How to build a better wind turbine? GE finds inspiration in MRIs

GE is using MRI — magnetic resonance imaging — technology to research ways to dramatically boost the energy-generating capabilities of wind turbines.

Part of a two-year, $3-million project from the US Department of Energy (DOE), the effort is aimed at developing a wind turbine generator that could support large-scale generation in the 10-megawatt (MW) to 15-megawatt range.

“With the industry’s desire for higher megawatt machines to maximize clean wind power opportunities in the US and around the globe, new technologies will be needed to support larger scale wind platforms,” said Keith Longtin, wind technology leader for GE Global Research. “The key challenge will be delivering solutions that achieve the right scale and cost.”

Longtin said the superconducting magnets used to make lower-cost, higher-image-quality MRIs could also help to develop more powerful wind turbines.

“For wind turbines, we want to apply them to generate more wind power at a lower cost of electricity,” he said. “The applications are different, but the basic technology is the same.”

A wind turbine’s electrical generator converts the mechanical energy generated by the blades into usable electrical power. The more effective the generator, the more mechanical energy can be turned into electricity.

Most wind turbines today use conventional generators connected to a gearbox, which steps up lower blade speeds into higher speeds before the energy reaches the generator. While such gearboxes are effective in current wind turbines, they become more costly as turbines grow larger because of additional weight and maintenance requirements.

In other words, it’s possible to build larger-scale wind turbines, but they come with a cost: higher electricity prices.

Longtin said the innovative application of superconducting technology could enable significant improvements to the generator and make it more economical to eliminate the gearbox. The keys are reducing the size and weight of the generator, while reducing speed and increasing torque. Using superconducting technology reduces weight by virtue of the high magnetic fields that can be created by the superconducting field winding and the fact that the heavy iron in the superconducting generator can be reduced.

GE’s superconducting machine design will use a novel architecture and cryogenic cooling to improve the reliability of the complete machine. Its proposed design aims for twice the torque density of competing technologies. It will also reduce dependence on the rare earth materials found today in all permanent magnet machines for wind. The larger power levels of these machines, coupled with their improved energy conversion efficiency, should lead to more favorable economies of scale.

The potential result: fewer towers will be needed for a given wind-farm output because each individual turbine can generate more output. The could translate to a lower cost for wind energy.