Our cost for wind energy today is higher than our cost for coal power. Why? Because dollars spent building coal plants return far more energy than dollars spent building wind turbines. Put another way, a large coal plant can consistently produce power at 90% of its capacity. Even at the most favorable wind locations in North America with the best turbine technology, energy output averages only 40% of turbine capacity because the wind does not always blow. The economic value of Iowa wind farms is further reduced by the fact that energy output is lowest during the peak electricity demand months of July and August.