The Coyote argues succinctly:
Environmentalists seem to all feel that capitalism is the enemy of sustainability, but in fact capitalism is the greatest system to promote sustainability that has ever been devised. Every single resource has a price that reflects its relative scarcity as compared to demand. Scarcer resources have higher prices that automatically promote conservation and seeking of substitutes. So an analysis of an investment's ability to return its cost is in effect a sustainability analysis. What environmentalists don't like is that wind does not cover the cost of its resources, in other words it does not produce enough power to justify the scarce resources it uses. Screwing around with that to only look at some of the resources is just dishonest.