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0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1-eV)/GaInAs(0.7-eV) Four-Junction Solar Cell: Preprint

Description: We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga0.5In0.5P/GaAs/Ga0.75In0.25As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga0.75In0.25As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap GaxIn1-xAs fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the GaxIn1-xAs fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.
Date: May 1, 2006
Creator: Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W. & Kurtz, S. R.
Partner: UNT Libraries Government Documents Department

1,3-Propanediol Made From Fermentation-Derived Malonic Acid: Office of Industrial Technologies (OIT) Agriculture Project Fact Sheet

Description: 1,3-Propanediol is one of two ingredients used in producing polytrimethylene terephthalate (PTT), a polymer which can be used in polyester and nylon applications. Researchers are developing a process to ferment biomass feedstock to malonic acid using filamentous fungi and then catalytically convert malonic acid to 1,3-propanediol.
Date: September 12, 2001
Creator: Carde, T.
Partner: UNT Libraries Government Documents Department

1?10 kW Stationary Combined Heat and Power Systems Status and Technical Potential: Independent Review

Description: This independent review examines the status and technical potential of 1-10 kW stationary combined heat and power fuel cell systems and analyzes the achievability of the DOE cost, efficiency, and durability targets for 2012, 2015, and 2020.
Date: November 1, 2010
Creator: Maru, H. C.; Singhal, S. C.; Stone, C. & Wheeler, D.
Partner: UNT Libraries Government Documents Department

10 MW Supercritical CO2 Turbine Test

Description: The Supercritical CO2 Turbine Test project was to demonstrate the inherent efficiencies of a supercritical carbon dioxide (s-CO2) power turbine and associated turbomachinery under conditions and at a scale relevant to commercial concentrating solar power (CSP) projects, thereby accelerating the commercial deployment of this new power generation technology. The project involved eight partnering organizations: NREL, Sandia National Laboratories, Echogen Power Systems, Abengoa Solar, University of Wisconsin at Madison, Electric Power Research Institute, Barber-Nichols, and the CSP Program of the U.S. Department of Energy. The multi-year project planned to design, fabricate, and validate an s-CO2 power turbine of nominally 10 MWe that is capable of operation at up to 700°C and operates in a dry-cooled test loop. The project plan consisted of three phases: (1) system design and modeling, (2) fabrication, and (3) testing. The major accomplishments of Phase 1 included: Design of a multistage, axial-flow, s-CO2 power turbine; Design modifications to an existing turbocompressor to provide s-CO2 flow for the test system; Updated equipment and installation costs for the turbomachinery and associated support infrastructure; Development of simulation tools for the test loop itself and for more efficient cycle designs that are of greater commercial interest; Simulation of s-CO2 power cycle integration into molten-nitrate-salt CSP systems indicating a cost benefit of up to 8% in levelized cost of energy; Identification of recuperator cost as a key economic parameter; Corrosion data for multiple alloys at temperatures up to 650ºC in high-pressure CO2 and recommendations for materials-of-construction; and Revised test plan and preliminary operating conditions based on the ongoing tests of related equipment. Phase 1 established that the cost of the facility needed to test the power turbine at its full power and temperature would exceed the planned funding for Phases 2 and 3. Late in Phase 1 an opportunity arose to collaborate ...
Date: January 29, 2014
Creator: Turchi, Craig
Partner: UNT Libraries Government Documents Department

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

Description: We have fabricated 15.4%- and 12.4%-efficient CuIn1-XGaXSe2 (CIGS)-based photovoltaic devices from solution-based electrodeposition (ED) and electroless-deposition (EL) precursors. As-deposited precursors are Cu-rich CIGS. Additional In, Ga, and Se are added to the ED and EL precursor films by physical vapor deposition (PVD) to adjust the final film composition to CuIn1-XGaXSe2. The ED and EL device parameters are compared with those of a recent world record, an 18.8%-efficient PVD device. The tools used for comparison are current voltage, capacitance voltage, and spectral response characteristics.
Date: May 25, 1999
Creator: Bhattacharya, R. N.; Batchelor, W.; Contreras, M. A.; Noufi, R. N. (National Renewable Energy Laboratory); Hiltner, J. F. & Sites, J. R. (Department of Physics, Colorado State University)
Partner: UNT Libraries Government Documents Department

17.5% p-Type Silicon Heterojunction Solar Cells with HWCVD a-Si:H as the Emitter and Back Contact

Description: Thin hydrogenated amorphous silicon (a-Si:H) layers deposited by hot-wire chemical vapor deposition (HWCVD) are used as both emitters and back contacts in silicon heterojunction solar cells. Low interface recombination velocity and high open-circuit voltage are achieved by a low substrate temperature (<150 deg C) intrinsic a-Si:H deposition which ensures immediate amorphous silicon deposition. This is followed by deposition of doped a-Si:H at a higher temperature (>200 deg C) which appears to improve dopant activation. With an i/n a-Si:H emitter, we obtain a confirmed efficiency of 17.1% on textured p-type float-zone (FZ) silicon with a screen-printed aluminum back-surface-field (Al-BSF) contact. Employing a-Si:H as both the front emitter and the back contact, we achieve a confirmed efficiency of 17.5%, the highest reported efficiency for a p-type c-Si based heterojunction solar cell.
Date: November 1, 2005
Creator: Wang, T. H.; Page, M. R.; Iwaniczko, E.; Wang, Q.; Xu,Y.; Yan, Y. et al.
Partner: UNT Libraries Government Documents Department

20% Wind Energy by 2030

Description: This analysis explores one clearly defined scenario for providing 20% of our nations electricity demand with wind energy by 2030 and contrasts it to a scenario of no new wind power capacity.
Date: July 1, 2008
Partner: UNT Libraries Government Documents Department

20% Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S. Electricity Supply; Executive Summary (Revised)

Description: This document is a 21-page summary of the 200+ page analysis that explores one clearly defined scenario for providing 20% of our nation's electricity demand with wind energy by 2030 and contrasts it to a scenario of no new U.S. wind power capacity.
Date: December 1, 2008
Partner: UNT Libraries Government Documents Department

20% Wind Energy - Diversifying Our Energy Portfolio and Addressing Climate Change (Brochure)

Description: This brochure describes the R&amp;D efforts needed for wind energy to meet 20% of the U.S. electrical demand by 2030. In May 2008, DOE published its report, 20% Wind Energy by 2030, which presents an in-depth analysis of the potential for wind energy in the United States and outlines a potential scenario to boost wind electric generation from its current production of 16.8 gigawatts (GW) to 304 GW by 2030. According to the report, achieving 20% wind energy by 2030 could help address climate change by reducing electric sector carbon dioxide (CO2) emissions by 825 million metric tons (20% of the electric utility sector CO2 emissions if no new wind is installed by 2030), and it will enhance our nation's energy security by diversifying our electricity portfolio as wind energy is an indigenous energy source with stable prices not subject to fuel volatility. According to the report, increasing our nation's wind generation could also boost local rural economies and contribute to significant growth in manufacturing and the industry supply chain. Rural economies will benefit from a substantial increase in land use payments, tax benefits and the number of well-paying jobs created by the wind energy manufacturing, construction, and maintenance industries. Although the initial capital costs of implementing the 20% wind scenario would be higher than other generation sources, according to the report, wind energy offers lower ongoing energy costs than conventional generation power plants for operations, maintenance, and fuel. The 20% scenario could require an incremental investment of as little as $43 billion (net present value) more than a base-case no new wind scenario. This would represent less than 0.06 cent (6 one-hundredths of 1 cent) per kilowatt-hour of total generation by 2030, or roughly 50 cents per month per household. The report concludes that while achieving the 20% wind ...
Date: May 1, 2008
Partner: UNT Libraries Government Documents Department

21-kW Thin-Film PV Technology Validation -- An NREL/Solar Energy Centre of India MOU Cooperative Project

Description: This paper summarizes findings during a one-week (27-31 October 2003) site visit to the Thin-Film Technology Test Bed at India's Solar Energy Centre (SEC) near New Delhi. The U.S. and Indian governments signed a Memorandum of Understanding in March 2000 to undertake a 50-50 cost-shared 21-kW thin-film PV technology validation project to evaluate the performance of thin-film photovoltaic (PV) modules under Indian climatic conditions. This project benefits Indian researchers by giving them experience with cost-effective PV materials, and it benefits the United States because data will be sent to the appropriate U.S. thin-film PV manufacturers for evaluation and analysis. During the visit, NREL personnel engaged in technical discussions regarding thin-film PV technologies with Ministry of Non-Conventional Energy Sources engineers and scientists. Issues included inspecting the newly constructed arrays, discussing better methods of electrically loading the PV arrays, taking I-V traces, and gathering baseline I-V data.
Date: January 1, 2005
Creator: McNutt, P. F. & Ullal, H. S.
Partner: UNT Libraries Government Documents Department

50% Advanced Energy Design Guides: Preprint

Description: This paper presents the process, methodology, and assumptions for the development of the 50% Energy Savings Advanced Energy Design Guides (AEDGs), a design guidance document that provides specific recommendations for achieving 50% energy savings above the requirements of ANSI/ASHRAE/IESNA Standard 90.1-2004 in four building types: (1) Small to medium office buildings, (2) K-12 school buildings, (3) Medium to big box retail buildings, (4) Large hospital buildings.
Date: July 1, 2012
Creator: Bonnema, E.; Leach, M.; Pless, S.; Liu, B.; Wang, W.; Thornton, B. et al.
Partner: UNT Libraries Government Documents Department

80 and 100 Meter Wind Energy Resource Potential for the United States (Poster)

Description: Accurate information about the wind potential in each state is required for federal and state policy initiatives that will expand the use of wind energy in the United States. The National Renewable Energy Laboratory (NREL) and AWS Truewind have collaborated to produce the first comprehensive new state-level assessment of wind resource potential since 1993. The estimates are based on high-resolution maps of predicted mean annual wind speeds for the contiguous 48 states developed by AWS Truewind. These maps, at spatial resolution of 200 meters and heights of 60 to 100 meters, were created with a mesoscale-microscale modeling technique and adjusted to reduce errors through a bias-correction procedure involving data from more than 1,000 measurement masts. NREL used the capacity factor maps to estimate the wind energy potential capacity in megawatts for each state by capacity factor ranges. The purpose of this presentation is to (1) inform state and federal policy makers, regulators, developers, and other stakeholders on the availability of the new wind potential information that may influence development, (2) inform the audience of how the new information was derived, and (3) educate the audience on how the information should be interpreted in developing state and federal policy initiatives.
Date: May 1, 2010
Creator: Elliott, D.; Schwartz, M.; Haymes, S.; Heimiller, D.; Scott, G.; Flowers, L. et al.
Partner: UNT Libraries Government Documents Department

10MW Class Direct Drive HTS Wind Turbine: Cooperative Research and Development Final Report, CRADA Number CRD-08-00312

Description: This paper summarizes the work completed under the CRADA between NREL and American Superconductor (AMSC). The CRADA combined NREL and AMSC resources to benchmark high temperature superconducting direct drive (HTSDD) generator technology by integrating the technologies into a conceptual wind turbine design, and comparing the design to geared drive and permanent magnet direct drive (PMDD) wind turbine configurations. Analysis was accomplished by upgrading the NREL Wind Turbine Design Cost and Scaling Model to represent geared and PMDD turbines at machine ratings up to 10 MW and then comparing cost and mass figures of AMSC's HTSDD wind turbine designs to theoretical geared and PMDD turbine designs at 3.1, 6, and 10 MW sizes.
Date: May 1, 2011
Creator: Musial, W.
Partner: UNT Libraries Government Documents Department

10th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Extended Abstracts and Papers from the Workshop, Copper Mountain Resort; August 14-16, 2000

Description: The 10th Workshop provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and non-photovoltaic fields. Discussions included the various aspects of impurities and defects in silicon-their properties, the dynamics during device processing, and their application for developing low-cost processes for manufacturing high-efficiency silicon solar cells. Sessions and panel discussions also reviewed thin-film crystalline-silicon PV, advanced cell structures, new processes and process characterization techniques, and future manufacturing requirements to meet the ambitious expansion goals described in the recently released US PV Industry Roadmap. The Workshop also provided an excellent opportunity for researchers in private industry and at universities to recognize a mutual need for future collaborative research. The three-day workshop consisted of presentations by invited speakers, followed by discussion sessions. In addition, there was two poster sessions presenting the latest research and development results. The subjects discussed included: solar cell processing, light-induced degradation, gettering and passivation, crystalline silicon growth, thin-film silicon solar cells, and impurities and defects. Two special sessions featured at this workshop: advanced metallization and interconnections, and characterization methods.
Date: August 11, 2000
Creator: Sopori, B.L.; Gee, J.; Kalejs, J.; Saitoh, R.; Stavola, M.; Swanson, D. et al.
Partner: UNT Libraries Government Documents Department

11th Workshop on Crystalline Silicon Solar Cell Materials and Processes, Extended Abstracts and Papers, 19-22 August 2001, Estes Park, Colorado

Description: The 11th Workshop will provide a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and non-photovoltaic fields. Discussions will include the various aspects of impurities and defects in silicon--their properties, the dynamics during device processing, and their application for developing low-cost processes for manufacturing high-efficiency silicon solar cells. Sessions and panel discussions will review impurities and defects in crystalline-silicon PV, advanced cell structures, new processes and process characterization techniques, and future manufacturing demands. The workshop will emphasize some of the promising new technologies in Si solar cell fabrication that can lower PV energy costs and meet the throughput demands of the future. The three-day workshop will consist of presentations by invited speakers, followed by discussion sessions. Topics to be discussed are: Si Mechanical properties and Wafer Handling, Advanced Topics in PV Fundamentals, Gettering and Passivation, Impurities and Defects, Advanced Emitters, Crystalline Silicon Growth, and Solar Cell Processing. The workshop will also include presentations by NREL subcontractors who will review the highlights of their research during the current subcontract period. In addition, there will be two poster sessions presenting the latest research and development results. Some presentations will address recent technologies in the microelectronics field that may have a direct bearing on PV.
Date: August 16, 2001
Creator: Sopori, B.
Partner: UNT Libraries Government Documents Department

15th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Extended Abstracts and Papers

Description: The National Center for Photovoltaics sponsored the 15th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 7-10, 2005. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The workshop addressed the fundamental properties of PV silicon, new solar cell designs, and advanced solar cell processing techniques. A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell designs, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The theme of this year's meeting was 'Providing the Scientific Basis for Industrial Success.' Specific sessions during the workshop included: Advances in crystal growth and material issues; Impurities and defects in Si; Advanced processing; High-efficiency Si solar cells; Thin Si solar cells; and Cell design for efficiency and reliability module operation. The topic for the Rump Session was ''Si Feedstock: The Show Stopper'' and featured a panel discussion by representatives from various PV companies.
Date: November 1, 2005
Creator: Sopori, B. L.
Partner: UNT Libraries Government Documents Department

16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Program, Extended Abstracts, and Papers

Description: The National Center for Photovoltaics sponsored the 16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes held August 6-9, 2006 in Denver, Colorado. The workshop addressed the fundamental properties of PV-Si, new solar cell designs, and advanced solar cell processing techniques. It provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The Workshop Theme was: "Getting more (Watts) for Less ($i)". A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell structures, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The special sessions included: Feedstock Issues: Si Refining and Purification; Metal-impurity Engineering; Thin Film Si; and Diagnostic Techniques.
Date: August 1, 2006
Creator: Sopori, B. L.
Partner: UNT Libraries Government Documents Department