Renewable energy has a critical role to play in reducing
greenhouse gases and leading the United States toward energy
independence. That role should soon be getting bigger: The U.S.
government is pushing for a 100 percent increase in renewable
energy by 2012. The two biggest sources are the wind and the
sun. But the variable nature of wind and solar energy can cause
problems with matching supply to demand—problems that would be
greatly eased if only we had a really good way of storing
electricity on an industrial scale. Currently there are several
storage systems vying for dominance. Compressed-Air Energy
Storage At night, when the strongest winds blow and customers
are sleeping, unused wind-generated electricity can run giant
compressors, forcing large amounts of air into sealed
underground spaces. When demand rises during the day, the
compressed air can be used to spin turbines, turning the energy
back into electricity. Georgianne Peek, a mechanical engineer at
Sandia National Laboratories in New Mexico, sa