As a sailor, Mike Zuteck often had observed the way a sail rig twists in the wind. The motion sparked an idea for a new wind-turbine blade that could generate more energy in low-speed wind conditions.
“You learn something from making the boat move better with the wind,” said Zuteck, a wind-energy consultant based in Clear Lake, Texas, who has been racing sailboats since his days on the Massachusetts Institute of Technology’s sailing team in the 1960s. “It’s a thinking you pick up from observing the wind move."
The fiberglass-and-epoxy-resin blade looks like a carving knife that has been curved – or swept – near the tip. The so-called “sweep twist” blade was designed to be more attuned to wind's natural movement, potentially producing more energy in low wind and reducing fatigue loads, or wear and tear, on the blade.
Knight & Carver, which is designing and making the blade, expects to commercialize it later this year. The company hopes the blade will open slower-wind regions currently closed to wind-energy production. The company expects the technology to capture 5 to 10 percent more energy in regions with low wind speeds.
Such regions, which have an average wind speed of 5.8 meters per second, measured at a height of 10 meters, are so abundant in the United States that the technology could increase by twentyfold the amount of land that can be used to generate wind energy, according to Sandia National Laboratories, which have tested prototypes.
Because slower wind regions often are near areas where power is already loaded onto the grid today, such as in the Midwest, the blade also could reduce the cost of transmission, said Gary Kanaby, director of business development for Knight & Carver.
Tom Ashwill, who leads Sandia’s blade research in Albuquerque, N.M, said the blades will cost about 10 percent more than traditional blades. That might not sound so enticing, but it means existing wind farms with 750-kilowatt turbines that were popular in the 1990s could increase electricity generation just by replacing their worn blades, without having to add more turbines. Knight & Carver plans to target that market initially for retrofitting.
And because blades make up only about 15 percent of the total turbine cost, according to Ashwill, the new and improved blade would increase the overall cost by only 1.5 percent more, making them more cost effective overall.
The idea has gained recognition.
At WindPower 2008 in June, the project was selected as one of the U.S. Department of Energy's top 10 program accomplishments. Knight & Carver also raised $12.5 million in its first round of funding from the Global Environment Fund earlier this year.
Maureen Hand, a senior engineer with the National Renewable Energy Laboratory's National Wind Technology Center in Golden, Colo., called the project “unique,” especially in an environment of rising wind-turbine costs.
“Any increase in energy capture will deliver cost savings and have a positive impact on the industry,” she said.
