Each year, the US sets off the equivalent of 20-30 atomic bombs worth of explosives, effectively obliterating entire features of its own landscape. Why? To get at the coal that's inconveniently located beneath the mountains of Appalachia.

That jaw-dropping figure came towards the end of a session at last month's meeting of the American Association for the Advancement of Science called "The True Cost of Coal." Most methods of resource extraction and use come with various forms of what are called externalities, or costs that aren't included in the final product, but distributed across society as a whole in the form of things like environmental degradation and damage to health.

Calculating these hidden costs is obviously a challenge, and the researchers involved doing so tend to produce a range of values to reflect the uncertainty. But for coal, most of the estimates suggests that its true cost is about double the price of the energy produced with it, and may be quite a bit more.

Melissa Ahern of Washington State University described some of the environmental impacts that have resulted from the mountaintop removal process in Appalachia: over 500 peaks gone, 2,000 miles of streams eliminated, and over 140 billion gallons of coal slurry currently held in storage ponds. But her research has focused primarily on the health costs of the mining.

This presents a bit of a challenge, given that the Appalachian communities where the mining takes place are extremely poor, and poverty and low education are associated with a lot of health problems. In addition, many of the problems associated with coal mining—particulates from the mining process and water contamination—don't respect the county borders that divide up the health care data.

But even after adjusting for the variations in things like income and education, counties with active coal mines came out far worst in many measures of health. These include the problems you'd expect from mining, such as cardiopulmonary and respiratory issues, black lung, hypertension, and kidney disease. But they also include things like a 25 percent increase in birth defects in mining counties.

Ahern summed up the fate of people located near mines rather grimly: "Their property value goes down to zero, then they get ill, then they die."

It doesn't get much better from an energy standpoint, according to Samir Doshi of Queen's University in Canada (he's the one who provided the atomic bomb figure), since the energy intensity of mountaintop removal is roughly three times that of normal coal mining. Between the health issues, the energy and environmental costs, and the fact that we're less than a decade away from the peak of coal extraction from Appalachia, Doshi argued that there was little about it that made any sense, especially considering that it supplies only about four percent of the nation's electricity right now, and there is enough coal being mined in the west to support its export.

Coal doesn't get much better when you burn it, either. Doshi went through a laundry list of problems: carbon dioxide emissions, particulates, acid rain, heavy metal contamination from what's left after it's burned. He said that most of the Midwest is near a coal plant that emits a ton of mercury each year, while the residual contamination on the East Coast is so bad that "pregnant women are simply told not to eat fish."

So, can we add all this up? Doshi and his collaborators have attempted to do so, including the impacts of climate, air quality, mercury damages, coal transport deaths, public health issues, subsidies for extraction, and the loss of value of the abandoned land. At the low end, their estimates suggest that coal's additional costs run about 9.4 cents a kilowatt-hour (¢/kwhr) in the US. Even that compares unfavorably with the typical cost of power in the US, which is about 9.7¢/kwhr.

And that's the low estimate. Their best estimate places the additional costs at 17.8¢/kwhr—on its own, that's more than the typical cost of existing wind power (14.9¢/kwhr). The worst case is a staggering 26.9¢/kwhr.

Is it possible to start including those costs into our energy economy? It probably can't be done quickly without a rather severe disruption, given that coal supplies about 45 percent of the US' electricity. At the same time, however, it generates 80 percent of the carbon emissions produced by electric generation, so even a small tax on carbon would be sufficient to reduce coal's use.

In the mean time, there has been very little in the way of new coal capacity in the US for roughly two decades. As the oldest, least efficient, and most polluting plants get retired, at least some of coal's problems will begin to take care of themselves.