Beacon to develop flywheel energy-storage unit

Tyngsboro, Massachusetts-based Beacon Power has been selected by the US Department of Energy (DOE) to develop a next-generation flywheel energy-storage system.

The flywheel module would be capable of storing four times the energy at one eighth of the cost per energy unit, compared with the company’s current Gen 4 flywheel.

Flywheel energy-storage systems work by accelerating a cylindrical assembly, called a rotor or flywheel, to a very high speed and maintaining the energy in the system as rotational energy. The energy is converted back by slowing down the flywheel. The flywheel system itself is a kinetic or mechanical battery that spins at very high speeds to store energy that is instantly available when needed.

The proposed 100kWh system will use a ’flying ring’ − a lightweight hoop of co-mingled fibre composite with bonded magnetic materials mounted on the structure. This configuration eliminates the need for a central shaft and hub, increasing energy density to 76Wh/kg.

The developers of the flywheel also aim to make it capable of more than 40,000 full charge/discharge cycles in its lifetime, thereby achieving a cost per storage cycle below $0.025/kWh (£0.017/kWh).

’If successful, the development of the flywheel will open up a number of new, commercially attractive applications and markets for clean, long-life flywheel-based energy storage,’ said Bill Capp, Beacon’s president and chief executive officer.

If it were to be eventually commercialised, Beacon expects that the flywheel system would be suitable for a variety of applications, including wind-diesel-storage hybrid systems.