great, if it works

"The mammoth 800-plus meter (2625 ft) tall tower will instantly become one of the world's tallest buildings [...] The Arizona tower will be a staggering 800 metres or so tall - just 30 meters shorter than the colossal Burj Khalifa in Dubai, the world's tallest man-made structure. To put that in context - it will stand more than double the height of the Empire State building in New York City, and it'll be as much as 130 meters in diameter at the top."

Sounds good! Let's hope it works out.

EnviroMission plans massive solar tower for Arizona

"The sun beats down on a large covered greenhouse area at the bottom, warming the air underneath it. Hot air wants to rise, so there's a central point for it to rush towards and escape; the tower in the middle. And there's a bunch of turbines at the base of the tower that generate electricity from that natural updraft."

More from the article:

The advantages of this kind of power source are clear:
• Because it works on temperature differential, not absolute temperature, it works in any weather;
• Because the heat of the day warms the ground up so much, it continues working at night;
• Because you want large tracts of hot, dry land for best results, you can build it on more or less useless land in the desert;
• It requires virtually no maintenance - apart from a bit of turbine servicing now and then, the tower "just works" once it's going, and lasts as long as its structure stays standing;
• It uses no 'feed stock' - no coal, no uranium, nothing but air and sunlight;
• It emits absolutely no pollution - the only emission is warm air at the top of the tower. In fact, because you're creating a greenhouse underneath, it actually turns out to be remarkably good for growing vegetation under there.