Date: Dec 24, 2014 Author: Peter Fairley Source: IEEE Spectrum (
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Flywheel-based energy storage got a black eye with the 2011 bankruptcy filing of Beacon Power Corp., a leading energy storage company, based in Massachusetts, whose technology upgrades pushed flywheels to grid-scale applications. But that blemish proved ephemeral. New investors pulled Beacon Power out of bankruptcy, and last July the firm started a second commercial facility, in Hazle, Pa., to provide power-grid-regulation services. Beacon is attacking new markets that would take the technology in a new direction, followed closely by new grid-scale flywheel competitors.
Recent entrants in the flywheel field include Boston's Helix Power, cofounded by former Beacon Power chief technical officer Matt Lazarewicz, and Williams Advanced Engineering, based in Wantage, England, which is scaling up technology from the flywheel-based hybrid drivetrains it built for Formula One race cars.
The quick revival of Beacon—and of flywheels' reputation—was a direct result of a change in the way grid operators in the United States pay for frequency regulation. To prevent damage to equipment, the frequency of an AC grid must not deviate by much more than a few tenths of a hertz. But when loads are added or subtracted from the grid, it can reduce or increase the frequency. Energy storage systems can bring the frequency back in line by quickly adding or subtracting power. Under the new "Pay for Performance" regulations, begun in 2012 after years of consideration, Beacon earns a premium, because the 200 flywheels in each of its plants correct frequency deviations on the grid far more quickly than the power plants that have traditionally regulated AC grids can. Each plant can release or absorb up to 20 megawatts of power.
While competitors offering fast-acting, battery-based facilities also earn that premium, they are less well adapted to repeated cycling. What's more, flywheel costs are dropping fast, according to proponents. Beacon Power CEO Barry Brits says the company's next plants, two of which are in advanced planning, will cost less than half as much as the new plant in Pennsylvania. Another difference is that Brits plans to find buyers for those plants, rather than continuing to act as an owner-operator, thus reducing Beacon Power's financial needs.
Recent entrants in flywheel development are adopting the same risk-limiting approach. Canadian start-up Temporal Power's first facility—a 2-MW frequency-regulation plant in Minto, Ont., that started stabilizing for the provincial grid operator last year—is owned and operated by another firm. "We're in the business of producing turnkey facilities. That's less risky and less capital intensive," says Temporal Power cofounder and chief technology officer Jeff Veltri.
Flywheel competitors are similarly tracking Beacon's expansion into new markets. For example, a slew of recent flywheel installations by Beacon, Temporal, and others help grids cope with intermittent renewable energy. One such project on Alaska's Kodiak Island showcases the flywheel's ruggedness relative to batteries, according to Darron Scott, CEO of the local utility, Kodiak Electric Association.
KEA's 2-MW flywheel system is being installed by Zurich-based ABB, which acquired Australian flywheel manufacturer Powercorp in 2011. Scott says the flywheel system will become KEA's first line of defense against varying power flows from wind turbines, relieving a 3-MW battery system that is wearing out faster than expected. "We use our batteries a couple of hundred times of day—a lot more than we'd modeled," says Scott.
Beacon is working on a similar project designed to allow Alaska's Saint Paul Island—smaller than Kodiak Island—to run exclusively on wind power about 15 percent of the time, with Beacon's flywheels providing all of the grid's voltage and frequency regulation.
Applications such as these are driving a trend toward flywheels with larger motor generators, which can push and pull energy out of the spinning rotors faster. Brits says Beacon is testing a larger motor that nearly doubles its flywheels' 160-kilowatt charge/discharge capacity. Temporal Power's flywheels already operate at plus or minus 500 kW.
Helix Power is developing 1-MW machines to target yet another grid-scale energy-storage application: capturing energy from braking electric trains as they enter the approximately 9,000 mass-transit stations worldwide. The opportunity has been proven with other technologies, such as the combination of ultracapacitors and batteries that is capturing energy from trains in Philadelphia. But Helix Power's Lazarewicz bets that its flywheels will be more cost effective.
He adds that this and other industrial applications can operate "behind the power meter," remaining largely immune to regulatory hang-ups such as the multiyear wait for tiered pricing on frequency regulation that Lazarewicz lived through at Beacon Power.
