http://www.time.com/time/2002/inventions/toc.html

Solar tower
http://www.time.com/time/2002/inventions/rob_tower.html

Want cheap, green electricity? The Australians have a simple answer. First, build a 20,000-acre greenhouse to trap and heat air. Then build a colossal tower 1 km (.62 miles) tall in the middle of it. The warm air from the greenhouse will rise through the tower as it would through a chimney, turning turbines and generating enough electricity to power 200,000 Australian homes. It may sound like science fiction, but the project is on track to get approved by the Australian government. If completed, the $800 million solar tower will be the tallest man-made structure in the world.

To Learn More: enviromission.com.au