Saw this one over on GizMag…
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.
Time Magazine had it in their 2002 ‘Best Inventions’ category.
$800 million, powers 200,000 Australian homes, and uses up no fuels, and has very little maintenance. AND the greenhouses can be used for other things – all they have to be is hot. I’ll take it!