But now, some nonbattery technologies are gaining traction as utilities continue to look for economical ways to capture and store power. FLYWHEELS: Flywheels store electricity in the form of kinetic energy. COMPRESSED AIR: Machines that use compressed air have been around for more than 100 years. In the old days, the heat from the compressed air would be vented, and later the air would be reheated using a natural-gas-fired motor. Hydrostor, however, removes the heat from the compressed air and stores it in a tank filled with waxes and salts.

Source: Wall Street Journal May 22, 2017 01:52 UTC