I first wrote about solar towers in August, 2009. Now, Southern California Public Power Authority (SCPPA) says they have agreed to buy power from two 2,500-foot towers to be built between the towns of Parker and Quartzsite in La Paz County, Arizona, with construction to start in 2012.
Each tower will be surrounded by a mile-wide greenhouse designed to heat air, which will then rise through the tower after passing through turbines. The rated peak capacity will be 200 megawatts for each tower.
According to SCPPA, “The Solar Tower facility is anticipated to generate more than 1,000,000 MWhs of renewable energy per year.” The towers were developed and will be built by an Australian company, EnviroMission. I could not find figures on the exact cost, but an October, 2010, estimate by Phoenix Business Journal puts the figure at somewhere between $700 million and $1 Billion. In December, 2010, the Arizona Republic put the cost at $750 million for one tower. That capital cost works out to about $3,750 per Kwh capacity. To put that in perspective, coal plants cost abut $3,167 per Kwh, natural gas plants cost about $1,003 per Kwh, and solar voltaic plants cost about $4,755 per Kwh according to the Energy Information Administration. So far there are no data on how much of the peak capacity will actually be available. Availability is generally near 90% for fossil fuel plants and less than 25% for solar voltaic plants.
If built, the towers will be the tallest structures in the U.S. and second only to the Burj Khalifa skyscraper in Dubai.