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Solar Resources Measurements in Houston, TX -- Equipment Only: Cooperative Research and Development Final Report, CRADA Number CRD-06-204

Description: Loaning Texas Southern University equipment in order to perform site-specific, long-term, continuous, and high-resolution measurements of solar irradiance is important for developing renewable resource data. These data are used for several research and development activities consistent with the NREL mission: (1) establish a national 30-year climatological database of measured solar irradiances; (2) provide high quality ground-truth data for satellite remote sensing validation; (3) support development of radiative transfer models for estimating solar irradiance from available meteorological observations; (4) provide solar resource information needed for technology deployment and operations. Data acquired under this agreement will be available to the public through NREL's Measurement & Instrumentation Data Center - MIDC (http://www.nrel.gov/midc) Or the Renewable Resource Data Center - RReDC (http://rredc.nrel.gov). The MIDC offers a variety of standard data display, access, and analysis tools designed to address the needs of a wide user audience (e.g., industry, academia, and government interests).
Date: September 1, 2012
Creator: Stoffel, T.
Partner: UNT Libraries Government Documents Department

Sensible Heat, Direct, Dual-Media Thermal Energy Storagy System: Phase 1 Final Technical Report

Description: Work under this project has ultimately focused on the development of a modular packed bed based thermal energy storage system. The design assumes the use of standard segments of carbon steel pipe filled with spherical materials creating a packed bed. These materials are assumed to be manufactured in such a way that the spherical shape is uniform throughout the packed bed. Out of 32 candidate materials evaluated, 8 materials remain. Each material meets the Phase I milestones that were specified for this storage system: a round trip efficiency in excess of 93%, and a required volume of packed bed material that does not exceed the volume of molten salt used in a two-tank storage system with equivalent thermal performance.
Date: November 4, 2011
Creator: Newmarker, Marc & Campbell, Mark
Partner: UNT Libraries Government Documents Department

Final Technical Report

Description: Design, validate at prototype level, and then demonstrate a full size, 800 MWht Thermal Energy Storage (TES) system based on Phase Changing Material (PCM) TES modules with round trip efficiency in excess of 93%. The PCM TES module would be the building block of a TES system which can be deployed at costs inline with the DOE benchmark of 2020. The development of a reliable, unsophisticated, modular, and scalable TES system designed to be massmanufactured utilizing advanced automated fabrication and assembly processes and field installed in the most cost-effective configuration could facilitate the attainment of a Levelized Cost of Energy (LCOE) of $.07/kWh by 2015. It was believed that the DOE targets can be attained by finding the best combinationTES module size, its optimal integration in the power cycle, and readily available PCM. Work under this project ultimately focused on the development and performance evaluation of a 100kWht prototype heat exchanger. The design utilizes a commercially available heat exchanger product to create a unique latent heat PCM storage module. The novel ideal associated with this technology is the inclusion of an agitation mechanism that is activated during the discharge process to improve heat transfer. The prototype unit did not meet the performance goals estimated through modeling, nor did the estimated costs of the system fall in line with the goals established by DOE.
Date: March 16, 2012
Creator: Newmarker, Marc & Campbell, Mark
Partner: UNT Libraries Government Documents Department

Research and Development for Novel Thermal Energy Storage Systems (TES) for Concentrating Solar Power (CSP)

Description: The overall objective was to develop innovative heat transfer devices and methodologies for novel thermal energy storage systems for concentrating solar power generation involving phase change materials (PCMs). Specific objectives included embedding thermosyphons and/or heat pipes (TS/HPs) within appropriate phase change materials to significantly reduce thermal resistances within the thermal energy storage system of a large-scale concentrating solar power plant and, in turn, improve performance of the plant. Experimental, system level and detailed comprehensive modeling approaches were taken to investigate the effect of adding TS/HPs on the performance of latent heat thermal energy storage (LHTES) systems.
Date: September 26, 2013
Creator: Faghri, Amir; Bergman, Theodore L & Pitchumani, Ranga
Partner: UNT Libraries Government Documents Department

Innovative Phase Change Thermal Energy Storage Solution for Baseload Power Phase 1 Final Report

Description: The primary purpose of this project is to develop and validate an innovative, scalable phase change salt thermal energy storage (TES) system that can interface with Infinia’s family of free-piston Stirling engines (FPSE). This TES technology is also appropriate for Rankine and Brayton power converters. Solar TES systems based on latent heat of fusion rather than molten salt temperature differences, have many advantages that include up to an order of magnitude higher energy storage density, much higher temperature operation, and elimination of pumped loops for most of Infinia’s design options. DOE has funded four different concepts for solar phase change TES, including one other Infinia awarded project using heat pipes to transfer heat to and from the salt. The unique innovation in this project is an integrated TES/pool boiler heat transfer system that is the simplest approach identified to date and arguably has the best potential for minimizing the levelized cost of energy (LCOE). The Phase 1 objectives are to design, build and test a 1-hour TES proof-of-concept lab demonstrator integrated with an Infinia 3 kW Stirling engine, and to conduct a preliminary design of a 12-hour TES on-sun prototype.
Date: May 15, 2013
Creator: Qiu, Songgang
Partner: UNT Libraries Government Documents Department

Performance Testing using Silicon Devices - Analysis of Accuracy: Preprint

Description: Accurately determining PV module performance in the field requires accurate measurements of solar irradiance reaching the PV panel (i.e., Plane-of-Array - POA Irradiance) with known measurement uncertainty. Pyranometers are commonly based on thermopile or silicon photodiode detectors. Silicon detectors, including PV reference cells, are an attractive choice for reasons that include faster time response (10 us) than thermopile detectors (1 s to 5 s), lower cost and maintenance. The main drawback of silicon detectors is their limited spectral response. Therefore, to determine broadband POA solar irradiance, a pyranometer calibration factor that converts the narrowband response to broadband is required. Normally this calibration factor is a single number determined under clear-sky conditions with respect to a broadband reference radiometer. The pyranometer is then used for various scenarios including varying airmass, panel orientation and atmospheric conditions. This would not be an issue if all irradiance wavelengths that form the broadband spectrum responded uniformly to atmospheric constituents. Unfortunately, the scattering and absorption signature varies widely with wavelength and the calibration factor for the silicon photodiode pyranometer is not appropriate for other conditions. This paper reviews the issues that will arise from the use of silicon detectors for PV performance measurement in the field based on measurements from a group of pyranometers mounted on a 1-axis solar tracker. Also we will present a comparison of simultaneous spectral and broadband measurements from silicon and thermopile detectors and estimated measurement errors when using silicon devices for both array performance and resource assessment.
Date: June 1, 2012
Creator: Sengupta, M.; Gotseff, P.; Myers, D. & Stoffel, T.
Partner: UNT Libraries Government Documents Department

Equipment Only - Solar Resources Measurements at the University of Texas at Austin, TX: Cooperative Research and Development Final Report, CRADA Number CRD-07-222

Description: Faculty and staff at the University of Texas at Austin collected solar resource measurements at their campus using equipment on loan from the National Renewable Energy Laboratory. The equipment was used to train students on the operation and maintenance of solar radiometers and was returned to NREL's Solar Radiation Research Laboratory upon completion of the CRADA. The resulting data augment the solar resource climatology information required for solar resource characterizations in the U.S. The cooperative agreement was also consistent with NREL's goal of developing an educated workforce to advance renewable energy technologies.
Date: January 1, 2013
Creator: Stoffel, T.
Partner: UNT Libraries Government Documents Department

Solargenix Energy Advanced Parabolic Trough Development

Description: The Solargenix Advanced Trough Development Project was initiated in the Year 2000 with the support of the DOE CSP Program and, more recently, with the added support of the Nevada Southwest Energy Partnership. Parabolic trough plants are the most mature solar power technology, but no large-scale plants have been built in over a decade. Given this lengthy lull in deployment, our first Project objective was development of improved trough technology for near-term deployment, closely patterned after the best of the prior-generation troughs. The second objective is to develop further improvements in next-generation trough technology that will lead to even larger reductions in the cost of the delivered energy. To date, this Project has successfully developed an advanced trough, which is being deployed on a 1-MW plant in Arizona and will soon be deployed in a 64-MW plant in Nevada. This advanced trough offers a 10% increase in performance and over an 20% decrease in cost, relative to prior-generation troughs.
Date: November 1, 2005
Creator: Gee, R. C. & Hale, M. J.
Partner: UNT Libraries Government Documents Department

Status of APS 1-Mwe Parabolic Trough Project

Description: Arizona Public Service (APS) is currently installing new power facilities to generate a portion of its electricity from solar resources that will satisfy its obligation under the Arizona Environmental Portfolio Standard (EPS). During FY04, APS began construction on a 1-MWe parabolic trough concentrating solar power plant. This plant represents the first parabolic trough plant to begin construction since 1991. Site preparation and construction activities continued throughout much of FY05, and startup activities are planned for Fall 2005 (with completion early in FY06). The plant will be the first commercial deployment of the Solargenix parabolic trough collector technology developed under contract to the National Renewable Energy Laboratory. The plant will use an organic Rankine cycle (ORC) power plant, provided by Ormat. The ORC power plant is much simpler than the conventional steam Rankine cycle plant and allows unattended operation of the facility.
Date: November 1, 2005
Creator: Canada, S.; Brosseau, D.; Kolb, G.; Moore, L.; Cable, R. & Price, H.
Partner: UNT Libraries Government Documents Department

Optical Materials, Adhesive and Encapsulant, III-V, and Optical Characterization Evaluation: Cooperative Research and Development Final Report, CRADA Number CRD-07-216

Description: SolFocus is currently developing solar technology for utility scale application using Winston collector based concentrating photovoltaics (CPV). Part of that technology development includes small mirror dishes and front surface reflectors, and bonding the separate parts to the assembly. Mirror panels must meet rigid optical specifications in terms of radius of curvature, slope errors and specularity. The reflective surfaces must demonstrate long term durability and maintain high reflectivity. Some bonded surfaces must maintain adhesion and transparency under high concentrations and high temperatures. Others will experience moderate temperatures and do not require transparency. NREL researchers have developed methods and tools that address these related areas.
Date: November 1, 2012
Creator: Kempe, M.
Partner: UNT Libraries Government Documents Department

PV Ramping in a Distributed Generation Environment: A Study Using Solar Measurements; Preprint

Description: Variability in Photovoltaic (PV) generation resulting from variability in the solar radiation over the PV arrays is a topic of continuing concern for those involved with integrating renewables onto existing electrical grids. The island of Lanai, Hawaii is an extreme example of the challenges that integrators will face due to the fact that it is a small standalone grid. One way to study this problem is to take high-resolution solar measurements in multiple locations and model simultaneous PV production for various sizes at those locations. The National Renewable Energy Laboratory (NREL) collected high-resolution solar data at four locations on the island where proposed PV plants will be deployed in the near future. This data set provides unique insight into how the solar radiation may vary between points that are proximal in distance, but diverse in weather, due to the formation of orographic clouds in the center of the island. Using information about each proposed PV plant size, power output was created at high resolution. The team analyzed this output to understand power production ramps at individual locations and the effects of aggregating the production from all four locations. Hawaii is a unique environment, with extremely variable events occurring on a daily basis. This study provided an excellent opportunity for understanding potential worst-case scenarios for PV ramping. This paper provides an introduction to the datasets that NREL collected over a year and a comprehensive analysis of PV variability in a distributed generation scenario.
Date: June 1, 2012
Creator: Sengupta, M. & Keller, J.
Partner: UNT Libraries Government Documents Department

Development and Testing of a Power Trough System Using a Structurally-Efficient, High-Performance, Large-Aperture Concentrator with Thin Glass Reflector and Focal Point Rotation

Description: Industrial Solar Technology has assembled a team of experts to develop a large-aperture parabolic trough for the electric power market that moves beyond cost and operating limitations of 1980's designs based on sagged glass reflectors. IST's structurally efficient space frame design will require nearly 50% less material per square meter than a Solel LS-2 concentrator and the new trough will rotate around the focal point. This feature eliminates flexhoses that increase pump power, installation and maintenance costs. IST aims to deliver a concentrator module costing less than $100 per square meter that can produce temperatures up to 400 C. The IST concentrator is ideally suited for application of front surface film reflectors and ensures that US corporations will manufacture major components, except for the high temperature receivers.
Date: November 1, 2005
Creator: May, E. K. & Forristall, R.
Partner: UNT Libraries Government Documents Department

Acciona Solar Technology Performance Evaluation: Cooperative Research and Development Final Report, CRADA Number CRD-10-384

Description: Under this agreement, NREL will work with Acciona to conduct joint testing, evaluation, and data collection related to Acciona's solar technologies and systems. This work includes, but is not limited to, testing and evaluation of solar component and system technologies, data collection and monitoring, performance evaluation, reliability testing, and analysis. This work will be conducted at Acciona's Nevada Solar One (NSO) power plant and NREL test facilities. Specific projects will be developed on a task order basis. Each task order will identify the name of the project and deliverables to be produced under the task order. Each task order will delineate an estimated completion date based on a project's schedule. Any reports developed under this CRADA must be reviewed by both NREL and Acciona and approved by each organization prior to publication of results or documents.
Date: January 1, 2014
Creator: Mehos, M. S.
Partner: UNT Libraries Government Documents Department

Sensitivity of Utility-Scale Solar Deployment Projections in the SunShot Vision Study to Market and Performance Assumptions

Description: The SunShot Vision Study explored the potential growth of solar markets if solar prices decreased by about 75% from 2010 to 2020. The ReEDS model was used to simulate utility PV and CSP deployment for this present study, based on several market and performance assumptions - electricity demand, natural gas prices, coal retirements, cost and performance of non-solar renewable technologies, PV resource variability, distributed PV deployment, and solar market supply growth - in addition to the SunShot solar price projections. This study finds that utility-scale solar deployment is highly sensitive to solar prices. Other factors can have significant impacts, particularly electricity demand and natural gas prices.
Date: April 1, 2013
Creator: Eurek, K.; Denholm, P.; Margolis, R. & Mowers, M.
Partner: UNT Libraries Government Documents Department

Analysis of the Impacts of Distribution-Connected PV Using High-Speed Data Sets: Preprint

Description: This paper, presented at the IEEE Green Technologies Conference 2013, utilizes information from high resolution data acquisition systems developed at the National Renewable Energy Laboratory and deployed on a high-penetration PV distribution system to analyze the variability of different electrical parameters. High-resolution solar irradiance data is also available in the same area which is used to characterize the available resource and how it affects the electrical characteristics of the study circuit. This paper takes a data-driven look at the variability caused by load and compares those results against times when significant PV production is present. Comparisons between the variability in system load and the variability of distributed PV generation are made.
Date: March 1, 2013
Creator: Bank, J. & Mather, B.
Partner: UNT Libraries Government Documents Department

Solar Technology Acceleration Center (SolarTAC): Cooperative Research and Development Final Report, CRADA Number CRD-07-259

Description: This agreement allowed NREL to serve as an advisor on SolarTAC - a collaborative effort between Xcel Energy, NREL, and the University of Colorado at Boulder. The collaboration was formed to accelerate pre-commercial and early commercial solar energy technologies to the marketplace. Through this CRADA, NREL participated in the deployment of solar energy generation technologies and related solar equipment for research, testing, validation, and demonstration purposes.
Date: October 1, 2011
Creator: Kramer, W.
Partner: UNT Libraries Government Documents Department

Quantum and Thermal Conversion of Solar Energy to Useful Work

Description: This paper will summarize the results of a thermodynamic analysis of quantum; and thermal processes for converting sunlight into useful work. Quantum and; thermal processes acting alone as well as combined quantum-thermal processes will be discussed. Two types of combined processes have been analyzed, the thermally coupled process and the thermally decoupled process. These processes were addressed because there is a hope that a combined quantum-thermal conversion system will prove to be cheaper than either system acting separately. A first step in determining cost is to determine maximum system efficiency. The analysis also indicates the concept with the greatest potential so that further efforts can focus on it. Previous analyses of the thermodynamics of quantum and thermal conversion have been performed by Haught (Ref. 1), Bolton (Ref. 2), Ross (Ref. 3) , and others. This paper will review Haught's analysis and present the results of an extension of this analysis to a thermally decoupled combined quantum/thermal system performed at SERI. Only systems using unconcentrated solar flux will be considered in the present analysis.
Date: December 1, 1983
Creator: Johnson, D. H.
Partner: UNT Libraries Government Documents Department

Trough Receiver Heat Loss Testing (Presentation)

Description: This presentation describes the design, fabrication, and qualification of an experimental capability for thermal loss testing of full-size trough receiver elements; and the testing on a variety of receivers.
Date: February 1, 2006
Creator: Lewandowski, A.; Feik, C.; Hansen, R.; Phillips, S.; Bingham, C.; Netter, J. et al.
Partner: UNT Libraries Government Documents Department

Metrics for Evaluating the Accuracy of Solar Power Forecasting: Preprint

Description: Forecasting solar energy generation is a challenging task due to the variety of solar power systems and weather regimes encountered. Forecast inaccuracies can result in substantial economic losses and power system reliability issues. This paper presents a suite of generally applicable and value-based metrics for solar forecasting for a comprehensive set of scenarios (i.e., different time horizons, geographic locations, applications, etc.). In addition, a comprehensive framework is developed to analyze the sensitivity of the proposed metrics to three types of solar forecasting improvements using a design of experiments methodology, in conjunction with response surface and sensitivity analysis methods. The results show that the developed metrics can efficiently evaluate the quality of solar forecasts, and assess the economic and reliability impact of improved solar forecasting.
Date: October 1, 2013
Creator: Zhang, J.; Hodge, B. M.; Florita, A.; Lu, S.; Hamann, H. F. & Banunarayanan, V.
Partner: UNT Libraries Government Documents Department