CHICAGO -- Expect an ancient form of energy - coal - to gain new attention in the coming years.
Stories of polar bears dying for lack of ice and receding glaciers around the world are giving new urgency to the study of man-made greenhouse gases - billions of tons of which are attributable to coal, the nation's largest source of electricity.
Many scientists believe such gases are responsible for global warming. And king among them is the normally innocuous gas, carbon dioxide, that results from combustion of fossil fuels, including coal.
About half of the nation's electricity comes from coal-fired plants using technology that has changed little in generations, with nearly all the remainder coming from dams, nuclear plants and natural gas.
Coal has historically been a cheap and reliable source of power. The United States has a supply of at least 250 years, and the coming year will see state authorities examining dozens of proposed new coal plants across the country.
But coal is also a remarkably dirty way to make electricity.
Coal burned for electrical generation in the United States gave off 2.1 billion metric tons of carbon dioxide in 2004, the latest year for which the federal Energy Information Administration has figures. That is about one-fifth of the world total of 10.6 billion tons of carbon dioxide, known chemically as CO2, billowing into the atmosphere. In terms of volume, carbon dioxide is the pre-eminent greenhouse gas.
Despite a growing global agreement that something must be done about carbon dioxide emissions from coal-fired plants, the United States has no national program or plan. But industry experts are betting that will change.
"There is an overwhelming consensus that this is a real problem," said John Rowe, chief executive of Exelon Corp. "You will not get an adequate response without a mandatory [national] program."
Rowe said his utility sold its coal-fired plants seven years ago, in part because he sees some kind of constraint on carbon dioxide emissions coming. Exelon is the nation's largest operator of nuclear plants, which emit no CO2.
Ways to limit carbon dioxide emissions have gotten little attention under the Bush administration. But with the Republicans' loss of Congress, some political leaders are planning to raise the issue in 2007.
Sen. Barbara Boxer, a California Democrat and the new chairwoman of the Senate Committee on Environment and Public Works, is promising to make greenhouse gases a priority.
"Nowhere is there a greater threat to future generations than the disastrous effects of global warming," she said recently.
While there is no federal plan, individual states are acting to curb CO2, although it remains unclear how effective those efforts will be.
California, for example, has adopted an ambitious program to reduce CO2 and other greenhouse gases by 25 percent in the next 13 years. The state can use energy-efficiency measures, alternative fuels, limits on emissions and the creation of a market to trade pollution credits.
In Illinois, market advocates point to the Chicago Climate Exchange as one model for reducing CO2 emissions. The exchange handles trades by companies and others that agree to reduce emissions each year. Participants that exceed their goal are given credits that they can sell to others that fail to meet their goals.
Among those using the exchange are United Technologies Corp., Michigan State University, Ford Motor Co. and DuPont Co.
Market-based exchanges have effectively reduced emissions of other pollutants, some observers say, but participation on the exchange is voluntary.
Meanwhile, some states are taking a harder stance toward CO2 from coal-fired power plants.
Seven states in the Northeast have formed the Regional Greenhouse Gas Initiative. Starting in 2009, CO2 emissions from coal-fired plants will be capped through 2014. They must be reduced 10 percent by 2019.
Traders will be able to buy and sell pollution allowances much like on the Chicago Climate Exchange. But the program - involving Maine, New Hampshire, Vermont, New York, Connecticut, New Jersey and Delaware - is mandatory.
Denise Sheehan, commissioner of the New York State Department of Environmental Conservation, said the states would have preferred a national plan, but felt they had to act as a region now.
"Many of the power generators would rather see a national program," Sheehan said. "Our hope is to be a model for national action."
Doug McFarlan, a spokesman for Midwest Generation, which operates six coal-fired generating plants in Illinois, said various states are serving as laboratories to devise new ways of reducing CO2 emissions. But he says his company would like to see some sort of a national program, if only for the sake of simplicity.
"As a general rule, we have always favored a national approach, if not an international approach, to these kinds of issues," McFarlan said. "Greenhouse gases are a global phenomenon. There clearly is an increasing urgency on the part of public policymakers."
The Sierra Club has a simple answer for reducing CO2 emissions from coal-powered plants: Use less electricity.
"There is on-the-shelf technology for a 20- to 40-percent cut" in electrical consumption, said Bruce Nilles, director of the Midwest clean energy campaign for the Sierra Club, noting that a switch from incandescent to fluorescent lighting and universal use of energy-efficient appliances would make a significant difference in emissions levels.
"We can do this," Nilles said. "This isn't rocket science. But we need to move fast."
Robert Manor writes for the Chicago Tribune.