Power grab
To make the most of solar and wind power, utilities need an affordable way to store energy for later use. Aquion Energy of Pittsburgh says it has developed a low-cost, longer-lasting alternative to existing storage options, including lithium-ion batteries. Aquion's battery stores electricity using sodium, which is safer and more abundant than lithium. As a result, storage costs about $300 per kilowatt-hour, roughly one-third the price of storage with lithium-ion batteries. The battery can also last up to five times as long as lithium batteries, because its electrodes are made from thicker wafers. Aquion, which recently received a $5 million grant from the U.S. Department of Energy, hopes to begin selling the batteries to solar-power companies by summer 2012 and eventually supply them to other utilities.

Stacking the deck
The electrode wafers shown here, made from manganese oxide, measure 2 inches square and 1.2 millimeters thick. They can be stacked and immersed in a solution of sodium and water to store electricity.

Recharge and reuse
Aquion's sodium-ion battery, which is about the size of a breadbox and weighs 5 pounds, is nontoxic and 100 percent recyclable.

"Energy storage has never been this safe, reliable, and affordable." —Scott Pearson, CEO, Aquion Energy