SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 1 - January 13, 2006
44 ENERGY PRODUCTION AND CONVERSION
Includes specific energy conversion systems, e.g., fuel cells; and solar, geothermal, windpower, and waterwave conversion systems; energy storage; and traditional power generators.
For technologies related to nuclear energy production see 73 Nuclear Physics.
For related information see also 07 Aircraft Propulsion and Power; 20 Spacecraft Propulsion and Power; and 28 Propellants and Fuels.
20060001874 Aerospace Corp., El Segundo, CA USA
Failure Model for a Leaking Nickel-Hydrogen
CellZimmerman, A. H.; Aug. 30, 2005; 19 pp.; In English; Original contains color illustrationsContract(s)/Grant(s): FA8802-04-C-0001Report No.(s): AD-A440426; ATR-2005(8555)-6; SMC-TR-06-02; No Copyright; Avail.: CASI: A03, Hardcopy
A model has been developed and used to analyze the loss of capacity and dry out of nickel-hydrogen cells as a result ofpressure vessel leaks. This analysis has allowed a number of conclusions to be drawn about the behavior of nickel-hydrogencells with leaks: Cells that are repeatedly cycled may not lose all capacity by leaking their hydrogen. There is a leak sizethreshold at 1-2.5 um below which nickel-hydrogen cells will not dry out by gas. There is a leak size threshold at 0.1-0.2 umbelow which it will be difficult to identify the rate of capacity loss as differing significantly from normal wear-related capacityloss rates. Pre-existing leaks smaller than about 0.1 um cannot be detected by typical leak detection methods. Leak latencycan occur if pre-existing subthreshold leaks grow in size during the cell operation. DTIC
Failure; Hydrogen; Leakage; Models
20060002036 Army Construction Engineering Research Lab., Champaign, IL USA
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Energy Trends and Their Implications for U.S. Army Installations
Fournier, Donald F.; Westervelt, Eileen T.; Sep. 1, 2005; 86 pp.; In English; Original contains color illustrationsReport No.(s): AD-A440265; ERDC/CERL-TR-05-21; No Copyright; Avail.: Defense Technical Information Center (DTIC)
The primary issues affecting energy options are those of availability, affordability, sustainability, and security. Sinceenergy resources are unevenly distributed around the world, and the impacts of energy consumption have global reach in bothenvironmental and political terms, any meaningful review of energy-related issues must take a global perspective. This worksynopsizes world and national energy issues (including energy source options, resource stocks, and future prognosis) in thecontext of how Army installations need to respond to changing trends. This report presents implications of actions that maybe taken in response to the national and world energy situation, to help the Army to make informed choices on energyutilization that will contribute to sustaining the Army’s mission. DTIC
Energy Consumption; Trends
20060002037 Army Communications-Electronics Command, Fort Belvoir, VA USA
Test and Evaluation of the Smart Fuel Cell C20-MP Direct Methanol Hybrid Fuel Cell System as a Soldier PowerSource
Cristiani, Jonathan; Sifer, Nicholas; Bolton, Christopher; Bostic, Elizabeth; Campbell, William; Cross, James; DuBois, Terry;Fomin, Pavel; Patil, Ashok; Reckart, Darwin; Oct. 31, 2005; 17 pp.; In EnglishReport No.(s): AD-A440442; APD-ES-05-10-001; No Copyright; Avail.: CASI: A03, Hardcopy
Recent advances in fully integrated, portable fuel cell system development have highlighted the potential benefits theymight offer to military users in the near term. Soldier power (1 watt - 100 watts direct current) fuel cell applications have seensignificant attention of late due to challenges in ongoing operations to meet power demands for the Warfighter’s equipment.This challenge has resulted in the use of secondary (rechargeable) batteries in the field, something that was only done intraining exercises prior to recent operations. Consequently, the logistics burden for dismounted Soldiers on missions longerthan 24 hours has become quite arduous. As such, the growing need for lightweight, rugged, and environmentally benignsoldier power systems has been targeted as an excellent entry market for portable fuel cell systems. DTIC
Evaluation; Fuel Cells; Methyl Alcohol; Supplying; System Effectiveness
20060002196 National Renewable Energy Lab., Golden, CO USA
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Improved Performance in CulnSe2 and Surface-Modified CuGaSe2 Solar Cells
AbusShama, J.; Noufi, R.; Johnston, S.; Ward, S.; Wu, X.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016461; NREL/CP-520-37411; No Copyright; Avail.: Department of Energy Information Bridge
In this paper, we present an update and review on the progress made in the development of low-bandgap CuInSe2 (CIS) and wide-bandgap CuGaSe2 (CGS) solar cells. Our research project is a primarily concerned with the optimization of the bottom and top cells of the tandem solar cell. This past year, we established new record total-area efficiencies of 15.0% and 10.2% for CIS and surface-modified CGS solar cells, respectively. These achievements were possible by modifying the growth process for CIS and CGS absorbers. We attempt to modify the surface region of the CGS absorber to be CIGS-like in composition.We also have designed a mechanical-stacked tandem solar cell where the 15% CIS cell serves as the bottom cell. The NREL-confirmed total-area efficiency for this tandem device is 15.31%. NTIS
Solar Cells; Copper Selenides; Indium Compounds; Energy Gaps (Solid State)
20060002197 National Renewable Energy Lab., Golden, CO USA
Analysis of Depletion-Region Collection in GalanNAs Solar Cells
Friedman, D. J.; Ptak, A. J.; Kurtz, S. R.; Geisz, J. F.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016462; NREL/CP-520-37418; No Copyright; Avail.: Department of Energy Information Bridge
We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf’s equations for the QE including a drift field E, and model E as being equal to the junction built-in voltage distributed uniformly across the depletion region. This allows us to calculate the QE as a function of L and depletion width WD. We show that if L is sufficiently small, increasing WD can actually decrease the QE. To determine how long L needs to be in a practical GaInNAs junction, we calculate from the QE the short-circuit current density as a function of WD and L. This allows us to estimate that L(sub ambipolar) needs to be greater than roughly 1 (micro)m in order to obtain enough photocurrent for the 4-junction application, giving guidance to the experimental effort to develop such cells. NTIS
Depletion; Solar Cells; Electric Potential; Short Circuit Currents
20060002201 National Renewable Energy Lab., Golden, CO USA
Experiments Involving Correlations Between CdTe Solar Cell Fabrication History and Intrinsic Device Stability
Albin, D.; McMahon, T.; Berniard, T.; Pankow, J.; Noufi, R.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016465; NREL/CP-520-37426; No Copyright; Avail.: Department of Energy Information Bridge
An orthogonal full-factorial design was used to study the effect of CdS and CdTe layer thickness, oxygen ambient during vapor CdCl(sub 2) (VCC) and the use of nitric-phosphoric (NP) acid as a pre-contact etch on the initial and stressed performance of CdS/CdTe small-area devices. The best initial device efficiency (using thinner CdS, thicker CdTe, no oxygen during VCC, and NP etch) also showed poor stability. Increasing the CdS thickness significantly improved stability with only a slight decrease in resulting initial performance. All devices used a thin margin of CdTe around the perimeter of the backcontact that was shown to significantly reduce catastrophic degradation and improve overall test statistics. The latter degradation is modeled by the formation of a weak-diode/low shunt resistance localized near the edge of finished devices. This shunting is believed to occur through the CdS/CdTe interface, rather than along the device edge, and is exacerbated by thinner CdS films. NTIS
Cadmium Tellurides; Correlation; Fabrication; Solar Cells; Stability
20060002204 National Renewable Energy Lab., Golden, CO USA
Rapid Mapping of AR Coating Thickness on Si Solar Cells Using GT-FabScan 6000
Sopori, B.; Amieva, J.; Butterfield, B.; Li, C.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016489; NREL/CP-520-37478; No Copyright; Avail.: National Technical Information Service (NTIS)
A new technique for rapid mapping of the thickness of an antireflection (AR) coating on a solar cell is described. A filtered, reflectance (intensity) image of the AR-coated wafer is generated by a CCD camera mounted on a GTFabScan. This image is converted into a thickness image using a transformation relating local AR thickness to the local intensity in the image plane. The thickness map is generated in less than 100 ms. NTIS
Antireflection Coatings; Coating; Solar Cells; Thickness
20060002206 National Renewable Energy Lab., Golden, CO USA
Direct Write Contacts for Solar Cells
Kaydanova, T.; van Hest, M. F. A. M.; Miedaner, A.; Curtis, C. J.; Alleman, J. L.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016490; NREL/CP-520-37524; No Copyright; Avail.: Department of Energy Information Bridge
Ag, Cu, and Ni metallizations were inkjet-printed with near-vacuum deposition quality. The approach developed can be easily extended to other conductors such as Pt, Pd, and Au. Thick, highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and PCB have been printed at 100-200 deg C in air and N(sub 2), respectively. Ag grids were inkjet-printed on Si solar cells and fired through the silicon nitride antireflective layer at 850 deg C resulting in 8%-efficient cells. Next-generation multicomponent inks (including etching agents) have also been developed with improved fire-through contacts leading to higher cell efficiencies. PEDOT-PSS polymer-based conductors were inkjet-printed with conductivity as good or better than that of spin-coated films. NTIS
Printing; Solar Cells
20060002208 National Renewable Energy Lab., Golden, CO USA
High-Throughput Approaches to Optimization of Crystal Silicon Surface Passivation and Heterojunction Solar Cells
Wang, Q.; Page, M.; Yan, Y.; Wang, T.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016491; NREL/CP-520-37439; No Copyright; Avail.: Department of Energy Information Bridge
We use a high-throughput (combinatorial) hot-wire chemical vapor deposition system to passivate the crystal silicon surface and to grow heterojunction silicon solar cells. We study the effectiveness of crystal surface treatments by atomic H or/and NH(sub x) radicals, followed by the growth of thin hydrogenated amorphous silicon (a Si:H) films. Treatment and layer properties such as times, thicknesses, and gas mixtures can be continuously graded, creating a two-dimensional sample with each variable varying in one direction. This results in high-throughput optimization of the processes. Effective carrier lifetime is measured by photoconductive decay to evaluate the effectiveness of the surface passivation by surface treatments. The effective carrier lifetime increases from about 5 (micro)s without passivation to about 24 (micro)s with an optimized surface treatment and thickness a-Si:H on single-sided c-Si. Transmission electron microscopy reveals that a-Si:H, a mixed phase, or epitaxial growth of thin-film Si depending on the surface treatment. Improvement in effective carrier lifetime correlates with an immediate a-Si:H growth on c-Si, rather than a mixed phase and epitaxial Si growth. We have obtained an efficiency of 13.4% on a non-textured single-sided heterojunction solar cell on p-type CZ-Si processed with optimized surface treatment. NTIS
Crystal Surfaces; Crystals; Heterojunction Devices; Passivity; Silicon; Solar Cells; Vapor Deposition
20060002209 National Renewable Energy Lab., Golden, CO USA
Relationship of Recombination Lifetime and Dark Current In Silicon p-n Junctions
Ahrenkiel, R. K.; Metzger, W.; Page, M.; Reedy, R.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016492; NREL/CP-520-37438; No Copyright; Avail.: National Technical Information Service (NTIS)
Measurement of recombination and minority-carrier lifetimes has become a central activity in photovoltaic technology. The primary measurement techniques for silicon technologies are based on photoconductive decay (PCD) and microwave reflectance (mPCD). The measurement of the correct recombination lifetime depends on the carriers being confined to a given spatial region of a diagnostic structure. The internal electric fields separate the charges, and the measured value does not represent the real minority-carrier lifetime. In these cases, the measured quantity is a function of the true lifetime and the sample structure. Here, we examine these effects, both experimentally and theoretically, for the n(sup +)-p device structure common to terrestrial photovoltaics. NTIS
Dark Current; P-N Junctions; Silicon; Silicon Junctions
20060002210 National Renewable Energy Lab., Golden, CO USA
Comprehensive Model of Hydrogen Transport into a Solar Cell During Silicon Nitride Processing for Fire-Through Metallization
Sopori, B.; Reedy, R.; Jones, K.; Al-Jassim, M.; Aug. 2004; 12 pp.; In English Report No.(s): DE2005-15016499; NREL/CP-520-37477; No Copyright; Avail.: National Technical Information Service (NTIS)
A mechanism for the transport of H into a Si solar cell during plasma-enhanced chemical vapor deposition (PECVD) of a hydrogenated silicon nitride (SiN:H) layer and its subsequent fire-through metallization process is described. The PECVD process generates process-induced traps, which ‘’store’’ H at the surface of the solar cell. This stored H is released and diffuses rapidly into the bulk of Si during the high-temperature metallization-firing process. During the ramp-down, the diffused H associates with impurities and defects and passivates them. The firing step partially heals up the surface damage. The proposed model explains a variety of observations and experimental results. NTIS
Fires; Hydrogen; Metallizing; Silicon Nitrides; Solar Cells
20060002211 National Renewable Energy Lab., Golden, CO USA
Effective Interfaces in Silicon Heterojunction Solar Cells
Wang, T. H.; Iwaniczko, E.; Page, M. R.; Levi, D. H.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016495; NREL/CP-37457; No Copyright; Avail.: National Technical Information Service (NTIS)
This paper reviews the current commercial status of CuInSe2 alloys (collectively, CIS) and CdTe-based photovoltaic (PV) modules, comparing the performance of commercial products with the results achieved for solar cell and prototype module champions. We provide an update for these PV cell and module technologies, and also compare CIS and CdTe performance levels to the results achieved by the crystalline Si PV industry. This comparison shows that CIS and CdTe module technology presently offers the best (and perhaps only) approach for significantly exceeding the cost/performance levels established by crystalline Si PV technologies. A semi-empirical methodology is used for comparing ‘’champion’’ solar cell and prototype module data with performance achieved on manufacturing lines. Using a conservative assumption that thin-film technologies will eliminate the 40% of PV module costs arising from the Si wafer or ribbon, we estimate the future performance of all established PV module candidates, and conclude that, based on 2004 knowledge about each PV technology, CIS and CdTe should provide cost-competitive advantages over crystalline Si. NTIS
Heterojunction Devices; Heterojunctions; Silicon; Solar Cells
20060002212 National Renewable Energy Lab., Golden, CO USA
Enhanced-Depletion-Width GalnNAs Solar Cells Grown by Molecular-Beam Epitaxy
Ptak, A. J.; Friedman, D. J.; Kurtz, S.; Kiehl, J.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016500; NREL/CP-520-37479; No Copyright; Avail.: Department of Energy Information Bridge
GaInNAs, potentially useful in a 4-junction GaInP(sub 2)/GaAs/GaInNAs/Ge solar cell, suffers from very low minority-carrier collection lengths. To date, the currents available from GaInNAs solar cells are not high enough to increase the efficiency of a 3-junction device by adding this fourth junction. Here, we grow p-i-n GaInNAs solar cells by molecular-beam epitaxy with wide, intrinsic base layers and internal quantum efficiencies near 1.0. If similar 1.0-eV GaInNAs junctions can be successfully integrated into the 3-junction structure, the resulting 4-junction cell would have a higher efficiency. NTIS
Depletion; Molecular Beam Epitaxy; Solar Cells
20060002226 National Renewable Energy Lab., Golden, CO USA
Performance Parameters for Grid-Connected PV Systems
Marion, B.; Adelstein, J.; Boyle, K.; Hayden, H.; Hammond, B.; Feb. 2005; 14 pp.; In English Report No.(s): DE2005-15016389; NREL/CP-520-37358; No Copyright; Avail.: Department of Energy Information Bridge
The use of appropriate performance parameters facilitates the comparison of grid-connected photovoltaic (PV) systems that may differ with respect to design, technology, or geographic location. Four performance parameters that define the overall system performance with respect to the energy production, solar resource, and overall effect of system losses are the following: final PV system yield, reference yield, performance ratio, and PVUSA rating. These performance parameters are discussed for their suitability in providing desired information for PV system design and performance evaluation and are demonstrated for a variety of technologies, designs, and geographic locations. Also discussed are methodologies for determining system a.c. power ratings in the design phase using multipliers developed from measured performance parameters. NTIS
Photovoltaic Effect; Solar Energy
20060002355 National Renewable Energy Lab., Golden, CO USA
Excess Dark Currents and Transients in Thin-Film CdTe Solar Cells: Implications for Cell Stability and Encapsulation of Scribe Lines and Cell Ends in Modules
McMahon, T. J.; Berniard, T. J.; Albin, D. S.; Demtsu, S. H.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016455; NREL/CP-520-37380; No Copyright; Avail.: Department of Energy Information Bridge
We have isolated a non-linear, metastable, shunt-path failure mechanism located at the CdS/CdTe cell edge. In such cases, most performance loss, usually erratic, can be associated with the shunt path. We studied these shunt paths using dark current-transients and infrared (ir) imaging and find only one shunt path per cell and only at the cell corner wall, even in badly degraded cells. The effect on diminishing the cell’s efficiency far exceeds what would be expected from the cell’s linear shunt-resistance value. We propose that current transients and ir imaging be used as a ‘’fingerprint’’ of the source and magnitude of excess currents to evaluate the contribution of scribe-line edges and cell ends in thin-film module performance and degradation due to environmental stress. Protection afforded by, or contamination due to, new or currently used encapsulants can then be evaluated. NTIS
Cadmium Tellurides; Encapsulating; Modules; Solar Cells; Stability; Thin Films
20060002356 National Renewable Energy Lab., Golden, CO USA
Diamond-Like Carbon Coatings as Encapsulants for Photovoltaic Solar Cells
Pern, F. J.; Touryan, K.; Panosyan, Z.; Gippius, A. A.; Kontsevoy, J. A.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016452; NREL-CP-520-37374; No Copyright; Avail.: Department of Energy Information Bridge
High-quality single-layer and bilayer diamond-like carbon (DLC) thin films are fabricated by two technologies, namely, ion-assisted plasma-enhanced deposition (IAPED) and electron cyclotron resonance (ECR) deposition. Deposition on various substrates, such as sapphires and solar cells, has been performed at low substrate temperatures (50 (approx) 80 C). The two deposition technologies allow good control over the growth conditions to produce DLC films with desired optical properties, thickness, and energy bandgap. The bilayer-structured DLC can be fabricated by using IAPED for the bottom layer followed by ECR for the top layer, or just by IAPED for both layers with different compositions. The DLC films have shown good spatial uniformity, density, microhardness, and adhesion strength. They exhibit excellent stability against attack by strong acids, prolonged damp-heat exposure at 85 C and 85% relative humidity, mechanical scratch, ultrasonication, and irradiation by ultraviolet (UV), protons, and electrons. When deposited on crystalline Si and GaAs solar cells in single-layer and/or bilayer structure, the DLC films not only serve as antireflection coating and protective encapsulant, but also improve the cell efficiencies. NTIS
Carbon; Diamonds; Encapsulating; Photovoltaic Cells; Solar Cells
20060002357 National Renewable Energy Lab., Golden, CO USA
Properties of High-Efficiency CIGS Thin-Film Solar Cells
Ramanathna, K.; Keane, J.; Noufi, R.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016459; NREL/CP-520-37404; No Copyright; Avail.: Department of Energy Information Bridge
We present experimental results in three areas. Solar cells with an efficiency of 19% have been fabricated with an absorber bandgap in the range of 1.1-1.2 eV. Properties of solar cells fabricated with and without an undoped ZnO layer were compared. The data show that high efficiency cells can be fabricated without using the high-resistivity or undoped ZnO layer. Properties of CIGS solar cells were fabricated from thin absorbers (1 (micro)m) deposited by the three-stage process and simultaneous co-deposition of all the elements. In both cases, solar cells with efficiencies of 16%-17% are obtained. NTIS
Solar Cells; Thin Films
20060002358 National Renewable Energy Lab., Golden, CO USA
On-Sun Comparison of GaInP2/GaAs Tandem Cells with Top Cell Thickness Varied
McMahon, W. E.; Emergy, K. E.; Friedman, D. J.; Ottoson, L.; Young, M. S.; Feb. 2005; 12 pp.; In English Report No.(s): DE2005-15016451; NREL/CP-520-37376; No Copyright; Avail.: Department of Energy Information Bridge
This study compares the on-sun performance of a set of GaInP2/GaAs tandem cells with different GaInP2 top-cell thicknesses. Because high-efficiency III-V cells are best suited to concentrating photovoltaic (CPV) applications, the cells were mounted on a two-axis tracker with the incident sunlight collimated to exclude all except the direct beam. Current-voltage (I-V) curves were taken throughout the course of several days, along with measurements of the direct solar spectrum. Our two major conclusions are: (1) GaInP2/GaAs tandem cells designed for an ‘air mass 1.5 global’ (AM 1.5G) or a ‘low aerosol optical depth’ (Low AOD) spectrum perform the best, and (2) cells can be characterized indoors and modeled using outdoor spectra to predict the correct result. These results are equally valid for GaInP2/GaAs/Ge triple-junction cells. NTIS
Evaluation; Gallium Arsenides; Performance Tests; Solar Cells; Sun; Thickness
20060002369 National Renewable Energy Lab., Golden, CO USA
Hathaway ‘Solar Patriot’ House: A Case Study in Efficiency and Renewable Energy
Norton, P.; Hancock, E.; Barker, G.; Reeves, P.; May 2005; 64 pp.; In English Report No.(s): DE2005-15016267; NREL/TP-550-37731; No Copyright; Avail.: National Technical Information Service (NTIS)
This report details the monitored and modeled performance of a solar home outside ofWashington, D.C.We modeled the home energy performance using DOE2.2, performed numerous short-terms tests on the home and monitored its occupied performance for 29 months. The home uses modular construction, solar water heating, a ground-coupled heat pump, efficient appliances and compact fluorescent lighting to reduce its energy consumption by 35% compared to the Building America research benchmark home. The addition of 6kW of photovoltaics increases the savings to 67% compared to the Building America research benchmark. A more efficient shell to reduce space conditioning loads would have brought the home closer to its zero energy goals. However, even with efficient lighting and appliances, the lights, appliance and plug loads are a significant energy consumer. About 4 kWof PV are required to meet the needs of these loads alone. To achieve the zero energy goal with no further efficiency increases, the Hathaway house would need about 2.6 kW of PV in addition to the 6.0 kW it now has. NTIS
Energy Conservation; Evaluation; Performance Tests; Renewable Energy; Solar Houses
20060002391 National Renewable Energy Lab., Golden, CO USA
Crystalline Silicon Short-Circuit Current Degradation Study: Initial Results
Osterwald, C. R.; Pruett, J.; Moriarty, T.; Feb. 2005; 1 pp.; In English Report No.(s): DE2005-15016390; NREL-CP-520-37357; No Copyright; Avail.: Department of Energy Information Bridge
Following our observation of slow degradation of short-circuit current (Isc) in crystalline silicon (x-Si) modules that was correlated with ultraviolet (UV) exposure dose, we initiated a new study of individual x-Si cells designed to determine the degradation cause. In this paper, we report the initial results of this study, which has accumulated 1056 MJ/m2 of UV dose from 1-sun metal-halide irradiance, equivalent to 3.8 years at our test site. At this time, the control samples are unchanged, the unencapsulated samples have lost about 2% of Isc, and the samples encapsulated in module-style packages have declined from 1% to 3%, depending on the cell technology. NTIS
Crystallinity; Degradation; Exposure; Modules; Photovoltaic Conversion; Short Circuit Currents; Silicon
20060002399 Case Western Reserve Univ., Cleveland, OH USA
A Micro Hydrogen Air Fuel Cell
Savinell, Robert F.; Wainright, Jesse S.; Oct. 1, 2005; 119 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): F30602-97-2-0311; DARPA ORDER-J346; Proj-E117 Report No.(s): AD-A440192; AFRL-IF-RS-TR-2005-351; No Copyright; Avail.: Defense Technical Information Center (DTIC)
The object of this project is to produce a microfabricated hydrogen-air fuel cell by combining microfabrication techniques, polymer electrolyte fuel cell technology, and metal hydride fuel storage. The result will be a device capable of providing on-board electrical power for microelectronic circuits, sensors, and actuators with energy storage and power delivery capabilities considerably greater than that of thin-film batteries. Integrated packages of fuel cells (up to three cells in series) and fuel storage/hydrogen generation have been successfully fabricated and tested. Each of the major milestones has been achieved and the fabrication yields and device performance have been improved.We have also been looking for insertion opportunities and partners with which to develop this technology. Recently, we have signed an agreement of collaboration with The Ash lawn Group, LLC, of Alexandria, VA to develop this technology to provide power for ‘smart’ munitions. DTIC
Hydrogen Oxygen Fuel Cells; Microelectronics
20060002440 National Renewable Energy Lab., Golden, CO USA
InGaAs/GaAs QD Superlattices: MOVPE Growth, Structural and Optical Characterization, and Application in Intermediate-Band Solar Cells
Norman, A. G.; Hanna, M. C.; Dippo, P.; Levi, D. H.; Feb. 2005; 14 pp.; In English Report No.(s): DE2005-15016460; NRLE-C/-520-37405; No Copyright; Avail.: National Technical Information Service (NTIS)
We report on the growth and characterization of InGaAs/GaAs quantum dot (QD) superlattices for application in intermediate-band solar cells (IBSCs). Good optical and structural quality QD superlattices with up to 50 periods were obtained by metal-organic vapor-phase epitaxy (MOVPE) growth on (l brace)113(r brace)B GaAs substrates. Solar cells containing Si (partial derivative)-doped and undoped QD superlattice absorption regions have been fabricated and their performance compared with control cells containing undoped GaAs or undoped InGaAs/GaAs superlattice absorption regions. The QD superlattice cells exhibited photoresponses extended to longer wavelengths than the control cells. The introduction of QDs to the absorbing region of the solar cells resulted in a decrease in the open-circuit voltages and, in some cases, a decrease in the short-circuit currents of the cells. NTIS
Characterization; Gallium Arsenides; Indium Gallium Arsenides; Solar Cells; Superlattices
20060002453 NVE Corp., Eden Prairie, MN USA
Compact, Lightweight, Smart Battery Charger
Beech, Russell S.; Oct. 26, 2005; 55 pp.; In English Contract(s)/Grant(s): W15P7T-04-C-K604 Report No.(s): AD-A440548; CECOM/RDEC-0003AB; No Copyright; Avail.: CASI: A04, Hardcopy
A rugged, level-3 smart battery charger was developed and delivered to the Army. This compact, lightweight charger weighs 22.5 ounces and has a volume of 55 cubic inches. The charger accepts either a universal AC input or a 19-28 VDC input and charges at up to 18 V and 5 A. A daisy-chain capability is included, allowing up to 10 units to be connected to a single power outlet. The operating temperature range is -20 deg C to +55 deg C. Test units passed specified environmental tests including: altitude, humidity, thermal shock, vibration, loose cargo, and drop. Status and error indicators provide visual operating information, and a black-out feature provides on-off control of the indicators. DTIC
Battery Chargers; Smart Materials
Source: NASA
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