See: http://www.renewableenergyworld.com/rea/news/article/2011/08/batteries-for-energy-storage-new-developments-promise-grid-flexibility-and-stability
QUOTE: "The Electric Reliability Council of Texas Inc. (ERCOT) faced the renewable power industry's most critical issue in February 2008. With a huge wind portfolio in the state the wind died down, and ERCOT declared emergency conditions after a 1200-MW drop in production. The three-hour shortfall, accompanied by increasing overall electricity loads, very nearly caused rolling blackouts. . . ." - Jed
