One of the main criticisms of solar power as a key energy source is that it doesn’t work the minute the sun sets. Australian company EnviroMission Ltd., however, believes it has a solution on a grand scale. With its eye on a vast stretch of barren land in western Arizona, it hopes to build a solar tower, a gargantuan power plant that requires only the intense sunlight from the day to keep it fueled.

Unlike solar thermal plants, which are dependent on large quantities of water and use mirrors and sunlight to heat water into steam, EnviroMission’s solar tower would draw its energy purely from the four-square-mile large greenhouse on which it would be perched. Sunlight from the scorching Arizona sun would presumably heat the air in the greenhouse, which would in turn rise to the top of the peaked greenhouse and through a 2,400 ft-tall chimney. On its way up the half-mile-high tower, the hot air would spin the turbines in its path, generating electricity.

“It’s basically an upside-down hydroelectric dam,” said Christopher Davey, president of Australia-based EnviroMission Ltd.

Or so the science goes. EnviroMission has yet to actually develop a recent solar tower, and the last time the technology was tested was in a pilot project in Spain, which was demolished in 1989 after eight years of production. Although the Arizona Free Press article linked above provided no figures for the plant’s activity during this period, Davey argues that the very existence of the project proved the technology’s viability.

Using the greenhouse effect to beat the environmental consequences of the greenhouse effect? Now there’s an irony. The only issue in EnviroMission’s way now, however, is that age-old killer of many an ambitious idea—a lack of finances. Although Arizona officials have indicated interest in building two of the $750 million, 2oo-megawatt solar towers, EnviroMission’s task now is to raise money from U.S. investors. Without a single plant currently in operation, in November it received a letter from the Australian Securities Exchange, which was concerned with its solvency. EnviroMission, however, is optimistic: it recently raised $143,000 from U.S. investors and has the support of the Southern California Public Power Authority, which has agreed to negotiate a power-purchase agreement in the event that the company’s solar towers should see the light of day.

“This will enable Arizona to become a powerhouse. We would like La Paz County to become a new solar county.” [Davey said.]