The wind industry would benefit greatly from an inexpensive way to store a few megawatt-hours of wind generated power that is not needed at the moment. Another boon would be more powerful permanent magnets that would allow larger and lighter generators for wind turbines. As it happens, two British companies say they have answers for these shortcomings. One is developing a battery capable of storing up to 100 MWh. The other has found a way to pump a greater magnetic flux into a rare earth magnet than conventional methods allow. The two are part of a 16-company Clean and Cool Mission 2013 to the U.S. covered here:
Wind Power Performance’s Nick Kitchin
Wind Power Performance, the battery company, has a patent pending on its technology. Managing Director Nick Kitchin says it is a rechargeable bi-metal designed to scale from 1 to 100 MWh, deliver this energy over four to six hours, and work at over 80% efficiency. He also puts its life expectancy at about 30 years.
Such a battery would benefit the wind industry by storing large amounts of wind generated energy when it is not immediately needed and providing it back to the grid when the wind slows, or for peak shaving.
“To give a feel for scale, 1 MWh battery would fill a 40 ft. container and a 100 MWh battery would cover about 50 x 100m and be three stories high,” says Kitchin.
“Size doesn’t appear to be an issue in our target market. We are going in a different direction from many other battery manufacturers. Most are driven by the automotive market and are looking for high energy density in a lighter, smaller package. Our battery is static and does not have to be small. It just needs to be low cost, reliable, easy to maintain and safe,” he says.
Wind and solar are target markets. “By some projections, this is a $114 billion opportunity between now and 2017. It’s a large segmented market. But for those with a large scale, four-to-six hour delivery, there are few solutions aside from pumped hydro and compressed air.” The U.S. Department of Energy database reports energy storage globally now at about 300 MW.
Kitchin says the most important development is at the University of Sheffield in the UK. “We are working through a lab-based proof of concept. The next step will be to produce a 20-kWh battery, then 400-kWh unit, and then a 1-MWh demonstrator.”
A 10T Magnifye magnet can levitate several tons.
The magnet part of this story is further along in development. The company, Magnifye, has secured its patent. The company won’t be selling magnets but rather a way to magnetize those made of rare earth with greater flux density than previously possible.
“The best NdFeB magnet can hold a magnet flux density of 1 Tesla from conventional methods,” says magnetic scientist and development lead Tim Coombs. “But by energizing a YBCO magnet in the way we have developed, it becomes a superconducting at about 10 Tesla. That figure is significant because 10T is about 100 times more powerful than 1T.”
This would let generator firms either take weight out of current designs or produce generators with greater outputs. “Companies are looking to both directions, but the impulse is to build generators with greater outputs, especially for turbines headed offshore,” he says.
With respect to wind turbines, says Coombs, it is difficult to build a 10 MW machine by conventional means because, for starters, the gearbox is maxed-out at about 5 MW. “A direct drive is possible on paper, but in practice it becomes so large the costs spiral out of proportion to benefit. So the only way to get up to 10 MW would be by using superconducting PM generators.”
“To get 10T in a superconducting magnet by conventional means would be to use another 10-T magnet. Our method sort of pumps or strokes the field to 10T,” says Coombs. What’s more, he says the machine that produces the magnetization is small enough to fit in a person’s hand. “All we have to do show the magnet a magnetic field and make sure the magnetic field is varying. We can do that in a small space,” he says.
Magnet scientist Dr. Tim Coombs examines a 10T magnet.
He says the magnetic equipment solves other problems as well. “If you have a machine with permanent magnets and it gets too hot for a couple days, the magnets lose magnetism. Then you have to dismantle the machine and re-magnetize the magnets. We can re-magnetize them in the machine.”
Coombs says he has had positive conversations with several wind turbines OEMs but acknowledges that it would be at least several years before a one of them launches a turbine with magnets charged by his method.
Filed Under: Energy storage, Generators, News
