Linear Fresnel Collectors A Technology Overview SFERA Summer School 2012 June 28, 2012, Almería, Spain Jan Fabian Feldhoff E-mail: [email protected] www.DLR.de/SF • Slide 2 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Overview of CSP Systems Parabolic Trough Solar Tower Up to°C, Steam 550 Turbines Up toGas Turbines/Motors 1000°C, Linear Fresnel Dish-Stirling www.DLR.de/SF • Slide 3 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Why a special session about Fresnel? - Similar to parabolic trough, but… - …fixed receiver pipe while mirrors track - …trough shape “split” into multiple small mirror facets - …lower optical performance - …(probably) less expensive Source: Novatec Solar www.DLR.de/SF • Slide 4 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Overview 1. The Linear Fresnel Principle 2. Optical characteristics of Linear Fresnel Collectors (LFC) 3. Performance characteristics of LFCs 4. Components of LFCs 5. Overview existing LFC Plants 6. Outlook on LFC Developments 7. Final Remarks Source: DLR www.DLR.de/SF • Slide 5 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Fresnel Principle - Augustin Jean Fresnel (1788−1828), French Physicist - Thin (low-weight and low-volume) lense for short focal lengths - First application in lighthouses: to focus light horizontally and make it visible over greater distances Pictures: Wikipedia www.DLR.de/SF • Slide 7 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Fresnel Principle > Linear Fresnel Collectors (LFC) Source: Novatec Solar: http://www.novatecsolar.com/20-1-Nova-1.html www.DLR.de/SF • Slide 8 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Optical Characteristics of LFC - Angle Definitions - Calculation formula θlong θtrans θi www.DLR.de/SF • Slide 9 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Solar Optics of LFC > Solar Angle Definitions www.DLR.de/SF • Slide 10 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Solar Optics of Parabolic Trough Collectors www.DLR.de/SF • Slide 11 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Solar Optics of LFC > Main Angles Transversal angle θtrans Angle between zenith and projection of straight line to the sun into the transversal plane Longitudinal angle θlong Angle between zenith and projection of straight line to the sun into the longitudinal plane Incidence angle θi Angle between straight line to the sun and section line of intersection between incidence plane and transversal plane - Transversal and incidence angle are used to characterize optical behavior of LFC (since relevant optical effects are best described by these two angles) www.DLR.de/SF • Slide 12 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Solar Optics of LFC > Angle Definitions Further Description in enerMena report, section III.4. Graphics and formulas taken from: H. Schenk, M. Eck: YIELD ANALYSIS FOR PARABOLIC TROUGH SOLAR THERMAL POWER PLANTS – A BASIC APPROACH, enerMENA report, DLR Stuttgart, March 2012. Available online soon: www.dlr.de/enermena www.DLR.de/SF • Slide 13 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC - Optical Efficiency - Incidence Angle Modifier - Heat losses/ efficiency - Dependency on season - Comparison with Parabolic Trough www.DLR.de/SF • Slide 14 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Efficiency of a line focus system (LFC and PTC) 100 % ηopt,0 - Peak optical efficiency ηopt* - Correction by current sun position ηth (DNI1) - PTC: incident angle DNI1 > DNI2 - LFC: incident & transversal angle Thermal Collector Efficiency ηth (DNI2) - Correction by other external effects (e.g. cleanliness) Temperature Difference Fluid - Ambient - Correction by heat loss www.DLR.de/SF • Slide 15 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Optical efficiency - Peak efficiency lower than for parabolic troughs due to - Astigmatism (mirrors on horizontal plane cannot reach ideal parabola) - Shading by receiver - Projected mirror surface - At low sun position: - Shading - Blocking - Cosine losses www.DLR.de/SF • Slide 16 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Incidence Angle Modifier - Incidence Angle Modifier 1.2 (IAM) 1 - IAM = IAMlong* IAMtrans 0.8 - Longitudinal IAM usually function of incidence 0.6 angle (not longitudinal IAM [-] 0.4 angle): IAMlong = f(θi) IAM longitudinal - Usually derived from ray- 0.2 IAM transversal tracing 0 - Includes cosine, spillage, 020406080100 shading, blocking etc. EinfallswinkelAngle / [°]° www.DLR.de/SF • Slide 17 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Incidence Angle Modifier 1.0 1.0 0.9 Parabolic Trough 0.9 0.8 0.8 0.7 0.7 0.6 0.6 0.5 0.5 IAM [-] 0.4 IAM [-] 0.4 Novatec Solar (Nova 1) 0.3 0.3 cos. incidence angle transversal IAM 0.2 0.2 0.1 IAM 0.1 longitudinal IAM 0.0 0.0 0 102030405060708090 0 102030405060708090 Incidence angle [°] incidence angle / transversal angle [°] Longitudinal IAM similar for Parabolic trough and Linear Fresnel For Fresnel additional component due to transversal effects www.DLR.de/SF • Slide 18 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Heat Losses - Heat loss correlation usually given in [W/m] - Receiver characteristic, independent from collector - Recommended for vacuum receivers: ସ ݍ௟௢௦௦ ൌܿଵܶ௔௕௦ ൅ܿସܶ௔௕௦ - For low temperature and non-vacuum T³ sufficient www.DLR.de/SF • Slide 19 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Efficiency from Heat Loss - Take coefficients from heat loss curve (c1, c4) - Correct by DNI (or beam irradiance Gb) and aperture width wap - For high temperatures - Use correction with T4 [T in °C] or at least T3 - Use absorber temperature [1] - DNI also has an effect on heat losses! See e.g. [2] As a rule of thumb: * * 1 4 therm,coll opt HL opt c1 Tabs c4 Tabs T = 100…600°C: DNI wap 2 a (T T ) a (T T ) * 1 fluid amb 2 DNI fluid amb T = 100…400°C: therm,coll opt wap DNI wap DNI [1] Burkholder, F., and Kutscher, C., 2008, "Heat-Loss Testingof Solel'sUVAC3 Parabolic Trough Receiver," NREL/TP-550-42394 [2] Burkholder, F., and Kutscher, C., 2009, "Heat loss testing of Schott's 2008 PTR70 Parabolic Trough Receiver " NREL/TP-550-45633 www.DLR.de/SF • Slide 20 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Performance of LFC > Annual Yield Modeling - Analog to parabolic trough plants, only considering different IAM - Repeat for various years and “typical meteorological year”, since highly dependent on DNI distribution and location - see latest activities of guiSmo project for more details: http://www.solarpaces.org/Tasks/Task1/modelingguidelines.htm www.DLR.de/SF • Slide 21 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Comparison with PTC > Study Overview - Some selected studies: - Dersch J., M. G., Eck M., Häberle A., 2009, "Comparison of linear Fresnel and parabolic trough collecor systems - system analysis to determine break-even costs of linear fresnel collectors," SolarPaces 2009, Berlin. - Morin, G., Dersch, J., Eck, M., et al., 2011, "Comparison of Linear Fresnel and Parabolic Trough Collector power plants," Solar Energy, pp. 12. - Giostri, A., Binotti, M., Silva, P., et al., 2011, "Comparison of two Linear Collectors in solar thermal Plants: Parabolic Trough vs. Fresnel," ASME 2011 5th International Conference on Energy Sustainability, Washington, DC, USA. - Schenk, H., Hirsch, T., Feldhoff, J.F., et al., 2012, “Energetic comparison of Linear Fresnel and Parabolic Trough Collector Systems,” ASME 2012 6th Int. Conference on Energy Sustainability, San Diego, CA, USA. (to be released in July 2012) www.DLR.de/SF • Slide 22 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Comparison with PTC > Optical performance 1.0 PT rho_tr = 0,20,40,60° PT rho_tr = 80° 0.9 LF theta_trans 0° - Scaled EuroTrough PTC 0.8 LF theta_trans 20° LF theta_trans 40° vs. Novatec LFC ......... 0.7 LF theta_trans 60° - Both with vacuum 0.6 LF theta_trans 80° 0.5 absorber 0.4 0.3 0.2 optical efficiency [-] 0.1 0.0 0 102030405060708090 Incidence angle [°] Optical performance of Fresnel lower especially at low sun angles www.DLR.de/SF • Slide 23 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Comparison with PTC > Optical performance - Include optics in site characterization for line focus systems www.DLR.de/SF • Slide 25 > SFERA Summer School 2012 > Linear Fresnel Collectors > Fabian Feldhoff > June 28, 2012 Comparison with PTC > Optical power input 1000 PT March 20 PT June 21 900 PT Dec 12 LF March 20 LF June 21 LF Dec 12 800 700 600 500 400 300 optical power in [W/m²] 200 100 Location Daggett, USA 0 3 6 9 12151821 local time [h] - Fresnel shows summer peak, while PTC shows broader plateau www.DLR.de/SF • Slide 26 > SFERA Summer School 2012 > Linear