DOE Approved Wind Turbine Solution

AML’s DOE-Approved Superconducting Wind Turbine

AML has defined superconducting offshore turbine generator technology for the U.S. Department of Energy–and the world

Offshore wind is one of the most important and sustainable energy sources actively pursued by government and industry.  Abundant wind resources, favorable for generating clean electricity using wind turbines, are available along the coasts of the United States, in close proximity to major metropolitan areas. In order to harvest the energy from this wind in the most economic manner, large offshore wind turbines, each capable of producing enough electricity for several thousand homes, are required.

U.S. Department of Energy Validation

According to the National Offshore Wind Strategy Plan released by the US Department of Energy (DOE) in February of 2011, offshore wind represents a prime opportunity to reduce imports of energy from foreign sources, reduce energy-related emissions and stimulate revitalization of key sectors of our economy.


DOE has followed with action:  In a highly competitive solicitation, AML’s direct-drive, superconducting generator (SG) design for offshore wind turbine drivetrains was selected by DOE as an important component of its offshore wind strategy.  Next Generation of Wind Turbine Generators – U.S. Department of Energy

AML’s SG solution was chosen over solutions proposed by several prominent competitors, including global giants GE and Eaton Corporation, because it provides a number of critical advantages over current state-of-the-art direct-drive generators based on permanent magnets.  Such generators do not scale well to increased power levels, and their use in wind turbines over 6 megawatts is questionable in terms of mass and economic feasibility. Moreover, the rare earth materials required for the manufacture of permanent magnets pose the challenges of rising costs and increasingly uncertain availability.


The powerful advantages of AML’s Superconducting Generator

The “Generator Mass Comparison” shown here illustrates the relative size comparison of AML’s SG versus other options.

Among its other advantages:

  • It is much lighter.  At 10 MW of power, the SG weighs less than 150 metric tons, compared to 300 metric tons for an equivalent direct-drive, permanent magnet generator1, translating into significant cost savings for both the generator and the balance of wind turbine components.
  • It reduces the cost of energy. Ultimately, the system design is driven by the goal of minimizing the levelized cost of the energy (COE) produced by wind turbines. In the National Offshore Wind Strategy Plan for the United States, the COE targets for offshore wind power are $0.10/kWh by 2020 and $0.07/kWh by 2030.  The AML SG, along with other technology improvements in wind turbines, has the potential to reach a COE of $0.077/kWh for a 10-MW turbine.
  • It is scalable.  Of equal importance to reaching targeted COE numbers, is the ability of this class of machines to scale beyond 10 MW in power output. Scaling projections, comparing SGs with other direct-drive generator technologies, show that at larger sizes and lower speeds the size and weight advantages of a SG, and correspondingly COE differences, become even more pronounced.
  • No dependence on rare earth materials. This system relies on a superconductor composed of mainly magnesium and boron, both of which are in abundant supply from multiple global sources.  A stated goal of the US Department of Energy (DOE) is a critical materials strategy that pursues the development of substitute materials and technology for rare earth materials due to increasing costs and serious supply chain concerns for these materials.2
  • It is market-ready to meet growing demand.  By 2025, the equivalent of 8,000 10-MW SGs will be required to meet the rapidly expanding demand for offshore wind power around the world. AML’s SG design has been fully vetted to meet (DOE) performance standards.

The gateway platform for commercialization

The successful design of the AML superconducting generator for offshore wind power serves as the foundation for any application that calls for a large superconducting rotating machine. There are many industrial and electrical grid applications for synchronous condensers and large motors that can achieve greater than 99% efficiency.

AML is seeking qualified strategic partners

AML is looking for visionary organizations who wish to leverage our know-how in superconducting electrical machinery into a high-performance electrical machinery business, addressing large markets such as wind, electrical grid components and industrial motors. Historically, AML has used its relationships with leading companies in superconductor development and cryogenic cooling to collaborate in the realization of superconductor-based systems.  These relationships, along with other new ones, will continue to be used to achieve multiple generations of high-performance superconducting electrical machinery.

For more information on AML’s offshore wind energy program, email us at:

  1. “Electromagnetic Optimization of Direct Drive Generators” D. Bang and H. Polinder, UpWind Project, October 2010.
  2. “Critical Materials Strategy,” US Department of Energy, December 2011.