Wind energy is one of the fastest-growing electrical energy sources in the United States. The United States installed over 5,200 MW in 2007 and experts are forecasting for as much to be installed in 2008. The United States cumulative installed capacity as of Dec. 31, 2007, was 16, 596 MW. Wind turbines have evolved rapidly over the past 20 years and the turbines have grown in size from 100 kW in the early 1980s to over 2.5 MW today. The evolution of wind technology is expected to continue over the next two decades resulting in a continued improvement in reliability and energy capture with a modest decrease in cost. The development of new and innovative rotors, drive systems, towers, and controls is expected to enable this continued improvement in the cost effectiveness of wind technology. Wind energy can supply 20% of the United States electricity needs by 2030 and will be a significant contributor to the worlds electricity supply.