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July 6, 2009 Issue Posted June 25, 2009, 5:00PM EST

Green Business

Water Towers to Catch the Wind

Rooftop water towers may be good for more than just storing H2O. They make ideal scaffolds for small-scale urban windmills, says Cleveland State University's Majid Rashidi, a mechanical engineer who is testing turbine kits that can be fitted onto water towers.

Altitude is the first selling point. The squat, cylindrical towers are perched up high, where winds are best. What's more, their round shape acts as a "concentrator"—meaning gusts hitting the front of the tower gather and slide around it like a river flowing around a stump. That boosts the force of the wind hitting the turbine. In a prototype atop a four-story building in downtown Cleveland, turbines on a tower are pumping out up to four times more energy than an identical rig on a simple mast nearby, says Rashidi. The turbines start spinning at lower wind speeds, too.

Getting independent-minded building managers to adopt this scheme en masse may not be easy in some cities. But the economics behind Rashidi's patent-pending design should help make it attractive. Four turbines together generate around 6 kilowatts of electricity, enough to meet the needs of up to half a dozen families. In mass production, the wind kits would cost under $5,000, he estimates.

—Adam Aston

Seeking Greener Refrigerants

A new National Academy of Sciences report has fanned fears about refrigerants known as hydrofluorocarbons (HFCs), which were once thought to be environmentally benign. Used in air conditioners as well as in fridges and freezers, the refrigerants are a greenhouse gas as much as 12,500 times more potent than carbon dioxide, the report says. So great are their effects that the rising use of HFCs in developing economies could potentially swamp the CO2 reduction efforts under way in most developed countries. Greenpeace, the environmental advocacy group, is now pushing the U.S. Environmental Protection Agency to approve a substitute gas called Greenfreeze, which is used widely in Europe.

—Adam Aston

After a Record, Renewables Falter

For the first time, worldwide investment in clean energy technologies such as wind, solar, and geothermal outpaced spending on new plants powered by coal, natural gas, and other fossil fuels in 2008. The total—$155 billion—rose 5% over 2007, setting an all-time investment record. But 2009 is unlikely to beat—or even match—that. The ongoing market collapse continues to cripple spending in 2009, says Ethan Zindler, head of North American research at New Energy Finance, a market analysis firm that recently released Global Trends in Sustainable Energy Investment 2009 in collaboration with REN21, a U.N.-affiliated think tank. The financial freeze through the first half of 2009 has sharply slowed spending in renewables. While investment may yet rebound, total spending this year is all but certain to fall, adds Zindler, perhaps by as much as 39%.

—Adam Aston

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