On energy

Ever since the Arab oil embargo of 1973, U.S. dependence on foreign sources of energy has been a major concern among politicians and policymakers. As gas prices have continued to climb, U.S. energy policy has simmered as a political issue.

The energy debate has an environmental component. The burning of fossil fuels such as coal, natural gas and oil produces carbon dioxide, No. 1 among the greenhouse gases scientists say are causing the climate to change. In 2009, a Democratic-controlled House passed legislation aimed at reducing pollution by capping emissions and allowing companies that can't meet those limits to buy emission credits from those under their cap. Republicans blocked that proposal.

The political divide on energy is between proponents (mostly Republicans) of increased domestic production of oil and natural gas and continued use of coal, and supporters (mostly Democrats) of green energy, who see increased use of alternative energy sources, such as biofuels, solar and wind, as a way to reduce foreign oil dependency and save the planet.

Most of the GOP 2012 hopefuls reject the conclusion that human activity contributes to climate change, and all propose expanding domestic drilling for oil. President Obama, who says he believes the conclusions on global warming, supports cap-and-trade and is a strong proponent of clean energy. Obama also has signaled support for more drilling.

By Larry Bivins, Gannett Washington Bureau