To make the most of solar wind power, utilities need an affordable way to store energy for later use. Aquion 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 killowatt-hour, roughly one-third the price of stoarge 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 US Department of Energy, hopes to begin selling the batteries to solar-power companies by summer 2001 and eventually supply them to other utilities.