High-Tech Flywheels Help Bring Stability to Grid

Pioneering flywheel developer Beacon Power is becoming one of the success stories of the evolving power grid. Its flywheels help to correct the obvious shortcomings of grid 1.0 by storing electricity during slow periods and then instantly setting it free when it's needed to regulate grid frequency. So as grid loads are added or subtracted, Beacon's flywheels are always ready to bring frequency back in line by instantly adding or subtracting power.

High speed vacuum chamber

Beacon’s technology is a carbon fiber composite rim spinning up to 16,000 rpm. These high speeds are possible in a sealed near-frictionless vacuum chamber, with a magnetic field supporting the rotor. Effortlessly performing more than 175,000 full depth charge and discharge cycles, Beacon's flywheels easily outlast other storage technologies - particularly lithium batteries.

Always spinning in the same direction, the flywheel can instantly shift back and forth between charging and discharging modes. When charging (or absorbing) energy, the flywheel’s motor acts like a load and draws power from the grid to accelerate the rotor to a higher speed. When discharging, the motor is switched into generator mode, and the inertial energy of the rotor drives the generator, injecting electricity back into the grid. 

Pay for performance mandates

After a period of slow growth, Beacon suddenly declared bankruptcy in 2011. The Massachusetts-based company was down but not out, and was saved when Houston-based private equity firm Rockland Capital bought it. Scott Harlan, managing partner of Rockland, told Salon that he could see that renewable power was making the grid more unstable, and that Beacon’s flywheels were a very profitable solution. That was possible because the Federal Energy Regulatory Commission (FERC) had just mandated that grid operators compensate faster-performing systems like flywheels at a higher rate for peaking and frequency regulation services.

FERC had a "very material role” in Beacon’s rebirth, CEO Barry Brits told EnergyBiz. “Our challenge in repaying the original debt had been that natural gas prices were really low. But Rockland was able to realize that with the FERC ruling, the project could become valuable.” 

In 2011 FERC's Order 755 increased the pay for “fast” responding sources, like batteries or flywheels, bidding in frequency regulation service markets, where Beacon sells its power.

Beacon's future improved even more with FERC Order 784. Playing to Beacon's strength, it played fast batteries, flow batteries, and flywheels against slower gas or coal-fired plants in the ancillary services market. Also, it expanded the pay-for-performance requirements to ensure that speed and accuracy, two storage strengths, is considered when utilities purchase regulation service for transmission.

While competitors offering fast-acting batteries also earn the same premium, flywheels have a strong competitive advantage because they're better at repeated cycling. What’s more, flywheel costs are dropping. Beacon Power CEO Barry Brits says the company’s next plants will cost less than half as much as the new plant in Hazel Pennsylvania that came online last summer.

Isolated micro-grids

Beacon is now taking its technology out to a micro-grid on Alaska’s Saint Paul Island, located in the middle of the Bering Sea. In addition to providing all of the small grid’s voltage and frequency regulation, the flywheel energy storage will be integrated into the existing wind-diesel microgrid, allowing it to run exclusively on wind power 15 percent of the time.

Beacon’s technology will deliver fuel savings of up to 30 percent over pre-flywheel levels. During excess wind, the flywheel energy storage system absorbs energy and then recycles it back into the system to ride through subsequent drops in wind production providing time to start-up backup generators. As a result, the micro-grid will reduce both wind curtailment and its diesel fuel consumption.

“Beacon Power is excited to be involved in such a groundbreaking project,” said Brits. “This is an opportunity for us to demonstrate the extended storage capabilities of the Beacon Power flywheel system which will increase integration of wind power into the local grid.”

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