Wind energy is the nation's fastest-growing form of renewable energy. Despite sometimes heated debates (even here at Mother Earth News) about the aesthetics of wind farms and the reliability of wind power, according to Business Week, in the past five years, output from wind farms has grown tenfold. Today, wind farms meet 1 percent of U.S. energy needs. Advocates of wind energy say wind could someday supply 10 percent of all U.S. electricity, as it does already in countries like Spain.
One of the largest complaints about wind (and solar) energy is a lack of constant supply. If the wind stops blowing, people depending on the breeze are in trouble — or are they? A group of Midwest utilities outside of Dallas Center, Iowa, is currently working on technology that could solve the problem of storing wind energy by tucking it away underground. The system works by funneling compressed air into a deep well. Thousands of feet below the surface of the Earth, the compressor pumps air into layers of sandstone. The porous sandstone acts essentially like a big balloon, and when wind supply is low, the flow is reversed and the chamber empties, bringing a whoosh of air back up the pipe and into a natural-gas-fired turbine.
This isn't a distant pipe dream, either; the project began in 2003 and is expected to go online in 2011. There are already two compressed-air storage facilities operating in the world (one on Germany and one in Alabama), but they are not driven by wind turbines.