Grid Scale, Hydropower, Solar, Storage

Desert Sunrise: Concentrating Solar Power Makes Worldwide Progress

At the International Energy Agency’s biennial SolarPACES 2008, held this year in Las Vegas, there were many signs that the sleeping solar giant of the desert, Concentrating Solar Power (CSP), is waking up.

The primary attendees and organizers of SolarPACES are scientists, engineers and industry representatives involved in either CSP electric power or the use of concentrated sunlight to generate chemical fuels. On the research side, the US Department of Energy’s Sandia National Laboratories and National Renewable Energy Lab (NREL), the German Aerospace Agency – DLR, and Spain’s Ciemat are doing much of the heavy lifting. At the 2008 conference, there were also presentations by CSP industry representatives from Abengoa Solar, Acciona Solar, Ausra, BrightSource Energy, Iberdrola, Sener, Solar Millennium, with Nevada Power, Arizona Public Service, the Salt River Project, and Sacramento Municipal Utility District representing regional utilities.

One high point of this year’s conference was a tour of Acciona Solar’s recently dedicated 64-megawatt (MW) Nevada Solar One parabolic trough plant that feeds electricity to Nevada Power through a long-term power purchase agreement. A sign that the industry is coming into its own was the presence of numerous representatives of supplier industries, including glass, turbine, and aluminum manufacturers.

Most symposium topics at SolarPACES dealt with technical issues related to plant design, optics, and utilizing storage for the better studied parabolic trough plant design, of which California’s long-running SEGS has been the prime example. Central receiver, parabolic dish, and Compact Linear Fresnel Reflector (CLFR) designs also received some attention. While commercial test beds for CSP are still limited to the few existing plants, test facilities are available at Sandia; PSA in Almeria, Spain; Odeillo in the French Pyrenees and CSIRO in Australia.

Other scientific and engineering presentations were based on simulations and analyses of sophisticated models of plant output and operating behavior. Most presentations reinforced the utility of integrating thermal storage into plant designs, with storage media molten salt, water, thermal oil, concrete, and rocks all under study or in deployment.

Besides the tour of Nevada Solar One, the conference was further energized by recent announcements of new CSP projects.

  • Abengoa Solar’s 280 MW parabolic trough project with 6-hour molten salt storage for the investor-owned utility Arizona Public Service will be designed to supply the late afternoon and evening electric load of the Arizona summer.

  • Ausra has just signed a power purchase agreement with Northern California’s PG&E to build the world’s first CLFR plant at 177 MW in California’s Central Valley.

  • Solel is to construct a 553 MW complex of parabolic trough power plants in the Mojave Desert to fulfill a 25-year power purchase agreement with PG&E.

  • BrightSource Energy plans a 400 MW power tower plant in California.

  • In Spain, 800 MW are online, currently under construction or planned.

  • The world’s first commercial central receiver (power tower) plant, PS10, at 11 MW is now online near Seville. Abengoa is now constructing a larger version, called PS20.

  • Solar Millennium, Flagsol, Cobra S.A. and Sener S.A. are finishing work on a 50 MW parabolic trough plant called Andasol 1 in the province of Granada. It is the first commercial CSP plant with molten salt storage and is scheduled to go online later this year.

  • Construction has started on the almost identical Andasol 2 with plans going forward for Andasol 3 at the same location.

  • Solar Tres, a central receiver design based on the U.S. demonstration plant of the late 1990’s, is reported to be close to obtaining financing, making it the first baseload solar power plant with round the clock power generation during the summer.

  • Iberdrola is building a 50 MW parabolic trough plant at Puertollano in southern Castile, with plans for others.

Outside of Spain and the U.S., there were announcements of small CSP additions to conventional fossil power plants in Algeria and Egypt as well as an experimental plant in Germany.

Many of the discussions that touched on U.S. policy focused on the uncertainty of the now endangered 30% investment tax credit (ITC), upon which all announced U.S. projects depend. Additionally, some conservationists are concerned about interference in the habitats of desert wildlife, including the Mojave ground squirrel, by large solar developments in the very favorable Western Mojave desert. There are moves to block development there that, tragically, would pit one set of environmental concerns against another. By contrast, Spanish participants were well satisfied with the current Spanish and European policy environment that is based on a feed-in tariff system; although, the CSP industry would prefer that regulators lift the 50 MW project size cap.

Michael Hoexter, Ph.D., a renewable energy and energy efficiency advocate, has helped California utilities implement and market energy and resource efficiency programs. His views on the transition to a sustainable energy economy and the valuation of energy and energy services can be found at