CSP Parabolic Trough Technology for Brazil A comprehensive documentation on the current state of the art of parabolic trough collector technology

1. Introduction 1.1. History 1.2. Aspects for Parabolic Trough Design 2. Overview on Parabolic Trough Collectors 2.1. First Commercial Collector Generation 2.2. Currently Available Parabolic Trough Collectors 2.3. Recent Collector Developments 3. Financial Parameters 3.1. Levelized Cost of Electricity 3.2. Comparison of Parabolic Trough Power Plants 4. Technological Developments 4.1. General Trends 4.2. Further Cost Reduction Potential 19/03/2014 Content Page 2

In 45 minutes, the sun sends more energy to the earth than humans consume in an entire year. With solar power plants more power can be generated on only 1% of the earth s deserts than fossil fuels produce globally today. The future belongs to whoever succeeds in using these reserves effectively and profitably. Investing here is investing in the market of the future. Our future energy supply must be based on the use of renewable energies. Solar power plants make a valuable contribution to a sustainable and climatefriendly generation of energy. Concentrating Solar Power (CSP) allows to convert the existing Solar energy into dispatchable electricity. 19/03/2014 Introduction Page 3

Technology split Projects of global under CSP construction, projects under commissioning construction, or commissioning operational or already operational as of Dec. 2013. Dish 707 Fresnel 4,245 4 342 Parabolic Trough Power Tower Source: CSP Today Global Tracker, December 2013 Parabolic Troughs are the single most important technology used. 19/03/2014 Introduction Page 4

Brazil Saudi Arabia California Andasol /Spain Stuttgart Dish Stirling Parabolic Trough 500 m from tower towards pole Fresnel Tower 500m East/West Tower Height 180 m 500 m from tower towards equator 19/03/2014 Comparison of CSP Technologies Page 5

LCOE [ /kwh] Brazil: Direct Normal Irradiation (DNI) at a high level. Higher DNI leads to lower levelized cost of electricity (LCoE). 0,35 LCOE and direct normal iradiance (DNI) 0,30 0,25 0,20 0,15 0,10 0,05 0,00 1500 1750 2000 2250 2500 2750 3000 3250 DNI [W/(m^2 * a)] design output: 50 MW storage: 6 h O&M and insurance: 3 % of total investment Operation time: 25 years Interest Rate : 8 % 19/03/2014 Solar Irradiance and LCOE Page 6

early 20th century First 45 kw parabolic trough collector plant by Shuman and Boys 80ies First commercial parabolic trough power plants in the Mojave Dessert in California (SEGS) 2004 Introduction of feed in tarif (FIT) by the Spanish government 2008 Andasol: first commercial parabolic trough power plant in Europe 19/03/2014 History Page 8

19/03/2014 Andasol Plants (2009) Page 9

Direct radiation Tracking system Glass tube Absorber tube with selective coating Parabolic concentrator with reflecting surface The trough is tracking the sun on a single axis (elevation axis) Direct radiation is focused on an absorber tube A heat transfer fluid pumped through the absorber tube and is heated up Steam is produced and runs a turbine Heat is stored in storage tanks to produce electricity on demand Principle of a Solar Parabolic Trough Power Plant 19/03/2014 Page 11

Parabolic Trough power plant functional principle 19/03/2014 Page 12

Pros short distance between reflector and absorber tube low energy losses delivers dispatchable energy Cons limited operation temperature (by heat transfer fluid) higher cosine losses than dish Even terrain required proven technology bankable lower part costs lower LCoE Proven technology low area demand low energy losses Easy to scale 10 MW to 250 MW Pros and Cons of Parabolic Troughs 19/03/2014 Page 13

Torque Tube Torque Box Space Frame Steel Aluminum + high stiffness and strengths + low thermal expansion -- high mass + low mass -- low stiffness -- high thermal expansion Supporting Structure 19/03/2014 Page 14

Genealogy of Parabolic Trough Collectors 19/03/2014 Page 15

LS-2: - Torque tube design - able to achieve good optical accuracy - easy to assemble - good optical performance - high costs - aperture width: 5m - SCE: 7.8 m - SCE per SCA: 6 - SCA length: 47 m LS-3: - Space frame truss design - 2x as long and larger aperture - inadequate torsion stiffness - cost savings not demonstrated - lower optical performance - aperture width: 5.76 m - SCE: 12 m - SCE per SCA: 8 - SCA length: 96 m Collector Development 19/03/2014 Page 17

Solar Collector Element (SCE) Structure: Torque boxes Length: 12 m Aperture width (gross): 5.76 m Aperture area (net): 68 m² HCE Diameter: 70 mm Solar Collector Assembly SCA SCA: Length: 12 SCE per SCA 150 m Aperture area: 816 m² Drive: Hydraulic drive system Euro Trough Key figures 19/03/2014 Page 19

Solargenix (SGX) 2: - used in 1 MW Saguaro Plant in Arizona - extruded aluminum space frame - easy to assemble - developed by Solargenix Energy and NREL - SCA length: 96 m - SCE: 8 m - SCE per SCA: 12 - Aperture width: 5 m EuroTrough: - torque box of about 1.5 x 1.4 m to increase stiffness - 150 m long collectors - high optical quality of the prototype - used for 50 MW plants in Spain, Egypt, India and the US - developed by European companies - SCE length: 12 m - Aperture width: 5.76 m - SCE per SCA: 12, SCA length: 150 m Collector Development 19/03/2014 Page 20

SENERtrough - Torque tube supported on sleeve bearings - stamped arms to support the reflector panels - most common collector today - Aperture width: 5.76 - SCE length: 12 m - SCA length: 150 m ENEA collector - Torque tube as main structure element - Molten salt as heat transfer fluid - reflector panels: special aluminum honeycomb facet with thin glass mirrors - Developed by: ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) - Aperture width: 5.76 m - SCA length: 100 m Collector Development 19/03/2014 Page 21

HelioTrough - torque tube with constant stiffness along the whole collector - reduced number of parts (mirrors, HCE etc.) - Increased lifetime - cost reduction of maintenance and assembly - Improved optical efficiency - Aperture width: 6.78 m, Aperture area; 1263 m² - SCE: 19 m / SCA: 191 m - Developed by: sbp and Flagsol Ultimate Trough - world largest collector - peak optical efficiency of 82.7% - truss torque box desgin - continuous mirror surface - economic use of material - high stiffness allows increased span of 24.5 meter - Aperture: 7.51 m, Aperture area: 1716 m² - SCE: 24.6 m, SCA length: 240 m - total solar field cost savings up to 20 % - Prototype in California - Developed by: sbp, Flabeg (German Consortium) New collector developments 19/03/2014 Page 23

SENERtrough - torque tube - increased aperture width, collector element length and focal length - drive pylon structure: vertical pipe - Developed by SENER - Aperture width: 6.87 - SCE length: 13.2 m - SCE per SCA: 12 - aperture area / SCA: 1048 m² SkyTrough - aluminum space frame - reflective polymer mirror film attached on an aluminum sheed instead of reflector panels - aperture width: 6 m - SCE length: 14 m - SCA: 115 m - aperture area / SCA: 656 m² - Developed by: Skyfuel New collector developments 19/03/2014 Page 24

Large Aperture Trough (LAT) 73 - aluminum space frame - reflective polymer film - Aperture width: 7.3 m - SCE length: 12 m - SCA: 192 m - Aperture area / SCA: 1392 - developed by Gossamer Space Frames and 3M Abengoa E2 - steel space frame collector - Aperture width: 5.76 m(ls-3) - SCA length: 125 m - monolithic glass reflector panels - developed by Abengoa New collector developments 19/03/2014 Page 25

LCOE [ /kwh] Overall performance value Usually used to compare different options for power generation Calculation: Total investment costs incl. all expenses (e.g. O&M, taxes, insurance) divided by cumulated electric energy produced during the complete operational time Unit: / kwh Parametric calculation to show the impact of the DNI on the LCOE (50 MW with 6 h storage) 0,35 0,30 0,25 0,20 0,15 LCOE and direct normal iradiance (DNI) 0,10 0,05 0,00 1500 1750 2000 2250 2500 2750 3000 3250 DNI [W/(m^2 * a)] design output: 50 MW storage: 6 h O&M and insurance: 3 % of total investment Operation time: 25 years Interest Rate : 8 % Levelized Cost of Electricity LCoE 19/03/2014 Page 27

Comparison of Parabolic Troughs Power Plants EuroTrough collector (established, reliable performance data) Solar irradiance (DNI): 2500 W/m^2 Operational period: 25 years Investment costs Earth works & Foundations Parabolic trough costs HTF system (with HTF) other solar field costs power block storage EPC costs Owner costs spec. Investments annuity of investment costs O&M costs and insurance spec. O&M costs Total annual costs LCOE 50 MW 50 MW 100 MW 100 MW 200 MW 200 MW 6 h Storage w/o Storage 6 h Storage w/o Storage 6 h Storage w/o Storage M 213 125 392 232 726 420 M 7 4 14 9 28 16 M 58 35 111 67 215 120 M 14 7 26 14 50 27 M 5 3 8 5 15 9 M 60 57 110 105 200 190 M 40 0 69 0 120 0 M 22 13 41 25 75 44 M 7 4 12 8 22 13 M /MW 4 3 4 2 4 2 M 14 8 25 15 47 27 M 6 4 12 7 22 13 k /MW/a 128 75 118 70 109 63 M /a 20 12 37 22 68 40 /kwh 0,108 0,111 0,098 0,102 0,094 0,095 Electric Output and Thermal Storage 19/03/2014 Page 29

LCOE, normalized[%] Comparison of Parabolic Troughs Power Plants LCOE (normalized ): impact of TES and up-scaling 100 90 80 70 without TES with TES 60 50 50 100 200 design output [MW] (LCOE normalized to 50MW design output and without TES) LCOE can be reduced by Power plant scale-up (parabolic trough collector scale-up not considered here) Integration of thermal storage (increased controllability, utilization of the turbine) Electric Output and Thermal Storage 19/03/2014 Page 30

1 300 m 1 050 m EuroTrough, 510 120 m² UltimateTrough, 466 731 m² 1 500 m 1 750 m Header piping ET UT Ratio north-south [m] 1'678 n/a east-west [m] 6'840 3'757 55% total [m] 8'518 3'757 44% HFT volume [m³] 1'813 1'353 75% The Ultimate Trough shows a cost reduction of about 20 to 25% compared to the EuroTrough by: decreasing specific solar field cost [ /m²] by going large increased of optical performance (8%) by stress free mirror attachment Due to increased collector dimensions & optical performance one UT loop will have more than twice the thermal power compared with ET Loop Improvements of current generation collectors 19/03/2014 Page 32

Collector Type EuroTrough UltimateTrough Ratio UT/ET Aperture Width m 5.77 7.51 130% Significant cost reduction due to Number of loop specific parts (Drives, Sensors, Local Control Board, Cabling, Swivel joints, Control & Separation valves, loop interconnection piping) significantly reduced by 50 to 60% Less piping (material, installation, insulation) Less heat transfer fluid Lower installation, commissioning and operation cost SCE length m 12.0 24.5 204% SCA per SCA # 12 10 83% SCA length m 147.8 246.7 167% Aperture Area / SCA m² 817.5 1,716.0 210% Solar field m² 510,120 466,731 91,5% Capacity (gross) 8 h storage MW 50 50 100% Loops # 156 68 44% SCE # 7,296 2,720 37% Drives/ Sensors/ Controls # 608 272 45% Pylon foundations # 7,800 2,992 38% Swivel joint assemblies # 1,248 544 44% Cross over pipes # 156 68 44% Comparison EuroTrough Ultimate Trough 19/03/2014 Page 33

Large scale Innovative design Low specific cost [ /m²] for structure, civil works and assembly by going large - 7.5 m Aperture Largest Parabolic Trough Collector significant reduction of parts with related cost savings the amount of heat transfer fluid (HTF) is reduced by 25 % overall solar field costs about 23 % less compared to EuroTrough LCOE is decreased by about 11% compared to EuroTrough Steel structure with low accuracy allows effective sourcing Simplicity in assembly allows low skilled labor requirements and time efficiency Cost Reduction by 20-25% (Compared to the currently available EuroTrough collector) High optical accuracy Close to perfect - Intercept factor 99.2% @ 94 mm HCE 97.5% @ 70 mm HCE Optimized for molten salt systems for higher energy efficiency Source: Riffelmann et al., Performance of the Ultimate Trough Collector with Molten Salts as Heat Transfer Fluid, SolarPACES 2012, Marrakesh, September 2012 Cost reduction by scale up 19/03/2014 Page 34

Net annual energy [GWh] The Ultimate Trough collector is ready for molten salt operation: The higher concentration factor using a 70 mm receiver tube compensates the higher thermal losses at elevated temperatures while the intercept remains high at 97.5%.This leads to a significantly higher thermal efficiency compared to troughs with a lower concentration ratio. Electrical isolation of HCE for impedance heating is available HCE supports suitable for higher expansion length due to elevated temperatures are available Higher operating temperature Requires higher concentration ratio Requires higher optical performance 620 610 600 590 580 570 560 550 60 70 80 90 100 HCE diameter [mm] The commonly available receiver diameter of 70mm is the optimum diameter for the Ultimate Trough high-aperture collector for use with molten salt. The graph shows that the maximum annual yield of a given power plant (120MW gross output and 14h of thermal storage, located in Daggett, U.S.) is highest for a receiver diameter of 70mm. Source: Riffelmann et al., Performance of the Ultimate Trough Collector with Molten Salts as Heat Transfer Fluid, SolarPACES 2012, Marrakesh, September 2012 Molten salt operation 19/03/2014 Page 35

18 16,9-9 % -10 % 16 14 12 10 15,4 13,9-20 % 11,2-10 % 10,2-40 % 8 6 4 2 0 19/03/2014 LCoE Daggett [ -Cent/kWh]

Reflectors: Absorber tubes (HCEs): Significant cost reductions in glass mirror manufacturing Manufacturers increase accuracy and reflectivity Anti-soiling coating reduce O&M costs New reflector concepts: reflecting film / composite facets Manufacturers increase production procedures due to competition Reduction of thermal losses by using new procedures Development targets higher temperatures (> 500 C) for molten salt application Metal support structure: Drives and control: Larger structures allows for smaller solar fields this significantly reduces number of parts cost savings (e.g. drives, pylons, sensors, controls) Various drive concepts have been conceived and tested Hydraulic drives are the most cost efficient solution Manufacturers increase production procedures due to competition Further Cost Reduction Potential 19/03/2014 Page 38

As a federal enterprise, GIZ supports the German Government in achieving its objectives in the field of international cooperation for sustainable development. Published by Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Registered offices, Bonn and Eschborn, Germany CSP Parabolic Trough Technology for Brazil Address of Programme here T +55 61 2010-2070 E giz-brasilien@giz.de I www.giz.de/brazil Responsible schlaich bergermann und partner, sbp sonne gmbh Author(s) Finn von Reeken, Sarah Arbes, Dr. Gerhard Weinrebe, Markus Wöhrbach, Jonathan Finkbeiner Photo credits GIZ/schlaich bergermann und partner In cooperation with

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