Everything around me is wilting today, including me. Therefore it seems apt for me to search around for something solar-related to write about.
Found this quick update from Southern California Edison, which bills itself as the leading purchaser (not provider) of solar energy, buying about 90 percent of the current U.S. solar production. SCE has just signed a contract for 245 megawatts of solar power that's being produced through what it describes as the "first commercial effort using power tower solar thermal technology." The project will be sited near Lancaster, Calif., and is expected to start producing power in 2011. The technology is produced by eSolar, which apparently uses shorter towers than other solar tower providers. Here's some more information about its approach to solar towers.
For perspective, renewable sources contribute 16 percent of SCE's total energy portfolio. It has contracts for 1,205 megawatts of wind-generated energy, 906 megawatts of geothermal, 354 megawatts from solar sources, 174 megawatts from biomass, and 226 megawatts from small hydro.
This photo from Wikipedia gives you a visual idea of how tower technology differs from the solar panel technology that's been getting most of the ink this year. The photo is of the 11MW PS10 near Seville in Spain.
The towers use heliostats (mirrors) to track the sun's course throughout the door and direct it into a receiver on the top of the tower. The captured sunlight is used to boil water, creating steam that works with a traditional turbine to create electricity.