Back in October 2008, Xcel Energy started an innovative study in which it installed a 1-megawatt (MW) capacity battery (20 50-kW NGK Insulator batteries) near an 11-MW wind farm owned by Minwind Energy, LLC. The battery was supposed to store, when possibly, the wind energy and release it to the grid when necessary. For the past 21 months the utility has been collecting data and this week it released preliminary results.