Here's how they work: A massively large, transparent canopy, or collector, is suspended 2 to 20 meters (6 to 65 feet) off the ground, and the air beneath it, warmed by the sun, becomes hotter than the air outside. In the middle of the collector is a tall, slender tower. As the buoyant, warm air is drawn up through the tower, it passes through turbines attached to the tower's base that feed off the rising air's kinetic energy, powering a generator.

Solar updraft technology might sound like a futuristic power source, but the concept was first suggested 101 years ago by Isidoro Cabanyes, a Spanish army colonel.

"It's perfect for where you have lots of sun and lots of cheap, flat land,"