W Lead-Acid Battery • -35 MW • Nickel-Cadmium Battery, 27 MW Flywheels <25 MW Llthlum-Ion Battery -20 MW Redox-flow Battery <3 MW Source: Fraunholer Inslihrte. EPRI. Electricity Storage Technology Options, 2010. 9 Companies like A123 produce commercial scale batteries, but they are primarily for grid-smoot