Outlook on Concentrating Solar Power

1. Outlook on Concentrating Solar Power Manuel Romero Director Renewable Energy Division CIEMAT Avda. Complutense 2228040 Madrid Internacional Symposium: Energy and Sustainability Madrid, June 16-17, 2008

2. Outlook on CSP Structure: • What does CSP mean?. • What do they say about CSP?: • Thermodynamics • Economy • Contexto europeo, regional y mundial • Employment • Projects under development • Role of R&D • Solar towers • Parabolic troughs • Conclusions

3. Solar Thermal Power Plants: Ambition of bulk power production Fixed power To storage Thermal energy to turbine From storage From storage Solar direct supply Solar time Fixed power Thermal energy to turbine Fossil backup Fossil backup Solar direct supply Solar time • Unique integrability into conventional thermal plants • With thermal storage or fossil fuel backup solar thermal plants can provide firm capacity without the need of separate backup power plants and without stochastic perturbations of the grid. • Solar thermal can supply peak power in summerly heat periods when hydro and wind are scarce. • Application to the MW scale.

4. Solar thermal power plants

5. Are CSPs Competitive ? Wholesale Retail Power Power Small Hydro Solar Photovoltaics Concentrating Solar Biomass Geothermal Wind 10 20 30 40 50 Power Generation Costs in USD Cents/ kWh

6. New Market Entry • Up to 15 GW until 2020 at 5- 8 cents/kWh Next Generation Technology Market Introduction of Solar Thermal PowerStill in the learning curve Europe: New market entry

8. Ain Beni Mathar Hassi R’mel HVDC networks

9. CSP worlwide initiatives Source: Abengoa Solar

10. CSP worlwide initiatives

12. At the end of 2007 more than 50 CSP projects with about 2150 MW have been registered by the Ministry of Industry 50 MW 50 MW 350 MW 150 MW 500 MW 50 MW 500 MW 500 MW

13. Two decades of continuous R&D • EUROTROUGH, DISS, INDITEP, EURODISH, SOLAIR, SOLGATE, SOLHYCO, DISTOR

14. Impact of innovation on cost reduction 100 Scaling up 15% 90 80 R+D 60% Production cost 70 60 Market series 25% 50 40 Year 2005 2010 2015 2020 2025

15. Solar towers today: Early commercial plants ABENGOA SOLAR Steam Turbine Turbine 11.0MWe 40 bar, 250ºC » Steam Steam Solar receiver » Drum Drum Steam Storage System Steam Storage System Condenser 0,06 bar, 50ºC Heliostat Field Heliostat Field

16. ABENGOA SOLAR PS10: Heliostats aiming

17. ABENGOA SOLAR PS10: Concentrated beam

18. ABENGOA SOLAR PS20 and PS10 in Seville (Spain)

19. Solar Towers Today: Early commercial plants • This project is partially supported by the European Commission (Contract No. NNE5/2001/369), through an European Consortium formed by SENER, CIEMAT, ALSTOM-SIEMENS, SAINT GOBAIN and GHERSA.

20. Heliostats: Can innovations lower costs? 30% cost reduction through: • Ganged heliostats (>400 m2) • Megahelio with carousel (>200 m2) • Structurally integrated reflectors (GFRP, hollow extruded polymers) • Wireless/PV autonomous heliostat PSA-CIEMAT DLR Abengoa

21. Solar receiver: Reliable black-body is the key • Water-steam need to develop super-heating at high solar flux. • Volumetric should improve volumetric effect without penalizing fluid-dynamics and flux profile flexibility. • Molten salt should demonstrate long-term availability and increase peak flux • Particle receivers and falling films still to pass feasibility phase. • All should accumulate operational experience and long-term endurance tests. Operational range for different solar receivers (Source: A. Kribus)

22. Receivers: More compact, durable and efficient(Efficiency > 85%) SENER-CIEMAT

23. Heat storage: Essential to become dispatchable • 2-tank molten salt storage for central receiver plants. • Thermocline pebble bed. • Sand or mobile solid material for air and particle receivers • PCM/ fins storage for saturated water/steam

24. Optimizing solar integration • Hybrid Solar/fossil • Biomass • Modularity • New cycles • Hydrogen Project: SOLHYCO

25. Superheated Steam (104bar/380ºC) Molten salts Molten salts (hot tank) (hot tank) Molten salts Molten salts (cold tank) (cold tank) Reheated Steam 17bar/371ºC Reheated Today's European Trough Technology Diagram of an HTF (Heat Transfer Fluid) Solar Power Plant 395 ºC Oil Steam turbine Steam turbine G G Condenser Condenser Steam Steam generator generator Solar Field Solar Field . . Deaerator Deaerator Preheater Reheater Reheater 295 ºC Oil Oil expansion vessel Oil expansion vessel

26. Andasol 1: Under construction • Municipality of Aldeire (Granada). • Under construction. • Start Date: 3Q 2008. • Infrastructures of evacuation: October 2007. • Line and SE 66 kV: October 2007. • Satellite Plant of Gas: October 2007.

27. Andasol 1: Power block • Two storage tanks (ø= 36 m, h=14 m) • Storage capacity (h): 7,5h @ 50 MW • Molten salts: 28,000 Metric Tons/ • Melting temperature: 221º C • Working range: 291º C - 384º C

28. Tomorrow´s Trough Technology Current R+D activities related to Trough Technology • New receiver tube designs • New support structure designs • New solar reflectors • New working fluids for the solar field • New thermal storage systems

29. Glass pin to evacuate the air Glass-to-Metal weld Vacuum between the glass cover and the steel pipe Steel pipe with selective coating 'Getter' to keep and maintain the vacuum Expansion bellows Glass cover Solel design Schott design Current R+D activities related to Trough Technology Current absorbers glass-to-metal weld

30. Current R+D activities related to Trough Technology • New evacuated receiver tube designs with glass-to-metal welds The new receiver tube designs will be very similar to the Schott and SOLEL designs. The main benefit from these new designs will be a larger offer that will ensure reasonable prices • Partially-evacuated receiver pipes without glass-to-metal welding Glass-to-metal welding will be replaced by a mechanical seal. The main benefit of these receiver tubes is their superior durability and reliability at a price similar to evacuated receivers • Low-cost non-evacuated receiver pipes Glass-to-metal welds will be replaced by a simple seal and the selective coating will be replaced by black thermal paint. Though thermal losses will be higher than in evacuated tubes, the price will be much lower and they could be cost-effective for temperatures up to 300ºC • New selective coatings and anti-reflecting films New selective coatings with lower emissivity (<0,1 at 400ºC) and better thermal durability have already beendeveloped in laboratories. An industrial process for mass production is still pending New receiver tube designs The mid-term outcome of current R+D activities related to new receiver tubes will probably be better performance at a slightly lower cost and availability of cheaper products for T< 300ºC

31. Current R+D activities related to Trough Technology New working fluids for parabolic-trough collectors Major disadvantages of current HTF technology are: • limited maximum steam temperature (380ºC) • pollution and fire hazards Three new working fluids are being investigated to replace thermal oil and thus overcome its limitations: • molten salts • direct steam generation • gas

32. Sensible heat with molten salt (< 580ºC) Though huge two-tank molten-salt storage systems (1GWht) are being implemented in large parabolic- trough solar power plants, this technology has not yet been validated for this size. R&D is still required to investigate the long-term performance and reliability of big systems. • Latent heat with molten salt (phase change) (< 320ºC) DSG solar plants require thermal storage systems using phase-change materials (PCM). Several options for PCM storage systems are under study at present (DISTOR project) and a 200kWht prototype is also being evaluated at the PSA. • Sensible heat storage with concrete The goal of these R&D activities is to achieve a specific cost of 20 €/kWh of capacity. A 2x350 kWh prototype has been tested at the PSA with encouraging results. Current R+D activities related to Trough Technology New thermal storage systems There are three R&D lines at present, related to: Two-tank molten-salt storage systems seem to be the best short-to-medium-term option for HTF plants if reliability is confirmed by first operating results. PCM and concrete thermal storage systems seem feasible for DSG plants in the medium to long term.

33. 200 kWht prototype of PCM storage system designed and manufactured in the DISTOR project Current R+D activities related to Trough Technology New thermal storage systems 2x350 kWh prototype of concrete storage system installed and tested at the PSA

34. CONCLUSIONS CSP: • CSP introduces solar energy to high-value markets on high temperature processes, providing high capacity and dispatchability. • Solar thermal power plants offer a wide portfolio of integration options with heat storage or hybrid operation for massive production of electricity. • First commercial projects already going on in Spain and elsewhere. • STPP may integrate North-South Mediterranean electrical networks

35. Conclusions Solar towers: • Solar towers are nowadays on the verge of commercialization. • Early commercial plants (PS10, PS20, Almadén 20 and Solar Tres) will focus further R&D and will provide updated information on costs, efficiencies and O&M. These plants should be used to establish on-site diagnostic methodologies for concentrators and receivers. • Heliostats are today mature in terms of performance but still require substantial cost reduction. • Receivers need priority work on scaling-up, long-term endurance tests and more compact designs. • Better integration into hybrid schemes, biomass and/or higher efficiency cycles is required.

36. Conclusions Parabolic troughs: • More economical collector designs will be available in short-term with easy-to-implement quality control procedures • Receiver pipes designed to meet different requirements will be available in mid term (e.g., non-evacuated low-cost receivers for T<300ºC, semi-evacuated receivers for T< 400ºC) • The use of two-tank molten-salt storage systems in mid-to-long-term still strongly depends on first plant O&M results. PCM and concrete-based thermal storage systems will be available in mid-term (>6 years) • The oil of HTF technology will be replaced by other working fluids. The best option can not be found without testing it in a pre-commercial solar plant under real O&M conditions.