Rooftop windmillsAt Boston's Logan International Airport, propellers aren't just for planes. Massachusetts Port Authority, the airport's manager, is putting 20 turbines, each six feet across, on the roof of its administrative building. The whirligigs, Massport expects, will crank out some 100,000 kwh of power per year and shave about $13,000 from its energy bill.

Quicker boilingThink about all the steam used to heat buildings and power factories. If it took less energy to create steam for industrial uses, there'd be huge savings. Nanotechnologists at Rensselaer Polytechnic Institute say they cut the energy needed to boil water by 90%. The trick is a nearly invisible layer of nanorods--ultratiny columns of copper grown chemically on the inside of a vessel used to create steam.

Thriftier chipsYour PC conserves power in sleep mode. But a new chip design developed at the University of Michigan would do it about 30,000 times better. Described at a June symposium of the Institute of Electrical and Electronics Engineers, the energy-saving design could appear in tiny sensors and biomedical chips in 18 months.

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