Low Speed Wind Turbines
"Energy increases by the cube," says Andy Kruse quoted in the Oakland Tribune, vice president of Southwest Windpower. "If you double the wind speed, you get eight times the energy."
One way to generate more electricity in low wind speeds is to use larger blades. Southwest makes wind turbines that can be equipped with 7-foot or 10-foot diameter blades.
Southwest also is working on lighter, cheaper fiberglass blades with foam cores, he said.
Jim Dehlsen, co-founder of Clipper Windpower Inc., said his company has developed a massive 2.5 megawatt wind turbine with a custom-designed gearbox that's suitable for areas with lower wind speeds. The turbine uses a blade with a 305-foot diameter. That means the blade turns more slowly than those on smaller wind turbines, but also generates more torque.
Clipper's custom-designed gear boxes distribute the power from a wind turbine's blades to eight different generators. That helps the company's turbines generate more electricity even in varying wind speeds, and operate for 30 years instead of the 20-year industry standard, Dehlsen said.