Research Papers

Solar Field Optical Characterization at Stillwater Geothermal/Solar Hybrid Plant

[+] Author and Article Information
Guangdong Zhu

National Renewable Energy Laboratory,
15013 Denver West Parkway,
Golden, CO 80401
e-mail: Guangdong.Zhu@nrel.gov

Craig Turchi

National Renewable Energy Laboratory,
15013 Denver West Parkway,
Golden, CO 80401

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received July 26, 2016; final manuscript received December 2, 2016; published online January 27, 2017. Assoc. Editor: Wojciech Lipinski.The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.

J. Sol. Energy Eng 139(3), 031002 (Jan 27, 2017) (10 pages) Paper No: SOL-16-1342; doi: 10.1115/1.4035518 History: Received July 26, 2016; Revised December 02, 2016

Concentrating solar power (CSP) can provide additional thermal energy to boost geothermal plant power generation. For a newly constructed solar field at a geothermal power plant site, it is critical to properly characterize its performance so that the prediction of thermal power generation can be derived to develop an optimum operating strategy for a hybrid system. In the past, laboratory characterization of a solar collector has often extended into the solar field performance model and has been used to predict the actual solar field performance, disregarding realistic impacting factors. In this work, an extensive measurement on mirror slope error and receiver position error has been performed in the field by using the optical characterization tool called distant observer (DO). Combining a solar reflectance sampling procedure, a newly developed solar characterization program called firstoptic and public software for annual performance modeling called system advisor model (SAM), a comprehensive solar field optical characterization has been conducted, thus allowing for an informed prediction of solar field annual performance. The paper illustrates this detailed solar field optical characterization procedure and demonstrates how the results help to quantify an appropriate tracking-correction strategy to improve solar field performance. In particular, it is found that an appropriate tracking-offset algorithm can improve the solar field performance by about 15%. The work here provides a valuable reference for the growing CSP industry.

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Mills, D. , 2004, “ Advances in Solar Thermal Electricity Technology,” Sol. Energy, 76(1–3), pp. 19–31. [CrossRef]
Price, H. , Lupfert, E. , Kearney, D. , Zarza, E. , Cohen, G. , Gee, R. , and Mahoney, R. , 2002, “ Advances in Parabolic Trough Solar Power Technology,” ASME J. Sol. Energy Eng., 124(2), pp. 109–125. [CrossRef]
Zhu, G. , Wendelin, T. , Wagner, M. , and Kutscher, C. , 2014, “ History, Current-State and Future of Linear Fresnel Concentrating Solar Collectors,” Sol. Energy, 103, pp. 639–652. [CrossRef]
Andraka, C. E. , and Powell, M. P. , 2008, “ Dish Stirling Development for Utility-Scale Commercialization,” 14th Biennial CSP SolarPACES Symposium, Las Vegas, NV, Mar. 4–7.
Price, H. , and Kearney, D. , 2005, “ Recent Advances in Parabolic Trough Solar Power Plant Technology,” NREL Report No. CH-550-36422.
Zhu, G. , Neises, T. , Turchi, C. , and Bedilion, R. , 2015, “ Thermodynamic Evaluation of Solar Integration Into a Natural Gas Combined Cycle Power Plant,” Renewable Energy, 74, pp. 815–824. [CrossRef]
Dersch, J. , Geyer, M. , Herrmann, U. , Jones, S. A. , Bruce, K. , Kistner, R. , Ortmanns, W. , Pitz-Paal, R. , and Price, H. , 2004, “ Trough Integration Into Power Plants—A Study on the Performance and Economy of Integrated Solar Combined Cycle Systems,” Energy, 29(5–6), pp. 947–959. [CrossRef]
Turchi, C. , Zhu, G. , Wagner, M. , Williams, T. , and Wendt, D. , 2014, “ Geothermal/Solar Hybrid Designs: Use of Geothermal Energy for CSP Feedwater Heating,” Geothermal Resources Council 38th Annual Meeting, Portland, OR, Sept. 28-Oct. 1, OSTI No. 1170300.
Wendt, D. , Mines, G. , Turchi, C. , Zhu, G. , Cohan, S. , Angelini, L. , Bizzarri, F. , Consoli, D. , and A. De Marzo , 2015, “ Stillwater Hybrid Geo-Solar Power Plant Optimization Analyses,” Geothermal Resources Council Annual Meeting, Reno, NV, Sept. 20-23, OSTI No. 1253710.
DiMarzio, G. , Angelini, L. , Price, W. , Chin, C. , and Harris, S. , 2015, “ The Stillwater Triple Hybrid Power Plant: Integrating Geothermal, Solar Photovoltaic and Solar Thermal Power Generation,” World Geothermal Congress, Melbourne, Australia, Apr. 19–25, Paper No. 38001.
Far, A. , and Gee, R. , 2009, “ The Skytrough Parabolic Trough Solar Collector,” ASME Paper No. ES2009-90160.
Meyen, S. , Montecchi, M. , Kennedy, C. , Zhu, G. , Gray, M. , Crawford, J. , Hiemer, S. , Platzer, W. , Heimsath, A. , O'Neill, M. , Ziegler, S. , Brandle, S. , and Fernandez, A. , 2013, “ Parameters and Method to Evaluate the Solar Reflectance Properties of Reflector Materials for Concentrating Solar Power Technology,” SolarPACES, DLR Deutsches Zentrum für Luft und Raumfahrt, Köln, Germany.
Zhu, G. , Kearney, D. , and Mehos, M. , 2014, “ On Characterization and Measurement of Average Solar Field Mirror Reflectance in Utility-Scale Concentrating Solar Power Plants,” Sol. Energy, 99, pp. 185–202. [CrossRef]
Eck, M. , Barroso, H. , Blanco, M. , Burgaleta, J.-I. , Dersch, J. , Feldhoff, J. F. , Garcia-Barberena, J. , Gonzalez, L. , Hirsch, T. , Ho, C. , Kolb, G. , Neises, T. , Serrano, J. A. , Tenz, D. , Wagner, M. , and Zhu, G. , 2011, “ guiSmo: Guidelines for CSP Performance Modeling—Present Status of the SolarPACES Task-1 Project,” 17th SolarPACES Conference, Granada, Spain, Sept. 20–23.
Kearney, D ., 2011, “ Utility-Scale Parabolic Trough Solar Systems: Performance Acceptance Test Guidelines,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/SR-5500-48895.
Kearney, D. , 2013, “ Utility-Scale Power Tower Solar Systems: Performance Acceptance Test Guidelines,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/SR-5500-57272.
Pettit, R. B. , 1977, “ Characterization of the Reflected Beam Profile of Solar Mirror Materials,” Sol. Energy, 19(6), pp. 733–741. [CrossRef]
Montecchi, M. , 2013, “ Approximated Method for Modelling Hemispherical Reflectance and Evaluating Near-Specular Reflectance of CSP Mirrors,” Sol. Energy, 92, pp. 280–287. [CrossRef]
Meyen, S. , Lupfert, E. , Pernpeintner, J. , and Fend, T. , 2009, “ Optical Characterization of Reflector Material for Concentrating Solar Power Technology,” SolarPACES 2009, Berlin, Germany, Sept. 15–18.
Arvesen, J. C. , Greffin, R. N. , and Pearson, B. D. , 1969, “ Determination of Extraterrestrial Solar Spectral Irradiance From a Research Aircraft,” Appl. Opt., 8(11), pp. 2215–2232. [CrossRef] [PubMed]
Heimsath, A. , Kutscheidt, G. , and Nitz, P. , 2010, “ Detailed Optical Characterization of Reflector Materials for CSP Applications,” SolarPACES 2010, Perpignan, France, Sept. 21–24.
Nicodemus, F. E. , Richmond, J. C. , Hsia, J. J. , Ginsberg, I. W. , and Limperis, T. , 1977, “ Geometrical Considerations and Nomenclature for Reflectance,” National Bureau of Standards, Department of Commerce, Washington, DC.
Andraka, C. , Sadlon, S. , Myer, B. , Trapeznikov, K. , and Liebner, C. , 2009, “ SOFAST: Sandia Optical Fringe Analysis Slope Tool for Mirror Characterization,” SolarPACES 2009, Berlin, Germany, Sept. 15–18.
Wendelin, T. , May, K. , and Gee, R. , 2006, “ Video Scanning Hartmann Optical Testing of State-of-the-Art Parabolic Trough Concentrators,” ASME Paper No. ISEC2006-99172.
Pottler, K. , Lupfert, E. , Johnston, G. , and Shortis, M. , 2005, “ Photogrammetry: A Powerful Tool for Geometric Analysis of Solar Concentrators and Their Components,” ASME J. Sol. Energy Eng., 127(1), pp. 94–101. [CrossRef]
Roger, M. , Prahl, C. , and Ulmer, S. , 2008, “ Fast Determination of Heliostat Shape and Orientation by Edge Detection and Photogrammetry,” 14th CSP SolarPACES Symposium, Las Vegas, NV, Mar. 4–7.
Pottler, K. , Lupfert, E. , Ulmer, S. , Landmann, M. , and Mutzel, M. , 2011, “ Geometric Evaluation of Parabolic Trough Collector Module Ultimate Trough,” CSP Services GmbH, Cologne, Germany.
Ulmer, S. , Heinz, B. , Pottler, K. , and Lupfert, E. , 2009, “ Slope Error Measurements of Parabolic Troughs Using the Reflected Image of the Absorber Tube,” ASME J. Sol. Energy Eng., 131(1), p. 011014. [CrossRef]
Knauer, M. C. , Kaminski, J. , and Hausler, G. , 2004, “ Phase Measuring Deflectometry: A New Approach to Measure Specular Free-Form Surfaces,” Proc. SPIE 5457, p. 366.
Burke, J. , Li, W. , Heimsath, A. , von Kopylow, C. , and Bergmann, R. B. , 2013, “ Qualifying Parabolic Mirrors With Deflectometry,” J. Eur. Opt. Soc., 8, p. 13014. [CrossRef]
Heimsath, A. , Platzer, W. , Bothe, T. , and Wansong, L. , 2008, “ Characterisation of Optical Components for Linear Fresnel Collectors by Fringe Reflection Method,” SolarPACES Conference, Las Vegas, NV, Mar. 4–7.
Diver, R. B. , and Moss, T. A. , 2007, “ Practical Field Alignment of Parabolic Trough Solar Concentrators,” ASME J. Sol. Energy Eng., 129(2), pp. 153–159. [CrossRef]
Burkholder, F. , and Kutscher, C. , 2009, “ Heat Loss Testing of Schott's 2008 PTR70 Parabolic Trough Receiver,” National Renewable Energy Laboratory, Golden, CO, NREL Report No. NREL/TP-5500-45633.
Kutscher, C. , Burkholder, F. , and Stynes, K. , 2012, “ Generation of a Parabolic Trough Collector Efficiency Curve From Separate Measurements of Outdoor Optical Efficiency and Indoor Receiver Heat Loss,” ASME J. Sol. Energy Eng., 134(1), p. 011012. [CrossRef]
NREL, “ Heat Collection Element (HCE) Temperature Survey,” National Renewable Energy Laboratory, Golden, CO, accessed in 2015, http://www.nrel.gov/csp/lab_capabilities.html#heatcollection
Gee, R. , Brost, R. , Zhu, G. , and Jorgensen, G. , 2010, “ An Improved Method for Characterizing Reflector Specularity for Parabolic Concentrators,” 16th SolarPACES, Perpignan, France, Sept. 21–24.
Zhu, G. , and Lewandowski, A. , 2012, “ A New Optical Evaluation Approach for Parabolic Trough Collectors: First-Principle OPTical Intercept Calculation (FirstOPTIC),” ASME J. Sol. Energy Eng., 134(4), p. 041005. [CrossRef]
Zhu, G. , 2013, “ Study on the Optical Impact of Receiver Position Error on Parabolic Trough Collectors,” ASME J. Sol. Energy Eng., 135(3), p. 031021. [CrossRef]
Stynes, K. , and Ihas, B. , 2012, “ Slope Error Measurement Tool for Solar Parabolic Through Collectors,” World Renewable Energy Forum, Denver, CO, May 13–17.
Stynes, K. , and Ihas, B. , 2012, “ Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors,” ASME Paper No. ES2012-91283.
Prahl, C. , Stanicki, B. , Hilgert, C. , Ulmer, S. , and Roger, M. , 2011, “ Airborne Shape Measurement of Parabolic Trough Collector Fields,” 17th SolarPACES Conference, Granada, Spain, Sept. 20–23.
Devices and Services, 2014, “ Portable Specular Reflectometer 15R-USB,” Devices and Services, Co., Dallas, TX, accessed in 2015, http://www.devicesandservices.com/prod02.htm
SOC, 2009, “ SOC-100 User's Manual—Hemispherical Directional Reflectometer (HDR),” Surface Optics Corporations, San Diego, CA.
Binotti, M. , Zhu, G. , Gray, A. , Manzolini, G. , and Silva, P. , 2013, “ Geometric Analysis of Three-Dimensional Effects of Parabolic Trough Collectors,” Sol. Energy, 88, pp. 88–96. [CrossRef]
NREL, 2015, “ System Advisor Model 2015.1.30,” National Renewable Energy Laboratory, Golden, CO, accessed in 2015, https://sam.nrel.gov/
Sun 2 Market Solutions, 2012, “ Performance Comparison of Huiyin's Vacuum Receiver Tubes,” Huiyin-Group, Sun to Market Solutions S.L., Madrid, Spain, accessed in 2015, http://www.s2msolutions.com/
Bendt, P. , Rabl, A. , Gaul, H. W. , and Reed, K. A. , 1979, “ Optical Analysis and Optimization of Line Focus Solar Collectors,” Solar Energy Research Institute, Golden, CO.


Grahic Jump Location
Fig. 1

Schematic of mirror reflectance [13]

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Fig. 2

Distribution of solar specular reflectance (at 25 mrad and at a wavelength of 660 nm) among loops. Variability comes from measurement uncertainties and damage to some panels prior to construction.

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Fig. 3

Specular reflectance (at a wavelength of 660 nm) as a function of acceptance aperture size for four mirror panel samples

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Fig. 4

Fitted mirror specularity profile using a single-Gaussian approximation

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Fig. 5

A snapshot of distant observer (DO) optical characterization: raw photo (left) and scaled photo (right)

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Fig. 6

Rescaling of the raw image based on the target locations [40]

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Fig. 7

Receiver position error along x and z directions. Because these measurements were taken near the horizon, they represent a worst-case scenario that occurs during operation. Receiver position error during normal operating angles may be substantially less.

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Fig. 8

Slope error distribution over one collector module of a SkyTrough collector module (indexed by L5R2M10)

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Fig. 9

Slope error distribution attributes (mean value and RMS) for all sampled collector modules. Note that the mean value is dominated by the receiver's gravity-induced displacement, which is greatest at the low tracking angle while the DO measurements were conducted. Its impact on the collector performance is compensated by including a tracking-offset algorithm, to be discussed later.

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Fig. 10

Intercept factor calculation for all sampled collector modules

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Fig. 11

Intercept factor calculation for all sampled collector modules with and without tracking-offset algorithm

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Fig. 12

Incidence-angle modifier (IAM) curve: circles mark the predicted data points, and the line indicates the fitting function

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Fig. 13

Hourly SAM-predicted solar field thermal energy output for Stillwater based on measured parameters listed in Table 7




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