In early May, the U.S. Department of Energy kicked off an US$8 million R&D project for the development of lightweight compact high-performance generators, in order to cope with the trend for the development of high-capacity wind turbines.

The project covers the development of direct-driver generators and super-conductive generators, with four participants being ABB, WEG, AMSC, and GE. The DOE believes that the project, if successful, can halve the size and weight of generators, while cutting the levelised cost of electricity (LCOE) by 10-25%.

Direct-driver generator employs permanent magnet, in place of conventional gearbox, thereby making the generator smaller and lighter, in addition to slashing the use of rare earth.

The project will take advantage of ABB's technology for double stator generator and WEG's high-performance permanent-magnet direct-drive generator. In addition, ABB claims that its innovative magnet cooling system will be applied in the new product, which will facilitate the development of ultra high-capacity wind turbine, even reaching 15 MW.

Meanwhile, thanks to the employment of superconductive components, AMSC's generator boasts power output five to 10 times common models, on top of substantial reduction in weight, size, and rare-earth contents. A precedent is EcoSwing, a generator with superconductive components, sponsored by the EU, featuring lightweight and small size, with the employment of rare earth reaching only 1,000 grams. Its production cost stands at only US$18.7 per kilo, compared with US$45.5 of conventional models.

In addition, AMSC has developed a new generator employing HTS (high-temperature superconductor) materials, with size and weight only half of conventional models, and GE has developed high-performance ultra-lightweight LTS (low-temperature superconductor) generator, taking advantage of its own NMRI (nuclear magnetic resonance imaging) technology, which can facilitate the development of wind turbine with capacity as high as 13 MW. A number of technological bottleneck needs to be overcome for the commercialization of the technology, though.

Each of the four participants will be entitled to a subsidy of US$400,000 for the design and analysis of their product before selection of one for US$6.4 million for the development and testing of a prototype of new generator.