As John mentioned in his earlier post, flywheels can be used to smooth out short-term variations in demand at power plants, which makes them more efficient, or more importantly,can be ganged together for storing energy from variable sources like sun or wind. Last week the California Energy Commission was impressed, saying "California has made a significant commitment to deploy renewable energy placing greater demands on the state's electric grid. Technologies such as Beacon's flywheel-based energy storage system provide attractive options." after studying a prototype 100Kw system packed into a shipping container.
"Housed in a transportable shipping container, the basic Smart Energy Matrix is a compact frequency regulation services system that could be located nearly anywhere on the grid. The system is remotely controlled and monitored for maximum flexibility. Depending on operator requirements, it could be placed at or near a substation or within the distribution system, where additional benefits such as voltage regulation, backup support, or reactive power could be provided for even greater value. Scale-power versions of this system are being demonstrated now in California and New York."