Wind power stored underground

New compressed air storage plant announced in Iowa

In Iowa, USA, municipal utilities have announced plans to build a 269 megawatt plant for compressed air energy storage underground. The goal is to overcome the constant variations in the output of wind turbines. Construction of the plant will begin in 2009 and be completed by the end of 2011.

Electricity generated by wind farms at remote sites will be used for driving giant compressors at the storage site. The compressors will pump air into the ground, where it will be stored in porous rock formations. The air will be converted back into electricity by releasing the pressure and allowing the air to drive generator turbines.

Two similar storage plants are already in operation, one in Germany and one in Alabama, USA, both of about half the size of the unit planned in Iowa. The basic technology is well-proven but until recently has not been seen as a cost-effective technique.