The Knight & Carver Yacht Center was founded in 1971 along the southeastern shore of San Diego Bay, where it continues to build and repair large boats, specializing in custom-built yachts and commercial passenger vessels. Because so many boat hulls are made of fiberglass, the National City, CA-based boatyard also has worked extensively with fiberglass composites. So it was smart, really, when a wind turbine operator called the shipyard roughly 12 years ago to ask if Knight & Carver could repair a broken turbine blade. Figuratively speaking, the yard boss said, “Sure, we’ll give it a whirl.”
Today the Knight & Carver Wind Group operates as a separate company—a spinout, so to speak—with 250 employees, about twice as many as the yacht center. The wind group develops prototype turbine blades at facilities near its headquarters in National City, manufactures 82-foot-long turbine blades in a new facility the company built in Southeastern South Dakota, and dispatches dozens of wind turbine repair and maintenance crews to wind farms throughout the United States.
The Knight & Carver Wind Group is moving now to commercialize its design for an innovative curved wind turbine blade, which was developed to operate more efficiently than conventional turbine blades—and at lower wind speeds. A key feature of the blade, known as the Sweep Twist Adaptive Rotor, or STAR blade, is that it automatically twists to adjust to wind speeds. Twisting enables the massive blade to optimize the wind turbine’s energy output in much the same way that trimming a sail optimizes the speed of a sailboat. As a result, the STAR blade can operate in low winds of 10 mph to 15 mph, and adjusts its pitch as winds increase to reduce excessive loads on the electricity-generating turbine.
Sam Brown, Knight & Carver’s president, says the STAR blade was developed under a $3 million research and development project initiated by the U.S. Department of Energy. The company, which shared a third of the development cost, collaborated in research and development of the blade with scientists at U.C. Davis and the Sandia National Laboratory in Albuquerque, NM. The project began in 2006, and culminated last year with the DOE’s Wind and Hydropower Technologies division naming the STAR blade as one of the agency’s “Top 10 Program Accomplishments.’
A set of three prototype STAR blades, each more than 89 feet long and nearly 8 feet wide, were used to replace standard blades on an existing wind turbine in Tehachapi, CA. Brown says field tests show his company’s blades are producing more electricity.
“We’re seeing a minimum of 8 percent improvement over exactly the same turbines in exactly
