Department of Energy backs mega-turbine drivetrain concepts

The US Department of Energy is to fund a quartet of companies developing technology that could have potential for next-generation large on- and offshore wind turbines.

The DOE selected four projects for which it will provide up to US$8M to develop next-generation drivetrain technologies that will facilitate the continued growth of wind turbines for both land-based ‘tall wind’ and offshore applications.

The projects could enable more efficient, smaller, and lighter wind turbine generators to be developed, that will reduce costs and make wind power more affordable.

Each of the selected projects will receive up to US$400,000 to design a wind turbine generator that can be scaled up to at least 10 MW to capitalise on the trend of larger, more powerful wind turbines, especially for offshore applications.

Two projects are developing direct-drive permanent magnet generator designs that are smaller, lighter, less expensive, more reliable, more efficient, and use less rare earth content than conventional gearbox designs.

The companies benefiting from the funding include ABB in North Carolina, who will develop a lightweight double-stator generator that uses an innovative advanced magnet cooling system suitable for both geared and direct drive machines, scalable up to 15 MW.

WEG Energy Corporation in Georgia will develop a high-efficiency permanent magnet direct-drive lightweight generator to integrate into its existing platform.

Two projects will develop superconducting generators, which make a much stronger magnetic field using superconducting windings. This results in a significant size and mass reduction over conventional generators and significantly reduces the need for foreign-sourced rare earth materials.

The first will see American Superconductor Corporation in Massachusetts develop a high-efficiency lightweight wind turbine generator that incorporates high-temperature superconductor (HTS) materials to replace permanent magnets in the generator rotor, potentially reducing size and weight by 50%.

The advantage of an HTS design is the higher operating temperature of the generator windings, which significantly reduces the challenges associated with maintaining supercritical temperatures in the generator. The challenge with HTS machines is that the winding material is much more expensive, and it comes in relatively short lengths, necessitating many splices.

General Electric Research in New York will develop a high-efficiency ultra-light low temperature superconducting (LTS) generator, leveraging innovations from GE’s magnetic resonance imaging business.

The generator will be tailored for offshore wind and scalable beyond 12 MW. The advantage of LTS generators is the availability of low-cost LTS wire in lengths needed to wind the generator without splices. The challenge with LTS designs is the need to cool the windings to about 4° kelvin, which typically requires the use of liquid helium.

If successful, the research projects will result in designs up to 50% smaller and lighter while reducing the cost of wind generation by 10-25%.

After the projects complete the design and analysis phase, the DOE will select one to receive up to US$6.4M to build and test a scaled prototype on a wind turbine.