Output from US wind farms fell 6% in the first half of 2015 compared to the same period the year before, despite a 9% increase in generating capacity, according to the US Energy Information Administration . . . . The total generating capacity of all US wind farms was 65,877 megawatts at the end of 2014 . . . . The average cost to build a US wind farm was $1.71 million per megawatt in 2014 . . . . The average electricity price in 13 power purchase agreements signed in 2014 for 1,768 megawatts of new wind farms was $23.50 a megawatt hour, according to the Lawrence Berkeley National Laboratory. Most of the contracts were for new projects in the Midwest where the prices are lowest, made up in part by a higher average capacity factor in the region of 41% . . . . Energy storage continues to grow from a low base: 40.7 megawatts of new storage facilities were installed in the second quarter of 2015, nine times more than the installations in the same period the year before, according to GTM Research and the Energy Storage Association. Most storage activity is in PJM and California.