Wind has emerged as the nation's fastest-growing energy source, with thousands of towering turbines dotting the countryside from California to New England. Generating capacity has risen as much as 50 percent annually, encouraged by tax incentives and state laws mandating growth in renewable energy. Already, wind provides about 2 percent of electricity nationwide, and the Department of Energy says a 20 percent share by 2030 is possible with improvements in turbine technology, large-scale investment and better planning of the electrical grid. But opponents argue that wind turbines kill tens of thousands of birds and bats each year, mar pristine scenery and require far more land than traditional methods of power generation. The battle over wind is playing out in states such as Wisconsin, where the proximity of turbines to homes is an issue, and Vermont, where environmentalists are divided over two goals: protecting scenic vistas and reducing fossil fuel use.

David Hosansky is a freelance writer in the Denver area who specializes in environmental issues. He previously was a senior writer at CQ Weekly and the Florida Times-Union in Jacksonville, where he was twice nominated for a Pulitzer Prize.