Spain plugs in largest solar-tower power plant

April 28, 2009 6:36 AM PDT
Spain plugs in largest solar-tower power plant
by Martin LaMonica

At Abengoa Solar's facility in Spain, mirrors heat a liquid in a tower, on right, that produces steam to make up to 20 megawatts of electricity.

Abengoa Solar of Spain on Monday reported successful tests of its second solar tower in operation, in which the sun's heat is used to make electricity.

The 531-foot solar tower, located near Seville, Spain, features a number of improvements on the first design and has exceeded the anticipated output. Called PS20, the installation is the largest in the world with a capacity of 20 megawatts, enough electricity to supply 10,000 homes, according to the company.

A solar tower configuration uses a field of heliostats, or mirrors, to concentrate sunlight onto a receiver held in the tower. The heat creates steam which turns a turbine to make electricity. The PS20 project has 1,255 of these heliostats, with each heliostat having a surface area of 1,291 square feet.

Concentrating solar thermal technology has been used in desert areas in Spain and the southwest U.S. for decades and is seeing a resurgence as utilities seek out cost-effective solar power.

The traditional solar concentrating power uses rows of mirrored troughs that follow the sun over the course of the day.

Solar tower technology is considered the successor technology to mirrored troughs and is being pursued by a number of solar companies, including renewable energy powerhouse Abengoa and California start-ups BrightSource Energy and eSolar.

Abengoa Solar said that this installation improved on the first solar tower in Spain with better control systems and solar thermal energy storage system