In late October, Southern California Public Power Authority approved a contract to buy green power from EnviroMission Ltd., which for years has been planning to enter the renewable energy game with its wild design for a gargantuan "solar chimney tower" over twice as tall as the Empire State Building.
The tower represents a hybrid of solar and wind technology. The bright surface at the bottom of the artist's rendering is an expansive glass-covered greenhouse that bakes in the sun, heating air that pours into the 1,000-meter-high chimney, churning 35 electricity-generating turbines. One tower could power 100,000 households, claims EnviroMission.
According to EnviroMission the solar tower concept was proven in the 1980s, in a Spanish-German collaboration  whose smaller-scale tower yielded 50 kW of power. Starting in 2001, EnviroMission began focusing its attention on Australia, hoping to build its first utility-scale tower there. But in recent years EnviroMission diverted its attention to the U.S. When GreentechMedia spoke to EnviroMission's communications person, she alluded  to "less-than-helpful government policy and the sway of vested coal interests." In June 2009, EnviroMission filed for land applications in Arizona.
The project represents an engineering challenge as much as anything else. EnviroMission's CEO says his tower can be built for $700 million. One thousand meters represents what would be the tallest man-made structure in the world, soundly defeating the 828-meter Burj Khalifa in Dubai. That kind of talk shouldn't come lightly, and GreentechMedia may well be right to scoff: "What bank or financier takes on this type of project when earth-based (and reality-based) solar projects are available and already challenging enough?"
Despite the agreement from SCPPA, the EnviroMission tower remains in something of a limbo state. The details of the Power Purchasing Agreement are confidential, but it's likely that the utility has only committed to buying a certain amount of energy at a particular kilowatt-hour price--and if EnviroMission doesn't meet it, then the utility wouldn't have to buy. Still, asserts Davey in a press release, the agreement "is an important milestone that will allow finance to be secured." It's working on front-end engineering and design now.
In other words, astronauts at the International Space Station shouldn't expect to see this behemoth (which ultimately would be visible from space ) out their window anytime soon. The recent agreement, you might say, enables plans to finally be planned.
Still, one can dream--and animate: Download a video for a look inside a digital version of the tower here .