The cost of generating wind power in the U.S. fell to its lowest level ever last year, according to a report from the Department of Energy. Utility companies purchased wind power for 2.35 cents per kilowatt-hour on average last year, making the price of wind energy competitive with conventional power sources in many parts of the country. Wind power now meets on average 4.9 percent of the nation’s electricity demand, the DOE analysis found, and nine states used wind to produce more than 12 percent of their electricity. Iowa and South Dakota produced more than a quarter of their electricity from wind, Kansas generated roughly 22 percent from wind, and Texas remained the leading state for wind installations in 2014. With a total installed capacity of 66 gigawatts, the U.S. now ranks second only to China in wind power capacity.