Coal: A Primer

Abstract

This book chronicles almost five decades of efforts by the United States government to reduce the air pollution associated with burning coal, along with the often misleading political rhetoric surrounding those efforts. Given the central role that coal and its environmental consequences will play in our story, it’s helpful at the outset to understand some basic facts about the fuel. Short Answer: A combustible rock. Longer Answer: Coal is a fossil fuel—“fossil” because it’s primarily composed of the preserved remains of ancient plants and “fuel” because it can be burned to create energy. Most of the coal we use today was formed hundreds of millions of years ago when large swaths of the earth were covered in swampy forests. As plant life in these swamps died, it sank to the bottom of the water, where it was eventually buried under additional layers of sediment and slowly decomposed into a soggy, carbon-rich, soil-like substance known as peat. As still more time passed, this peat was further transformed by heat and pressure, a process known as carbonization, into the sedimentary rock we call coal. Short Answer: We mine it, mostly in Wyoming and Appalachia. Longer Answer: There are two basic methods of mining coal: underground mining and surface mining. Surface mining is typically used for shallow coal beds—those buried less than 200 feet deep. Miners access the fuel by simply removing (often with explosives) the trees and soil and rocks that sit atop it. Underground mining, by contrast, is used to extract coal that sits between 300 and 1,000 feet deep. The surface is left relatively undisturbed, and miners dig tunnels through which to enter the mine and retrieve the coal. Historically, underground mining was the more common of these two methods, but today, the majority of U.S. coal is produced at surface mines, which require far fewer workers to produce the same amount of coal. In addition to being cheaper to operate, surface mines are safer: both fatal and serious nonfatal injuries occur about three times more often in underground mines.