On average: While wind, gas and coal generation all got more expensive in 2007, it was for different reasons. Wind, with its cost lying mainly in the capital investment, was hit harder by the global hike in steel and copper prices than its competitors. They, however, were hit by rising fuel prices. The benefit of wind's high capital cost is that in a low risk market with low interest rates of 5% (right), its price falls dramatically compared with a high finance cost market of 8% (left). The average cost for wind is derived from a sample of 3000 MW of plant from 2007 using a 30% capacity factor; fuel prices are from the US Energy Information Administration and gas and coal generation costs from a range of sources.