Beacon Power: A Megawatt of Flywheel Energy Storage  

Renewable Energy World has a report on reasonably large scale energy storage using flywheels - Beacon Power Tests Megawatt of Flywheel Storage . The device can pump out 1 MW for 15 minutes.

Beacon Power Corporation, a company that designs and develops products and services to support electricity grid operation, announced that it has built and tested an integrated matrix of ten high-power flywheels that when operated together can absorb and supply a full megawatt (MW) of electricity. The system, located in Beacon's headquarters, will be the first of up to 5 MW of flywheel-based regulation capability that will be produced this year and commercially deployed to generate revenues from the provision of regulation services.

Until now, Beacon had been building and running individual flywheels in preparation for its first full megawatt implementation. Based on internal testing of an integrated matrix of ten flywheels, the company said that its one-megawatt Smart Energy Matrix can ramp up and down to absorb and supply a full megawatt of power.

Over the next few weeks, Beacon will begin system testing in conjunction with ISO New England, during which time the flywheel matrix will respond to actual ISO test signals to absorb and supply power. This plan will allow the company to meet its schedule to interconnect live to the grid and to begin performing frequency regulation services under an ISO New England Alternative Technologies Pilot Program scheduled to start on November 18.