The US Department of Energy (DoE) will back four companies' development of technology to underpin wind turbines of up to 15MW for use on- and offshore.

The DoE will commit funds to generator technology projects underway by GE, AMSC, ABB and WEG “that will facilitate the continued growth of wind turbines for both land-based tall wind and offshore applications”.

The US federal government department will give each up to $400,000 to back development of generators “that can be scaled up to at least 10MW to capitalise on the trend of larger, more powerful wind turbines, especially for offshore applications”.

It hopes the projects – two of which focus on direct-drive systems – will result in generator designs that are 50% smaller and can cut cost-of-energy by 10-25%.

One will be selected to receive up to $6.4m to deploy a prototype of its generator.

The four projects backed by DoE are:

  • ABB – a lightweight double-stator generator that uses an innovative advanced magnet cooling system suitable for both geared and direct drive machines, scalable up to 15MW.
  • WEG – a high-efficiency permanent magnet direct drive lightweight generator to integrate into its existing platform.
  • AMSC – 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%.
  • GE – a high-efficiency ultra-light low temperature superconducting (LTS) generator, tailored for offshore wind and scalable beyond 12MW, leveraging technology from the US giant's magnetic resonance imaging (MRI) business.

Like other markets, the US is seeing a shift towards larger turbines in its onshore wind sector, and is keen to deploy supersize machines at sea as its emerging offshore industry takes shape.

In its latest market report, industry body AWEA noted the average rotor diameter of an installed US turbine in 2018 was 116 metres, while the share of turbines deployed with rotors at least 120 metres in diameter jumped to 30% last year from 14% in 2017.

Average turbine hub height increased to 88 metres, with growing market interest in towers over 90 metres in height – 21% of turbines in 2018. The use of taller hub heights is occurring mainly in lower wind resource regions.

In 2018, applications for tower heights over 152.4 meters soared to 31% of all proposed wind projects versus 15% in 2017 and less than 5% before then, according to AWEA.