In the desert of western Arizona, a power company proposes to build the world's tallest chimney -- a tower, 2,600 feet tall, that would be the centerpiece of a giant non-polluting power plant, making electricity from the heat of the sun.
The project has been started by an Australian company called EnviroMission, which says it hopes, by the time it is finished construction in early 2015, to provide enough electricity to power the equivalent of 200,000 homes. It would burn no fuel. Nothing quite like it has ever been tried in America before.
In fact, nothing quite like it has been tried anywhere else in the world, aside from a small test project in Spain. The finished tower would be the second-tallest structure on the planet, just a hundred feet shorter than the Burj Khalifa luxury skyscraper in Dubai. It would be twice as tall as New York's Empire State Building.
"It would be conceited to say we have the solution," said Chris Davey, the president of EnviroMission's U.S. operations in Phoenix, "but it's a reasonable energy alternative."
When one mentions solar power, most people probably think of so-called photovoltaics -- those big, flat panels that have been used to power spacecraft, but so far have been considered too expensive for large-scale commercial use. EnviroMission plans something very different.
Its design consists of a giant, round greenhouse-like structure, under which air would become trapped and get very hot -- around 160 degrees Fahrenheit.
Hot air naturally tries to rise, so it would rush toward the tall tower in the center. On the way, it would pass through any of 32 turbines, whose turning blades would run generators and create electricity. The plant would burn no fuel, emitting no greenhouse gases.
"It's a very favorable operation," said John Drum, a member of the local county board of supervisors. "It'll bring quite a few jobs to our county, and when it's done there will be 40 to 50 people to run it."
It would also draw attention to this isolated place, off state route 95 north of Quartzsite, Ariz. Supporters say the view from the top on a clear day would be stupendous.
Clean Solar Energy, Even at Night
EnviroMission says the beauty of its design is that the plant doesn't only work in blazing sunlight. All it needs is for there to be some solar heating. The company says it has checked out possible sites in Kansas, Pennsylvania and rural New Jersey -- cooler, cloudier places than Arizona. Davey says the company's calculations show the chimney would even generate power at night. The air in the canopy would be warmed by the sand beneath it, which would have absorbed excess heat during the day.
"It's incredibly benign," Davey said. "No water, no dangerously high temperatures, no 'death rays' from mirrors, very few moving parts."
If it all sounds too good to be true, remember that the plant is still far from being built. Financing the project, currently estimated at $750 million, could be difficult. There is still a thicket of regulations to be dealt with. What's more, economics may simply not be on solar's side. Coal and natural gas, despite the air pollution and carbon dioxide they give off when burned, still generate electricity more cheaply.
Environmental advocates are conflicted too, not wanting to oppose a source of clean power or a boost to the local economy, but concerned that it might affect migrating birds and local wildlife, even in the desert.
"This thing seems to be a weird black hole at the moment," said Vashti Supplee, the director of bird conservation for the Arizona chapter of the National Audubon Society. She said it's possible that birds, migrating along the nearby Colorado River, would be confused by it. "I don't know what's going on with it."
She said she had not yet seen an Environmental Impact Statement, something required by law, and local land regulations had to be altered because nothing as tall as EnviroMission's tower had ever been contemplated in the area.
But EnviroMission's Davey said the company has moved slowly and quietly, so that it does not promise a miracle power source that does not work.
"All we're using," he said, "is warm air to drive turbines."