Honeywell's wheel-shaped WT6500 takes an entirely new approach. Magnets mounted near the tips of its 20 blades sweep through an outer ring of copper coils to produce a current, making the entire wheel the generator. Because this arrangement traps energy from the fast-moving blade tips and eliminates the heavy central generator, the WT6500 can pull a current from winds as slow as two miles an hour (most home turbines need 8mph gusts). Better suited to home use than other turbine designs, the wheel is six feet in diameter, whisper-quiet, and can produce up to 1,500 kilowatt-hours of power per year—enough to replace about 15 percent of an average household's energy bill. Depending on an area's clean-energy incentives, the turbine can pay for itself in only a couple of years, though most owners will make back their investment in five to 10.