In 1941, the Smith-Putnam Wind Turbine became the first wind turbine to feed AC power to the electric grid.
In a 25 mph wind, the wind turbine fed electricity into the grid of the Central Vermont Public Service Corporation. In 1943, a main bearing failure shut the turbine down for two years, due to wartime shortages. It went back online in early March of 1945. Shortly thereafter, a blade failed on the turbine. That meant the end of the project since wartime shortages made steel a luxury.
Learn more at http://www.wired.com/thisdayintech/2009/10/1019wind-turbine/.