this is a quote from the bulletin:
There’s no doubt that it works – efficiently, reliably, and simply. In 1982, Professor Jörg Schlaich’s engineering consultancy, Schlaich Bergermann and Partner (SBP) based in Stuttgart, Germany, built a 200m tall, 50-kilowatt prototype solar thermal tower near Manzanares, south-eastern Spain. The then West German government was sufficiently intrigued by Schlaich’s concept to subsidise construction of the prototype on foreign soil. By coincidence, it was completed as the most intense El Niño event of the 20th century heralded the onset of a rapid warming phase in global climate that continues today.
The greenhouse gas emissions gen-erated in the building phase would be recouped within the first two-and-a-half years of operation, says Davey. Thereafter, it’s a free lunch: zero emissions, convertible to carbon credits in a global market.
http://bulletin.ninemsn.com.au/bulle...ElemFormat=jpgThe Manzanares plant ran for seven years, with minimal tuning and maintenance, delivering electricity both night and day into the local power grid. Manzanares, in Spain’s La Mancha province, was selected because of its hot, dry climate but there was an unintended symbolism in the choice. Schlaich’s radical solar thermal system tilts not just at the great windmills sprouting from coastal landscapes in many developed nations, it throws down the gauntlet to conventional, coal-fired power stations.
Other solar thermal technologies focus the sun’s radiation with arrays of mirrors or sun-tracking, polished cylinders to vaporise water, and drive steam turbine generators. Their big drawback: they don’t run on moonshine. Schlaich’s solar tower generates energy 24 hours a day by exploiting three old principles: the chimney, greenhouse and windmill.
The “draw” that sustains an open-hearth fire exploits the temperature differential between the warm room and the cooler outside air, which is greatest on cold nights. Warm air rises, creating a convective flow. In the atmosphere, temperatures fall by 1°C per 100m of altitude, so the air at the top of a 1km-tall tower is about 10°C cooler than at the base. Schlaich’s design amplifies this differential by feeding heated air into the tower from a vast greenhouse “skirt” around its base.
The 5km-diameter greenhouse will be constructed of high-impact glass or polycarbonate supported on a metal frame. The Manzanares prototype experimented with both and suffered no damage in occasionally violent storms that delivered baseball-sized hailstones.
A convective airflow moving at 35km/h to 50km/h will spin the 32 wind turbines mounted about 40m above ground level, generating a peak output of 200MW.
here is the link to check it out yourselves...
http://bulletin.ninemsn.com.au/bulle...2001BA833!open