Do we still mine and burn coal in the U.S.?
Indeed we do-more than ever, in fact. About half of America's electricity is generated by burning coal. We consume about a billion tons each year, or roughly 20 pounds per person per day. And in the coming years, U.S. coal consumption is likely to increase. As of 2007, some 150 new coal plants were planned or given the go-ahead in the U.S. In addition, there is currently a push to use coal to create liquid fuels, especially diesel, which some hope will help wean America off imported oil.

How much coal does the United States have left?
According to official estimates from the U.S. Department of Energy, at current rates of consumption, we have at least 250 years' worth of coal within our borders. This number is something of an illusion, however, because it doesn't take into account the economic, environmental, and public health impacts of getting the coal out of the ground and burning it. The truth is, we've been mining coal for 150 years in America-and all the high-quality, easy-to-get stuff is gone. The coal that's left is increasingly dangerous, expensive, and environmentally destructive to extract.

How does America's coal consumption compare with that of China, which is also heavily dependent on coal?
China, which is still a developing nation, relies on coal for about 70 percent of its electricity and is building a new coal plant each week. In terms of sheer tonnage, China consumes more than twice as much coal as the U.S. But on a per-capita basis, China consumes only about one-third the amount of coal as the U.S.

What are the environmental and public health impacts of America's use of coal?
It's hard to come up with a good estimate, in part because the impacts are so enormous. But let's start with the consequences of mountaintop-removal mining in Appalachia. (Mountaintop-removal mining is a particularly destructive form of strip mining in which entire mountains are blasted apart to expose the coal seams inside; the rubble is typically dumped in nearby valleys.) Over the last several decades, 1,200 miles of streams and more than 400,000 acres of forests in Appalachia have been destroyed by mountaintop-removal mining. One recent study estimated that if this practice continues, within 40 years the region devastated by mining will be approximately the size of Rhode Island.

Burning coal is also a major contributor to air pollution. According to the Union of Concerned Scientists, a respected scientific advocacy group, annual emissions from a typical 500-megawatt coal plant include 10,000 tons of sulfur dioxide, the main cause of acid rain, which damages forests, lakes, and buildings; 10,200 tons of nitrogen oxide, a major cause of smog; 500 tons of small particles, which cause lung damage and other respiratory problems; 225 pounds of arsenic; 114 pounds of lead; and many other toxic heavy metals, including 48 tons of mercury. The mercury emissions are particularly troubling: Coal plants are a major source of mercury contamination in lakes and rivers throughout the nation. Health officials warn against eating certain kinds of fish caught in these waters, since mercury can cause birth defects, brain damage, and other ailments.

Indeed, the health impacts from this pollution are enormous. One in five Americans lives within 10 miles of a coal plant. According to the American Lung Association, pollution from coal plants causes the premature deaths of 24,000 people a year. In addition, air pollution from coal plants has been estimated to cause 38,200 heart attacks each year, as well as 554,000 asthma attacks.

Finally, there's global warming. Coal is by far the most carbon-intensive fossil fuel. For every ton of coal burned, between two and three tons of carbon dioxide (CO2), the main greenhouse gas, are created. In the U.S., coal plants emit about 1.5 billion tons of CO2 annually-more than one-third of the country's total man-made CO2 emissions. (Were it not for coal waste, incomplete combustion, and processing losses, the coal-plant emissions would be far higher.)

What is "clean coal"?
An industry slogan, mostly. Clearly, no fuel whose extraction requires the dismantling of Appalachian mountains can be accurately described as "clean." However, it is true that, when it comes to conventional smog-producing pollutants like sulfur dioxide, new coal plants built today are cleaner than the old coal burners built in the 1960s and 1970s (many of which are still in operation). According to one industry trade group, between 1970 and 2000, emissions of conventional pollutants have fallen by one-third even while the use of coal to generate electricity has tripled.

But the biggest problem with clean coal remains global warming. Coal plants that are built today emit just as much CO2 as coal plants built 50 years ago (there have been some marginal gains in efficiency, but not much). Even worse, some of the measures that are taken to reduce conventional air pollutants such as sulfur dioxide actually increase CO2 emissions.

Is there a way to burn coal without contributing to the overheating of the planet?
Maybe. There's a technological solution on the horizon: It's called carbon capture and storage, or CCS. On paper, CCS sounds simple: As coal is burned, remove the CO2 with a so-called scrubber or other device, pressurize it into what's known as a supercritical liquid (which is roughly the consistency of oil), then pump it underground. Depleted oil and gas wells make good storage sites, as do saline aquifers 2,000 feet or so underground. You can even pipe the CO2 offshore and inject it under the ocean floor.

Still, it's not at all clear that CCS is really a workable solution to the problem of CO2 emissions from coal. Squirting CO2 into old oil wells is no big deal-the oil and gas industry does it all the time to help push out stubborn reserves. But capturing billions of tons of CO2 from power plants and pumping it underground-and doing it safely, on a massive global scale, both in the West and in the developing world-is another thing altogether.

The technological issues involved in capturing and storing CO2 are not trivial. Unlike other pollutants-such as sulfur dioxide and nitrogen oxides, which are relatively easy to remove with a scrubber installed on the smokestack of a pulverized-coal plant-CO2 emerges in a diffuse stream that is difficult to filter. In fact, nobody has yet figured out a good way to capture CO2 from a smokestack that isn't prohibitively expensive and doesn't reduce the efficiency of the plant by as much as 30 percent. Other possibilities, such as burning the coal in pure oxygen, may someday make the job of capturing the CO2 output easier, but this technology is nowhere near ready for prime time.

It's more likely that capturing CO2 will require shifting to an entirely new kind of facility known as an integrated gasification combined cycle (IGCC) plant, which uses heat and pressure to transform coal into a gas, which can then be burned to generate power. The advantages of IGCC are many, including the fact that CO2 can be removed during the gasification process, when the volume of the gas is much smaller than it is when it is released up the stack of a conventional coal plant. The disadvantage of IGCC is that it is new and different, and the coal industry has a long history of fighting anything new and different. In any case, the important point is that the ability to capture CO2 is likely to apply only to new coal plants. Retrofitting the thousands of existing coal plants is, at the moment, a pipe dream. If and when the world gets serious about dealing with global warming, they will likely have to be bulldozed.

How much CO2 from coal plants will need to be buried in order to make a difference?
According to the popular "wedge theory" of Princeton professors Stephen Pacala and Robert Socolow, capturing and burying one billion tons of carbon from coal plants by 2050 would contribute one-seventh of the reduction they estimate we need to achieve to stabilize the Earth's climate.

What would it mean to capture and bury a billion tons of carbon from coal plants? Lynn Orr, a petroleum engineer who directs the Global Climate and Energy Project at Stanford University, estimates that to store a billion tons of carbon underground, the total inflow of CO2 would have to be roughly equal to the total outflow of oil and gas today. Needless to say, this would be an enormous engineering project.

Is burying CO2 safe?
Some environmentalists have unfairly compared underground CO2 storage to the burial of nuclear waste. CO2 is not radioactive, nor is it toxic by any conventional definition. But burying CO2 is not risk-free. The liquefied carbon gas is buoyant underground and can migrate through cracks in the Earth and around old well heads, pooling in unexpected places. This is troublesome because CO2 is an asphyxiant-in concentrations above 20 percent it can cause a person to lose consciousness in a breath or two. In theory, you could enter a basement flooded with CO2 and, because it's an invisible, odorless gas, you would never know it's there. There is also the slight but not insignificant risk of a geyser-like eruption of CO2 out of an underground storage facility-which, if it happened in a populated area, could be devastating.

Can coal contribute to America's energy independence?
Perhaps at the margins. Right now, there is virtually no connection between America's consumption of coal and U.S. dependence on Middle Eastern oil. But that could change. It is certainly possible to turn coal into liquid fuels that could power our vehicles. The process was pioneered in the 1920s and '30s by two German researchers, Franz Fischer and Hans Tropsch. Today, both South Africa and China have a number of coal-to-liquid-fuel plants.

But turning coal into liquid fuels is not the answer to America's energy problems. For one thing, these coal-to-liquids plants make diesel, not gasoline. (Brewing gasoline from coal is, for a variety of technical reasons, much more difficult and is beyond the capability of today's technology.) For another, these plants are so complex and so expensive that it's difficult to imagine any scenario in which a sufficient number of them could be built quickly enough to make more than a small dent in America's 20 million-barrels-per-day oil habit (cost estimates for a coal-to-liquids plant capable of producing 150,000 barrels of diesel a day-a modest size, as far as refineries go-run more than $7 billion).

The biggest problem, however, is that coal-to-liquids plants are a step backward when it comes to global warming. The amount of CO2 released when refining coal can be as much as 50 to 100 percent higher than when refining petroleum (the actual amount depends on the technology used). In theory, the CO2 from these plants could be captured and sequestered underground, but the costs and complexities of sequestering are not included in the sales pitches for most coal-to-liquids plants.

A better way to use coal to decrease our dependence on foreign oil would be to push for the deployment of plug-in hybrid vehicles. A plug-in hybrid is essentially a regular gasoline-electric hybrid, like the Toyota Prius, but outfitted with larger batteries and an electrical connector. You charge the car up at night, when electricity prices are low, then drive it on electric power during the day. If the electric power runs out, you can switch back to gas. To put it simply, plug-in hybrids displace oil with electricity. This not only saves on fuel but also cuts CO2 emissions.

What can I do to decrease coal consumption?
First, reduce your electricity usage: Replace each incandescent lightbulb with a compact fluorescent lamp (CFL); buy energy-efficient appliances; don't leave computers and other devices turned on when you're not using them. Second, purchase electricity generated by wind or other renewable sources from your local utility or power company (most power companies now offer a variety of "green power" programs). Finally, and most important, use your vote to support local and national politicians who favor tough limits on greenhouse gas emissions.

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