“When the wind blows, a pocket of low pressure air forms, pulling the
blade toward it, causing the rotor to turn. This is called lift. The “When the wind blows, a pocket of low pressure
air forms, pulling the blade toward it, causing the rotor to turn. This is called lift.
The turbines that use a new, low wind speed technology. The sweep twist adaptive
blade automatically twists to reduce stress on the turbine from the mechanical load produced during high wind.
Today, a standard HAWT (Horizontal Axis Wind Turbine)captures the wind’s
energy with three propeller-like blades mounted on a rotor. The turbine sits more than 200 feet atop a tower to take advantage
of stronger and less-turbulent wind. Elevated so high above the surface makes maintenance and repair costly; bearings and
shafts that transfer wind power from the turbine blades must be to withstand exceptional rigors in various weather conditions.
Newer HAWTs can make use of wind at lower velocities; such
advanced design has meant the addition of utility scale wind turbines in less windy (Class Four*) areas.
*Note: Wind power classes designate a range of mean wind power
density of approximate wind speed at specified heights above the ground. Areas designated as “Excellent” have
wind power Class Five or greater, and are suitable for utility-scale wind energy applications. These areas represent regions
where the wind power density exceeds 500 watts/m2 at 50m above the ground. Areas designated as “Good” have wind
power at four or better, and are also suitable for utility scale wind energy applications.
Nevertheless, these advanced designs can have increased stress at higher
velocities requiring the turbine to be stopped or the drive train disengaged. The innovative wind blade, which Knight &
Carver’s Wind Blade Division has developed, can operate over a wider range of wind speed thereby increasing the amount
of energy that a low wind speed turbine can produce.
Sized at 27.2 (85 ft) meters x 2.4 meters (7 ft),
the Adaptive Sweep Twist Blade is designed both for maximum efficiency
at lower-speed wind conditions and to automatically adjust to higher wind gusts when necessary.
In partnership with the U.S. Department of Energy, theUniversity of California at
Davis and Sandia National Laboratory Knight & Carver designed, fabricated and field tested this innovative component as
part of the Low Wind Speed Technology Project. The goal of the project is to reduce wind-powered electricity generation costs
at low-speed sites, and to open new areas of wind production by utilizing next-generation configurations, designs and concepts.
The DoE wind technology program supports public-private partnerships for multiple large wind systems (turbines over 100 kilowatts).
The program has a goal of achieving costs of 3 cents/kWh in class 4 wind regions by 2012.