Batteries are like Lego sets for the grid. They come in many types, can be stacked or enlarged to store more energy and can drive electricity for seconds to hours. On the longevity end, you'll find trailer-sized flow batteries like vanadium redox and zinc-bromide and high-temperature batteries like sodium-sulfur. These can supply up to 20 megawatts of power for hours [source: Gyuk]. On the burst-of-power end, lead-acid batteries are commonly used today. Other batteries include metal-air, lithium-ion, nickel-cadmium and lead-carbon. All batteries use and release energy through chemical reactions.
Batteries are all over the U.S. electricity grid, usually on the customer side, where factories, and maybe the computers in your office, use an uninterruptible power supply, or UPS to run electronics running during outages.
But batteries also back up the guts of the grid. In Charleston, W. Va., a substation used to overheat every time too many customers drew current through it. Then American Electric Power installed a battery to supply electricity on peak demand days, and the substation stopped overheating. Alaskans used to suffer outages with every glitch on the power line between Anchorage and Fairbanks until they installed a soccer-field-sized battery to cover the line during failure and repair.
Batteries can also help wind farms in places where wind blows only at night and customers use energy during the day.
There's talk of one day using plug-in hybrid electric cars, or PHEVs, with batteries that charge by plugging into the wall socket, for commercial electricity. With the right wiring in your house, your parked car could run your dishwasher. In the far future, many cars plugged into many garages could send electricity to wherever it's needed on the grid in an application called vehicle to grid, or V2G. But it's many years off, since the wall socket can't take electricity from the battery, and the cars aren't commercial.
Does this sound practical? Keep reading to find out how much it all costs.