Solar tower

A new proposal for the construction of a solar tower capable of generating 400 MW of electricity has been approved by the Namibian government. The solar tower, aptly named the “Greentower” will be 1.5 km (about 5,000 feet!) high and 280 m (918 feet) in diameter. The tower functions like a chimney. Air heated in an apron around the tower becomes relatively buoyant and wants to rise. The only path is up the chimney. Turbines on the ground or near the bottom of the tower convert the updraft into electricity.

In 1982, a small-scale experimental model of a solar chimney power plant was built under the direction of German engineer Jörg Schlaich in Manzanares, Ciudad Real, 150 km south of Madrid, Spain; the project was funded by the German government. The tower ran trouble-free for eight years, producing 50 kW of electricity, until it was decommissioned.

In recent years there has been renewed interest in the solar tower concept, a 1 km-high solar tower, capable of producing 200 MW is scheduled to be constructed by 2010 in Australia. Turbines can be installed in a ring around the base of the tower, with a horizontal axis, as planned for the Australian project, or, as in the prototype in Spain, a single vertical axis turbine can be installed inside the chimney.

Solar towers are relatively inefficient at converting sunlight to energy – about 1% of the sunlight falling on the apron is converted to electricity. Solar towers are inefficient but inexpensive.

http://www.enviromission.com.au/project/project.htm

– from sustainabledesignupdate