You can store energy in chemical batteries. Pentadyne Power stores it in moving objects.
The Chatsworth, Calif.-based company has created and sells uninterruptable power supply (UPS) for data centers and large power consumers that stores energy kinetically. A 25-pound mass spins in a vacuum chamber at a high speed. When a utility needs a jolt of electricity, kinetic power is converted to electrical power. When it's not needed, the mass just spins to conserve its energy.
The company uses a relatively small mass to avoid potential mishaps (imagine what would happen if a large mass came unstuck from … Read more