The answer is blowing in the (very gentle) wind

Generally, rooftop turbines can't produce electricity unless the wind is blowing six or eight miles per hour. This turbine is different. Developed by WindTronics, based in Muskegon, Michigan, it's only 6 feet in diameter and can generate energy at wind speeds of just two miles per hour. WindTronics moved the power-generating parts to the outside of the wheel, where the blades turn faster. Reducing the bulk in the center also allows the turbine to turn more easily. Says CEO Reg Adams: "We've turned traditional wind turbines inside out."

Aiming for the masses

Starting in November, WindTronics's turbines will be available for sale in Ace Hardware stores, under the Honeywell brand. The company hopes to sell 50,000 by the end of 2010.

Power production

The $5,499 device can produce up to 2,000 kilowatt-hours of electricity per year, or roughly 18 percent of the average household's use, according to CEO Reg Adams. But that assumes an average wind speed of 12.8 miles per hour; most homes will see far less. Nevertheless, the machine brings wind power within reach for low-wind areas.