New Fabric-Covered Blades to Lower Cost of Wind Energy
GE using architectural fabrics to make wind energy costs competitive with fossil fuels…Posted Dec 3, 2012
Engineers at General Electric are reaching back to an old technology which, coupled with modern materials, may be a breakthrough in lowering the cost of wind energy.
Using strong, lightweight architectural fabrics to cover wind turbine blades is less expensive than manufacturing blades made out of fiberglass, the conventional material used for wind turbine blades today. Fabric-covered blades also have improved performance in moderate wind conditions, and are easier and less expensive to install.
Early aircraft designs pioneered the use of fabric to cover structures made of wood or aluminum as a means to reduce weight. Fabric-covered biplanes fought the aerial dogfights of World War I, and were considered structurally sound but vulnerable to fire due to the flammable properties of the cloth and glues. The development of synthetic Dacron and chemical-based non-flammable glues are more recent advances in fabric-covered aircraft, and today many ultra-light aircraft are covered with pre-sewn Dacron envelopes.
According to GE principal engineer Wendy Lin, the new fabric-covered design could reduce blade costs 25% to 40%. Without releasing details about the fabric under development, Lin said it will be tough, flexible, and easy to assemble and maintain.
The fiberglass turbine blades used today have several limitations which contribute to the relatively high cost of wind energy. Fiberglass blades are expensive to make since they are labor intensive and require costly ‘clamshell’ molds. The turbine’s rotor diameter cannot exceed 120 meters due to the logistical constraints in building, transporting and installing such large pieces. And the large, heavy fiberglass blades underperform in moderate wind conditions, limiting wind farm installations to fewer and more remote high-wind locations.
GE’s advanced turbine blade uses architectural fabrics which are stretched over a lightweight metal spaceframe. The fabric is tensioned around ribs which run the length of the blade and is specially designed to meet the demands of wind blade operations. Applying the fabric over the frame is simpler than molding two fiberglass halves and joining them, which makes it possible to construct the blades on the wind farm site. This cuts the cost of transporting oversize turbine blades, and enables larger blades to be constructed which surpass the 120-meter rotor diameter size. Larger fabric-covered turbine blades would make lighter turbines that can capture more wind at lower wind speeds.
If field tests bear out the promise of GE’s fabric-covered turbine blades, this development represents a milestone in bringing clean wind energy to a level economic playing field with fossil-based fuels.
“The fabric we’re developing will be tough, flexible, and easier to assemble and maintain. It represents a clear path to making wind even more cost competitive with fossil fuels.”
The research project is being conducted with the US National Renewable Energy Laboratory (NREL) and the Virginia Polytechnic Institute and State University. The three-year project won $5.6m in funding support from the US Energy Department. Other project participants are Virginia Polytechnic Institute & State University (Virginia Tech) and NREL