A path for renewables

Growing concerns about climate change have spurred investment in America's renewable energy resources.

As of June 2008, 28 states and the District of Columbia had created renewable portfolio standards, which require that a certain percentage of their electricity be generated from renewables. Five other states have voluntary programmes. And this summer, the country's high gasoline prices have led Texas oil and gas executive T Boone Pickens to introduce a plan to expand greatly the use of wind farm