Researchers working at the Energy Department’s Sandia National Laboratory said they developed a new type of rotary electrical contact that promises to end the need for rare earth magnets in wind turbines.
Sandia said it it ready to partner with the renewable energy industry to develop what is said would be the next generation of direct-drive wind turbines.
The lab’s so-called Twistact technology takes what it said is a novel approach to transmitting electrical current between a stationary and rotating frame, or between two rotating assemblies having different speeds or rotational direction.
The innovation uses a pure-rolling-contact device to transmit electrical current along an ultra-low-resistance path. Twistact devices accomplish pure-rolling-contact galvanic connection using a flexible, electrically conductive belt and a matching set of epicyclic sheaves.
A study by the National Renewable Energy Laboratory found that substituting rare-earth magnets with a wire-wound rotor and Twistact module in a 10 MW direct-drive wind turbine eliminated the need for rare earth magnets without incurring penalties in power generation efficiency or levelized cost of energy.
A two-channel Twistact device for a multimegawatt direct-drive wind turbine application. Credit: Sandia Licensing and Technology Transfer Most utility-scale wind turbines depend on rare-earth magnets to operate. But rare-earth metals have always been in short supply, the researchers said. What’s more, their mining is linked to adverse environmental impacts, and competing applications such as electric vehicles place increasing demand on the resource.
Sandia said that its technology addresses two physical degradation processes common to high-maintenance brush or slip ring assemblies: sliding contact and electrical arcing. These limiting factors reduce the performance of traditional rotary electrical contacts and lead to short operating lifetimes and high maintenance or replacement costs, the lab said.
Twistact, on the other hand, has been proven through laboratory testing to be capable of operating over a 30-year service time of a multi-megawatt turbine without maintenance or replacement.
Other potential applications for the technology include synchronous motors and generators, electrified railways and radar towers. Twistact could also be used in replacing brush or slip rings in existing applications.
Sandia said it is now exploring opportunities to partner with generator manufacturers and others in the renewable energy industry to assist with the transfer of the technology into next-generation direct-drive wind turbines.
