Green Wombat had lunch Friday with EnviroMission’s Roger Davey and Kim Forte, who flew into San Francisco from Melbourne, Australia, to promote their solar tower project. (Green Wombat chronicled the company’s six-year quest to build the solar tower in "Tower of Power," which appeared in the August 2006 issue of Business 2.0 magazine.) Of the various Big Solar technologies out there, the solar tower is one of the most out there: A tower between 1,600 and 3,000 feet is surrounded by a glass canopy a mile or two wide, which heats the air underneath. Hot air rises and the tower operates as a vacuum. As the air is sucked into the tower, it produces wind to power an array of turbine generators clustered around the structure. The turbines in turn generate electricity. EnviroMission had purchased 24,000 acres of land on the edge of the outback in south east Australia to build the tower but got knocked back last October when it lost a bid for $57 million in government funding to cross-town rival Solar Systems. Since then, EnviroMission CEO Davey has focused on the U.S. market, studying potential sites in Texas, New Mexico and Arizona. In April, the company put in a bid to El Paso Electric (EE) in response to the utility’s request for proposals to supply 300 megawatts of renewable electricity. Davey says the company also has had contact with Arizona’s largest utility, Arizona Public Service (PNW), and California utilities like PG&E (PCG) and Southern California Edison (EIX). "Right now, the best market in the world for large-scale solar is the United States," says Davey. He says EnviroMission is currently reconfiguring the tower’s optimal size, having downsized it to qualify for the Australian government funding. But the first solar tower may well be built in China. EnviroMission’s joint venture with a Chinese development and construction company is close to receiving approval to build a kilometer-high solar tower outside Shanghai, Davey told Green Wombat. "I just got an email from China last night. Things are moving forward."
One of EnviroMission’s more interesting strategies is to work with Native American tribes. The company currently is conducting a site assessment of land owned by the Fort Mojave tribe that spans Arizona, California and Nevada. As the New York Times reported Friday, some Native American tribes in the Southwest are being riven by plans to build heavily polluting coal-fired plants on their land to take advantage of the rich mineral deposits. Clean technologies like the solar tower might provide a green alternative.
Green Wombat 
I have heard that a test tower in Spain (was it this company?) was noting a curious bi-product. The covering was causing nightly condensation to drip onto the desert below and resulted in vegetation blooms that they thought might be harvested as biomass. I wonder if this effect is large enough and dependable enough to be a selling point.
Or you might be able to condense the moisture out of the hot air currents leaving the 1000 ft. tube as recycled water.
According to the linked “Tower of Power” article, the 50 MW system has a collection area that is a 2 mile diameter circle, which is 3.14 square miles. That’s a little over 8 million square meters. So it receives a peak solar DNI of around 8 gigawatts. And it produces 50 megawatts (I’m assuming they are quoting peak output). That’s a conversion efficiency of 0.625%. Please, someone tell me I’ve made a mistake in this very basic calculation. Otherwise it is a ridiculous waste of space.
geo mark, how can it be a ridiculous waste of space if it makes use of desert acreage that would otherwise not be used, ever, for anything? this technology actually makes a worthless barren landscape very valuable.