Renewable Power's Growth in Colorado Presages National Debate When Colorado voters were deciding whether to require that 10 percent of the state's electricity come from renewable fuels, the state's largest utility fought the proposal, warning that any shift from coal and natural gas would be costly, uncertain and unwise. Then a funny thing happened. The ballot initiative passed, and Xcel Energy met the requirement eight years ahead of schedule. And at the government's urging, its executives quickly agreed to double the target, to 20 percent. In Colorado -- a state historically known for natural gas and fights over drilling -- wind and solar power are fast becoming prominent parts of the energy mix. Wind capacity has quadrupled in the past 18 months, according to Gov. Bill Ritter (D), and Xcel has become the largest provider of wind power in the nation. The politics and economics of energy are shifting here in ways that foretell debates across the country as states create renewable-energy mandates and the federal government moves toward limiting carbon emissions....