Images: Making wind power that lasts all day

When compressed air is not a possibility, there's always massive batteries. American Electric Power, a utility which operates in the Midwest and southern United States, has bought sodium sulfur (NAS) batteries from NGK Insulators of Japan. One of its battery purchases--part of a plan to buy 25 megawatts of storage this decade--will be used to store electricity generated by wind turbines next year.

This installation in Charleston, W.V., is used as a buffer capable of generating a few hours of power for an overloaded substation.

Photo by American Electric Power