EnviroMission, an Australian company, plans to build the world's largest solar tower energy plant in the world in Arizona by 2015. When completed, the central tower will be 2,625 feet tall, twice that of the Empire State Building, and one of the tallest structures on the planet.

It will output a substantial 200 MW which - depending on how you measure it - is enough to power 100,000-150,000 homes. Further, it requires no fuel but the sun, has zero emissions, and can produce power even when the sun isn't shining, temperatures are cool, and at night.

This technology is more properly known as a solar updraft tower.The more common solar power tower reflects the sun's rays off heliostats on the ground to a central point high up in the tower. The heat is used to create steam to power turbines, creating electricity. Solar updraft towers have a huge greenhouse-like structure surrounding the tower. The sun heats air under the canopy. Convection causes the air to flow into the tower, driving the turbines.

Solar updraft has some notable advantages over the typical solar power tower. First, no water is needed. Air powers the turbines, not steam. Using water to create power in a desert can be an obvious matter of some concern, even if modern solar power towers minimize water use as much as possible by reusing it.  Second, maintenance is way less. There are no reflectors and heliostats to maintain, just a huge greenhouse-like canopy and a turbine. Third, it works regardless of the temperature because it operates based on the difference between the air under the canopy and that at the top of the tower. Cool air at the top sucks out warm air from under the canopy. Fourth, it can create energy at night in the same simple manner because the ground is still warm (Some solar power towers can create power at night by storing excess heat in molten salt which can later be used to run the turbines).

Gizmag has a detailed article on this and some of the commenters ponder if such a huge power plant can withstand the rigors of an Arizona summer, with its blistering heat, ferocious thunderstorms, and high winds, as well as the cold winters. Of course, there are monsoons and haboobs to consider too. However, EnviroMission did build a test site in Spain some years back as a proof of concept, and it functioned fine. The Arizona project will be a grid-scale production facility.

It will cost $750 million, and EnviroMission says it will pay for itself in eleven years and last for eighty years with little maintenance needed. They already have contracts to sell the power too. Let's hope this gets built and functions as they think it will. Solar updraft tower technology could power Arizona, and more.