Wind power has long been the big beast of the renewable energy jungle. The technology to generate electricity from wind has been established for more than two decades, and in the past five years has been refined and expanded towards much larger and more powerful turbines including ones that can be used at sea, and towards very small turbines that can be fixed to office buildings or houses. Last year, the US led the world in wind power installations for the third consecutive year, according to the American Wind Energy Association. Global wind capacity increased by more than 20 gigawatts last year, of which more than 5GW was in the US. Spain and China each built about 3.5GW of new capacity, and the rate of expansion in all these big markets is increasing. Wind, however, is running into some problems. The massive expansion of wind generation capacity has outstripped the ability of manufacturers to keep up, leading to big order backlogs