Flywheels help NY power grid runs more smoothly

ALBANY, N.Y. (AP) — Some excess power on New York's electrical grid is being stored short-term in 200 flywheel batteries that can zap the power back into the system within seconds when needed.

The $69 million battery farm near the Massachusetts border in Stephentown, N.Y., was officially inaugurated in a ceremony Tuesday and addresses the problem of how to smooth out the ever-fluctuating balance between electricity supply and demand in power grids. Typically, power plants either ramp up or slow down production as needed.

Beacon Power of Tyngsborough, Mass., says its flywheel plant, which can store 20 megawatts, can balance the load about 100 times faster than typical power plants. The flywheel batteries provide a cleaner and more efficient buffer in a time when more intermittent power sources like wind and solar come are coming online, said Beacon president and chief executive officer Bill Capp.

"You need more of those balancing service to keep everything working," Capp said. "We're coming in at a perfect time, just when that need is being identified."

Beacon's flywheel batteries contain a rotor levitated magnetically in a seven-foot sealed chamber, where they spin up to 16,000 times per minute. The flywheels store power as motion — think of the way potters' wheels are hard to stop once they're up to speed. The rotors spin in a vacuum so there's less resistance.

"The whole rotor is levitated magnetically and there's just not much to go wrong," Capp said.

More traditional lithium ion batteries have been used for this kind of "frequency regulation," and there have been smaller flywheel demonstration projects, but this appears to the first large-scale flywheel regulation system hooked up to a power grid, said Haresh Kamath, program manager for energy storage at the industry-supported Electric Power Research Institute.

Kamath said that while flywheels cannot store a lot of energy, they are attractive because they can cycle up and down over and over again without degrading.

Beacon said its plants are designed to last 20 years or more.

The company plans to break ground soon on a second flywheel project in Hazle Township, Pa.