pacity 316 MW • Lead-Acid Battery ~35 MW • Nickel-Cadmium Battery, 27 MW Flywheels <25 MW Lithium-ion Battery ~20 MW Redox-flow Battery <3 MW Source: Fraunhofer Institute, EPRI, Electricity Storage Technology Options, 2010. ' Companies like A123 produce commercial scale batteries, but they are primarily for grid-smooth