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July 05, 2011

DOE funds new wind turbine designs and systems including two superconducting systems

The Department of Energy awarded nearly $7.5 million to help develop next generation wind turbines. Each project has been selected to receive up to $700,000 to conduct technology cost and readiness assessments during Phase I. Following the six-month Phase I funding period, several of the projects will be selected for award negotiations of up to an additional $2 million each over 18 months. Projects selected for Phase II awards will use the funding to conduct performance tests of the specific drivetrain components.



Below is the list of the projects selected for awards:

* Advanced Magnet Lab (Palm Bay, Florida) will develop an innovative superconducting direct-drive generator for large wind turbines. The project will employ a new technology for the drivetrain coil configuration to address technical challenges of large torque electric machines.

* Boulder Wind Power (Boulder, Colorado) will test an innovative permanent magnet-based direct-drive generator to validate performance and reliability of a large utility-scale turbine. Design requirements and optimization will also be documented for turbines up to 10 megawatts and for turbines deployed in offshore applications. The proposed generator design may operate at higher efficiencies than other permanent magnet generators.

* Clipper Windpower (Carpinteria, California) will develop and test a unique drivetrain design that enables increased serviceability over conventional gearboxes and is scalable to large capacity turbines.

* Dehlsen Associates, LLC (Santa Barbara, California) will design and test components of an innovative direct-drive concept. The proposed drivetrain configuration eliminates the need for gearboxes, power electronics, transformers, and rare earth materials. The design may also be applicable to marine hydrokinetic - or ocean power - devices.

* GE Global Research (Niskayuna, New York) will design and perform component testing for a 10 megawatt direct-drive generator employing low-temperature superconductivity technology. The proposed generator employs a unique stationary superconducting component design that reduces the risk of fluid leakage.

* National Renewable Energy Laboratory (Golden, Colorado) will optimize and test a hybrid design that combines the advantages of geared and direct-drives through an improved single-stage gearbox and a non-permanent magnet generator that reduces the need for rare earth materials. The technology developed will be scalable to 10 megawatts, and may be used to retrofit currently deployed 1.5 megawatt turbines.


GE believes it can develop an eight-megawatt generator that weights only 50 tons by adapting the superconducting electromagnets used in magnetic resonance imaging. Unlike a permanent magnet, an electromagnet creates a magnetic field when an electric current is applied to it. When made from coils of superconducting wire, it has no electrical resistance, making it more efficient, with the caveat that it must be cooled to minus 250 °C. The approach would eliminate the need for rare-earth materials, assuming GE can lower the cost enough to make it commercially viable.

Florida-based Advanced Magnet Lab, which also received DOE funding, believes it can build a 10-megawatt generator that weighs just 70 tons. As with GE's technology, the core of the company's innovation is a superconducting direct-drive generator. The company has developed a compact coil design based on double-helix windings that can carry high currents and handle the immense magnetic forces produced in the system.

Advanced Magnet Lab president Mark Senti says the high cost of superconducting materials and of cryogenically cooling makes no sense for today's three-megawatt wind turbines. But beyond six megawatts, he argues, the systems become competitive with conventional generator designs. At 10 megawatts, "it gives you the highest power-per-weight ratio."

There's also significant room for advancement. Senti says most superconducting wiring costs $400 per meter today, but new materials made out of inexpensive magnesium and boron powders promise to lower costs substantially. With improvements in manufacturing and less expensive cooling techniques, Senti figures superconducting technology could eventually become economical for wind turbines as small as two megawatts, making it ideal for both onshore and offshore markets.


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