March 17, 2009 4:00 AM PDT
Cascade Engineering has the rights to sell this Swift turbine, which is already installed in dozens of locations in the U.K., some attached to roofs on homes. Like other wind turbines, the Swift has blades that turn and power a generator. But rather than the typical three blades, the Swift has five and a ring that goes around them. That "outer diffuser" ring cuts the noise level to 35 decibels and reduces vibration, according to the company.
Photo by Cascade Engineering
Caption by Martin LaMonica
