Purchases of wind turbines and other equipment will decline 18 percent this year and won't return to 2011 levels for five years, according to Bloomberg New Energy Finance. Capital investment in wind-power assets worldwide will be $60.8 billion in 2012, down from $74.6 billion last year, as oversupply and waning government support in the United States and Europe cut demand, Bloomberg said. Total installations will decrease 13 percent to 47 gigawatts and will remain little changed until 2019, said Justin Wu, head of wind analysis at New Energy Finance.