According to the Department of Energy, 20 states and the District of Columbia have approved similar measures that require various percentages of electrical power come from renewable sources by the year 2020.
In fact, more and more states are forcing utilities toward wind, solar and other renewable energy sources in order to curb the consumption of coal and natural gas and spur greater U.S. energy independence along the way.
The burning of coal produces greenhouse gases such as carbon dioxide that contribute to climate change and global warming, and power plants fueled by natural gas pollute the air with sulfur dioxide as well.
Opposition to these measures is coming mostly from utilities and fossil fuel industries. They say the switch will be costly for consumers and businesses. In fact, the National Association of Manufacturers opposed a proposed federal requirement to use renewable energy during a Senate hearing last year -- because it would reduce the flexibility of utilities in choosing fuels and damage businesses by increasing costs.
In 2004, Colorado voters approved a referendum requiring that the state draw 10 percent of its electricity from renewable sources. In October, the state's largest utility -- Xcel Energy -- announced it would meet the 10 percent target by 2007.
Colorado's Xcel -- which serves 1.3 million customers -- is now studying how it could attain a higher percentage of renewable energy. The company is "looking at it" according to an Xcel spokesperson, who pointed out the intermittent reliability of wind and solar power.