If the U.S. is going to generate 20 percent of its electricity from the wind in the next 20 years, wind turbines will need to evolve in every way - larger, taller, less expensive, more reliable and more efficient. At NREL's National Wind Technology Center, engineers are preparing to install the two largest turbines ever tested at the laboratory. Key elements of a 1.5 MW General Electric turbine have begun arriving; instrumentation and equipment testing should begin by late summer. Installation of a 2.3 MW turbine from Siemens Power Generation is scheduled for late summer, too. Full story here.