If you think environmentalists' ideas about solar and wind power is only generating a lot of hot air, you may be on to something.

Until now, solar power and wind power technologies have largely developed along separate paths. But Australian-based EnviroMission Limited plans to change that by combining the two power sources. They plan to build a giant hot-air machine in the Outback that could conceivably power a small city.

The plan is to construct a kilometer-high vertical wind tunnel, which will funnel solar-heated air from ground level up to the much colder air at its tip.

The Solar Tower, seen here in an artist's concept drawing, would be a 1-kilometer (0.6 mile) high exhaust vent atop a greenhouse-type "heat farm." Built in the baking Australian Outback, the air beneath the glass would be heated even further due to its glass roof. And since hot air rises, its best escape would be up the inside of the central tower to the considerably colder and dryer regions a kilometer above. Power generating turbines would stand between the hot air and the entrance to the tower, to catch the high winds generated.

A fairly simple idea, really, aside from its scale. Enviromission has already built a 50kW prototype in Spain, and plans to build a 200MW in Australia next. That's enough energy to power 200,000 homes. All from simply generating hot air.

http://www.enviromission.com.au/ 

-- Robert Myers