“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
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
*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
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, the University
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.