconductor layer of the former being heavily doped and held in contact with an electrolytic solution contained in a second cell with an electrolytic solution contained in a second cell of the redox reaction chamber. By interconnecting a second electrode connected to the N (or P) type semiconductor structure and a first electrode in contact with an electrolytic solution contained in a first cell of the redox reaction chamber, the electrolytic solutions in the first and second cells store chemical energy converted from electrical energy obtained from light energy by means of the semiconductor photoelectric conversion structure. Furthermore, electric power may be obtained across the first electrode and a third electrode connected with the P (or N) type semiconductor layer of the semiconductor photoelectric conversion structure.

Yamazaki, S.

1985-06-25

32

Laser energy conversion  

NASA Technical Reports Server (NTRS)

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.

Jalufka, N. W.

1989-01-01

33

Session: Energy Conversion  

SciTech Connect

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.

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

1992-01-01

34

Ocean Wave Energy Conversion  

Microsoft Academic Search

ABSTRACT Ocean energy conversion has been of interest for many,years. Recent developments,such as concern over global warming,have renewed,interest in the topic. This report focuses on wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column,WEC devices are addressed with regards tocommercial prospects, environmental concerns, and current state-of-the art. This report also provides

Jennifer Vining

2005-01-01

35

Solar energy conversion.  

SciTech Connect

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.

Crabtree, G. W.; Lewis, N. S. (Materials Science Division); (California Inst. of Tech.)

2008-03-01

36

Mechanochemical Energy Conversion  

ERIC Educational Resources Information Center

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)

Pines, E.; And Others

1973-01-01

37

Electromechanical Energy Conversion.  

ERIC Educational Resources Information Center

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)

LePage, Wilbur R.

38

Energy-mass conversion  

NSDL National Science Digital Library

How do physicists make new particles? In this page of a particle physics tutorial, students are introduced to the concept of converting kinetic energy to mass. Students read that low-mass particles placed into an accelerator can be smashed together to produce more massive particles through the conversion of energy to mass. They see an example in which two pieces of fruit are accelerated and smashed, and additional types of fruit are produced. Copyright 2005 Eisenhower National Clearinghouse

Lawrence Berkeley National Laboratory. Particle Data Group

2002-01-01

39

Electromagnetic energy conversion at reconnection fronts.  

PubMed

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

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

2013-09-27

40

Wind energy conversion system  

DOEpatents

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.

Longrigg, Paul (Golden, CO)

1987-01-01

41

Energy conversion system  

DOEpatents

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.

Murphy, Lawrence M. (Lakewood, CO)

1987-01-01

42

Energy conversion system  

DOEpatents

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.

Murphy, L.M.

1985-09-16

43

Spectroscopic Measurement of Energy Conversion in Magnetic Reconnection during Spherical Tokamak Merging Experiment  

NASA Astrophysics Data System (ADS)

The University of Tokyo Spherical Tokamak (UTST) is a spherical tokamak device with unique feature of plasma merging (magnetic reconnection), which is utilized as a high-power plasma heating for non-inductive startup of high-beta plasma. During the plasma merging in the UTST device, intense emission of He II line (468.58nm) and impurity carbon lines were observed only in the vicinity of the X-point. This localized emission indicates the generation of energetic electrons inside the current sheet region, possibly due to the electron acceleration by the strong toroidal electric field induced by magnetic reconnection. This work was supported by JSPS KAKENHI (22246119 and 22686085), MEXT, Japan.

Kamio, Shuji; Takemura, Koichiro; Yamasaki, Kotaro; Cao, Qinghong; Itagaki, Hirotomo; Watanabe, Takenori; Yamada, Takuma; Inomoto, Michiaki; Takase, Yuichi; Yasushi, Ono

2012-10-01

44

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

45

Thermal Energy Conversion Branch  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

46

Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan  

ERIC Educational Resources Information Center

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.

Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

2014-01-01

47

Energy technologies and conversion systems  

SciTech Connect

The authors survey all aspects of energy technology. Specific subjects discussed include thermal conversion of wood, solar energy, tidal energy, and cogeneration systems. A glossary for each chapter, bibliographies, and 8 appendices are provided.

Kleinbach, M.H.; Salvagin, C.E.

1986-01-01

48

Dynamic Modelling, Simulation and Analysis of an Offshore Variable-Speed Directly-Driven Permanent-Magnet Wind Energy Conversion and Storage System (WECSS)  

Microsoft Academic Search

This paper presents the modelling, simulation and analysis of a 2 MW variable-speed directly-driven permanent magnet synchronous generator (PMSG) wind energy conversion and storage system (WECSS). The WECSS model presented consists of a pitch controlled wind turbine directly driving a 2 MW PMSG. The PMSG is connected to a host AC grid network via a controlled full-scale power converter system

Nicholas P. W. Strachan; D. Jovcic

2007-01-01

49

Magnetic field induced alignmentorientation conversion: Nonlinear energy shift and predissociation in Te2 B1u state  

E-print Network

effect of quadratic terms in Zeeman energy shift and magnetic predissociation PD , producing asymmetry crossing signals caused by B2 terms in Zeeman energy shift. © 1996 American Institute of Physics. S0021 Zeeman sublevels M,M with ener- gies EM ,EM , while MM M M 2 3 is the rate of relaxation of coherence

Auzinsh, Marcis

50

Ocean Thermal Energy Conversion (OTEC)  

NASA Technical Reports Server (NTRS)

Energy Research and Development Administration research progress in Ocean Thermal Energy Conversion (OTEC) is outlined. The development program is being focused on cost effective heat exchangers; ammonia is generally used as the heat exchange fluid. Projected costs for energy production by OTEC vary between $1000 to $1700 per kW.

Lavi, A.

1977-01-01

51

Energy conversion and utilization technologies  

SciTech Connect

The DOE Energy Conversion and Utilization Technologies (ECUT) Program continues its efforts to expand the generic knowledge base in emerging technological areas that support energy conservation initiatives by both the DOE end-use sector programs and US private industry. ECUT addresses specific problems associated with the efficiency limits and capabilities to use alternative fuels in energy conversion and end-use. Research is aimed at understanding and improving techniques, processes, and materials that push the thermodynamic efficiency of energy conversion and usage beyond the state of the art. Research programs cover the following areas: combustion, thermal sciences, materials, catalysis and biocatalysis, and tribology. Six sections describe the status of direct contact heat exchange; the ECUT biocatalysis project; a computerized tribology information system; ceramic surface modification; simulation of internal combustion engine processes; and materials-by-design. These six sections have been indexed separately for inclusion on the database. (CK)

Not Available

1988-06-01

52

Energy conversion system  

SciTech Connect

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.

Wang, F.E.

1981-06-30

53

Energy Conversion and Storage Program  

SciTech Connect

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.

Cairns, E.J.

1992-03-01

54

Laser energy conversion  

NASA Technical Reports Server (NTRS)

Laser radiation could possibly provide a feasible approach for the transmission of energy between stations and vehicles in space and on earth. The transmitted energy could be used for the operational requirements of the receiving space station, lunar base, or spacecraft. In addition, laser energy could also be employed to provide power for the propulsion of vehicles in space. The present status of development regarding the various technological areas involved in an implementation of these objectives is examined, taking into account the possibility of further advances needed to satisfy the technical requirements. Attention is given to laser-induced chemistry for converting the radiation energy into chemical energy. Other subjects considered are related to photovoltaics, optical diodes, thermo-electronics, laser rockets, and photon engines.

Billman, K. W.

1975-01-01

55

Energy conversion in the coronal plasma  

NASA Technical Reports Server (NTRS)

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.

Martens, P. C. H.

1986-01-01

56

Solar energy conversion.  

SciTech Connect

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.

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

2007-03-01

57

Review of betavoltaic energy conversion  

NASA Technical Reports Server (NTRS)

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.

Olsen, Larry C.

1993-01-01

58

Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan  

NASA Astrophysics Data System (ADS)

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.

Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

2014-02-01

59

Electromagnetic energy conversion at reconnection fronts  

NASA Astrophysics Data System (ADS)

Using a fortuitous conjunction between the ARTEMIS, THEMIS, Geotail and GOES we show that bursty bulk flows and plasmoids are observed symmetrically about the reconnection site during the course of a substorm. Flow bursts and proto-plasmoids have similar plasma acceleration/heating signatures, as well as positive and negative-excursion fronts of Z-component magnetic field within them. Observed on the two sides of the reconnection site these fronts are herein dubbed reconnection fronts. Multiple reconnection sites can be remotely sensed using energetic particles, enabling us to determine the location and motion of the X-points at the meridian of the aligned constellation: we find the active region moves down tail after onset; when it moves past X=-60Re a new (nearer-Earth) X-point starts and the global tail reconnection rate increases. Power conversion at kinetic structures within the fronts is significant. Using ARTEMIS total pressure estimates, pressure balance at the magnetopause, and a simple, monotonic profile of the flaring angle as function of distance we can obtain the total lobe flux. Integration of local electromagnetic power conversion at the fronts agrees with the global energy conversion measured by ARTEMIS, suggesting that these fronts are the dominant site of lobe magnetic energy conversion in the magnetotail.

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

2013-12-01

60

Electrochemistry for Energy Conversion  

NASA Astrophysics Data System (ADS)

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.

O'Hayre, Ryan

2010-10-01

61

Energy conversion apparatus  

SciTech Connect

Apparatus for converting fluid energy into mechanical energy may include a sail and a mast carried by a pivotally mounted support. The sail is mounted both directly to the mast and indirectly to the mast through a boom, which is pivotally mounted at its center or along its length about the mast, and which is also mounted for tilting movement about a fastening extending perpendicularly to the mast. Positioning means periodically causes the boom to yaw about the mast and to tilt. Opposite edges of the sail thus alternately become taut leading edges with respect to incident wind or water and the sail adopts an oscillating motion which powers mechanical drive means such as pumps. The positioning means may be an over-center spring return or, in an alternative embodiment, be a hydraulic control mechanism. Advantages are that, because the sail remains full, it does not flap during repositioning even when formed of a light flexible material, which reduces inertial problems. Useful mechanical energy can be derived with a low level of technology from a large volume of incident fluid moving at a relatively low speed. The pressure from the pumps can be maintained at a constant value even if the speed of the incident fluid should alter.

Lawson, D. A.

1984-10-09

62

Ocean wave energy conversion concepts  

Microsoft Academic Search

Nine ocean wave energy conversion techniques are described and discussed. These techniques include the use of heaving and pitching bodies, cavity resonators, wave focusing, pressure devices, surging devices, paddles, outriggers and combination devices. Examples of each technique are presented, and required subsystems are described. Finally a comparison study is performed based on efficiency, operational practicality and cost.

M. E. McCormick

1979-01-01

63

Turbulence and energy conversion research  

SciTech Connect

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.

Hutchinson, R.A.

1985-07-01

64

Closed loop energy conversion system  

Microsoft Academic Search

An energy conversion system is disclosed that utilizes a gravity flow of water from a high elevation to sea level utilizing gravity to provide large pressure gradients in pipe lines as large quantities of water move from a high elevation at low pressure to low elevations at high pressure and then move under controlled conditions to low atmosphere pressure to

Botts

1981-01-01

65

Advanced thermionic energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

66

An Overview of the Direct Energy Conversion Power Production Program  

SciTech Connect

The United States Department of Energy, Nuclear Energy Research Initiative (NERI) Direct Energy Conversion (DEC) project has as its goal the development of a direct energy conversion process suitable for commercial development. We define direct energy conversion as any fission process that returns usable energy without an intermediate thermal process. Enough of the project has been completed, roughly two thirds, to indicate that a viable direct energy device is possible. This paper reports on the progress of the DEC project. Three concepts are under development: Fission Electric Cell using magnetic insulation, Magnetic Collimator using magnetic fields to direct fission fragments to collectors, and Gas Vapor Core Reactor using magnetohydrodynamics to generate electrical current. Included in this paper area a short project description, an abbreviated summary of the work completed to date, a description of ongoing and future project activities, and a discussion of the potential for future research and development. (authors)

Rochau, G.; Cash, J.; King, D.; Morrow, C.; Seidel, D.; Slutz, S. [Sandia National Laboratories (United States); Anghaie, S.; Smith, B.M. [University of Florida, Gainesville, FL 32611 (United States); Brown, L. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Tsvetkov, P.; Hart, R.; Parish, T. [Texas A and M University, College Station, Texas 77843 (United States); Williams, R.; Jordan, K. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2002-07-01

67

Pyroelectric energy conversion: optimization principles.  

PubMed

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

Sebald, Gael; Lefeuvre, Elie; Guyomar, Daniel

2008-03-01

68

Biomass conversion processes for energy and fuels  

NASA Astrophysics Data System (ADS)

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.

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

69

Ocean thermal-energy conversion  

NASA Astrophysics Data System (ADS)

The principles underlying ocean thermal-energy conversion (OTEC) are reviewed, and a schematic layout of a system is included. The two systems currently under study, the open system and the closed system, are described. The prospect now, it is noted, is that OTEC plants will not be commercially viable on a widespread basis, even in the tropics. This is especially true of the large-scale plants that have been envisioned. A strong possibility is seen, however, that smaller plants, generating about 40 megawatts of electrical power, can survive commercially. The following conditions would favor their success: placement on land rather than at sea; placement in areas (such as islands) where alternative energy supplies are at a premium; and designing the plant to operate in conjunction with either an aquaculture or a desalination plant.

Ford, G.; Niblett, C.; Walker, L.

1983-03-01

70

The chemistry of energy conversion and storage.  

PubMed

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

Su, Dang Sheng

2014-05-01

71

Clean Fossil Energy Conversion Processes  

NASA Astrophysics Data System (ADS)

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.

Fan, L.-S.

2007-03-01

72

Solar energy, its conversion and utilization  

NASA Technical Reports Server (NTRS)

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.

Farber, E. A.

1972-01-01

73

Thermodynamics fundamentals of energy conversion  

NASA Astrophysics Data System (ADS)

The work reported in the chapters 1-5 focuses on the fundamentals of heat transfer, fluid dynamics, thermodynamics and electrical phenomena related to the conversion of one form of energy to another. Chapter 6 is a re-examination of the fundamental heat transfer problem of how to connect a finite-size heat generating volume to a concentrated sink. Chapter 1 extends to electrical machines the combined thermodynamics and heat transfer optimization approach that has been developed for heat engines. The conversion efficiency at maximum power is 1/2. When, as in specific applications, the operating temperature of windings must not exceed a specified level, the power output is lower and efficiency higher. Chapter 2 addresses the fundamental problem of determining the optimal history (regime of operation) of a battery so that the work output is maximum. Chapters 3 and 4 report the energy conversion aspects of an expanding mixture of hot particles, steam and liquid water. At the elemental level, steam annuli develop around the spherical drops as time increases. At the mixture level, the density decreases while the pressure and velocity increases. Chapter 4 describes numerically, based on the finite element method, the time evolution of the expanding mixture of hot spherical particles, steam and water. The fluid particles are moved in time in a Lagrangian manner to simulate the change of the domain configuration. Chapter 5 describes the process of thermal interaction between the molten material and water. In the second part of the chapter the model accounts for the irreversibility due to the flow of the mixture through the cracks of the mixing vessel. The approach presented in this chapter is based on exergy analysis and represents a departure from the line of inquiry that was followed in chapters 3-4. Chapter 6 shows that the geometry of the heat flow path between a volume and one point can be optimized in two fundamentally different ways. In the "growth" method the structure is optimized starting from the smallest volume element of fixed size. In "design" method the overall volume is fixed, and the designer works "inward" by increasing the internal complexity of the paths for heat flow.

Dan, Nicolae

74

Thermophotovoltaic Energy Conversion Development Program  

NASA Technical Reports Server (NTRS)

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.

Shukla, Kailash; Doyle, Edward; Becker, Frederick

1998-01-01

75

Biological Solar Energy Conversion and U.S. Energy Policy  

ERIC Educational Resources Information Center

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)

Pimentel, David; And Others

1978-01-01

76

Magnetic Materials in sustainable energy  

NASA Astrophysics Data System (ADS)

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.

Gutfleisch, Oliver

2012-02-01

77

Magnetic energy flow in the solar wind.  

NASA Technical Reports Server (NTRS)

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.

Modisette, J. L.

1972-01-01

78

Solar energy conversion by water photodissociation  

Microsoft Academic Search

Some aspects of the photochemical conversion of solar energy by simple nonbiological systems are discussed. The basic concepts of direct and catalyzed photodissociation of water are outlined. Water dissociation in closed-cycle processes based on endothermic photochemical reactions offers a potential solution to the problem of solar energy conversion. It is shown that transition metal commplexes whose excited state chemistry is

V. Balzani; L. Moggi; M. F. Manfrin; F. Bolletta; M. Gleria

1975-01-01

79

Energy Conversion Alternatives Study (ECAS)  

NASA Technical Reports Server (NTRS)

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.

1977-01-01

80

Assessment of ocean thermal energy conversion  

E-print Network

Ocean thermal energy conversion (OTEC) is a promising renewable energy technology to generate electricity and has other applications such as production of freshwater, seawater air-conditioning, marine culture and chilled-soil ...

Muralidharan, Shylesh

2012-01-01

81

Terrestrial solar thermionic energy conversion systems concept  

NASA Technical Reports Server (NTRS)

Results obtained from studies of a (1) solar concentrator, (2) solar energy receiver - thermionic converter system, and (3) solar thermionic topping system are described. Peripheral subsystems, which are required for any solar energy conversion system, are also discussed.

Shimada, K.; Swerdling, M.

1975-01-01

82

The Conversion of Waste to Energy  

E-print Network

Almost every industrial operation produces some combustible waste, but conversion of this to useful energy is often more difficult than with other energy recovery projects and requires careful attention to design, operating and maintaining...

John, T.; Cheek, L.

1980-01-01

83

Thermophotovoltaic Energy Conversion for Space Applications  

Microsoft Academic Search

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

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

2006-01-01

84

Energy conversion & storage program. 1994 annual report  

SciTech Connect

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.

Cairns, E.J.

1995-04-01

85

Energy Conversion in Natural and Artificial Photosynthesis  

PubMed Central

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

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

2010-01-01

86

Direct Mechanical Conversion of Ocean Wave Energy  

Microsoft Academic Search

Recently wave energy conversion has attracted renewed interest from governments and developers looking for alternative carbon free energy resources. Ocean waves have been shown to contain large quantities of power. However, it has proven very difficult to capture even a fraction of this energy in real ocean conditions. This paper reviews the complex energy flows associated with ocean waves and

L. Le-Ngoc; A. I. Gardiner

87

Conversion of radiant light energy in photobioreactors  

Microsoft Academic Search

The conversion of radiant light energy into chemical affinity by microorganisms in photobioreactors is examined. The kinetics of entropy production in the system is theoretically established from entropy and energy balances for the material and photonic phases in the reactor. A negative chemical affinity term compensated for by a radiant energy term at a higher level of energy characterizes photosynthetic

J. F. Cornet; C. G. Dussap; J. B. Gros

1994-01-01

88

Second NASA Conference on Laser Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

Billman, K. W. (editor)

1976-01-01

89

Thermionic energy conversion technology - Present and future  

NASA Technical Reports Server (NTRS)

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.

Shimada, K.; Morris, J. F.

1977-01-01

90

Thermionic Energy Conversion (TEC) topping thermoelectrics  

NASA Technical Reports Server (NTRS)

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.

Morris, J. F.

1981-01-01

91

Chemistry of energy conversion and storage.  

PubMed

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

Su, Dang Sheng

2012-03-12

92

Ocean Wave Energy Conversion - A Survey  

Microsoft Academic Search

Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. This paper gives a systematic and comprehensive overview of wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column WEC devices are addressed with regards to commercial prospects,

A. Muetze; J. G. Vining

2006-01-01

93

Photoelectrochemical cells - Conversion of intense optical energy  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

94

Electromagnetic wave energy conversion research  

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

95

SPS Energy Conversion Power Management Workshop  

NASA Technical Reports Server (NTRS)

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.

1980-01-01

96

High-Temperature Thermoelectric Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

Wood, C.

1987-01-01

97

Iron disulfide for solar energy conversion  

Microsoft Academic Search

Pyrite (Eg = 0.95 eV) is being developed as a solar energy material due to its environmental compatibility and its very high light absorption coefficient. A compilation of material, electronic and interfacial chemical properties is presented, which is considered relevant for quantum energy conversion. In spite of intricate problems existing within material chemistry, high quantum efficiencies for photocurrent generation (Eta

A ENNAOUI; S FIECHTER; C PETTENKOFER; N ALONSOVANTE; K BUKER; M BRONOLD; C HOPFNER; H TRIBUTSCH

1993-01-01

98

Control system applications in wave energy conversion  

Microsoft Academic Search

Significant improvements in the cost-effectiveness of wave energy devices may be possible with successful implementation of active control of device dynamics. The purpose of this paper is to present an overview of a number of recent applications of active control in wave energy conversion. Simpler frequency domain control applications including reactive control and latching are examined first. Next the difficulties

Umesh A. Korde

2000-01-01

99

Shallow solar pond energy conversion system  

Microsoft Academic Search

The concept of a shallow solar pond energy conversion system is presented as an effective way to produce large-scale electric power from solar energy. Water is used both for heat collection and heat storage. Inexpensive layers of weatherable transparent plastic over the water suppress heat loss to the environment. The hot water is stored in an insulated reservoir at night.

W. C. Dickinson; A. F. Clark; J. A. Day; L. F. Wouters

1976-01-01

100

Energy Forms, States and Conversions  

NSDL National Science Digital Library

Students participate in many demonstrations during the first day of this lesson to learn basic concepts related to the forms and states of energy. This knowledge is then applied the second day as students assess various everyday objects to determine what forms of energy are transformed to accomplish the object's intended task. Students use block diagrams to illustrate the form and state of energy flowing into and out of the process.

Office of Educational Partnerships,

101

Magnetic Materials Suitable for Fission Power Conversion in Space Missions  

NASA Technical Reports Server (NTRS)

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.

Bowman, Cheryl L.

2012-01-01

102

Harnessing surface plasmons for solar energy conversion  

NASA Technical Reports Server (NTRS)

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.

Anderson, L. M.

1983-01-01

103

Energy conversion & storage program. 1995 annual report  

SciTech Connect

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.

Cairns, E.J.

1996-06-01

104

A new wind energy conversion system  

NASA Technical Reports Server (NTRS)

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.

Smetana, F. O.

1975-01-01

105

Hydraulic wind energy conversion system  

NASA Astrophysics Data System (ADS)

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.

1981-07-01

106

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

PubMed

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

O?uz, Yksel; Gney, ?rfan; al?k, Hseyin

2013-01-01

107

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

PubMed Central

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

O?uz, Yksel; Gney, ?rfan; al?k, Hseyin

2013-01-01

108

US energy conversion and use characteristics  

SciTech Connect

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)

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

1982-02-01

109

Thermo electronic laser energy conversion  

Microsoft Academic Search

The thermo electronic laser energy converter (TELEC) is described and compared to the Waymouth converter and the conventional thermionic converter. The electrical output characteristics and efficiency of TELEC operation are calculated for a variety of design variables. Calculations and results are briefly outlined. It is shown that the TELEC concept can potentially convert 25 to 50 percent of incident laser

L. K. Hansen; N. S. Rasor

1976-01-01

110

Energy Conversion: Nano Solar Cell  

NASA Astrophysics Data System (ADS)

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 2.4910-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.

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

2009-09-01

111

The power of thermionic energy conversion  

SciTech Connect

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.

Ramalingam, M.L. (UES Inc., Dayton, OH (United States)); Young, T.J. (Air Force Wright Lab., Wright-Patterson AFB, OH (United States). Aerospace Power Div.)

1993-09-01

112

Ocean Thermal Energy Conversion LUIS A. VEGA  

E-print Network

Definition of the Subject Introduction OTEC History Ocean Thermal Resources Technical Limitations State of the Art 10- MW CC-OTEC Pilot Plant Site Selection Criteria for OTEC Plants OTEC Economics depths of 20 m (surface water) and 1,000 m. OTEC Ocean Thermal Energy Conversion, the process

113

Nanoscale Material Approaches to Thermoelectric Energy Conversion  

Microsoft Academic Search

Nanoscale material approaches -- superlattices, nano dots and second phase nano-inclusions -- have become the dominant approach to enhancing the figure of merit (ZT) in thermoelectric materials for various energy conversion applications. The primary mechanism for improvement has been the significant reduction in lattice thermal conductivity through phonon scattering processes in nanoscale materials, which are not fully understood, without affecting

Rama Venkatasubramanian

2009-01-01

114

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

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;

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

115

Status of thermoelectronic laser energy conversion, TELEC  

Microsoft Academic Search

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

E. J. Britt

1982-01-01

116

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

PubMed Central

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

Zhang, Xichao; Ezawa, Motohiko; Zhou, Yan

2015-01-01

117

Mode conversion in a magnetic photonic crystal waveguide  

NASA Astrophysics Data System (ADS)

In this work, we have reported a theoretical study of a magnetic photonic crystal waveguide (also called a magneto photonic crystal waveguide). This structure is formed by a triangular lattice of air holes in a bismuth iron garnet (BIG) film, grown on gallium gadolinium garnet substrates. Nonreciprocal TE-TM mode conversion is caused by the Faraday rotation if the magnetization is aligned along the z-axis, parallel to mode of propagation. The properties of this phenomenon are simulated using the beam propagation method. The conversion output has been simulated, and the Faraday rotation and modal birefringence have been calculated by varying the gyrotropy and the thickness of the BIG film. This magnetic photonic crystal waveguide has the advantage of enhancing Faraday rotation in optical isolators.

Otmani, H.; Bouchemat, M.; Hocini, A.; Boumaza, T.

2014-06-01

118

A survey of technologies used in wave energy conversion systems  

Microsoft Academic Search

Now-a-days, the energy extraction and conversion from the ocean waves has attracted large attention. A number of wave energy conversion systems have been proposed to convert the mechanical energy of the ocean wave into electrical energy. This paper presents a review of the status of wave energy conversion (WEC) technology and discusses the different types of devices used in present

Khalid. H. Mohamed; N. C. Sahoo; Taib B. Ibrahim

2011-01-01

119

Ocean thermal energy conversion: An overview  

NASA Astrophysics Data System (ADS)

Ocean thermal energy conversion, or OTEC is a technology that extracts power from the ocean's natural thermal gradient. This technology is being pursued by researchers from many nations; in the United States, OTEC research is funded by the U.S. Department of Energy's Ocean Energy Technology program. The program's goal is to develop the technology so that industry can make a competent assessment of its potential; either as an alternative or as a supplement to conventional energy sources. Federally funded research in components and systems will help OTEC to the threshold of commercialization. An overview of the OTEC technology is provided.

1989-11-01

120

Novel Nuclear Powered Photocatalytic Energy Conversion  

SciTech Connect

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.

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

2005-08-29

121

Approaches for biological and biomimetic energy conversion  

PubMed Central

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

LaVan, David A.; Cha, Jennifer N.

2006-01-01

122

Solar energy conversion with fluorescent collectors  

Microsoft Academic Search

A new principle for solar energy conversion is proposed and evaluated theoretically. Collection and concentration of direct\\u000a and diffuse radiation is possible by the use of a stack of transparent sheets of material doped with fluorescent dyes. High\\u000a efficiency of light collection can be achieved by light guiding and special design of collectors. The optical path length\\u000a in a triangular

A. Goetzberger; W. Greubel

1977-01-01

123

Renewable Energy Sources and Energy Conversion Devices  

Microsoft Academic Search

\\u000a Renewable energy sources are those sources that are regenerative or can provide energy, for all practical purposes, indefinitely.\\u000a These include solar, wind, geothermal, tidal, wave, hydropower and biomass.

Said Al-Hallaj; Kristofer Kiszynski

124

E2I EPRI Assessment Offshore Wave Energy Conversion Devices  

E-print Network

definition study in CY 2004. This study will produce system designs for wave energy conversion device powerE2I EPRI Assessment Offshore Wave Energy Conversion Devices Report: E2I EPRI WP 004 US Rev 1 #12;E2I EPRI Assessment - Offshore Wave Energy Conversion Devices Table of Contents Introduction

125

Thermal to electricity conversion using thermal magnetic properties  

DOEpatents

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.

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

2010-04-27

126

Ocean thermal energy conversion: Materials issues  

NASA Astrophysics Data System (ADS)

The Ocean thermal Energy Conversion (OTEC) Program, in the Ocean Energy Technology Division of the U.S. Department of Energy, is concerned with the development of options that can be utilized to extract and distribute significant amounts of energy from the ocean. The biofouling control and materials portion of the program is concerned with the development of effective and environmentally acceptable methods to minimize biofouling and corrosion in high thermal conductivity materials suitable for use in heat exchangers and condensers. The mechanical and chemical techniques employed for biofouling control are reviewed and the recent success with chlorination is presented. The corrosion of aluminum alloys, copper alloys, stainless steel, stainless alloys, and titanium in near-surface warm and deep cold water is reviewed with emphasis on aluminum alloys. The major materials issues are reviewed with emphasis on lifetime and cost.

Darby, J. B., Jr.

127

Ocean thermal energy conversion - materials issues  

SciTech Connect

The Ocean Thermal Energy Conversion (OTEC) Program, in the Ocean Energy Technology Division of the U.S. Department of Energy, is concerned with the development of options that can be utilized to extract and distribute significant amounts of energy from the ocean. The biofouling control and materials portion of the program is concerned with the development of effective and environmentally acceptable methods to minimize biofouling and corrosion in high thermal conductivity materials suitable for use in heat exchangers and condensers. The mechanical and chemical techniques employed for biofouling control are reviewed and the recent success with chlorination is presented. The corrosion of aluminum alloys, copper alloys, stainless steel, stainless alloys, and titanium in near-surface warm and deep cold water is reviewed with emphasis on aluminum alloys. The major materials issues are reviewed with emphasis on lifetime and cost.

Darby, J.B. Jr.

1984-01-01

128

Ocean Thermal Energy Conversion-materials issues  

SciTech Connect

The Ocean Thermal Energy Conversion (OTEC) Program, in the Ocean Energy Technology Division of the U.S. Department of Energy, is concerned with the development of options that can be utilized to extract and distribute significant amounts of energy from the ocean. The biofouling control and materials portion of the program is concerned with the development of effective and environmentally acceptable methods to minimize biofouling and corrosion in high thermal conductivity materials suitable for use in heat exchangers and condensers. The mechanical and chemical techniques employed for biofouling control is reviewed and the recent success with chlorination is presented. The corrosion of aluminum alloys, copper alloys, stainless steel, stainless alloys, and titanium in near-surface warm and deep cold water is examined with emphasis on aluminum alloys. The major materials issues are reviewed with emphasis on lifetime and cost.

Darby, J.B.

1984-09-01

129

Ocean energy conversion systems annual research report  

SciTech Connect

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.

Not Available

1981-03-01

130

Wind energy conversion: is it environmentally acceptable  

SciTech Connect

An overview of the current status of the knowledge regarding potential environmental impediments to the commercialization of Wind Energy Conversion System (WECS) is presented. The text also identifies pertinent studies conducted in each area and summarizes the conclusions of the studies. In rough order of importance, the identified environmental impediments to the widespread use of WECS are as follows: electromagnetic interference; land use; aesthetics visual pollution; noise; and biophysical effects. Assessment of the environmental impacts of wind energy conversion system as they reflect to the five generic areas investigated is summarized. The results indicate that of the five generic areas, only the television video signal interference and specific very local impacts related to land use and aesthetics are nonnegligible factors. The severity of the television interference problem has been well studied and verified analytical relationships have been established for determining the extent of the interference zone, which in even the worst case is limited to 4 to 6 km (2 or 3 miles) from a WECS with a rotor diameter of 38 m (125 ft). Fringe reception areas, where the worst interference is encountered, generally have access to cable television, which eliminates the problem. With smaller rotor diameters, the problem should be negligible and additional investigations are currently underway to verify this hypothesis. The potential problems relating to land use and aesthetics are site-specific and depending on the nature of the problem may be relatively hard to resolve. However, it can be concluded in general there appear to be no insurmountable environmental constraints on the general widespread use of wind energy conversion systems.

Cingo, R.P.

1980-11-01

131

Carbon aerogel electrodes for direct energy conversion  

DOEpatents

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.

Mayer, Steven T. (San Leandro, CA); Kaschmitter, James L. (Pleasanton, CA); Pekala, Richard W. (Pleasant Hill, CA)

1997-01-01

132

Carbon aerogel electrodes for direct energy conversion  

DOEpatents

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.

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

1997-02-11

133

Energy conversion device with improved seal  

DOEpatents

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.

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

1980-01-01

134

Energy transfer processes in solar energy conversion  

SciTech Connect

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.

Fayer, M.D.

1986-11-01

135

Recycling of Wasted Energy: Thermal to Electrical Energy Conversion  

NASA Astrophysics Data System (ADS)

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.

Lim, Hyuck

136

OCEAN THERMAL ENERGY CONVERSION PROGRAMMATIC ENVIRONMENTAL ASSESSMENT  

SciTech Connect

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.

Sands, M.Dale

1980-08-01

137

Plasmon-graviton conversion in a magnetic field in TeV-scale gravity  

E-print Network

Kaluza-Klein (KK) gravitons emission rates due to plasmon-graviton conversion in magnetic field are computed within the ADD model of TeV-scale gravity. Plasma is described in the kinetic approach as the system of charged particles and Maxwell field both confined on the brane. Interaction with multidimensional gravity living in the bulk with $n$ compact extra dimensions is introduced within the linearized theory. Plasma collective effects enter through the two-point correlation function of the fluctuations of the energy-momentum tensor. The estimate for magnetic stars is presented leading to the lower limit of the D-dimensional Plank mass.

E. Yu. Melkumova

2011-12-13

138

The viability of thermal energy conversion utilizing black body radiation  

Microsoft Academic Search

Modern thermal energy conversion devices are focused on energy extraction based, upon thermal couple structures. Our work presents a novel mechanism for realizing thermal energy converters based upon black body radiation. Radiative energy conversion is not limited only to heat pump techniques, thus very high efficiencies are theoretically possible (?85%). The presented power density estimates are on the order of

Quentin Diduck; Martin Margala

2003-01-01

139

Proceedings of the 33. intersociety energy conversion engineering conference  

Microsoft Academic Search

These papers were presented at the Intersociety Energy Conversion Engineering Conference, August of 1998. The topics of the papers included aerospace power analyses and simulation, space energy conversion, applications and requirements for space power systems, space solar power, terrestrial energy, aerospace batteries, aerospace power management, aerospace power electronics, aircraft power, dual use technologies, electric propulsion, wireless energy transmission, terrestrial thermoelectric,

Anghaie

1998-01-01

140

Downsized superconducting magnetic energy storage systems  

NASA Astrophysics Data System (ADS)

Scaled-down superconductive magnetic energy storage systems (DSMES) and superconductive magnetic energy power sources (SMEPS) are proposed for residential, commercial/retail, industrial off-peak and critical services, telephone and other communication systems, computer operations, power back-up/energy storages, power sources for space stations, and in-field military logistics/communication systems. Recent advances in high-Tc superconducting materials technology are analyzed. DSMES/SMEPS concepts are presented, and design, materials, and systems requirements are discussed. Problems ar identified, and possible solutions are offered. Comparisons are made with mechanical and primary and secondary energy storage and conversion systems.

Palmer, David N.

141

Energy conversion efficiencies of thermoelectric pallets (Bi2Pb3,Bi2Te3 and Pb2Te3) under the influences of electric and magnetic fields  

NASA Astrophysics Data System (ADS)

This paper aims to introduce the ability of thermo electric pallets to convert waste heat into electricity and also about the effect of electric or magnetic fields, which can exist already or applied in the conditions of their operation. Three thermo electric pallets (Bi2Pb3,Bi2Te3 and Pb2Te3) of cylindrical dimensions are prepared by 15mm mixture of different compositions. Thermo emf generations are carried out in the normal mode and then under the influence of applied electric and magnetic fields of different magnitudes in the temperature range of 460K.

Singh, Jaspal; Verma, S. S.

2013-06-01

142

Engineering Interfaces for Photovoltaic Energy Conversion  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) and the related quantum dot-sensitized solar cells (QDSSCs) show promise as inexpensive, efficient next-generation photovoltaic technologies. A typical cell design consists of a sensitizer chemisorbed to a nanoporous TiO2 substrate; the sensitizer absorbs a photon and an excited electron is injected into the TiO2 where it diffuses to the anode. However, many devices suffer from a high rate of electron-hole recombination at the interface between TiO2 and the hole conductive material, leading to reduced conversion efficiency. In this work we explore whether a passivating layer at the interface can improve efficiency by acting as a barrier against electron recombination. We have studied both organic and inorganic approaches to modifying the interfacial properties in DSSC and QDSSC devices. In studies of CdS-based QDSSCs, a series of organic self-assembled monolayers were formed at the interface, and their effect on CdS uptake and resulting optoelectronic and device properties was investigated. In DSSCs, nanoscale inorganic dielectric films of different thicknesses were applied to the interface using atomic layer deposition prior to dye absorption. The effect on device performance was measured experimentally and compared with predictions from kinetic models. The results of these investigations will be discussed in the context of the ability of interface engineering to improve photovoltaic energy conversion.

Bent, Stacey

2011-03-01

143

Programs in energy conservation: Energy Conversion and Utilization Technologies  

SciTech Connect

The Energy Conversion and Utilization Technologies (ECUT) Program was established as an interdisciplinary applied research and exploratory development program as a result of a 1979 Department of Energy (DOE) Technology Base Assessment. The assessment identified a deficiency in the level of federal support for technology base research needed to sustain long-term efficiency improvements in the conversion and use of energy. The ECUT Program is administered by the Office of Energy Utilization Research, which is in DOE's Office of the Deputy Assistant Secretary for Conservation. ECUT focuses on five interdisciplinary research areas that are generic to energy conservation: combustion, materials, thermal sciences, biocatalysis, and tribology. By challenging conventional wisdom in combination with careful planning, sound decisions, and well-spent dollars, ECUT researchers are pioneering exciting new technologies. In this brochure, we highlight the program's unique approach and some of its major accomplishments.

Not Available

1988-12-01

144

Stretchable energy storage and conversion devices.  

PubMed

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

Yan, Chaoyi; Lee, Pooi See

2014-09-10

145

Lighter than air wind energy conversion system  

SciTech Connect

A lighter-than-air (Lta) wind energy conversion system (Wecs) is described wherein the lta envelope carries a main rotor and electrical generator to take advantage of high wind speeds available at high altitudes. The lta envelope is tethered to a ground based mooring system designed to provide self-orientation for the lta envelope. In a preferred embodiment, heavy mechanical transmissions are eliminated by providing a hollow bladed main rotor which drives an induction turbine positioned within a substantially linear duct which is, in turn, preferably located along the longitudinal axis of the lta envelope. The output of the induction turbine is coupled to an electrical generator whose output is, in turn, transmitted to the ground via the tethering system.

Benoit, W.R.

1982-09-21

146

Thermoelectric energy conversion with solid electrolytes  

NASA Technical Reports Server (NTRS)

The alkali metal thermoelectric converter (AMTEC) is a device for the direct conversion of heat to electrical energy. The sodium ion conductor beta-double prime-alumina is used to form a high-temperature regenerative concentration cell for elemental sodium. An AMTEC of mature design should have an efficiency of 20 to 40 percent, a power density of 0.5 kilowatt per kilogram or more, no moving parts, low maintenance requirements, high durability, and efficiency independent of size. It should be usable with high-temperature combustion, nuclear, or solar heat sources. Experiments have demonstrated the feasibility of the AMTEC and confirmed the theoretical analysis of the device. A wide range of applications from aerospace power to utility power plants appears possible.

Cole, T.

1983-01-01

147

Rotating flux compressor for energy conversion  

SciTech Connect

The rotating flux compressor (RFC) converts rotational kinetic energy into an electrical output pulse which would have higher energy than the electrical energy initially stored in the compressor. An RFC has been designed in which wedge-shaped rotor blades pass through the air gaps between successive turns of a solenoid, the stator. Magnetic flux is generated by pulsing the stator solenoids when the inductance is a maximum, i.e., when the flux fills the stator-solenoid volume. Connecting the solenoid across a load conserves the flux which is compressed within the small volume surrounding the stator periphery when the rotor blades cut into the free space between the stator plates, creating a minimum-inductance condition. The unique features of this design are: (1) no electrical connections (brushes) to the rotor; (2) no conventional windings; and (3) no maintenance. The device has been tested up to 5000 rpm of rotor speed.

Chowdhuri, P.; Linton, T.W.; Phillips, J.A.

1983-01-01

148

Energy Conversion in Photosynthesis: A Paradigm for Solar Fuel Production  

Microsoft Academic Search

Solar energy has the capacity to fulfill global human energy demands in an environmentally and socially responsible manner, provided efficient, low-cost systems can be developed for its capture, conversion, and storage. Toward these ends, a molecular-based understanding of the fundamental principles and mechanistic details of energy conversion in photosynthesis is indispensable. This review addresses aspects of photosynthesis that may prove

Gary F. Moore; Gary W. Brudvig

2011-01-01

149

Direct energy conversion using liquid metals  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

150

Magnetic Energy Release in Relativistic Plasma  

NASA Astrophysics Data System (ADS)

The efficiency of the energy conversion rate in the relativistic magnetic reconnection is investigated by means of Relativistic Resistive Magnetohydrodynamic (R2MHD) simulations. We confirmed that the simple Sweet-Parker type magnetic reconnection is a slow process for the energy conversion as theoretically predicted by Lyubarsky (2005). After the Sweet-Parker regime, we found a growth of the secondary tearing instability in the elongated current sheet. Then the energy conversion rate and the outflow velocity of reconnection jet increase rapidly. Such a rapid energy conversion would explain the time variations observed in many astrophysical flaring events. To construct a more realistic model of relativistic reconnection, we extend our R2MHD code to R3MHD code by including the radiation effects (Relativistic Resistive Radiation Magnetohydrodynamics R3MHD). The radiation field is described by the 0th and 1st moments of the radiation intensity (Farris et al. 2008, Shibata et al. 2011). The code has already passed some one-dimensional and multi-dimensional numerical problems. We demonstrate the first results of magnetic reconnection in the radiation dominated current sheet.

Takahashi, Hiroyuki R.; Ohsuga, Ken

2012-09-01

151

Theoretical efficiency limits for thermoradiative energy conversion  

NASA Astrophysics Data System (ADS)

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/m2 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.

Strandberg, Rune

2015-02-01

152

Axial inlet conversion to a centrifugal compressor with magnetic bearings  

SciTech Connect

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).

Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))

1994-01-01

153

Photonic Crystals for Enhancing Thermophotovoltaic Energy Conversion  

SciTech Connect

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.

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

2003-03-01

154

Status of thermoelectronic laser energy conversion, TELEC  

NASA Technical Reports Server (NTRS)

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.

Britt, E. J.

1982-01-01

155

Ocean thermal energy conversion: Perspective and status  

NASA Astrophysics Data System (ADS)

The use of the thermal gradient between the warm surface waters and the deep cold waters of tropical oceans was first proposed by J. A. d'Arsonval in 1881 and tried unsuccessfully by George Claude in 1930. Interest in Ocean Thermal Energy Conversion (OTEC) and other renewable energy sources revived in the 1970s as a result of oil embargoes. At that time, the emphasis was on large floating plants miles from shore producing 250 to 400 MW for maintained grids. When the problems of such plants became better understood and the price of oil reversed its upward trend, the emphasis shifted to smaller (10 MW) shore based plants on tropical islands. Such plants would be especially attractive if they produce fresh water as a by-product. During the past 15 years, major progress has been made in converting OTEC unknowns into knowns. Mini-OTEC proved the closed cycle concept. Cost effective heat exchanger concepts were identified. An effective biofouling control technique was discovered. Aluminum was determined to be promising for OTEC heat exchangers. Heat transfer augmentation techniques were identified, which promised a reduction on heat exchanger size and cost. Fresh water was produced by an OTEC open cycle flash evaporator, using the heat energy in the seawater itself. The current R and D emphasis is on the design and construction of a test facility to demonstrate the technical feasibility of the open cycle process. The 10 MW shore-based, closed cycle plant can be built with today's technology; with the incorporation of a flash evaporator, it will produce fresh water as well as electrical power; both valuable commodities on many tropical islands. The open cycle process has unknowns that require solution before the technical feasibility can be demonstrated. The economic viability of either cycle depends on reducing the capital costs of OTEC plants and on future trends in the costs of conventional energy sources.

Thomas, Anthony; Hillis, David L.

156

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)

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.

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

1976-01-01

157

Science of Nanofluidics and Energy Conversion  

NASA Astrophysics Data System (ADS)

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

Xu, Baoxing

158

Wind Energy Conversion Using a Self-Excited Induction Generator  

Microsoft Academic Search

A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated

G. Raina; O. P. Malik

1983-01-01

159

Experimental demonstration of thermoacoustic energy conversion in a resonator  

Microsoft Academic Search

Using thermoacoustic energy conversions, both amplification and damping of acoustic intensity are demonstrated. A differentially heated regenerator is installed near the velocity node of the resonator and thereby a high specific acoustic impedance and a traveling wave phase are obtained. It is shown that the gain of acoustic intensity resulting from the traveling wave energy conversion reaches 1.7 in a

Tetsushi Biwa; Yusuke Tashiro; Uichiro Mizutani; Motoki Kozuka; Taichi Yazaki

2004-01-01

160

Material tradeoffs in direct thermal to electric energy conversion systems  

Microsoft Academic Search

Thermoelectric devices allow direct conversion of heat into electricity without any moving parts. However the energy conversion efficiency has been limited due to parasitic Joule heating in the thermoelectric material as well as the heat leakage from the hot to the cold junction mainly through phonons. Using thermionic emission over heterostructures and electron energy filtering, high Seebeck coefficient and high

Ali Shakouri

2011-01-01

161

Proceedings of the 25th intersociety energy conversion engineering conference  

Microsoft Academic Search

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

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

1990-01-01

162

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

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}.

Schleyer, F.; Cairns, Iver H. [School of Physics, University of Sydney, NSW 2006 (Australia); Kim, E.-H. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2013-03-15

163

Performance of Tornado Wind Energy Conversion Systems  

SciTech Connect

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.

Volk, T.

1982-09-01

164

Research on energy conversion system of floating wave energy converter  

NASA Astrophysics Data System (ADS)

A wave power device includes an energy harvesting system and a power take-off system. The power take-off system of a floating wave energy device is the key that converts wave energy into other forms. A set of hydraulic power take-off system, which suits for the floating wave energy devices, includes hydraulic system and power generation system. The hydraulic control system uses a special "self-hydraulic control system" to control hydraulic system to release or save energy under the maximum and the minimum pressures. The maximum pressure is enhanced to 23 MPa, the minimum to 9 MPa. Quite a few experiments show that the recent hydraulic system is evidently improved in efficiency and reliability than our previous one, that is expected to be great significant in the research and development of our prototype about wave energy conversion.

Zhang, Ya-qun; Sheng, Song-wei; You, Ya-ge; Wu, Bi-jun; Liu, Yang

2014-03-01

165

Theoretical investigation of solar energy conversion and water oxidation catalysis  

E-print Network

Solar energy conversion and water oxidation catalysis are two great scientific and engineering challenges that will play pivotal roles in a future sustainable energy economy. In this work, I apply electronic structure ...

Wang, Lee-Ping

2011-01-01

166

Coronal Magnetic Energy Releases  

NASA Astrophysics Data System (ADS)

This book brings together a variety of review articles on dynamical phenomena in the solar corona in order to work out the unifying aspects of magnetic energy releases. The experimental data from groundbased methods of radio astronomy as well as from satellites are also discussed. The book addresses researchers in astrophysics, and planetary science but should also be accessible to graduate students.

Benz, Arnold O.; Krger, Albrecht

167

Modeling and Control of AWS-Based Wave Energy Conversion System Integrated Into Power Grid  

Microsoft Academic Search

In this paper, the model of Archimedes wave swing (AWS) based wave energy conversion (WEC) system is proposed where a new coordinate transformation for the linear permanent magnet generator between the abc frame of reference and the dq0 frame of reference is proposed and the model of the LPMG in dq0 reference frame suitable for power system dynamic and stability

Feng Wu; Xiao-Ping Zhang; Ping Ju; Michael J. H. Sterling

2008-01-01

168

Conversion of laser energy to gas kinetic energy  

NASA Technical Reports Server (NTRS)

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.

Caledonia, G. E.

1977-01-01

169

Contribution of ocean thermal energy conversion to world energy needs  

NASA Astrophysics Data System (ADS)

Ocean Thermal Energy Conversion (OTEC) can provide energy to all countries. It can deliver the energy (1) to regions bordered by warm ocean waters via direct electric-power transmission or (2) to other areas not bordered by warm ocean waters, via an energy-intensive material produced on OTEC plantships cruising on the high seas in the tropics. Ammonia is an outstanding choice for an energy-intensive material because it can (a) replace ammonia now made from natural gas to conserve fuel, (b) serve as a synthetic fuel, or (c) provide an easily transported, storable source of hydrogen for fuel cells to generate electric power where needed anywhere in the world. Costs of OTEC ammonia and of electricity delivered directly or via fuel cells are projected to be competitive with costs of electricity from coal or nuclear plants by 1990, if rapid OTEC development is pursued.

Avery, W. H.; Dugger, G. L.

1980-07-01

170

Plasmon-assisted radiolytic energy conversion in aqueous solutions  

PubMed Central

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

Kim, Baek Hyun; Kwon, Jae W.

2014-01-01

171

Open cycle ocean thermal energy conversion system  

DOEpatents

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.

Wittig, J. Michael (West Goshen, PA)

1980-01-01

172

Simulation of the O-X-B conversion process in dense magnetized plasmas  

NASA Astrophysics Data System (ADS)

Electron Bernstein waves (EBWs) are special electrostatic cyclotron waves which propagate with a short wavelength in hot plasma. EBWs are useful for core plasma heating, current drive and temperature diagnostics in high density plasma devices like stellarators and tokamaks. The resonance of EBWs is close to the cyclotron harmonics, and they do not have a density cut-off. The ordinary-extraordinary-Bernstein(O-X-B) conversion is one of the processes for generating EBWs. The generated EBW propagates in the region with density higher than ordinary wave cut-off and is strongly absorbed at the electron cyclotron harmonics. As such, EBWs may provide local electron heating and current drive. This double conversion process has been simulated using the XOOPIC code. XOOPIC is a 2D PIC code with 3D electrostatic and electromagnetic field solvers for slab and cylindrical geometries. The O-X-B simulation has been done in a slab plasma, using the electromagnetic field solver and a surface impedance wave source to generate the O-wave. The maximum energy transformation in O-X conversion will be ensured with the optimized refractive index, parallel to toroidal magnetic field. Moreover, the dependence of the conversion efficiency on the density gradient scale length will be considered.

Asgarian, Mohammad Ali; Verboncoeur, John; Parvazian, Akbar

2012-10-01

173

NASA-OAST program in photovoltaic energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

174

Potassium plasma cell facilitates thermionic energy conversion process  

NASA Technical Reports Server (NTRS)

Thermionic energy converter converts nuclear generated heat directly into high frequency and direct current output. It consists of a potassium plasma cell, a tantalum emitter, and a silver plated copper collector. This conversion process eliminates the steam interface usually required between the atomic heat source and the electrical conversion system.

Richards, H. K.

1967-01-01

175

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

DOEpatents

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.

Dziendziel, Randolph J. (Middle Grove, NY); Baldasaro, Paul F. (Clifton Park, NY); DePoy, David M. (Clifton Park, NY)

2010-09-07

176

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

DOEpatents

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.

Dziendziel, Randolph J. (Middle Grove, NY); DePoy, David Moore (Clifton Park, NY); Baldasaro, Paul Francis (Clifton Park, NY)

2007-01-23

177

Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion  

SciTech Connect

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.

Dasgupta, Neil; Yang, Peidong

2013-01-23

178

Radiative energy receiver for high performance energy conversion cycles  

NASA Technical Reports Server (NTRS)

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.

Rault, D.; Hertzberg, A.

1982-01-01

179

Maximum Power Point Tracking for Ocean Wave Energy Conversion  

Microsoft Academic Search

Many forms of renewable energy exist in the world's oceans, with ocean wave energy showing great potential. However, the ocean environment presents many challenges for cost-effective renewable energy conversion, including optimal control of a wave energy converter (WEC). This paper presents a maximum power point tracking (MPPT) algorithm for control of a point absorber WEC. The algorithm and testing hardware

Ean A. Amon; Ted K. A. Brekken; Alphonse A. Schacher

2012-01-01

180

Economic Factors and Incentives for Ocean Wave Energy Conversion  

Microsoft Academic Search

Ocean energy conversion systems have recently seen renewed interest, stimulated mostly by today's increasing energy discussions. In addition to ocean current energy converters, several commercial ocean wave energy projects have already been undertaken; however, no clear economic model exists for developers to follow. Therefore, this paper focuses on U.S. economic factors that affect the use of wave power for generation

Jennifer G. Vining; Annette Muetze

2009-01-01

181

A review of ocean wave energy conversion systems  

Microsoft Academic Search

The start of the new millennium has been co-incident with an energy crisis. With the price of energy increasing and concerns about environmental damages as a result of using fossil fuels, there is a growing attention toward utilization of renewable energy sources. In particular, ocean energy conversion has been of interest for many years. In this paper, different types of

R. Sabzehgar; M. Moallem

2009-01-01

182

Soft materials for linear electromechanical energy conversion  

E-print Network

We briefly review the literature of linear electromechanical effects of soft materials, especially in synthetic and biological polymers and liquid crystals (LCs). First we describe results on direct and converse piezoelectricity, and then we discuss a linear coupling between bending and electric polarization, which maybe called bending piezoelectricity, or flexoelectricity.

Antal Jakli; Nandor Eber

2014-07-29

183

Superconducting energy storage magnet  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

184

An Overview of the Progress in Photoelectrochemical Energy Conversion.  

ERIC Educational Resources Information Center

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)

Parkinson, Bruce

1983-01-01

185

Semiconductor Nanowires and Nanotubes for Energy Conversion  

NASA Astrophysics Data System (ADS)

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

Fardy, Melissa Anne

186

A summary of USSR thermionic energy conversion activity  

NASA Technical Reports Server (NTRS)

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.

Rasor, N. S.

1978-01-01

187

Energy conversion device with support member having pore channels  

DOEpatents

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.

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

2014-01-07

188

Space electric power design study. [laser energy conversion  

NASA Technical Reports Server (NTRS)

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.

Martini, W. R.

1976-01-01

189

Conversion of laser energy to gas kinetic energy  

NASA Technical Reports Server (NTRS)

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.

Caledonia, G. E.

1975-01-01

190

Nanowires for thermal energy conversion and management  

NASA Astrophysics Data System (ADS)

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.)

Chen, Renkun

191

Ris Energy Report 2 Bioenergy conversion  

E-print Network

energy from biomass but, ultimately, the energy originates from combustion. Be it either the direct or electric energy. The burning of wood and other solid biomass is the old- est energy technology used by man identify two basic preconditions for energy pro- duction from biomass: Firstly, biomass, mostly in solid

192

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

PubMed

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

McKendry, Peter

2002-05-01

193

Energy Conversion and Storage Program: 1992 Annual report  

SciTech Connect

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.

Cairns, E.J.

1993-06-01

194

Superconducting magnetic energy storage  

SciTech Connect

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.

Hassenzahl, W.

1988-08-01

195

Sustainable systems for the storage and conversion of energy are dependent on interconnected  

E-print Network

SEMTE abstract Sustainable systems for the storage and conversion of energy are dependent energy systems for harvesting low availability thermal energy and for providing integrated power, cooling performance buildings, renewable energy conversion, and energy storage can be streamlined by identifying

Reisslein, Martin

196

Conversion from film to magnetic cassette recording for current meter  

Microsoft Academic Search

This report describes a conversion of the Geodyne 102 current meter, which recorded its data on film, to digital cassette tape recording. Sufficient information is included to enable the reader to implement this modification.

A. I. Nakamura; R. R. Harvey

1978-01-01

197

High power density thermophotovoltaic energy conversion  

NASA Astrophysics Data System (ADS)

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.

Noreen, Darryl L.; Du, Honghua

1995-01-01

198

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

NASA Astrophysics Data System (ADS)

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.

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

1980-04-01

199

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

200

Preliminary results on the conversion of laser energy into electricity  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

201

A high temperature solar energy conversion device using optical waveguides  

Microsoft Academic Search

The properties of optical waveguides are used in the construction of a high temperature solar energy conversion device, in which loss of energy due to re-radiation into the atmosphere is minimized. A collector of the device is a bunch of optical waveguides transmitting electromagnetic waves with frequencies only above a certain cut-off frequency. The device also consists of a cavity

A. P. Patel

1984-01-01

202

Water wave energy conversion device using flexible membranes  

Microsoft Academic Search

A device for conversion of sea wave energy comprises partially inflated bag-like enclosures formed from flexible impermeable material. The enclosures are connected via non return valves to a high pressure conduit and a low pressure return conduit so as to act as an air pump or bellows as the sea rises and falls around the enclosures. A turbine extracts energy

1979-01-01

203

Engineering nanoscale phonon and photon transport for direct energy conversion  

Microsoft Academic Search

Nanostructures have a profound impact on the transport of heat and energy by electrons, phonons, and photons. In this paper, we will discuss some of the nanoscale heat transfer effects on phonon and photon transport and their implications for thermoelectric and thermophotovoltaic energy conversion technologies. For example, low thermal conductivity materials with good electrical properties are required in solid-state refrigerators

G. Chen; A. Narayanaswamy; C. Dames

2004-01-01

204

Nanostructured materials for advanced energy conversion and storage devices  

Microsoft Academic Search

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments

Antonino Salvatore Aric; Peter Bruce; Bruno Scrosati; Jean-Marie Tarascon; Walter van Schalkwijk

2005-01-01

205

Current developments in small wind energy conversion systems  

Microsoft Academic Search

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

A. C. Hansen; C. P. Butterfield

1980-01-01

206

The plasmadynamics and ionization kinetics of thermionic energy conversion  

Microsoft Academic Search

Radiation by a Cesium recombination laser operating in a different thermionic converter as an energy efficient process is discussed. To reduce the plasma arc drop, thermionic energy conversion was studied. It is predicted that it is possible to generate the required laser light from a thermionic-type Cesium plasma. A numerical method is developed to solve the thermionic plasma dynamics. The

J. L. Lawless Jr.; J. L. Jr

1981-01-01

207

Thermionic Energy Conversion with Nanoscale Materials and Devices  

Microsoft Academic Search

Prior studies on electron emission show possibly beneficial effects of nanoscale phenomena on energy-conversion characteristics. For example, recent work has shown that the electric field around a nanoscale field emission device can increase the average energy of emitted electrons. This geometric effect could be useful in cooling devices based on the Nottingham effect. We consider here the hypothesis that nanoscale

Yang Liu; Timothy S. Fisher

2006-01-01

208

Three-dimensional electron magnetohydrodynamic reconnection. III. Energy conversion and electron heating  

NASA Astrophysics Data System (ADS)

Further observations are presented of a magnetic reconnection experiment with three-dimensional fields in the parameter regime of electron magnetohydrodynamics. The initial magnetic configuration is imposed via a Helmholtz coil, whose field is added to or subtracted from a uniform background magnetic field. Energy is transferred from the coil's external power supply into thermal energy of electrons and kinetic energy of ions via the decay of the imposed magnetic field configuration. For the case when the Helmholtz coil field opposes the background field, thus creating a field-reversed configuration, the magnetic energy convects in the whistler mode and dissipates over large distances resulting in negligible heating. For the case when the Helmholtz coil field is added to the background field, magnetic field annihilation leads to strong localized electron heating and acceleration of unmagnetized ions via space-charge electric fields. The energy conversion to electron heat is observed in regions away from magnetic nulls and a new mechanism for breaking the frozen-in condition is proposed.

Urrutia, J. M.; Stenzel, R. L.; Griskey, M. C.; Strohmaier, K. D.

2003-07-01

209

Energy balance of wheat conversion to ethanol  

SciTech Connect

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.

Stumborg, M.A.; Zentner, R.P.; Coxworth, E. [SPARC, Saskatoon (Canada)

1996-12-31

210

Pin stack array for thermoacoustic energy conversion  

DOEpatents

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.

Keolian, Robert M. (Monterey, CA); Swift, Gregory W. (Santa Fe, NM)

1995-01-01

211

Status of wind-energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

212

ECE 331 Electromechanical Energy Conversion Catalog Description: Energy conversion principles for electric motors. Steady-state  

E-print Network

(primary), Julia Zhang (secondary) Course Content: Magnetic circuits, magnetic materials, permanent magnets, non-linear magnetic circuits, single-and-three-phase transformers. Balanced wye and delta-connected three-phase circuits with measurements of active and re-active power. Principles of electromechanical

213

Energy Conversion, Mixing Energy, and Neutral Surfaces with a Nonlinear Equation of State  

E-print Network

Energy Conversion, Mixing Energy, and Neutral Surfaces with a Nonlinear Equation of State JONAS energy, it is generally assumed that it does not produce a restoring buoyancy force. However, it is here effect) such a neutral displacement is accompanied by a conversion between internal energy E

Nycander, Jonas

214

Theoretical efficiency limits for energy conversion devices  

Microsoft Academic Search

Using energy more efficiently is a key strategy for reducing global carbon dioxide emissions. Due to limitations on time and resources, actions must be focused on the efficiency measures which will deliver the largest gains. Current surveys of energy efficiency measures assess only known technology options developed in response to current economic and technical drivers. However, this ignores opportunities to

Jonathan M. Cullen; Julian M. Allwood

2010-01-01

215

Energy Conversion and Storage Program. 1990 annual report  

SciTech Connect

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.

Cairns, E.J.

1992-03-01

216

IECEC '91; Proceedings of the 26th Intersociety Energy Conversion Engineering Conference, Boston, MA, Aug. 4-9, 1991. Vol 6  

NASA Astrophysics Data System (ADS)

Papers are presented on aerospace power systems (burst and pulse power, simulation, solar dynamics, and space nuclear systems, etc.), conversion technologies, electrochemical conversion, and energy conservation. Consideration is also given to energy systems and alternative fuels, renewable resource systems, Stirling engines and applications, and innovative and advanced systems (e.g., superconducting power and magnetic devices at high temperature).

217

Thermionic energy conversion (TEC) topping thermoelectrics  

SciTech Connect

Long-respected international experts on thermoelectrics (Dixon, Ertl and Goldsmid supported by Ure) determine the probable maximum figure of merit (ZT) for fully matured thermoelectric generators as about unity from ordiary temperatures to 2000 K. Thus the maximum efficiency for fully matured thermoelectrics would be approximately 0.414 (l - r/sub T/)/(1.414 + r/sub T/) where r/sub T/ is the ratio of cold and hot junction temperatures. This limitation contrasts with the recent burst of enthusiasm for high-temperature thermoelectrics - based on calculated figures of merit and efficiencies that increase more and more rapidly with rising temperatures. Unfortunately these calculations neglect internal radiation effects which 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. Therefore the quotation from Thermoelectricy: Science and Engineering by Heikes and Ure apparently still prevails: ...thermoelectric devices appear difficult to extend in the direction of high temperature, while thermionic devices become inefficient at low temperature. Accordingly consideration of thermoelectric power generation with high-temperature heat sources should include utilization of 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.

Morris, J.F.

1981-01-01

218

Improving wind power quality using an integrated Wind Energy Conversion and Storage System (WECSS)  

Microsoft Academic Search

This paper details the modeling, controller development, simulation and analysis of an integrated 2MW variable-speed Wind Energy Conversion and Storage System (WECSS) in dynamic simulation software PSCAD. The WECSS presented consists of a pitch controlled wind turbine directly driving a 2MW permanent magnet synchronous generator (PMSG). The PMSG is connected to its host power system via a controlled full-scale power

Nicholas P. W. Strachan; Dragan Jovcic

2008-01-01

219

Primary Photosynthetic Energy Conversion in Bacterial Reaction Centers  

NASA Astrophysics Data System (ADS)

The development of human societies is strongly influenced by the available energetic resources. In a period where the limitations of conventional fossil energy carriers become as evident as the often uncontrollable dangers of nuclear energy, one has to reconsider regenerative energy resources. Here photovoltaic or photochemical use of solar energy is an important approach. Since the early days of evolution some two billion years ago, the dominant energetic input into the life system on earth occurs via the conversion of solar energy performed in photosynthetic organisms. The fossil energy carriers that we use and waste today have been produced by photosynthesis over millions of years. In the race for an extended and versatile use of solar energy, semiconductorbased photovoltaic devices have been developed. However, even after decades of intense engineering they cannot serve as a competitive alternative to fossil energy. Under these circumstances new alternatives are required. One line of scientific development may use the operational principles of photosynthesis since photosynthesis is still our main energy source. In this respect, we will present results on the basic concepts of energy conversion in photosynthetic bacteria, which could be used as a guideline to alternative light energy conversion systems.

Zinth, Wolfgang; Wachtveitl, J.

220

Layout design optimization for magneto-electro-elastic laminate composites for maximized energy conversion under mechanical loading  

NASA Astrophysics Data System (ADS)

Magneto-electro-elastic (MEE) laminate composites with piezoelectric and piezomagnetic phases can be utilized as materials providing energy conversion among magnetic, electric and mechanical energies. This work is concerned with the development of a systematic design method of MEE composites with maximized conversion of mechanical energy to electric and/or magnetic energy. To predict the energy conversion phenomena, a fully coupled MEE theory is employed. A composite plate is assumed to be simply supported and is discretized into a number of laminates for analysis using a semi-analytic finite element method. Since the optimal stacking sequences for piezoelectric/piezomagnetic phases and the optimal thickness for each phase must be simultaneously determined, we propose formulating the design problem as a topology optimization problem. To implement the topology optimization, two interpolation models, the standard SIMP (solid isotropic material with penalization) model and the micromechanics model, are investigated. After solving benchmark test problems, design examples dealing with multifunctional composites are considered.

Sun, Kyung Ho; Kim, Yoon Young

2010-05-01

221

Status of wind-energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

222

Vibration-to-electric energy conversion  

Microsoft Academic Search

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) tech- nology. A low-power controller IC has been fabricated in a 0 6m CMOS pro- cess and has been tested and

Scott Meninger; Jose Oscar Mur-Miranda; Rajeevan Amirtharajah; Anantha Chandrakasan; Jeffrey Lang

1999-01-01

223

Vibration-to-electric energy conversion  

Microsoft Academic Search

Abstract: A system is proposed to convert ambient mechanicalvibration into electrical energy for use in powering autonomouslow power electronic systems. The energy is transduced throughthe use of a variable capacitor. Using microelectromechanical systems(MEMS) technology, such a device has been designed for thesystem. A low-power controller IC has been fabricated in a 0.6- mCMOS process and has been tested and measured

Scott Meninger; Jose Oscar Mur-miranda; Rajeevan Amirtharajah; Anantha P. Chandrakasan; Jeffrey H. Lang

2001-01-01

224

Emerging electrochemical energy conversion and storage technologies  

PubMed Central

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

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

2014-01-01

225

Emerging electrochemical energy conversion and storage technologies  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

226

Supramolecular Structures for Photochemical Energy Conversion  

SciTech Connect

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.

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

2003-08-26

227

Effects of semiconduction on electromechanical energy conversion in piezoelectrics  

NASA Astrophysics Data System (ADS)

We study the effect of semiconduction on mechanical-to-electrical energy conversion through a theoretical analysis on the thickness-extensional vibration of a piezoelectric semiconductor plate driven mechanically. An analytical solution is obtained. A ZnO plate is used as a numerical example. Results show that both the electrical output power and the energy conversion efficiency are sensitive to semiconduction at a moderate carrier density of 1015 m?3, and that the effect of the dissipation due to semiconduction can be comparable to the effect of material damping when the material quality factor is in the usual range of 102103.

Li, Peng; Jin, Feng; Yang, Jiashi

2015-02-01

228

Photoassisted electrolysis of water - Conversion of optical to chemical energy  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

229

The plasmatron: Advanced mode thermionic energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

230

3. Energy conversion, balances, efficiency, equilibrium  

E-print Network

or kinetic energy effects): U = Q + W, and since no work is done: U = Q This implies that all heat is used of thermodynamics." Picture:B05 A B (The 2nd Law: Maxwell's Demon (M1888) /1) bo Akademi University | Thermal "Thermodynamics. An Engineering Approach", McGraw-Hill (1998) GC05: L. Gonick, C. Criddle "The cartoon guide

Zevenhoven, Ron

231

Energy Conversion Technologies 1.0 Introduction  

E-print Network

efficiencies (in the Rankine cycle, the amount of energy available for extraction by the working fluid (water #12;2 for supercritical [1]. (Critical temperature and pressure for water are 705 ºF (374 ºC) and 3210, water can exist only in the gaseous phase [2].) The pulverized coal is burned in a steam generator

McCalley, James D.

232

Compact harsh environment energy conversion systems  

E-print Network

The quest for energy is leading the industry into drilling deeper wells. Typically, a temperature gradient of 1C/150 ft can be expected, with bottom hole temperatures reaching beyond 200C in many areas of the world. Moreover, the increased...

Ahmed, Shehab

2009-05-15

233

Proceedings of the 25th intersociety energy conversion engineering conference  

SciTech Connect

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.

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

1990-01-01

234

Energy and materials conversion with the help of regeneration and energy transformation  

Microsoft Academic Search

The comprehension of the unity of materials and energy conversion is the basis for energetic effective design of materials conversion processes. Besides regenerative heat utilisation energy transformation can open up further possibilities of energy saving. The principal procedure for the design of energetic effective regenerative heat transfer systems and the effects which are within reach with regeneration are shown through

Dietrich Hebecker; Petra Bittrich

2001-01-01

235

Energy conversion in Purple Bacteria Photosynthesis  

E-print Network

The study of how photosynthetic organisms convert light offers insight not only into nature's evolutionary process, but may also give clues as to how best to design and manipulate artificial photosynthetic systems -- and also how far we can drive natural photosynthetic systems beyond normal operating conditions, so that they can harvest energy for us under otherwise extreme conditions. In addition to its interest from a basic scientific perspective, therefore, the goal to develop a deep quantitative understanding of photosynthesis offers the potential payoff of enhancing our current arsenal of alternative energy sources for the future. In the following Chapter, we consider the trade-off between dynamics, structure and function of light harvesting membranes in Rps. Photometricum purple bacteria, as a model to highlight the priorities that arise when photosynthetic organisms adapt to deal with the ever-changing natural environment conditions.

Felipe Caycedo-Soler; Ferney J. Rodriguez; Luis Quiroga; Guannan Zhao; Neil F. Johnson

2011-07-01

236

Energy conversion in Purple Bacteria Photosynthesis  

E-print Network

The study of how photosynthetic organisms convert light offers insight not only into nature's evolutionary process, but may also give clues as to how best to design and manipulate artificial photosynthetic systems -- and also how far we can drive natural photosynthetic systems beyond normal operating conditions, so that they can harvest energy for us under otherwise extreme conditions. In addition to its interest from a basic scientific perspective, therefore, the goal to develop a deep quantitative understanding of photosynthesis offers the potential payoff of enhancing our current arsenal of alternative energy sources for the future. In the following Chapter, we consider the trade-off between dynamics, structure and function of light harvesting membranes in Rps. Photometricum purple bacteria, as a model to highlight the priorities that arise when photosynthetic organisms adapt to deal with the ever-changing natural environment conditions.

Caycedo-Soler, Felipe; Quiroga, Luis; Zhao, Guannan; Johnson, Neil F

2011-01-01

237

Wave energy conversion in a random sea  

Microsoft Academic Search

The wind wave power delivered to several hypothetical wave energy converters is predicted using the Pierson-Moskowitz wave spectrum. Two general types of converters are considered: First, the half-plane type which is dependent on wave direction, but not normally dependent on wave frequency. The second type is the omni-directional which is independent of wave direction but normally frequency dependent. Results of

M. E. McCormick

1978-01-01

238

Design requirements for interfaces in solar energy conversion technologies  

Microsoft Academic Search

Candidate materials for improving the durability and economics of solar energy conversion systems (SECS) are reviewed. A 30-yr lifetime is regarded as necessary for solar collector and concentrator materials in order to offset the high initial costs of SECS in parabolic dish, heliostat, parabolic trough, flat plate collector, OTEC, solar cell, and wind turbine configurations. The materials are required to

B. L. Butler

1982-01-01

239

Probabilistic performance assessment of wind energy conversion systems  

Microsoft Academic Search

This paper describes the development of a general probabilistic model of an autonomous wind energy conversion system (WECS) composed of several wind turbines (wind farm) connected to a load and a battery storage. The proposed technique allows the simulation of wind farms containing identical or different wind turbines types and considers a bidirectional flow of power in and out of

S. H. Karaki; R. B. Chedid; R. Ramadan

1999-01-01

240

Intelligent control of a class of wind energy conversion systems  

Microsoft Academic Search

This paper discusses the control problem for a class of wind energy conversion systems (WECS). It first develops a detailed model and then compares four control algorithms based on conventional and intelligent control theories. A simple PI conventional controller for the exciter loop is carried out by using a first order model. When the system operating points change, the PI

R. Chedid; F. Mrad; M. Basma

1999-01-01

241

Limiting efficiencies for photovoltaic energy conversion in multigap systems  

Microsoft Academic Search

Multigap systems are better matched to the sun's spectrum than single gap systems and are, therefore, more efficient as photovoltaic converters. This paper reviews the different thermodynamic approaches used in the past for computing the limiting efficiency for the conversion of solar energy into work. Within this thermodynamic context, the limit ranges from 85.4% to 95.0% depending on the assumptions

Antonio Mart; Gerardo L. Arajo

1996-01-01

242

Wireless Sensor Network Energy Conversation Nathan A. Menhorn  

E-print Network

Wireless Sensor Network Energy Conversation Techniques Nathan A. Menhorn October 20, 2005 #12;Contents 1 Introduction to Wireless Sensor Networks 3 1.1 General Overview A Wireless Sensor Network Glossary 68 2 #12;Chapter 1 Introduction to Wireless Sensor Networks 1.1 General

243

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

ERIC Educational Resources Information Center

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.

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

244

Control strategy for AWS based wave energy conversion system  

Microsoft Academic Search

The controller for Archimedes wave swing (AWS) based wave energy conversion (WEC) system is designed in this paper. Based on the model of the AWS based WEC system in the d-q frame of reference, the control strategy of the WEC system under the irregular wave is derived. The AWS based WEC is regulated to be in resonance with the wave

F. Wu; X. P. Zhang; P. Ju

2010-01-01

245

Performance optimization of a pneumatic wave energy conversion device  

Microsoft Academic Search

The purpose of this study was, for the first time, to optimize the performance of a pneumatic wave energy conversion device. The experiments of Jolly and Newmaster (1979) and Trop and Casey (1980) left a capture chamber and turbine for further investigation. To optimize the system performance the turbine had to be first analyzed so that its power performance curves

S. W. Surko

1982-01-01

246

Analysis of three solar energy conversion systems. Final report  

Microsoft Academic Search

Research was conducted in a dynamic real-life environment involving people living in an urban homestead, called TERAD House, which had been retrofitted to provide people with an on-going demonstration of residential energy conservation measures. The goal of the research was to evaluate the thermal performance of three solar conversion systems designed for and installed on TERAD House; (1) domestic solar

P. W. DeVore; E. D. Summers

1982-01-01

247

Polycrystalline iron sulphide based semiconductors for solar energy conversion  

Microsoft Academic Search

Potentialities of iron sulphide semiconductors for solar energy conversion have been outlined. Iron sulphide semiconductors have been characterized with respect to their bulk (XRD, EDAX), surface (XPS) and electronic (UV-Vis reflectance spectroscopy) structure. Materials have been formed into electrodes by screenprinting and have been thermally activated under different conditions.

P. L. Antonucci; A. S. Aric; N. Giordano; V. Antonucci

1995-01-01

248

A study of water electrolysis with photovoltaic solar energy conversion  

Microsoft Academic Search

The performance of the hydrogen production system consisting of the photovoltaic array and the water electrolysis unit is studied. The results of the calculation are compared with available experimental data and the performance of a hydrogen production plant by means of photovoltaic solar energy conversion is determined for two typical locations. A method for the estimation of the power matching

C. Carpetis

1982-01-01

249

Quantitative evaluation of Ocean Thermal Energy Conversion (OTEC): Executive briefing  

NASA Astrophysics Data System (ADS)

The results of an independent quantitative evaluation of Ocean Thermal Energy Conversion (OTEC) for central station applications are summarized. A central station power plant located in the Gulf of Mexico and delivering power to the mainland United States was emphasized. The evaluation of OTEC is based on three important issues: resource availability, technical feasibility, and cost.

Gritton, E. C.; Pei, R. Y.; Hess, R. W.

1980-08-01

250

Guidelines in Wave Energy Conversion System Design  

E-print Network

mentions that the Pelamis is able to work in sea states with a power of at least 15 kilowatts per meter. Wave Dragon Wave Dragon is an overtopping device, which was developed in Denmark and Wales, and it was also reviewed by the EPRI in 2004... be done at the device site location. The Wave Dragon uses large wings (reflectors) to drive water into the reservoir. When water flows through the reservoir, it turns low head turbines to generate energy. The device takes advantage of its height...

Guiberteau, K. L.; Liu, Y.; Lee, J.; Kozman, T.

2014-01-01

251

Thermodynamic limits to the conversion of blackbody radiation by quantum systems. [with application to solar energy conversion devices  

NASA Technical Reports Server (NTRS)

Using general thermodynamic arguments, we analyze the conversion of the energy contained in the radiation from a blackbody to useful work by a quantum system. We show that the energy available for conversion is bounded above by the change in free energy in the incident and reradiated fields and that this free energy change depends upon the temperature of the receiving device. Universal efficiency curves giving the ultimate thermodynamic conversion efficiency of the quantum system are presented in terms of the blackbody temperature and the temperature and threshold energy of the quantum system. Application of these results is made to a variety of systems including biological photosynthetic, photovoltaic, and photoelectrochemical systems.

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

1982-01-01

252

Advanced materials for high-temperature thermoelectric energy conversion  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

253

Future of photovoltaic energy conversion in developing countries  

SciTech Connect

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.

Hogan, S.

1980-04-01

254

Control policies for wind-energy conversion systems  

Microsoft Academic Search

Wind energy is usually converted into electrical energy through a wind rotor driving a generator. It is well known that maximum conversion efficiency occurs when the wind rotor is loaded in such a way that its rotational speed is allowed to fluctuate in sympathy with wind-speed variations. In the paper, the wind-rotor\\/generator dynamics are investigated for a number of control

I. K. Buehring; L. L. Freris

1981-01-01

255

Saturation and energy-conversion efficiency of auroral kilometric radiation  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

256

Proceedings of the sixth international conference on thermoelectric energy conversion  

SciTech Connect

This book presents the papers given at a conference on thermoelectric energy conversion. Topics considered at the conference included thermoelectric materials, the computer calculation of thermoelectric properties, the performance of crss-flow thermoelectric liquid coolers, thermoelectric cooler performance corrections for soft heat sinks, heat exchange in a thermoelectric cooling system, the optimal efficiency of a solar pond and thermoelectric generator system, and thermoelectric generation utilizing industrial waste heat as an energy source.

Rao, K.R.

1986-01-01

257

SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOFC  

SciTech Connect

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.

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

2003-06-09

258

SPS energy conversion and power management workshop. Final report  

SciTech Connect

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)

Not Available

1980-06-01

259

Linear mode conversion of Langmuir/z-mode waves to radiation: Averaged energy conversion efficiencies, polarization and applications to Earth's continuum radiation.  

NASA Astrophysics Data System (ADS)

Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in a density gradient. It is relevant to planetary continuum radiation, type ? and ? radio bursts, and ionospheric radio emissions. This paper analyses LMC by calculating angle-averaged energy (epsilon) and power (epsilon _{p}) conversion efficiencies in both 2D and 3D for Langmuir/z-mode waves (including upper hybrid waves for perpendicular wave vectors) converting to free-space radiation in turbulent plasmas. The averages are over the distributions of the incoming Langmuir/z-mode wave vectors k, density scale lengths L and angles alpha and delta, where alpha is the angle between k and the background magnetic field B _{0}, and delta is the angle between the density gradient ?N _{0} and B _{0}. The results show that the averaged and un-averaged conversion efficiencies are dependent on gammabeta, where gamma is the adiabatic index and beta is related to the electron temperature T _{e} by beta = T _{e}/m _{e}c (2) . The averaged energy conversion efficiencies are proportional to gammabeta in 2D and to (gammabeta) (3/2) in 3D, whereas the power conversion efficiencies are proportional to (gammabeta) (1/2) in 2D and gammabeta in 3D. The special case of a perpendicular density gradient (delta ? 90() ) is considered and used to predict the conversion efficiencies of terrestrial continuum radiation (TCR) in three known source regions the plasmapause, magnetopause, and the plasma sheet. The observed energy conversion efficiencies are estimated and are found to be consistent with the 2D and 3D predicted efficiencies; importantly these results imply that LMC is a possible generation mechanism for TCR. The polarization of TCR is also predicted: TCR should be produced primarily in the o-mode at the plasmapause and in both the o- and x-modes at the magnetopause and plasma sheet. These predictions are consistent with previous independent predictions and observations.

Schleyer, Fiona; Cairns, Iver; Kim, Eun-Hwa

260

Linear mode conversion of Langmuir/z mode waves to radiation: Averaged energy conversion efficiencies, polarization, and applications to Earth's continuum radiation  

NASA Astrophysics Data System (ADS)

Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in a density gradient. It is relevant to planetary continuum radiation, type II and III radio bursts, and ionospheric radio emissions. This paper analyzes LMC by calculating angle-averaged energy (?) and power (?p) conversion efficiencies in both 2-D and 3-D for Langmuir/z mode waves (including upper hybrid waves for perpendicular wave vectors) converting to free-space radiation in turbulent plasmas. The averages are over the distributions of the incoming Langmuir/z mode wave vectors k, density scale lengths L, and angles ? and ?, where ? is the angle between k and the background magnetic field B0 and ? is the angle between the density gradient ?N0 and B0. The results show that the averaged and unaveraged conversion efficiencies are dependent on ??, where ? is the adiabatic index and ? is related to the electron temperature Te by ? = Te/mec2. The averaged energy conversion efficiencies are proportional to ?? in 2-D and to (??)3/2 in 3-D, whereas the power conversion efficiencies are proportional to (??)1/2 in 2-D and ?? in 3-D. The special case of a perpendicular density gradient (??90) is considered and used to predict the conversion efficiencies of terrestrial continuum radiation (TCR) in three known source regions: the plasmapause, magnetopause, and the plasma sheet. The observed energy conversion efficiencies are estimated and are found to be consistent with the 2-D and 3-D predicted efficiencies; importantly, these results imply that LMC is a possible generation mechanism for TCR. The polarization of TCR is also predicted: TCR should be produced primarily in the o mode at the plasmapause and in both the o and x modes at the magnetopause and plasma sheet. These predictions are consistent with previous independent predictions and observations.

Schleyer, Fiona; Cairns, Iver H.; Kim, Eun-Hwa

2014-05-01

261

A high-efficiency energy conversion system  

SciTech Connect

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.

Belcher, A.E.

1996-12-31

262

Conversion of solar energy in space for use on Earth  

SciTech Connect

[open quotes]The key to advance global development is to provide adequate supplies of energy at an affordable cost, and to place increasing reliance on renewable energy sources that are compatible with the environment. There is a window of opportunity that may be open for only a few decades to find solutions capable of maintaining the Earth as a liveable planet. There is a growing consensus that to achieve this goal, energy options will have to be developed that rely increasingly on solar energy conversion on earth and in space.[close quotes] Dr. Peter E. Glaser, Vice President Arthur D. Little, Inc. Cambridge, MA, discusses the progression of the technology.

Glaser, P.E. (Arthur D. Little, Inc., Cambridge, MA (United States))

1993-06-01

263

Oxygen electrochemistry as a cornerstone for sustainable energy conversion.  

PubMed

Electrochemistry will play a vital role in creating sustainable energy solutions in the future, particularly for the conversion and storage of electrical into chemical energy in electrolysis cells, and the reverse conversion and utilization of the stored energy in galvanic cells. The common challenge in both processes is the development of-preferably abundant-nanostructured materials that can catalyze the electrochemical reactions of interest with a high rate over a sufficiently long period of time. An overall understanding of the related processes and mechanisms occurring under the operation conditions is a necessity for the rational design of materials that meet these requirements. A promising strategy to develop such an understanding is the investigation of the impact of material properties on reaction activity/selectivity and on catalyst stability under the conditions of operation, as well as the application of complementary in situ techniques for the investigation of catalyst structure and composition. PMID:24339359

Katsounaros, Ioannis; Cherevko, Serhiy; Zeradjanin, Aleksandar R; Mayrhofer, Karl J J

2014-01-01

264

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

SciTech Connect

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.

Kim, Eun-Hwa; Johnson, Jay R. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Cairns, Iver H. [School of Physics, University of Sydney, Sydney, New South Wales 2002 (Australia)] [School of Physics, University of Sydney, Sydney, New South Wales 2002 (Australia)

2013-12-15

265

Thermal stress analysis of IGBT modules in VSCs for PMSG in large offshore Wind Energy Conversion Systems  

Microsoft Academic Search

Components for offshore wind farms are required to be highly reliable due to harsh environmental conditions and poor accessibility for maintenance. Direct-Drive Permanent Magnet Synchronous Generator (PMSG) connected with back to back converters represents an attractive solution for large offshore Wind Energy Conversion Systems (WECSs). Large direct driven Wind Turbine Generators (WTGs) operate at lower speed compared to conventional geared

Riccardo Pittini; Salvatore D'Arco; Magnar Hernes; Astrid Petterteig

2011-01-01

266

LQR with integral action applied to a wind energy conversion system based on doubly fed induction generator  

Microsoft Academic Search

This paper presents the design of a Linear Quadratic Regulator (LQR) with Integral action (LQRI) applied to a wind energy conversion system (WECS) based on doubly fed induction generator (DFIG). The controller is used to achieve speed regulation for maximum power extraction from the wind turbine, DC bus voltage regulation, to make the machine draw its magnetizing current only from

Bachir Kedjar; Kamal Al-Haddad

2011-01-01

267

Mode Conversion and Energy Partitioning at Active Volcanoes  

NASA Astrophysics Data System (ADS)

It has recently been shown that correlations of seismic noise and coda wave provide rich information on the Greens function between observation sites. Such technique, known as seismic interferometry, are often based on the assumption of equipartitioning, and thus the energy partitioning of diffuse waves has been widely studies from the view points of wave theory and experimental/field observations. Recently, using an active seismic experiment at Asama volcano, Japan, Yamamoto and Sato (2010) quantified the scattering characteristics of multiple scattering and conversion scattering, and pointed out that P energy from active sources is rapidly converted to S energy and it takes only a few seconds that the local energy ratio approaches the equipartition based on the radiative transfer modeling using the estimated scattering parameters. To obtain a direct evidence of mode conversion and energy partitioning in shallow heterogeneous structure of active volcanoes and have implications for seismic interferometry, we conducted a seismic array observation in Nov. 2008 as a part of an active seismic experiment at Sakurajima volcano, Japan. We deployed a small square-shaped array composed of four three-component short-period seismometers, and decomposed the observed wavefield into P and S energies. Observed seismograms are characterized by spindle-like envelopes having small P-onsets and long codas lasting for more than 10 sec, and the decomposed P and S energies show the following characteristics in high frequency bands (4-8Hz and 8-12Hz): S energy rapidly increase just after the arrival of direct P wave, and S energy exceed P energy about 2 sec after the first arrival; the ratio of P and S energies make the gradual transition to the equipartition over about 5-10 sec. These behaviors can be well explained by the radiative transfer theory including mode conversion in a medium having the mean free path of about 1km. Another interesting finding from the array observation is that the local energy ratios in ambient noise and coda wave are almost the same. The fact indicates that even the ambient noise, which is basically generated by random excitation of ballistic waves, is in equipartition state due to strong scattering in heterogeneous volcanic environment. Observed good correlation between the site amplification factors estimated from ambient noise and coda wave also supports the hypothesis that these wave fields share almost same composition. These results suggest that the mode conversion and multiple scattering have an indispensable effect on the seismic wave propagation in heterogeneous volcanic environments. We expect our results on the energy partitioning and its transition to be of help to justify the applicability of seismic interferometry and pseudo-reflection method at active volcanoes.

Yamamoto, M.; Nishimura, T.; Tsutsui, T.; Iguchi, M.

2010-12-01

268

Thermoelectric Energy Conversion: Future Directions and Technology Development Needs  

NASA Technical Reports Server (NTRS)

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.

Fleurial, Jean-Pierre

2007-01-01

269

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

NASA Technical Reports Server (NTRS)

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.

1975-01-01

270

Fluidized-bed energy technology for biomass conversion  

Microsoft Academic Search

Fluidized-bed technology offers several unique features for use in small-scale biomass energy conversion. Results are reported in the use of a 61-cm fluidized-bed reactor for combustion and on the use of 61-, 30-, and 5-cm reactors for gasification. combustion trials using agricultural biomass feeds have identified several problem areas. Slagging and fouling can occur at bed temperatures as low as

E. J. Soltes; W. A. Lepori; T. C. Pollock

1982-01-01

271

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

Microsoft Academic Search

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

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

1983-01-01

272

Thermo-photo-voltaic conversion from high temperature energy sources  

Microsoft Academic Search

The concept of a thermo-photo-voltaic (TPV) energy converter is introduced and the device compared with thermoelectric and thermionic converters. Features of the TPV converter are that the entire device is kept at room temperature, potential power densities on the order of 10 watts\\/cm3, and potential conversion efliciencies of 30 percent. Considerations for TPV converter design are presented and compared with

B. D. Wedlock

1962-01-01

273

A new microcontroller based solar energy conversion modular unit  

Microsoft Academic Search

This paper presents the design and the implementation of a new microcontroller-based solar energy conversion modular unit. The unit consists of an array of solar panels, a step-up chopper, a single-phase inverter, an AC mains power source and a microcontroller-based control unit. The novelty of this unit is that the switching device of the chopper is not only used for

F. Huang; Gao Zhimin; T. Forughian; D. Tien

1997-01-01

274

Thermophotovoltaic energy conversion using photonic bandgap selective emitters  

DOEpatents

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.

Gee, James M. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Fleming, James G. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

2003-06-24

275

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

276

Compact magnetic energy storage module  

DOEpatents

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.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01

277

Compact magnetic energy storage module  

DOEpatents

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.

Prueitt, M.L.

1994-12-20

278

Mathematical simulation of Ocean Thermal Energy Conversion Seawater Systems  

SciTech Connect

A mathematical model and computer code have been developed to predict the performance of the Seawater System (SWS) of an Ocean Thermal Energy Conversion (OTEC) power plant. A time-dependent, one-dimensional model is constructed for the fluid flow through the SWS based on the fundamental conservation equations of mass, momentum, and energy. Boundary conditions include system response to seaway dynamics. A finite difference method is used to solve the conservation equations. Auxiliary relations for evaluating friction and heat transfer coefficients and special modeling of sumps and pumps are included. Predictions of OTEC-1 pilot plant performance are presented.

Wassel, A.T.; Elhobashi, S.E.; Farr, J.L.; Potts, R.L.

1984-05-01

279

Optimisation of a Small Non Controlled Wind Energy Conversion System for Stand-Alone Applications  

E-print Network

Optimisation of a Small Non Controlled Wind Energy Conversion System for Stand-Alone Applications. This article proposes a method to optimize the design of a small fixed-voltage wind energy conversion system are shown and discussed. Key words Wind energy conversion system, stand-alone application, nonlinear

Paris-Sud XI, Université de

280

The State of the Art of Generators for Wind Energy Conversion Systems  

E-print Network

The State of the Art of Generators for Wind Energy Conversion Systems Yassine Amirat, Mohamed Benbouzid, Bachir Bensaker and René Wamkeue Abstract--Wind Energy Conversion Systems (WECS) have become. I. INTRODUCTION Wind energy conversion is the fastest-growing source of new electric generation

Boyer, Edmond

281

A Framework for Reliability and Performance Assessment of Wind Energy Conversion Systems  

E-print Network

1 A Framework for Reliability and Performance Assessment of Wind Energy Conversion Systems proposes a framework for reliability and dynamic performance assessment of wind energy conversion systems--Reliability, Dynamic Performance, Wind Power, Wind Energy Conversion System (WECS), Doubly-Fed Induction Generator

Liberzon, Daniel

282

The State of the Art of Generators for Wind Energy Conversion Systems  

E-print Network

243 1 The State of the Art of Generators for Wind Energy Conversion Systems Y. Amirat, M. E. H. Benbouzid, B. Bensaker, R. Wamkeue and H. Mangel Abstract--Wind Energy Conversion Systems (WECS) have become of the studied generators is provided in Fig. 2. II. WIND ENERGY BACKGROUND A. Wind Power Conversion

Paris-Sud XI, Université de

283

Challenges for clean and high-efficiency energy conversion systems  

SciTech Connect

In this presentation, issues of energy and environment are examined in the view of Japan and of earth, giving particular attention on thermal issues of mechanical engineering, and on power generation engineering utilizing natural energy, fossil fuels, nuclear energy and new energy conversion systems. The studies are summarized as the status and trend of R and D in Japan. It is important to accelerate upgrading the technical capability applicable for solutions to the Level where such technologies would be widely accepted and promoted on earth. The importance is enhanced when the accelerated speed of evolution in issues of energy, environment and economy is considered together with the size of inertia they have, and when the time allocated for us is realized to be surprisingly short. It is concluded that a consolidated international effort is further required as well as the reinforced cooperation of academies and industry.

Tsuge, Ayao; Matsuo, Tokuji

1999-07-01

284

Site selection for small wind energy conversion systems for US Department of Energy field evaluation program  

NASA Astrophysics Data System (ADS)

The site selection procedure followed to locate two qualified sites for the installed and monitoring of two commercially available small wind energy conversion systems as part of the U.S. Department of Energy's Field Evaluation Program is described. The aim of the evaluation program is to gain operating experience with wind systems in actual locations and to identify the siting and operational issues involving wind energy conversion systems. The two sites selected were approved as test sites for the program.

Bailey, B. H.

1980-10-01

285

Studies of power conditioning circuits for superconductive magnetic energy store  

Microsoft Academic Search

The superconductive magnetic energy store (SMES) approach to utility-load leveling has the potential for very high energy conversion efficiency and fast response to changes in load demands. It can be used to improve utility system operation economics and system stabilities. The power-conditioning circuit interfacing an SMES and a utility network consists of thyristor or gate-turn-off (GTO) device bridges of the

J. Wang; J. Skiles; R. Kustom; T. Ise; F. Tsang; J. Cleary

1988-01-01

286

Investigation of direct solar-to-microwave energy conversion techniques  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

287

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

288

NOAA Technical Memorandum ERL PMEL-11 CONVERSION FROM FILM TO MAGNETIC CASSETTE RECORDING  

E-print Network

FOR THE GEODYNE 102 CURRENT METER Alex I. Nakamura Robert R. Harvey Pacific Marine Environmental Laboratory. · · · · · · ·· . · · · ·· · · · . · · · ·· · · · . ·· · · · ·· · · · · · · · · · · · · 15 iii #12;#12;JIMAR 78-0002 CONVERSION FROM FILM TO MAGNETIC CASSETTE RECORDING FOR THE GEODYNE 102) PMEL 356* This report describes a conversion of the Geodyne 102 aurTent meter~ which recorded its data

289

Cogeneration from Waste Energy Streams Four Energy Conversion Systems Described  

Microsoft Academic Search

In times of rapid growth in the costs of energy of all types, renewed interest comes for cogeneration. Specifically, the recovery of waste energy has become economical and the potential for growth of cogeneration systems to utilize waste heat is high. Cogeneration systems for bottoming cycles and waste energy recovery from process streams are described. The nature of the energy

James Palmer

1981-01-01

290

Ocean Thermal Energy Conversion (OTEC) A New Secure Renewable Energy Source  

E-print Network

and Commercial Applications 1 Dr. Ted Johnson Director of Alternative Energy Programs Development Lockheed MartinOcean Thermal Energy Conversion (OTEC) A New Secure Renewable Energy Source For Defense New Ventures #12;What is OTEC? OTEC B fiOTEC Benefits: Large Renewable Energy Source 3-5 Terawatts

291

Nanostructured transition metal oxides for energy storage and conversion  

NASA Astrophysics Data System (ADS)

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

Li, Qiang

292

Renewable energy from the sea - organic Rankine Cycle using ocean thermal energy conversion  

Microsoft Academic Search

Rankine cycles using refrigerant- and benzene-series fluids as working fluids in converting low-grade energy from renewable energy resources such as solar energy and ocean thermal energy were investigated in this study. The main purpose is to verify the feasibility of utilizing ocean energy (i.e., ocean thermal energy conversion, OTEC) which can also be combined with solar energy in an organic

S. K. Wang; T. C. Hung

2010-01-01

293

Surface conversion techniques for low energy neutral atom imagers  

NASA Technical Reports Server (NTRS)

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.

Quinn, J. M.

1995-01-01

294

Photovoltaic and thermal energy conversion for solar powered satellites  

NASA Technical Reports Server (NTRS)

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.

Von Tiesenhausen, G. F.

1976-01-01

295

Low cost composite materials for wind energy conversion systems  

NASA Technical Reports Server (NTRS)

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).

Weingart, O.

1980-01-01

296

Heat transfer research for ocean thermal energy conversion  

NASA Astrophysics Data System (ADS)

In this lecture an overview of the heat- and mass-transfer phenomena of importance in ocean thermal energy conversion (OTEC) is presented with particular emphasis on open-cycle OTEC systems. Also included is a short historical review of OTEC developments in the past century and a comparison of open- and closed-cycle thermodynamics. Finally, results of system analyses, showing the effect of plant size on cost and the near-term potential of using OTEC for combined power production and desalination systems are briefly discussed.

Kreith, F.; Bharathan, D.

1987-03-01

297

Advanced solar energy conversion. [solar pumped gas lasers  

NASA Technical Reports Server (NTRS)

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.

Lee, J. H.

1981-01-01

298

Method and apparatus for testing electrochemical energy conversion devices  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

299

Quantitative analysis of a wind energy conversion model  

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

300

Nanostructured solar irradiation control materials for solar energy conversion  

NASA Astrophysics Data System (ADS)

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.

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

301

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

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

302

Visible light to electrical energy conversion using photoelectrochemical cells  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

303

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

SciTech Connect

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.

Mamone, Salvatore, E-mail: s.mamone@soton.ac.uk; Concistr, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H., E-mail: mhl@soton.ac.uk [School of Chemistry, University of Southampton, Southampton SO17 1BJ (United Kingdom); Lei, Xuegong; Li, Yongjun [Department of Chemistry, Columbia University, New York, New York 10027 (United States)] [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Goh, Kelvin; Horsewill, Anthony J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2014-05-21

304

Energy conversion processes based on molecular excited states  

NASA Astrophysics Data System (ADS)

The major emphasis of our DOE-supported research efforts remains the use of molecular excited states in energy conversion processes. In the past year we have made significant progress in the distinct areas of: (1) electronic structure, photophysical and photochemical properties of MLCT-based excited states, (2) design and characterization of metallopolymeric films as a basis for photoelectrodes containing MLCT-based chromophores, and (3) excited state photoelectrochemical cells based on excited state redox quenching. We have continued to develop synthetic routes to new MLCT excited states, most recently to a series of complexes. Systematic variations (from electron-donating to electron-withdrawing properties) allow control to be gained over changes in emission energies (E sub em), excited state redox potentials, ground state absorption energies, and radiative and nonradiative decay rate constants and perhaps, most importantly, open up two new families of excited states for photoredox applications.

Meyer, T. J.

1987-03-01

305

Quantum coherence in photosynthesis for efficient solar-energy conversion  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

306

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

NASA Astrophysics Data System (ADS)

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? is obtained, which is in good agreement with efficiencies computed via full-wave simulations.

Ali Asgarian, M.; Verboncoeur, J. P.; Parvazian, A.; Trines, R.

2013-10-01

307

Conversion of relic gravitational waves into photons in cosmological magnetic fields  

SciTech Connect

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.

Dolgov, Alexander D.; Ejlli, Damian, E-mail: dolgov@fe.infn.it, E-mail: ejlli@fe.infn.it [Dipartimento di Fisica e Scienze della Terra, Polo Scientifico e Tecnologico-Edificio C, Universit degli Studi di Ferrara, Via Saragat 1, 44122 Ferrara (Italy)

2012-12-01

308

Organic electronics on fibers for energy conversion applications  

NASA Astrophysics Data System (ADS)

Currently, there is great demand for pollution-free and renewable sources of electricity. Solar cells are particularly attractive from the standpoint of sunlight abundance. However, truly widespread adoption of solar cells is impeded by the high cost and poor scalability of existing technologies. For example, while 53,000 mi2 of 10% efficient solar cell modules would be required to supply the current U.S. energy demand, only about 50 mi2 have been installed worldwide. Organic semiconductors potentially offer a route to realizing low-cost solar cell modules, but currently suffer from low conversion efficiency. For organic-based solar cells to become commercially viable, further research is required to improve device performance, develop scalable manufacturing methods, and reduce installation costs via, for example, novel device form factors. This thesis makes several contributions to the field of organic solar cells, including the replacement of costly and brittle indium tin oxide (ITO) electrodes by inexpensive and malleable, thin metal films, and the application of external dielectric coatings to improve power conversion efficiency. Furthermore, we show that devices with non-planar geometries (e.g. organic solar cells deposited onto long fibers) can have higher efficiencies than conventional planar devices. Building on these results, we demonstrate novel fiber-based organic light emitting devices (OLEDs) that offer substantially improved color quality and manufacturability as a next-generation solid-state lighting technology. An intriguing possibility afforded by the fiber-based device architectures is the ability to integrate energy conversion and lighting functionalities with textiles, a mature, commodity-scale technology.

O'Connor, Brendan T.

309

Nitride metal - semiconductor superlattices for solid state thermionic energy conversion  

NASA Astrophysics Data System (ADS)

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.

Wortman, Robert David

310

IEEE TRANSACTIONS ON ENERGY CONVERSION, 2006 1 Distributed Control Agents Approach to Energy  

E-print Network

IEEE TRANSACTIONS ON ENERGY CONVERSION, 2006 1 Distributed Control Agents Approach to Energy is an important step toward improved fight- through and self-healing capabilities of naval warships a new scheme for an energy management system in the form of distributed control agents. The control

Lai, Hong-jian

311

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

PubMed Central

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.

Grabbe, Mrten; Leijon, Mats

2015-01-01

312

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

NASA Technical Reports Server (NTRS)

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.

Juhasz, Albert J.; Sawicki, Jerzy T.

2003-01-01

313

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

NASA Astrophysics Data System (ADS)

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.

Juhasz, Albert J.; Sawicki, Jerzy T.

2004-02-01

314

Performance optimization of a pneumatic wave energy conversion device  

NASA Astrophysics Data System (ADS)

The purpose of this study was, for the first time, to optimize the performance of a pneumatic wave energy conversion device. The experiments of Jolly and Newmaster (1979) and Trop and Casey (1980) left a capture chamber and turbine for further investigation. To optimize the system performance the turbine had to be first analyzed so that its power performance curves could be determined. These curves were needed to help define the possible overall performance of the system, and for the impedance matching of the system necessary for performance optimization. With this knowledge, an appropriate generator was purchased and a generator-turbine linkage designed and built. The completed system was then analyzed in the 380 ft wave tank at the U.S. Naval Academy to establish its optimum performance. From the research it is clear that pneumatic wave energy conversion is a promising concept. With several hundred of these devices situated some 100 km off the coast of the Pacific Northwest each device would be producing from 50 to 200 kW which would be transferred back to shore.

Surko, S. W.

1982-08-01

315

Proceedings of the Chornobyl phytoremediation and biomass energy conversion workshop  

SciTech Connect

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.

Hartley, J. [Pacific Northwest National Lab., Richland, WA (United States)] [Pacific Northwest National Lab., Richland, WA (United States); Tokarevsky, V. [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)] [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)

1998-06-01

316

Plasmadynamics and ionization kinetics of thermionic energy conversion  

SciTech Connect

To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)

Lawless, J.L. Jr.; Lam, S.H.

1982-02-01

317

Design requirements for interfaces in solar energy conversion technologies  

NASA Astrophysics Data System (ADS)

Candidate materials for improving the durability and economics of solar energy conversion systems (SECS) are reviewed. A 30-yr lifetime is regarded as necessary for solar collector and concentrator materials in order to offset the high initial costs of SECS in parabolic dish, heliostat, parabolic trough, flat plate collector, OTEC, solar cell, and wind turbine configurations. The materials are required to transfer a maximum amount of intercepted energy without degrading from exposure to UV radiation, wind, water, dust, and temperature cycling. Glass and mirrored surfaces for reflecting or refracting optical subsystems are currently made from soda-lime, boro- and aluminosilicate, and must resist chemicals, abrasion, and permeability, and have good strength, flexibility, coefficient of expansion, and Young's modulus. Additional concerns are present in photochemical, solar cell, and in substrata components and systems.

Butler, B. L.

1982-04-01

318

All silicon electrode photocapacitor for integrated energy storage and conversion.  

PubMed

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

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

2015-04-01

319

Controlled cellular energy conversion in brown adipose tissue thermogenesis  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

320

Current developments in small wind energy conversion systems  

NASA Astrophysics Data System (ADS)

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.

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

1980-05-01

321

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

NASA Technical Reports Server (NTRS)

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.

1988-01-01

322

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

NASA Astrophysics Data System (ADS)

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.

1988-03-01

323

Solid State Energy Conversion Alliance 2nd Annual Workshop Proceedings  

SciTech Connect

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.

National Energy Technology Laboratory

2001-03-30

324

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

SciTech Connect

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}.

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

1996-12-31

325

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

DOEpatents

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.

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

1997-01-01

326

Proceedings of the 30. intersociety energy conversion engineering conference. Volume 3  

Microsoft Academic Search

This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and

D. Y. Goswami; L. D. Kannberg; S. Somasundaram; T. R. Mancini

1995-01-01

327

Exchange biased magnetoelectric composites for magnetic field sensor application by frequency conversion  

NASA Astrophysics Data System (ADS)

A comparison is presented between magnetoelectric composite sensors based on AlN and FeCoSiB with and without exchange bias coupling. All layer stacks were fabricated by thin film deposition on Si substrates. Whereas sensors without exchange bias exhibit a low limit of detection in the 1 pT/?Hz regime for resonant AC fields, such sensors fail at the detection of low frequency signals. Accordingly, their detection limit increases to about 10 nT/?Hz for alternating magnetic fields with 10 Hz frequency and an integration time equal to 3 s. A frequency conversion technique based on magnetic modulation of the sensors improves their detection limit by about one order of magnitude. However, frequency conversion can be applied more effectively to magnetoelectric sensors with exchange biased multilayers as a magnetostrictive phase. As a result, their limit of detection is about 180 pT/?Hz for 10 Hz signals and an integration time of 1 s. This is in contrast to the magnetoelectric coefficient ?ME of the two types of sensors. Whereas ?ME equals 6.9 kV/cm Oe for non-biased composites and resonant fields, it is by a factor of 8 smaller for the exchange biased composites. The nonetheless arising improvement of sensor performance with regard to the limit of detection for magnetic fields with low frequencies can be explained by a significantly lower magnetic noise contribution during modulation of the exchange biased sensors.

Rbisch, V.; Yarar, E.; Urs, N. O.; Teliban, I.; Knchel, R.; McCord, J.; Quandt, E.; Meyners, D.

2015-05-01

328

Energy transfer processes in solar energy conversion. Final report  

SciTech Connect

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)

Fayer, M.D.

1984-01-01

329

Conversion of concentrated solar thermal energy into chemical energy.  

PubMed

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

Tamaura, Yutaka

2012-01-01

330

Refractory materials for high-temperature thermoelectric energy conversion  

NASA Technical Reports Server (NTRS)

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.

Wood, C.; Emin, D.

1983-01-01

331

Distribution Category: Magnetic Fusion Energy  

E-print Network

Distribution Category: Magnetic Fusion Energy (UC-20) ANL/FPP/TM-175 ANL/FPP/TM--175 DE83 015751 on the reference 11mlter 4 3-2 Eroslon/redeposltion of a carbon limiter coating at a 150 eV edge temperature. 4 4 to be a reasonable design and should provide an opportunity to test high power and particle loadings. Carbon Is recom

Harilal, S. S.

332

Energy Conversion Options for Advanced Radioisotope Power Systems  

NASA Astrophysics Data System (ADS)

Static and dynamic energy conversion technologies for Advanced Radioisotope Power Systems (ARPSs) are reviewed and their impact on the system's total mass and specific electrical power and the amount of 238PuO2 fuel needed for the heat source are assessed and compared. Conversion technologies considered are Segmented and cascaded Thermoelectric, Alkali-Metal Thermal-to-Electric Conversion, and Free Piston Stirling Engines (FPSEs) and, for comparison, SiGe thermoelectric. Estimates for a 100 We ARPS indicate that when using SiGe thermoelectric, operating between 1273 K and 573 K, 8 General Purpose Heat Source (GPHS) modules would be required and the system's specific power is ~ 4.6 We/kg. Using STE converters, operating between 973 K and 373 K, 5 GPHS modules are required and the ARPS's specific power is ~ 7.28 We/kg. The next generation STE converters that could operate between 1273 K and 573 K, for a projected system efficiency of 13.8%, decrease the number of GPHS modules needed to 4 and increase the system's specific power to ~ 9.9 We/kg. With cascaded SiGe-STE converters, operating between 1273 K and 373 K, the system's efficiency could be as much as 16%, requiring only 3 GPHS modules, for an estimated specific power of 10.7 We/kg. This specific power is more than twice that for SOA RTG. With the current version 1.0 of FPSEs, the 100 We ARPS needs only two GPHS modules, but its specific power (4.1 we/kg) is slightly lower than that of SOA RTG (4.6 We/kg). Future introduction of versions 1.1 and 2.0 engines, with slightly higher conversion efficiency and significantly lower mass, could increase the system's specific power to ~ 7.5 We/kg, using the same number of GPHS modules as version 1.0 engines. With Na-AMTEC and K-AMTEC, the 100 We ARPS needs 3 and 4 GPHS modules, respectively, for an estimated specific power of 5.3 and 5.8 We/kg, respectively.

El-Genk, Mohamed S.

2003-01-01

333

Biomass conversion Task 4 1988 program of work: International Energy Agency Bioenergy Agreement  

Microsoft Academic Search

For biomass to meet its potential as an energy resource, conversion processes must be available which are both efficient and environmentally acceptable. Conversion can include direct production of heat and electricity as well as production of intermediate gaseous, liquid, and solid fuels. While many biomass conversion processes are commercially available at present, others are still in the conceptual stage. Additional

1987-01-01

334

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

NASA Astrophysics Data System (ADS)

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.

Anderson, Brett; Burstein, Alison; Gentile, Charles

2007-11-01

335

Bio-inspired Approaches to Solar Energy Conversion  

NASA Astrophysics Data System (ADS)

Natural photosynthesis is carried out by organized assemblies of photofunctional tetrapyrrole chromophores and catalysts within proteins that provide specifically tailored environments to optimize solar energy conversion. Artificial photosynthetic systems for practical solar fuels production must collect light energy, separate charge, and transport charge to catalytic sites where multi-electron redox processes will occur. The primary goal of our research in this field is to understand the fundamental principles needed to develop integrated artificial photosynthetic systems. These principles include how to promote and control: 1) energy capture, charge separation, and long-range directional energy and charge transport, 2) coupling of separated charges to multi-electron catalysts for fuel formation, and 3) supramolecular self-assembly for scalable, low-cost processing from the nanoscale to the macroscale. The central scientific challenge is to develop small, functional building blocks, having a minimum number of covalent linkages, which also have the appropriate molecular recognition properties to facilitate self-assembly of complete, functional artificial photosynthetic systems. This lecture will describe our use of ultrafast optical spectroscopy and time-resolved EPR spectroscopy to understand charge transport in self-assembled structures for artificial photosynthesis.

Wasielewski, Michael

2012-02-01

336

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

NASA Technical Reports Server (NTRS)

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.

1986-01-01

337

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

NASA Astrophysics Data System (ADS)

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.

1986-07-01

338

Impact of different macronutrient definitions and energy conversion factors on energy supply estimations  

Microsoft Academic Search

The magnitude of differences in energy supply using different definitions for carbohydrates and protein as well as different energy conversion factors was investigated. Food supply data for 19992001 from FAOSTAT were used for nine countries with different types of diets. Nutrient values were derived from USDA and the British food composition tables for three definitions of carbohydrate (total, available by

U. R. Charrondiere; S. Chevassus-Agnes; S. Marroni; B. Burlingame

2004-01-01

339

Wave Energy Conversion Overview and it's Renewable Energy Potential for the Oil and Gas Industry  

E-print Network

Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. Part II provides an overview of the energy density found in ocean waves and how it is calculated...

Pastor, J.; Liu, Y.; Dou, Y.

2014-01-01

340

Plasmon Enhanced Solar-to-Fuel Energy Conversion  

E-print Network

Future generations of photoelectrodes for solar fuel generation must employ inexpensive, earth-abundant absorber materials in order to provide a large-scale source of clean energy. These materials tend to have poor electrical transport properties and exhibit carrier diffusion lengths which are significantly shorter than the absorption depth of light. As a result, many photo-excited carriers are generated too far from a reactive surface, and recombine instead of participating in solar-to-fuel-conversion. We demonstrate that plasmonic resonances in metallic nanostructures and multi-layer interference effects can be engineered to strongly concentrate sunlight close to the electrode/liquid interface, precisely where the relevant reactions take place. By comparing spectral features in the enhanced photocurrent spectra to full-field electromagnetic simulations, the contribution of surface plasmon excitations is verified. These results open the door to the optimization of a wide variety of photochemical processes by...

Thomann, I; Chen, Z; Clemens, B M; Jaramillo, T F; Brongersma, Mark L

2011-01-01

341

Shelf mounted ocean thermal energy conversion platform, revised preliminary report  

NASA Astrophysics Data System (ADS)

This report relates model tests of a generic Ocean Thermal Energy Conversion (OTEC) platform. The objective of these tests is to aid in the evaluation of new OTEC designs and to present a data base for design purposes. The test plant has been designed to provide a data base for comparison with current and projected analytical tools as well as comparisons of results from one model configuration to another. The new conceptual OTEC designs are different from the typical offshore (jacket type) structure which is quite transparent to waves. The major difference is the addition of large submerged power production modules to the frame. These proposed modules offer a large surface area to obstruct the flow and thereby increase the global wave forces acting on the structure.

1984-03-01

342

Monolithic Interconnected Modules (MIMs) for Thermophotovoltaic Energy Conversion  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

343

Materials and structures for stretchable energy storage and conversion devices.  

PubMed

Stretchable energy storage and conversion devices (ESCDs) are attracting intensive attention due to their promising and potential applications in realistic consumer products, ranging from portable electronics, bio-integrated devices, space satellites, and electric vehicles to buildings with arbitrarily shaped surfaces. Material synthesis and structural design are core in the development of highly stretchable supercapacitors, batteries, and solar cells for practical applications. This review provides a brief summary of research development on the stretchable ESCDs in the past decade, from structural design strategies to novel materials synthesis. The focuses are on the fundamental insights of mechanical characteristics of materials and structures on the performance of the stretchable ESCDs, as well as challenges for their practical applications. Finally, some of the important directions in the areas of material synthesis and structural design facing the stretchable ESCDs are discussed. PMID:24643976

Xie, Keyu; Wei, Bingqing

2014-06-11

344

Photochemical energy conversion by membrane-bound photoredox systems  

SciTech Connect

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.

Tollin, G.

1992-03-01

345

Siting handbook for small wind energy conversion systems  

SciTech Connect

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.

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

1980-03-01

346

Tandem photovoltaic solar cells and increased solar energy conversion efficiency  

NASA Technical Reports Server (NTRS)

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.

Loferski, J. J.

1976-01-01

347

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

SciTech Connect

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.

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

2012-01-01

348

Performance analysis of energy conversion via caloric effects in first-order ferroic phase transformations.  

PubMed

A finite-time thermodynamic model of ferroic refrigerators and generators, based on first order phase transformation, is given. We use this model to evaluate a novel method of converting heat directly into electricity based on the martensitic phase transformation accompanied by an abrupt change in magnetic ordering recently discovered [Srivastava et al., Adv. Energy Mater., 2011, 1, 97]. In this paper, we study the efficiency and power output of this method. The formulas of efficiency and power output in terms of material constants, design parameters, and working conditions are derived. The Clausius-Clapeyron coefficient is shown to be important to the efficiency. The figure of merit, as a dimensionless parameter, of energy conversion using the new method is introduced. It is shown that, as the figure of merit goes to infinity, the efficiency approaches the Carnot efficiency. Thermodynamic cycles of the new energy conversion method are optimized for a maximum power output. The matching criteria between materials and working temperatures of such optimized cycles are derived. Using these criteria, one can choose the most suitable materials under given working conditions, or decide the best working conditions for available materials. PMID:24836947

Song, Yintao

2014-07-01

349

Alkali layered compounds interfaces for energy conversion and energy storage  

NASA Technical Reports Server (NTRS)

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.

Papageorgopoulos, Chris A.

1996-01-01

350

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

SciTech Connect

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

Lian, Tianquan [PI, Emory Univ.

2013-09-01

351

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems  

E-print Network

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems B. Beltran, T. Ahmed power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two (National Renewable Energy Laboratory) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures

Boyer, Edmond

352

Development and testing of a point absorber wave energy conversion device  

Microsoft Academic Search

Wave energy conversion as a means for small scale energy production is approaching commercial viability. This paper presents the undergoing development of a wave energy conversion device at the University of Hawaii at Manoa. The device is a three part point absorber with two buoys, one floating and absorbing incoming waves; the other maintaining tension on the third mechanism, the

J. W. Foster; P. Garambois; R. Ghorbani

2011-01-01

353

The International Adoption of Photovoltaic Energy Conversion Is Japan a Lead Market?  

Microsoft Academic Search

This paper explores on the basis of a case study on photovoltaic energy conversion (PV) whether countries can actively create a lead market for new technology. Solar energy conversion has fascinated people and politicians as an alternative to oil and nuclear energy. Since the discovery of photovoltaic cells that directly convert solar irradiation into electricity it is expected that the

Marian Beise

2004-01-01

354

Boron-rich solids: A chance for high-efficiency high-temperature thermoelectric energy conversion  

Microsoft Academic Search

Thermoelectric energy conversion is a very reliable way of generating electrical power, for example from solar heat or from waste industrial thermal energy. Boron-rich solids are shown to be very promising candidates for high efficiency thermoelectric energy conversion. The outstanding high melting points and extraordinary chemical stability allow their use under extreme conditions which are not accessible by most other

Helmut Werheit

1995-01-01

355

M13 bacteriophage-enabled assembly of nanocomposites : synthesis and application in energy conversion devices  

E-print Network

Lack of energy supply and non-uniform distribution of traditional energy sources, such as coal, oil, and natural gas, have brought up tremendous social issues. To solve these issues, highly efficient energy conversion ...

Dang, Xiangnan

2013-01-01

356

Advanced Energy Conversion Technologies and Architectures for Earth and Beyond  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

357

Numerical analysis of magnetic field in superconducting magnetic energy storage  

SciTech Connect

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.

Kanamaru, Y. (Kanazawa Inst. of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921 (JP)); Amemiya, Y. (Chiba Inst. of Tech., Narashino (Japan))

1991-09-01

358

Energy magnetization and the thermal Hall effect.  

PubMed

We obtain a set of general formulas for determining magnetizations, including the usual electromagnetic magnetization as well as the gravitomagnetic energy magnetization. The magnetization corrections to the thermal transport coefficients are explicitly demonstrated. Our theory provides a systematic approach for properly evaluating the thermal transport coefficients of magnetic systems, eliminating the unphysical divergence from the direct application of the Kubo formula. For a noninteracting anomalous Hall system, the corrected thermal Hall conductivity obeys the Wiedemann-Franz law. PMID:22182111

Qin, Tao; Niu, Qian; Shi, Junren

2011-12-01

359

Optimized vacuum thermionic energy conversion using diamond materials  

NASA Astrophysics Data System (ADS)

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.

Smith, Joshua; Bilbro, Griff; Nemanich, Robert

2009-03-01

360

Environmental programs for ocean thermal energy conversion (OTEC)  

SciTech Connect

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.).

Wilde, P.

1981-07-01

361

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

SciTech Connect

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.

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

1983-07-01

362

Forced reconnection in the near magnetotail: Onset and energy conversion in PIC and MHD simulations  

NASA Astrophysics Data System (ADS)

Using two-dimensional particle-in-cell (PIC) together with magnetohydrodynamic (MHD) 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.

Birn, J.; Hesse, M.

2014-01-01

363

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

NASA Technical Reports Server (NTRS)

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.

Birn, J.; Hesse, Michael

2014-01-01

364

Historical Overview and Fundamental Aspects of Molecular Catalysts for Energy Conversion  

Microsoft Academic Search

In this chapter we focus on the historical background of the electrocatalysts especially of molecular catalysts that are considered\\u000a as key technology for energy conversion systems. The energy conversion is a basic process with which humans can utilize natural\\u000a energy by converting into useful forms of energy such as heat, electricity, or other secondary energies. The most important\\u000a process to

T. Okada; T. Abe; M. Kaneko

365

Investigation and development of new materials for electrochemical energy conversion  

NASA Astrophysics Data System (ADS)

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.

Ivanovskaya, Anna

366

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

NASA Technical Reports Server (NTRS)

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.

Baresi, Larry

1989-01-01

367

Direct Energy Conversion for Nuclear Propulsion at Low Specific Mass  

NASA Technical Reports Server (NTRS)

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.

Scott, John H.

2014-01-01

368

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

NASA Astrophysics Data System (ADS)

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.

Baresi, Larry

1989-03-01

369

Roles for solar thermal conversion systems in our energy economy  

Microsoft Academic Search

The NSF solar thermal conversion program, which is at a conceptual analysis and exploratory research level, is outlined with respect to mission, system, subsystem, and components and materials. Major conclusions are that solar thermal conversion electrical powerplants are most competitive with fossil fuels powerplants for intermediate or peaking power applications, and that central receiver solar thermal systems appear to offer

D. F. Spencer; A. B. Greenberg

1975-01-01

370

AC conductivity of nanoporous metal-oxide photoanodes for solar energy conversion  

E-print Network

AC conductivity of nanoporous metal-oxide photoanodes for solar energy conversion Steven J. Konezny% solar-to-electric energy conversion efficiency) exploited the large surface area of nanoporous thin for solar photoconversion is analyzed using a model based on fluctuation-induced tunneling conduction (FITC

Konezny, Steven J.

371

Power system dynamics influenced by a power electronic interface for variable speed wind energy conversion systems  

Microsoft Academic Search

A study of the influence of a wind energy conversion system on power system dynamics is presented in this paper. The wind energy conversion system is interfaced into a power system through a power electronic system including a voltage source converter (VSC) at the grid side. This paper investigates the system performance during a power system disturbance; a voltage sag

Z. Chen; Y. Hu

2004-01-01

372

Photostability, laser energy conversion efficiency and absorption of IR heptamethine cyanine dyes absorbing beyond 1 ?m  

Microsoft Academic Search

The optical absorption, photostability and energy conversion efficiency of a series of heptamethine IR dyes are reported and results related to chemical structure. The high photostability and high laser energy conversion efficiency of several of the dyes indicate potential use in IR dye lasers.

Jinlong Zhang; Weimei Luo; Zhenghua Zhu

1995-01-01

373

Analysis and design of offshore energy conversion devices under modeling uncertainties  

Microsoft Academic Search

A comprehensive, versatile framework is discussed for analysis and design of offshore energy (waves and\\/or wind) conversion devices in presence of modeling uncertainties. The framework is founded on a probabilistic characterization of the uncertainty in the models for the excitation, the system (wave energy conversion device) and its performance. Stochastic simulation is proposed for evaluating the associated probabilistic integral quantifying,

Alexandros Taflanidis; Eva Loukogeorgaki; Demos Angelides

2011-01-01

374

Sliding mode control of torque ripple in wind energy conversion systems with slip power recovery  

Microsoft Academic Search

This paper deals with wind energy conversion systems (WECS) with slip power recovery. These systems use a double-output induction generator, which is connected directly to grid by stator and through a static converter by rotor. An appropriate control of the converter allows the WECS to operate at the optimum tip speed ratio, maximizing the efficiency of the energy conversion. Wind

H. De Battista; Ricardo Julib Mantz

1998-01-01

375

Possible Applications and Limitations of Multi-Walled Carbon Nanotubes to Solar Energy Conversion  

Microsoft Academic Search

Recent experimental work has shown that multi-walled carbon nanotubes (MWCNT) can behave like receiving antennas for visible light.[1] One possible application for this newly observed behavior for carbon nanotubes might be for solar energy conversion. Pontential applications and limitations of this technology to solar energy conversion will be discussed. *Y. Wang et. al., Applied Physics Letters, Vol. 85, No. 13,

Robert Friedfeld

2005-01-01

376

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

SciTech Connect

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.

Authors, Various

1980-01-01

377

Photovoltaic solar energy conversion in the '80s  

NASA Astrophysics Data System (ADS)

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.

Chevalier, I.

1981-04-01

378

Decreasing geothermal energy conversion costs with advanced materials  

SciTech Connect

If the Geothermal Technology Division (GTD) is to meet its programmatic objectives in hydrothermal fluid production and energy conversion, it is essential that new materials of construction be available. Level III Program Objectives include (1) reducing the costs associated with lost circulation episodes by 30% by 1992, (2) reducing the costs of deep wells and directionally dried wells by 10% by 1992, (3) reducing well-cementing problems for typical hydrothermal wells by 20% by 1991, and (4) the development of a corrosion-resistant and low-fouling heat exchanger tube material costing no more than three times the cost of carbon steel tubes by 1991. The Brookhaven National Laboratory (BNL) materials program is focused on meeting these objectives. Currently, work is in progress on (1) high temperature chemical systems for lost circulation control, (2) advanced high temperature (300/sup 0/C), lightweight (approx. 1.1 g/cc), CO/sub 2/-resistant well cementing materials, (3) thermally conductive composites for heat exchanger tubing, and (4) ultra high temperature (600/sup 0/C) cements for magma wells. In addition, high temperature elastomer technology developed earlier in the program is being transferred for use in the Geothermal Drilling Organization programs on drill pipe protectors, rotating head seals, and blow-out preventors. Recent accomplishments and the current status of work in each subtask are summarized in the paper.

Kukacka, L.E.

1988-03-01

379

Photochemical conversion of solar energy in the environment. Book chapter  

SciTech Connect

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.)

Zepp, R.G.

1991-01-01

380

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

SciTech Connect

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)

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

1981-02-01

381

Amphoteric oxide semiconductors for energy conversion devices: a tutorial review.  

PubMed

In this tutorial review, we discuss the defect chemistry of selected amphoteric oxide semiconductors in conjunction with their significant impact on the development of renewable and sustainable solid state energy conversion devices. The effect of electronic defect disorders in semiconductors appears to control the overall performance of several solid-state ionic devices that include oxide ion conducting solid oxide fuel cells (O-SOFCs), proton conducting solid oxide fuel cells (H-SOFCs), batteries, solar cells, and chemical (gas) sensors. Thus, the present study aims to assess the advances made in typical n- and p-type metal oxide semiconductors with respect to their use in ionic devices. The present paper briefly outlines the key challenges in the development of n- and p-type materials for various applications and also tries to present the state-of-the-art of defect disorders in technologically related semiconductors such as TiO(2), and perovskite-like and fluorite-type structure metal oxides. PMID:23257778

Singh, Kalpana; Nowotny, Janusz; Thangadurai, Venkataraman

2013-03-01

382

Analysis of a direct energy conversion system using medium energy helium ions  

E-print Network

ANALYSIS OF A DIRECT ENERGY CONVERSION SYSTEM USING MEDIUM ENERGY HELIUM IONS A Thesis by JESSE JAMES CARTER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Ron Hart Committee Members, Leslie Braby Wayne Saslow Head of Department...

Carter, Jesse James

2006-08-16

383

Modeling and analysis of hybrid geothermal-solar thermal energy conversion systems  

E-print Network

Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy geothermal resources augmented with solar energy. The goal is to find cost-effective hybrid power cycles that take advantage of ...

Greenhut, Andrew David

2010-01-01

384

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...

385

Ocean thermal energy conversion plants : experimental and analytical study of mixing and recirculation  

E-print Network

Ocean thermal energy conversion (OTEC) is a method of generating power using the vertical temperature gradient of the tropical ocean as an energy source. Experimental and analytical studies have been carried out to determine ...

Jirka, Gerhard H.

386

Efficiency evaluation of oxygen enrichment in energy conversion processes  

SciTech Connect

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.

Bomelburg, H.J.

1983-12-01

387

Permanent Magnet Synchronous Generator-Based Standalone Wind Energy Supply System  

Microsoft Academic Search

In this paper, a novel algorithm, based on dc link voltage, is proposed for effective energy management of a stand- alone permanent magnet synchronous generator (PMSG)-based variable speed wind energy conversion system consisting of bat- tery, fuel cell, and dump load (i.e., electrolyzer). Moreover, by maintaining the dc link voltage at its reference value, the output ac voltage of the

C. N. Bhende; S. Mishra; Siva Ganesh Malla

2011-01-01

388

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

SciTech Connect

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.

Shepard, Kenneth L

2013-03-31

389

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

Microsoft Academic Search

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

Thomas F. Valone

2010-01-01

390

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

Microsoft Academic Search

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 1970s. 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

Thomas F. Valone

2010-01-01

391

Hierarchically structured carbon nanotubes for energy conversion and storage  

NASA Astrophysics Data System (ADS)

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.

Du, Feng

392

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

SciTech Connect

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.

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

1998-09-01

393

Chalmers University of Technology Henrik Thunman Department of Energy Conversion  

E-print Network

, dry ash free) 50% C, 6% H, 44% O Typical Elemental analysis for char during Conversion Balance of Element Species Carbon, Hydrogen, Oxygen Typical Elemental analysis for wood (on mass combustion situation (on mass, dry ash free)

394

Semiconductor Physics and Quantum Solar Energy Conversion PV-related research at CvO University Oldenburg  

E-print Network

Semiconductor Physics and Quantum Solar Energy Conversion PV-related research at CvO University Oldenburg GRECO Cvo UNI OL/ Nds.PV-Symp. 06-2009 semiconductor physics / quantum solar energy conversion;Semiconductor Physics and Quantum Solar Energy Conversion Semiconductor Physics and Quantum Solar Energy

395

On O-X mode conversion in a cold magnetized 2D inhomogeneous plasma in the electron cyclotron frequency range  

E-print Network

In this paper a reduced set of the partial differential wave equations valid in the conversion layer close to O-mode cutoff surface and accounting for the magnetic field 2D inhomogeneity with no restriction to an angle between the toroidal direction and the magnetic field direction is derived. An integral representation of a solution to the derived set of equation is given. For the particular case of small angle between O mode cut-off surface and X mode cut-off surface an explicit expressions for both the electric field components and the conversion coefficients are obtained and its properties are considered in details.

A. Popov

2006-09-27

396

Unit Conversions  

NSDL National Science Digital Library

This resource is a digital tool for performing unit conversions. It provides the additional feature of displaying cancellation of terms, enabling users to gain a deeper understanding of the mathematical processes involved in converting units. Users can convert among 25 quantities, including units such as force, temperature, energy, and current. Also available are less commonly used units, such as illuminance and magnetic flux. In addition, the calculations respect the number of significant figures. It is part of Web-Based Computer Aided Instruction, a set of free resources for teachers and learners.

Taha Mzoughi

397

Characterization of Coal and Biomass Conversion Behaviors in Advanced Energy Systems  

Microsoft Academic Search

Currently, energy from coal accounts for about 23% of the energy consumed in the United States and it is projected that coal use will increase over the next few decades. Because of the low efficiencies and high pollutant emission characteristics of present-day schemes for converting the energy in coal to useful energy, advanced energy conversion schemes having high efficiencies and

Reginald E. Mitchell; Paul A. Campbell; Liqiang Ma; Ilkka Saarenp

398

Biomass conversion Task 4 1988 program of work: International Energy Agency Bioenergy Agreement  

SciTech Connect

For biomass to meet its potential as an energy resource, conversion processes must be available which are both efficient and environmentally acceptable. Conversion can include direct production of heat and electricity as well as production of intermediate gaseous, liquid, and solid fuels. While many biomass conversion processes are commercially available at present, others are still in the conceptual stage. Additional research and development activities on these advanced concepts will be necessary to fully use biomass resources. Ongoing research on biomass conversion processes is being conducted by many nations throughout the world. In an effort to coordinate this research and improve information exchange, several countries have agreed to a cooperative effort through the International Energy Agency's Bioenergy Agreement (IEA/BA). Under this Agreement, Task IV deals specifically with biomass conversion topics. The cooperative activities consists of information exchange and coordination of national research programs on specific topics. The activities address biomass conversion in a systematic manner, dealing with the pretreatment of biomass prior to conversion, the subsequent conversion of the biomass to intermediate fuels or end-product energy, and then the environmental aspects of the conversion process. This document provides an outline of cooperative work to be performed in 1988. 1 fig., 2 tabs.

Stevens, D.J.

1987-12-01

399

Magnetic properties and energy-mapping analysis.  

PubMed

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

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

2013-01-28

400

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

SciTech Connect

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.

Cho, Suwon, E-mail: swcho@kgu.ac.kr [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do 443-760 (Korea, Republic of)] [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do 443-760 (Korea, Republic of); Kwak, Jong-Gu [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)] [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)

2014-04-15

401

A twisted wire-shaped dual-function energy device for photoelectric conversion and electrochemical storage.  

PubMed

A wire-shaped energy device that can perform photoelectric conversion and electrochemical storage was developed through a simple but effective twisting process. The energy wire exhibited a high energy conversion efficiency of 6.58?% and specific capacitance of 85.03??F?cm(-1) or 2.13?mF?cm(-2), and the two functions were alternately realized without sacrificing either performance. PMID:24740877

Sun, Hao; You, Xiao; Deng, Jue; Chen, Xuli; Yang, Zhibin; Chen, Peining; Fang, Xin; Peng, Huisheng

2014-06-23

402

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

E-print Network

efficiency limits Appl. Phys. Lett. 101, 073905 (2012); 10.1063/1.4746425 Improved power conversion efficiency of InP solar cells using organic window layers Appl. Phys. Lett. 98, 053504 (2011); 10 cases, predicts solar energy-conversion efficiencies of

Atwater, Harry

403

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

SciTech Connect

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.

Stevens, D.J.

1986-12-01

404

Efficient energy conversion from laser to proton beam in a laser-foil interaction  

SciTech Connect

Demonstrated is a remarkable improvement on the energy conversion efficiency from laser to protons in a laser-foil interaction by particle simulations. The total laser-proton energy conversion efficiency becomes 16.7%, although a conventional plane foil target serves a rather low efficiency. In our previous study we found that Al multihole thin-foil target was efficient for the energy conversion from laser to protons [Y. Nodera and S. Kawata, Phys. Rev. E 78, 046401 (2008)], and the energy conversion efficiency was 9.3%. In our 2.5-dimensional particle-in-cell simulations the Al multihole structure is also employed, and the parameters of the Al multihole wing width and length are optimized in the paper. The present results clarify the roles of the target Al hole width and depth in the laser-proton energy conversion. The main physical reason for the enhancement of the conversion efficiency is a reduction of the laser reflection at the target surface area. The optimized multihole foil target provides a remarkable increase in the laser-proton energy conversion efficiency as shown above.

Takahashi, K.; Kawata, S.; Satoh, D.; Barada, D. [Graduate School of Engineering, Utsunomiya University, 7-1-2 Yohtoh, 321-8585 Utsunomiya (Japan); Ma, Y. Y. [Graduate School of Engineering, Utsunomiya University, 7-1-2 Yohtoh, 321-8585 Utsunomiya (Japan); Department of Physics, College of Science, National University of Defense Technology, 410073 Changsha (China); Kong, Q.; Wang, P. X. [Institute of Modern Physics, Fudan University, 200433 Shanghai (China)

2010-09-15

405

Activation entropy, activation energy, and magnetic viscosity  

NASA Astrophysics Data System (ADS)

Starting from an exact quantum-statistical description, the influence of the shape of the energy landscape on the magnetic viscosity is investigated. Magnetic phase-space analysis based on Kramers' escape-rate theory of chemical reaction kinetics theory shows that the activation entropy associated with thermally activated hopping modifies the magnetic viscosity by reducing the attempt-frequency prefactor compared to an earlier prediction by Brown [W. F. Brown, Phys. Rev. 130, 1677 (1963)]. Energetic contributions are analyzed in terms of a model applicable to a range of coherent and noncoherent magnetization processes, and in the long-time limit deviations from the linear logarithmic magnetic-viscosity law are found.

Skomski, R.; Kirby, R. D.; Sellmyer, D. J.

1999-04-01

406

Dam-Atoll for concentration and conversion of ocean wave energy  

Microsoft Academic Search

A simple wave energy conversion device has recently been patented by Lockheed. The Dam-Atoll concept uses passive structure and the principle of wave refraction as the primary elements to convert wave energy into usable energy. Each unit can provide 1 to 2 MW in an area of adequate wave energy resource. Plans have been formulated for additional development work which

T. P. Higgins; C. P. Sherburne

1981-01-01

407

On the thermionic emission from nitrogen-doped diamond films with respect to energy conversion  

Microsoft Academic Search

Thermionic energy converters utilize thermal energy and efficiently transform it into more useful electrical energy. A key aspect in thermionic energy conversion is the emission of electrons at elevated temperatures, where the electron emitter is separated from the collector by a vacuum gap and a voltage is generated due to the temperature difference between the emitter and collector. In this

F. A. M. Koeck; J. M. Garguilo; R. J. Nemanich

2004-01-01

408

The behavior of magneto-acoustic-gravity waves near the cusp resonance in a lossless, compressible, isothermal, stratified, electrically conducting, and uniformly magnetized atmosphere. I. Mode conversion approach  

SciTech Connect

In the present paper the propagation of (internal) magneto-acoustic-gravitywaves is analyzed in a compressible, isothermal, stratified, electricallyconducting atmosphere that is permeated by a uniform, nearly horizontal magneticfield. The conversion, near the so-called cusp resonance of a longacoustic-gravity wave into a short slow magneto-acoustic wave, is demonstratedby means of boundary layer theory based on the smallness of the verticalcomponent of the magnetic field. The magneto-acoustic wave subsequently carriesthe energy off upward, which in the limit of a horizontal magnetic field wouldbe fed into the cusp resonance /ital ad//nfinitum/. This gives rise to singularfields. The scaling of the tendency toward singular behavior of a field quantitywith the obliqueness of the magnetic field is discussed, as well as the partialreflection of the long acoustic-gravity wave.

Kamp, L. P. J.

1989-07-01

409

Power conversion system utilizing reversible energy of liquefied natural gas  

Microsoft Academic Search

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

Hoskinson

1982-01-01

410

Energy Distribution in Melvin's Magnetic Universe  

E-print Network

We use the energy-momentum complexes of Landau and Lifshitz and Papapetrou to obtain the energy distribution in Melvin's magnetic universe. For this space-time we find that these definitions of energy give the same and convincing results. The energy distribution obtained here is the same as we obtained earlier for the same space-time using the energy-momentum complex of Einstein. These results uphold the usefulness of the energy-momentum complexes.

S. S. Xulu

1999-12-22

411

Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean  

E-print Network

A global estimate of the energy conversion rate from geostrophic flows into internal lee waves in the ocean is presented. The estimate is based on a linear theory applied to bottom topography at O(110) km scales obtained ...

Nikurashin, Maxim

412

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage  

E-print Network

Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit ...

Swallow, Jessica Gabrielle

413

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...

414

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...

415

Thick and Thin Film Polymer CNT Nanocomposites for Thermoelectric Energy Conversion and Transparent Electrodes  

E-print Network

gradient. Thermoelectric materials harvest electricity from waste heat or any temperature gradientThick and Thin Film Polymer ­ CNT Nanocomposites for Thermoelectric Energy Conversion in the environment. Polymers are intrinsically poor thermal conductors (desired behavior for thermoelectrics

Fisher, Frank

416

Exploring electron and phonon transport at the nanoscale for thermoelectric energy conversion  

E-print Network

Thermoelectric materials are capable of solid-state direct heat to electricity energy conversion and are ideal for waste heat recovery applications due to their simplicity, reliability, and lack of environmentally harmful ...

Minnich, Austin Jerome

2011-01-01

417

Exploring heat transfer at the atomistic level for thermal energy conversion and management  

E-print Network

Heat transfer at the scales of atoms plays an important role in many applications such as thermoelectric energy conversion and thermal management of microelectronic devices. While nanoengineering offers unique opportunities ...

Tian, Zhiting

2014-01-01

418

Use of a Conversational Computer Program in Operator Training for Improved Energy Efficiency  

E-print Network

Energy efficient operation of process equipment requires attentive operation by well-trained personnel. Use of a computer simulation model together with a conversational computer program, which provides dynamic game playing opportunities...

Brickman, S. W.; Mergens, E. H.

1980-01-01

419

Nanostructural engineering of vapor-processed organic photovoltaics for efficient solar energy conversion from any Surface  

E-print Network

More than two billion people in the world have little or no access to electricity. To be empowered they need robust and lightweightrenewable energy conversion technologies that can be easily transported with high yield ...

Macko, Jill Annette (Jill Annette Rowehl)

2014-01-01

420

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

NASA Technical Reports Server (NTRS)

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.

Lee, G.

1978-01-01

421

Recent developments in high-temperature photonic crystals for energy conversion  

E-print Network

After decades of intense studies focused on cryogenic and room temperature nanophotonics, scientific interest is also growing in high-temperature nanophotonics aimed at solid-state energy conversion. These latest extensive ...

Rinnerbauer, Veronika

422

Magnetic bearings for inertial energy storage  

NASA Technical Reports Server (NTRS)

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.

Rodriguez, G. Ernest; Eakin, Vickie

1987-01-01

423

The Magnetic Free Energy in Active Regions  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

424

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

DOEpatents

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.

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

2000-01-01

425

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes  

NASA Technical Reports Server (NTRS)

Thermionic conversion data obtained from a variable gap cesium diminiode with a hot pressed, sintered lanthanum hexaboride emitter and an arc melted lanthanum hexaboride collector are presented. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.

Kroeger, E. W.; Bair, V. L.; Morris, J. F.

1978-01-01

426

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes  

NASA Technical Reports Server (NTRS)

This paper presents thermionic-conversion data obtained from a variable-gap cesium diminiode with a hot-pressed, sintered lanthanum-hexaboride emitter and an arc-melted lanthanum-hexaboride collector. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.

Kroeger, E. W.; Bair, V. L.; Morris, J. F.

1978-01-01

427

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)

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.

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

1976-01-01

428

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

NASA Astrophysics Data System (ADS)

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.

Pratap, Alok; Urasaki, Naomitsu; Senju, Tomonobu

2013-10-01

429

Magnetic induction systems to harvest energy from mechanical vibrations  

E-print Network

This thesis documents the design process for magnetic induction systems to harvest energy from mechanical vibrations. Two styles of magnetic induction systems - magnet-through-coil and magnet-across-coils - were analyzed. ...

Jonnalagadda, Aparna S

2007-01-01

430

THE CONVERSION OF BIOMASS TO ETHANOL USING GEOTHERMAL ENERGY DERIVED FROM HOT DRY ROCK  

E-print Network

97505 THE CONVERSION OF BIOMASS TO ETHANOL USING GEOTHERMAL ENERGY DERIVED FROM HOT DRY ROCK of biomass to fuel ethanol is considerable. In addition, combining these two renewable energy resources -- geothermal energy derived from the vast resource of Hot Dry Rock (HDR) in our country, and biomass

431

Abstract--This paper addresses the problem of controlling wind energy conversion systems (WECS) which involve  

E-print Network

Abstract-- This paper addresses the problem of controlling wind energy conversion systems (WECS-inverter. The goal of control is to maximize wind energy extraction and this needs letting the wind turbine rotor wind energy extraction) only for one wind speed value depending on the considered value of turbine

Paris-Sud XI, Université de

432

Optimum control strategies in energy conversion of PMSG wind turbine system without mechanical sensors  

Microsoft Academic Search

The amount of energy obtained from a wind energy conversion system (WECS) depends not only on the characteristics of the wind regime at the site, but it also depends on the control strategy used for the WECS. In order to determine the gain in energy derived from one concept as compared against another, models of several autonomous WECS have been

Kelvin Tan; Syed Islam

2004-01-01

433

A novel thermomechanical energy conversion cycle Ian M. McKinley, Felix Y. Lee, Laurent Pilon  

E-print Network

, refrigeration, and heat pump cycles, according to the second law of thermodynamics [2]. In fact, many sourcesA novel thermomechanical energy conversion cycle Ian M. McKinley, Felix Y. Lee, Laurent Pilon of a novel cycle converting thermal and mechanical energy directly into electrical energy. The new cycle

Pilon, Laurent

434

High energy product in Battenberg structured magnets  

NASA Astrophysics Data System (ADS)

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.

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

435

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

SciTech Connect

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.

Leenheer, Andrew J.; Narang, Prineha; Atwater, Harry A., E-mail: haa@caltech.edu [Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, Pasadena, California 91125 (United States); Lewis, Nathan S. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, Pasadena, California 91125 (United States)

2014-04-07

436

Inter-machine comparison of the termination phase and energy conversion in tokamak disruptions with runaway current plateau formation and implications for ITER  

NASA Astrophysics Data System (ADS)

The termination of the current and the loss of runaway electrons following runaway current plateau formation during disruptions have been investigated in the JET, DIII-D and FTU tokamaks. Substantial conversion of magnetic energy into runaway kinetic energy, up to 10 times the initial plateau runaway kinetic energy, has been inferred for the slowest current terminations. Both modelling and experiment suggest that, in present devices, the efficiency of conversion into runaway kinetic energy is determined to a great extent by the characteristic runaway loss time, ?diff, and the resistive time of the residual ohmic plasma after the disruption, ?res, increasing with the ratio ?diff/?res. It is predicted that, in large future devices such as ITER, the generation of runaways by the avalanche mechanism will play an important role, particularly for slow runaway discharge terminations, increasing substantially the amount of energy deposited by the runaways onto the plasma-facing components by the conversion of magnetic energy of the runaway plasma into runaway kinetic energy. Estimates of the power fluxes on the beryllium plasma-facing components during runaway termination in ITER indicate that for runaway currents of up to 2 MA no melting of the components is expected. For larger runaway currents, minimization of the effects of runaway impact on the first wall requires a reduction in the kinetic energy of the runaway beam before termination and, in addition, high plasma density ne and low ohmic plasma resistance (long ?res) to prevent large conversion of magnetic into runaway kinetic energy during slow current terminations.

Martn-Sols, J. R.; Loarte, A.; Hollmann, E. M.; Esposito, B.; Riccardo, V.; FTU; DIII-D Teams; EFDA Contributors, JET

2014-08-01

437

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

PubMed

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

Herrmann, Sven; Ritchie, Chris; Streb, Carsten

2015-04-01

438

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

NASA Astrophysics Data System (ADS)

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.

Valone, Thomas F.

2010-01-01

439

Application of Nuclear Energy to Bitumen Upgrading and Biomass Conversion  

SciTech Connect

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)

Mamoru Numata; Yasushi Fujimura [JGC Corporation (Japan); Takayuki Amaya [Ministry of Education, Culture, Sports, Science and Technology - MEXT, Japan 2-5-1 Marunouchi Chiyoda-ku, Tokyo 100-8959 (Japan); Masao Hori [Nuclear Systems Association, 1-7-6 Toranomon Tokyo, 105-0001 (Japan)

2006-07-01

440

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

SciTech Connect

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.

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

1988-12-01

441

CESIUM PLASMA STUDIES FOR THERMIONIC ENERGY CONVERSION. Final Report  

Microsoft Academic Search

A new method for measuring the volume recombination coefficient a of ; thermal cesium plasmas in steady state has been devised and perfected. In this ; method, a thermal cesium plasma column is magnetically confined between two ; plasma generators. The plasma is generatcd by contact ionization and thermionic ; emission. The rate of plasma generation is controlled by the

R. C. Knechtli; J. Y. Wada

1962-01-01

442

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

443

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

444

Biomass Energy and Biochemical Conversion Processing for Fuels and Chemicals  

Microsoft Academic Search

Biomass, mainly in the form of wood, is the oldest form of energy used by humans. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles, and providing process heat for industrial facilities. Biomass potential includes wood and animal and plant wastes. Biomass, mainly now represents only 3% of primary energy consumption in

Mustafa Balat

2006-01-01

445

Investigations on the energy conversion in sonochemical processes  

Microsoft Academic Search

In the present work the energy transformation in sonochemical processes is studied by using electrical power measurement techniques and calorimetry. The influence of the ultrasonic amplitude and the properties of the irradiated medium on the efficiency of the equipment is shown. With increasing temperature and increasing solvent vapor pressure less energy can be brought into the fluid. More energy is

Jan-Martin Lning; Christian Horst; Ulrich Hoffmann

2002-01-01

446

The wells air turbine for wave energy conversion  

Microsoft Academic Search

The wave energy devices currently in operation in the United Kingdom and India and those that are to be built in Europe are based on the principle of the oscillating water-air column. In these devices the pneumatic energy of the oscillating air column is converted to mechanical energy of rotation by a Wells turbine. A monoplane (single plane) Wells turbine

S. Raghunathan

1995-01-01

447

Thermodynamic Inefficiency of Conversion of Solar Energy to Work.  

ERIC Educational Resources Information Center

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)

Adamson, Arthur W.; And Others

1984-01-01

448

Research on energy conversion mechanism of a screw centrifugal pump under the water  

NASA Astrophysics Data System (ADS)

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.

Quan, H.; Li, R. N.; Su, Q. M.; Han, W.; Cheng, X. R.; Shen, Z. J.

2013-12-01

449

High electrokinetic energy conversion efficiency in charged nanoporous nitrocellulose/sulfonated polystyrene membranes.  

PubMed

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

Haldrup, Sofie; Catalano, Jacopo; Hansen, Michael Ryan; Wagner, Manfred; Jensen, Grethe Vestergaard; Pedersen, Jan Skov; Bentien, Anders

2015-02-11

450

Higher-order lattice Boltzmann simulation of energy conversion of electrokinetic nanobatteries  

NASA Astrophysics Data System (ADS)

As a novel green technology to harvest electric power, electrokinetic batteries appeal to more theoretical investigation in order to optimize their physical parameters, and hence to achieve higher energy conversion efficiency at nanoscales as expected. Generally, transport phenomena at nanoscales are out of the scope of continuum fluid mechanics theories. In addition, the electric double layer (EDL) requires a more comprehensive description incorporating image effect and ion size effect. In this study, the higher-order Lattice Boltzmann method (LBM) and the modified Poisson-Boltzmann theory (MPB) are used to investigate electrokinetic phenomena in nanochannels. Energy conversion is studied in terms of ion size, and dielectric properties of liquid and solid. 24.95% mechanical-electrical energy conversion efficiency may be achieved in a 16 nm electrokinetic battery. And hence about 6% mechanical energy can be utilized by the external load of the electrokinetic nanobattery.

Liu, Y.; Yang, J.

2009-04-01

451

Potential environmental consequences of ocean thermal energy conversion (OTEC) plants. A workshop  

SciTech Connect

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.

Walsh, J.J. (ed.)

1981-05-01

452

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

PubMed

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

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

2014-01-01

453

A universal electromagnetic energy conversion adapter based on a metamaterial absorber  

PubMed Central

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

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

2014-01-01

454

A universal electromagnetic energy conversion adapter based on a metamaterial absorber  

E-print Network

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, solar cell, 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.

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

2013-01-01

455

A universal electromagnetic energy conversion adapter based on a metamaterial absorber  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

456

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

SciTech Connect

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.

Meneghini, Orso [ORAU, Oak Ridge, Tennessee (United States); Choi, Myunghee [IMSOL-X, San Diego, California (United States); Volpe, Francesco [Columbia University, New York, New York (United States)

2014-02-12

457

A variable speed wind energy conversion scheme for connection to weak AC systems  

Microsoft Academic Search

A three level control system for a variable speed wind energy conversion scheme (VSWECS) supplying a weak AC power system is presented. The objective of the control strategy is to maximize energy capture and simultaneously to support the voltage of the bus where the VSWECS is connected. Using an insulated gate bipolar transistor (IGBT) inverter, both control of active and

A. S. Neris; N. A. Vovos; G. B. Giannakopoulos

1999-01-01

458

Probabilistic performance assessment of autonomous solar-wind energy conversion systems  

Microsoft Academic Search

This paper describes the development of a general probabilistic model of an autonomous solar-wind energy conversion system (SWECS) composed of several wind turbines (wind farm), several photovoltaic (PV) modules (solar park), and a battery storage feeding a load. The model takes into consideration outages due to the primary energy fluctuations and hardware failure. It allows the simulation of wind farms

S. H. Karaki; R. B. Chedid; R. Ramadan

1999-01-01

459

Sep 05:"Toward Computational Design of Iron-Based Chromophores for Solar Energy Conversion"  

E-print Network

Sep 05:"Toward Computational Design of Iron-Based Chromophores for Solar Energy Conversion, Department of Biochemistry, East Carolina University (Dept) Nov 21: "Taking snapshots along the solar energy and Organic-Metal Halide Perovskites for Next Generation Solar Cells" Professor Prashant Kamat, Department

Reid, Scott A.

460

Wave Energy Conversion in Restricted Waters by a Heaving Cylinder\\/Linear--lnductance System  

Microsoft Academic Search

Results of an experimental study of a heaving wave energy converter are presented. The heaving system consists of a vertical, right, circular cylinder equipped with a linear-inductance electromechanical energy conversion device. The results show that open circuit resistance has little effect on the response of the heaving system. Furthermore, by closing the electrical circuit with a variable resistor, the performance

M. McCormick; D. Johnson; R. Hebron; J. Hoyt

1981-01-01

461

Wave energy conversion with an oscillating water column on a fixed offshore platform  

Microsoft Academic Search

The purpose of this study is to examine the feasibility of practical wave energy conversion using an oscillating water column (OWC) and a counter-rotating turbine on a fixed offshore platform. A linear array of such platforms along a coastline, with the power transmitted ashore by submarine cable, constitutes the type of wave energy powerplant discussed herein. The OWC concept utilizes

W. L. Green; J. J. Campo; J. B. Miles; J. A. Miller; J. E. Parker

1983-01-01

462

Conversion of chemical into mechanical energy by synthetic polymers (chemomechanical systems)  

Microsoft Academic Search

The isothermal conversion of chemical energy into mechanical work underlies the motility of living organisms. Chemomechanical systems based on synthetic polymers are the only artificial systems able to convert chemical energy directly into mechanical work. They may have potential uses where power supply is limited (e.g. under water, in space). They are considered as transducers or receptors, whereby semimicroscopic deformation

Yoshihito Osada

463

January 2011: ME 533-Energy Conversion Dr. William M. Carey, Professor of Mechanical Engineering  

E-print Network

the potential on a national and regional basis, 3.)performing a thermal analysis of the system, 4.)performing, and Solar Energy Conversion Systems employing vapor power and gas power cylces.2.) The analysis of renewable a comparative analysis with alternatives, 5.) performing a cost and energy cost analysis, 6.) assessment

464

2012: ME 533-Energy Conversion Dr. William M. Carey, Professor of Mechanical Engineering  

E-print Network

the potential on a national and regional basis, 3.)performing a thermal analysis of the system, 4.)performing, and Solar Energy Conversion Systems #12;employing vapor power and gas power cylces.2.) The analysis a comparative analysis with alternatives, 5.) performing a cost and energy cost analysis, 6.) assessment

465

Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses  

ERIC Educational Resources Information Center

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

Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

2013-01-01

466

New Generic Approach for the Analysis of Energy Conversion System Models  

Microsoft Academic Search

This paper proposes a new approach in the field of energy conversion systems analysis and synthesis. The method is based on a generic and multi-platform description syntax, that clearly separates the information concerning the physical behavior of the modeled technology (e.g. mass and energy balances and chemical reactions) from the information necessary to apply one or more system analysis methods

Raffaele Bolliger; Helen Beckera; Franois Marchal

2009-01-01

467

Graphene-based photovoltaic cells for near-field thermal energy conversion  

E-print Network

Graphene-based photovoltaic cells for near-field thermal energy conversion Riccardo Messina to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular important source of energy. By approaching a photovoltaic (PV) cell3 in proximity of a thermal emitter

Paris-Sud XI, Université de

468

Vibration-to-electric energy conversion using a mechanically-varied capacitor  

E-print Network

Past research in vibration energy harvesting has focused on the use of variable capacitors, magnets, or piezoelectric materials as the basis of energy transduction. How- ever, few of these studies have explored the detailed ...

Yen, Bernard Chih-Hsun, 1981-

2005-01-01