Clipper Windpower, a wind power company based in California, received an "Outstanding Research and Development Partnership Award" from the U.S. Department of Energy (DOE) for the design and development of its 2.5 MW Liberty Wind Turbine, the largest wind turbine manufactured in the U.S. The turbine was developed under a partnership with DOE and its National Renewable Energy Laboratory (NREL). Commercial sales started in June 2006 for the new Liberty turbine and now amount to more than 5,600 MW (2,240 units) of firm and contingent orders for deliveries in 2007 through 2011.[1] There have been problems with the gearboxes of the first installed turbines at the steel winds wind farm requiring their replacement[2]
