Large Wind Technology
Large wind turbine research improves the commercial viability and supports greater 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. This page describes the highlights of the Wind Energy Program's research in this field.
Goal
The Wind Energy Program's goal is to reduce the cost of electricity for 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 (kWh) by 2012 and offshore systems in Class 6 winds (6.7 m/s at a height of 10 m) to 7 cents/kWh by 2014.
Wind turbines are currently capable of producing electricity at 5 - 8 cents/kWh in Class 4 wind regimes across the United States.
Research Project Highlights
These are some of the key research project highlights from the Wind Energy Program's research in large wind technology.
Prototype Development
During the past two decades, the Wind Energy Program has worked with industry to develop a number of prototype technologies, many of which have become commercially viable products. One example is the GE Wind Energy 1.5-MW wind turbine. At the end of 2007, GE had more than 6,500 of these machines installed worldwide. The design of GE's 1.5-MW machine is based on work conducted with GE and its predecessors (Zond and Enron). Since the early 1990s, the program worked with these companies to test components such as blades, generators, and control systems on the various generations of machines that led to GE's 1.5-MW workhorse. Another project that is demonstrating commercial success 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 research and development work with the Wind Energy Program. The company installed 170 MW of its 2.5-MW machine in 2007.
Component Development
The Wind Energy Program also works with industry partners to improve the performance and reliability of system components. Knight & Carver's Wind Blade Division in National City, California, worked with program researchers at Sandia National Laboratories to develop an innovative wind turbine blade that the company expects to increase energy capture by 5% to 10%. The most distinctive characteristic of the Sweep Twist Adaptive Rotor (STAR) blade is a gently curved tip, which unlike the vast majority of blades in use, is specially designed to take maximum advantage of all wind speeds, including marginal speeds. The blade was tested for endurance at the National Renewable Energy Laboratory in 2008.
To support the development of more reliable gearboxes, the program has worked with several companies to design and test innovative drivetrain concepts. Clipper's Liberty wind turbine incorporates a highly innovative multiple-drive path gearbox that feeds four advanced permanent-magnet generators. 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 that shows potential for reducing tower-head weight and drivetrain costs. Northern Power Systems (NPS) constructed a permanent-magnet generator with a novel power converter to allow variable-speed operation. The NPS converter was chosen by the American Wind Energy Association for its 2006 Technical Achievement Award.