Last week, the California Energy Commission approved the construction and operation of four solar-thermal power plants in the town of Blythe, with a planned overall capacity of around 1 gigawatt-the largest such installation yet. But to get the green light, the project developers had to redesign the plants to use a cooling technology that reduces their efficiency by 5 to 10 percent and increases the cost of electricity by 5 to 7 percent, according to Solar Millennium, which is jointly developing the project with Ferrostaal and Chevron.
Most solar-thermal plants, such as Solar Millennium's massive Andasol plants in Spain, require a cooling tower that carries the heat away by evaporating water. On average, a typical 300-megawatt steam-cycle generator with cooling towers loses some 11 million liters of water a day to evaporation. However, plants can use dry cooling -- essentially a gigantic radiator -- instead. This uses 90% less water, but is less efficient.
Full story from IEEE Spectrum