Should the lesser prairie chicken become listed as threatened or endangered - and it's close now - there would be significant restrictions on companies hoping to plant towering turbines across a five-state region believed to have some of the nation's best wind energy potential. "We've never seen the likes of this," said Texas Parks and Wildlife Department wildlife biologist Heather Whitlaw, who is part of conservation efforts with the other states and believes the bird could be listed within two years. "Anybody who puts anything on our landscape would be evaluated in one form or another."

The SunZia transmission line that would link sun and wind power from central New Mexico with cities in Arizona is just the sort of energy project an environmentalist could love -- or hate. And it is just the sort of line the Interior Department has been tasked with promoting -- or guarding against. If built, the 460-mile line would carry about 3,000 megawatts of power, enough to avoid the need for a handful of coal-fired plants and to help utilities meet mandated targets for use of renewable fuel.

Wind power offers the potential of clean, inexhaustible, if intermittent, energy. But where to site wind turbines in relation to homes and communities is a major and growing point of controversy around the world and in the U.S. Here's why.