1. Session 7: CSP Part 2 Agenda Discussion of Homework Power Tower Dish/Engine Hybrid Systems Homework Assignment

2. CSP: Power Tower 2

3. Power Tower with Storage 290 C (554 F) 565 C (1049 F) Sun-tracking mirrors Tower mounted receiver Storage fluid: Molten salt Salt/Steam heat exchanger Conventional steam plant Source: NREL website 3

4. Power Tower Characteristics Solar Multiple = thermal power from collector field peak thermal power for power block For a plant in Mohave Desert Solar Multiple = 2.7 Capacity Factor = 65% (w/o storage, CF =25%) Storage Provides Dispatchability Accommodate transient clouds Ability to operate during peak load demand periods 4

5. Power Tower Pros and Cons Pros Dispatchable Cover Peak Demand Accommodate clouds Good efficiency Cons Not modular, can’t provide power until complete Not viable for small power output 5

6. Power Tower History Source: NREL website 6

7. Solar Two Barstow, CA Goal: Demonstrate Molten Salt Storage Source: NREL website 7

8. Solar Two Performance Receiver: Boeing’s Rocketdyne Division Handle Transients: 290 C to 570 C in less than 1 minute (transient clouds) Salt 60% sodium nitrate, 40% potassium nitrate Melts at 220 C (428 F) Low viscosity (similar to water) High wetting factor (hard to contain) 8

9. State-of-Art: Gemasolar Output: 19.9 MWe, 110 GWh/year Storage: 15 hours, molten salt 140-meter high tower 2650 120-m2 heliostats Initial Operation: May 2011 Location: Spain Owner: Torresol Energy Sources: http://www.nrel.gov/csp/solarpaces/project_detail.cfm/projectID=40,http://www.nrel.gov/csp/solarpaces/project_detail.cfm/projectID=40 http://en.wikipedia.org/wiki/Gemasolar 9

10. Dish/Engine CSP 10

11. How do these relate to CSP? Source: NASA Photo Source: Kockums Website 11

12. 12 Dish/Stirling Based on these Technologies MacDonald Douglas Aircraft developed a dish based on aircraft structural design Kockums developed a Stirling engine design based on an Air Independent Propulsion system for submarines Source: Kockums Website Source: SES Presentation to AZ/NV SAE, 2005

13. 13 Dish-Stirling Approach Stirling Energy Systems, Inc. Source: SES Presentation to AZ/NV SAE, 2005

14. 14 Relative Advantages Of Dishes Vs. Other Concentrating Technologies Distributed Generation AND Central Power Plant Capabilities Minimal Water Usage Easier To Site And More Environmentally Friendly: – No Site Leveling Required – No Defoliation

15. 15 Solar Dish Stirling Operation Dish Concentrator Focuses Sun’s Energy On Receiver Stirling Engine Converts Thermal Energy To Electrical Energy Source: SES Presentation to AZ/NV SAE, 2005

16. 16 Dish Stirling Principles of Operation Dish Concentrator Focuses Sun’s Energy On Receiver Stirling Engine Converts Thermal Energy To Electrical Energy Source: SES Presentation to AZ/NV SAE, 2005

17. 17 Dish Stirling - Twice As Efficient As Next Best Solar Sun Daily Energy Per Unit Area (kW hr/sq m) ESTIMATED ANNUAL ENERGY Solar Dish Stirling629 kWh/m2 Central Receiver327 kWh/m2 Parabolic Trough260 kWh/m2 Tracking Photovoltaic217 kWh/m2 Daily Generated Energy Per Unit Area (kW hr/sq m) Solar Dish Stirling Central Receiver Central Receiver Parabolic Trough Parabolic Trough Tracking Photovoltaic Source: Southern California Edison and Sandia National Laboratories

18. Solar-to-Bus bar Peak Efficiency-30% PARASITIC 30.0 GENERATOR 31.4 PCU ENGINE 33.3 RECEIVER TEMP.DIF 78.9 RECEIVER 79.3 AVAILABLE IRRADIANCE 100 INTERCEPT 88.1 REFLECTIVITY 91.1 0 20 40 60 80 100 91.196.79099.54294.895.5 SUBSYTEM EFFICIENCY POWER PERFORMANCE (%) 18 Dish Receiver Parasitics Source: SES Presentation to AZ/NV SAE, 2005

19. 19 SES Dish Stirling System Characteristics Concentrator Glass Area..................91.01 m 2 (979.72 ft 2) @82 mirrors Receiver Aperture……………………8 in diameter; 0.349 ft 2 area Concentration Ratio…………………2704 Design Wind Speed-Operating…….30 mph-Survival…..90 mph Mirror Type…...................................Silvered glass; 0.7 mm thick Reflectivity……………………………>91% Module Height……………………….11.89 m (39 ft) Module Width………………………..11.28 m (37ft) Module weight……………………….14,900 lbs Sunlight-to-busbar efficiency………29.4 percent (at 1000 watts/m2) Source: SES Presentation to AZ/NV SAE, 2005

20. 20 Source: SES Presentation to AZ/NV SAE, 2005

21. CONNECTING PISTONS TO A CRANKSHAFT Source: SES Presentation to AZ/NV SAE, 2005

22. 22 Stirling Engine and Receiver Source: SES Presentation to AZ/NV SAE, 2005

23. 23 Kockums 4-95 Stirling Engine Source: SES Presentation to AZ/NV SAE, 2005

24. 24 Kockums 4-95 Stirling Engine Source: SES Presentation to AZ/NV SAE, 2005

25. 25 Kockums 4-95 Engine Key Parameters Net Power Rating......................25kW at 1000W/m 2 insolation Electrical Power…....................480, 60 Hz, 3 Phase Generator........1800 rpm induction Engine Type…….Kinematic Stirling Number of Cylinders……Four Double-Acting Pistons Displacement…………….Each Piston at 95cc Operating Speed………..1800 rpm Working Fluid………Hydrogen Engine Temperature……720 0 C (1328 0 F) Engine Pressure……….20 MPa Power Control…………Variable Pressure Cooling………………Water/Air Radiator Coolant Temperature….50 0 C (122 0+ F) Power Conversion Weight…<1500 lbs Source: SES Presentation to AZ/NV SAE, 2005

26. Installation of SES Dish at UNLV 26

27. The History of Stirling Energy Systems 1996 SES buys Dish design and hardware from MacDonald Douglas /California Edison 1997 SES licenses Stirling engine technology from Kockums 2004 SES redesigns Dish 2005 SES installs 6 units at Sandia Nat’l Labs, Albuquerque, N.M. 2005 SES signs PPAs for 800 MWe with 2 California utilities 2007SES redesigns both Engine and Dish 2010 SES installs 60 units in Peoria, AZ 2011 SES files Chapter 7 Bankruptcy due to falling PV prices and global financial issues 27

28. The Future of Dish/Engine Stirling engine long-term reliability not proven Hybrid gas turbine system is being developed by several companies Dish can be used for concentrated PV (CPV) Source: SunLab 28

29. Southwest Solar Technology Hybrid Fossil – Solar Brayton Largest commercial solar dish in the world 320 sq m of aperture area 250 kW thermal power focus diameter 0.5 m Tracking accuracy is within 0.1 deg Source: SST 29

30. SST: I-10 and Salt River Source: SST 30

31. Hybrid and Advanced Systems 31

32. Hybrid Fossil Fuel System Relatively easy to put in-line for trough and power tower Difficult to introduce with dish/Stirling Relatively easy to put in-line with dish/Brayton Source:G. CohenSolargenix Energy presentation to IEEE Renewable Energy, Las Vegas, May 16, 2006 32

33. Hybrid Fossil Options Topping: Needed to get higher input temperature to engine Supplemental: Provides additional energy when needed Stand Alone: Provides all power input if needed Source:G. CohenSolargenix Energy presentation to IEEE Renewable Energy, Las Vegas, May 16, 2006 33

34. Trough Storage/Hybrid Concept Source: Overview on Thermal Storage Systems, Ulf Herrmann et al., FLABEG Solar International GmbH, Workshop on Thermal Storage for Trough Plants, February 20-21, 2002. 34

35. Air Receiver with Storage Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104. 35

36. Power Tower Gas Turbine Plant Source: Schwarzbozl, P., et al. Solar gas turbine systems: Design, cost and perspectives. Solar Energy 80 (2006) 1231-1240. 36

37. Power Tower Combined Cycle Source: Schwarzbozl, P., et al. Solar gas turbine systems: Design, cost and perspectives. Solar Energy 80 (2006) 1231-1240. 37

38. Hybrid Power Tower Combined Cycle Concept Solar Air Preheating Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104. 38

39. Conceptual Design with Solar Turbines Recuperated 3.5 MWe Gas Turbine Source: Schwarzbozl, P., et al. Solar gas turbine systems: Design, cost and perspectives. Solar Energy 80 (2006) 1231-1240. 39

40. Reflective Tower Concept Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104. 40

41. Solarization of Honeywell 75 kWe Parallon Microturbine 41

42. Homework Assignment Prepare for quiz over CSP Review slides for next lecture