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Sandia Technology logo A quarterly research and development magazine.

Spring 2007
Volume 9, No. 1

SANDIA TECHNOLOGY MAGAZINE

news notes


Sandia helps develop new wind turbine blade design

turbine blade
The first STAR blade was tested in January at Knight & Carver’s fabrication facility in San Diego.

A new wind turbine blade design, developed by researchers at Sandia in partnership with Knight & Carver of San Diego, promises to be more efficient than current designs. It should significantly reduce the cost-of-energy of wind turbines at low-windspeed sites.

Named “STAR” for Sweep Twist Adaptive Rotor, the blade is the first of its kind produced at a utility-grade size. Its most distinctive characteristic is a gently curved tip, or “sweep,” which unlike the vast majority of blades in current use, is specially designed for low-wind-speed regions like the Midwest. The sites targeted by this effort have annual average wind speeds of 5.8 meters per second, measured at 10-meter height. Such sites are abundant in the U.S. and would increase by 20-fold the available land area that can be economically developed for wind energy.

graphs
Graphs illustrate several innovative prototype blade designs for improved wind efficiency. Green outline shows curve, or sweep, in Knight & Carver design. Extra twist built into the blade reduces fatigue in high wind and allows longer blade length — resulting in 5-8 percent more energy generation. Red, white and blue blade drawings are of 9-meter prototypes, showing three innovations aimed at creating more design efficiencies.
At 27.1 meters — almost three meters longer than the baseline blade it will replace — STAR improves energy capture at lower wind speeds. The blade curves toward the trailing edge, which allows it to respond to turbulent gusts in a way that lowers fatigue to the blade. It is made of fiberglass and epoxy resin.

“This design allows the blade to twist more than traditional designs, thus relieving some of the effects of gusty turbulent wind on blade life,” says Tom Ashwill, who leads Sandia’s blade research efforts. “This then allows us to grow the blade length for the same rotor, providing for increased energy capture of 5 to 10 percent and yet retaining the same expected fatigue life.”

The K&C contract is part of the Low Wind Speed Technology project that targets wind sites that are not the strongest but plentiful. In late 2005, DOE and Sandia awarded Knight & Carver the $2 million contract that includes $800,000 in K&C cost share. Sandia’s role in the project has been in directing design and test planning. The K&C team provided the detailed design and blade fabrication. Four blades will be fabricated in the first quarter of 2007. Three will be flight-tested on a turbine in Iowa.

Other members of the design team are Dynamic Design of Davis, Calif.; MDZ Consulting of Clear Lake Shores, Texas; University of California, Davis; and NSE Composites of Seattle, Wash.

Technical contact: Tom Ashwill (505) 845-8457, tdashwi@sandia.gov
Media contact: Chris Burroughs, (505) 844-0948, coburro@sandia.gov