Large Wind Technology

Goal

The performance goal for the large wind turbine (LWT) research is to reduce the cost of electricity from large land-based wind systems in Class 4 winds (5.8 m/s at a height of 10 m) to 3.6 cents per kilowatt-hour by 2012 and 7 cents per kilowatt-hour for offshore systems in Class 6 (6.7 m/s at a height of 10 m) winds by 2014. Wind turbines are currently capable of producing electricity at 0.04 - 0.09 cents/kWh in the Class 4 wind regimes that are broadly available across the United States, depending on many factors, including project financial structure. The program's strategy is to increase the commercial viability and deployment of wind energy by improving the reliability and performance of existing technology while setting the stage for future wind technologies advanced through applied research and market assessment.

2006 Research Project Highlights

Prototype Development

During the past two years, the Wind Energy Program has completed several cost-shared research and development (R&D) partnerships with industry that produced commercially viable products. One project that demonstrated commercial viability in 2006 is the new 2.5-MW wind turbine manufactured by Clipper Windpower. Clipper produced a prototype of its 2.5-MW Liberty wind turbine in 2005 after only three years of cooperative R&D. The company experienced significant growth in 2006 through the sale of its new machine with 875 MW of firm commitments for 2007 and 5,000 MW of contingent orders for delivery over the next four years.

Component Development

The program also engaged in several partnerships to improve the performance of system components in 2006. Northern Power Systems (NPS) completed a very successful partnership with the program to produce a modular, highly efficient power electronics package that can be scaled for use in a wide range of wind turbines, from small to multimegawatt systems. According to the company, the new converter improves wind turbine reliability, energy capture, and grid performance, and it was chosen by the American Wind Energy Association for its 2006 Technical Achievement Award. Tests completed on both the converter and the NPS 1.5-MW direct-drive generator, also developed under the program, demonstrated high-quality power output.

Global Energy Concepts (GEC) fabricated a 1.5-MW, single-stage drivetrain with a planetary gearbox and a medium-speed (190 rpm), permanent-magnet generator. The simple gearbox design and moderate-sized generator show potential for reducing tower-head weight and drivetrain costs. The company completed initial testing of this drivetrain on the 2.5-MW dynamometer test facility at the National Renewable Energy Laboratory. The generator is currently being upgraded and a second phase of testing is planned for 2007.

Genesis Corporation, is testing a new tooth form for gearboxes that promises major improvements in power density while reducing the costs of these devices. The company completed the first round of testing with positive results and is now working to refine its design.

Knight & Carver produced the first in a series of wind turbine blades. Called the STAR for sweep-twist adaptive rotor, the 27.4-m blade is curved to relieve pressure on both the blade and the turbine. Manufactured at Knight & Carver's blade division in San Diego, California, the new blade is designed to passively reduce loads thereby allowing a larger more productive rotor. This concept also shows potential for significant cost and manufacturing advantages.