Friday, June 23, 2006

How to Clean Coal

Feature Story
Coal gasification
How to Clean Coal

by Craig Canine

If we burn this stuff the old way, the planet is toast. But a new technology is waiting in the wings.

Iwas traveling along a remote highway in North Dakota about 80 miles northwest of Bismarck when an enormous black V suddenly appeared on the horizon, looming above a vast, empty sea of straw-stubbled fields. As I drove closer, the V resolved itself into the twin towers -- the mast and boom -- of a crane-like contraption of startling proportions. The angled boom rose about 20 stories into the prairie sky, attached at its base to what looked like a rotating warehouse big enough to cover a baseball field. Somewhere inside, an operator controlled the movements of a scoop bucket suspended from the boom with steel cables. The operator plunked the bucket down a hundred yards from where he sat, then reeled it in with a horizontal cable. This was the dragline, from which, I soon learned, the machine gets its name. Biting into the side of a 100-foot-deep valley of its own making, the bucket scooped up 10 ordinary dump trucks' worth of rock and dirt -- a portion of the "overburden" above a buried layer of coal. Hoisting a 160-ton chunk of earth into the sky, the dragline performed a pirouette, then upended its bucket atop a ridge of artificial mountains off to the side.

Photo of draglinesThe dragline was one of two such machines that work 24 hours a day at the Freedom Mine, one of the dozen largest coal mines in the United States. The sheer scale of the spectacle was awe inspiring, but I also found it deeply unsettling. Coal, as the petroleum geologist Kenneth Deffeyes writes in his recent book Beyond Oil, "is the best of fuels; it is the worst of fuels." It is best because it's the most plentiful and least expensive U.S. domestic energy source. It is worst, Deffeyes writes, "for a long list of reasons: killer smog, acid rain, atmospheric carbon dioxide, mercury pollution, acid mine drainage, and a choice between hazardous underground mines and surface-disturbing open-pit mines." For many people in the environmental movement, coal's liabilities far outweigh whatever assets it may have. Yet the use of coal has increased every year, without a pause, for two centuries. Last year, the world burned more than five billion tons of coal, spewing 10 billion tons of carbon dioxide into the atmosphere. (The multiplication of mass occurs because each atom of carbon from the burned coal combines with two heavier atoms of oxygen from the atmosphere, thereby more than doubling the weight of the original coal in CO2 emissions.) Coal-fired power plants are the single largest source of man-made CO2, accounting for one quarter to one third of the world's total.

We now stand at a watershed moment. An entire generation of obsolete coal-fired power plants built in the 1950s and 1960s needs to be replaced, and U.S. utility companies have announced their intention of building more than 100 new coal plants over the next 10 to 15 years. Unless something happens soon to tilt the balance toward more environmentally benign alternatives, nearly all of those power plants will use the old-fashioned, intrinsically dirty technology known as pulverized coal. The largest plants will have generating capacities of around 1,000 megawatts (MW), enough to supply electricity to as many as 900,000 homes. Such a plant costs close to $1 billion to build and has an operating expectancy of 60 years or longer. Every year of its lifetime, it will spout six million tons of CO2 into the atmosphere -- about the same as two million cars.

Each of these high-carbon investments is "a Pandora's box that we are handing to our kids," says David Hawkins, director of the Climate Center at the Natural Resources Defense Council (NRDC). "If the plants are not designed up front to capture their CO2, they will lock us into large amounts of global-warming emissions for their entire operating lifetimes."

The threat of massive carbon lock-in becomes truly staggering when the rest of the world enters the picture. Although the United States now emits more CO2 than any other country, accounting for 20 percent of the world's total, China is catching up fast and will probably take the lead by 2020. It has already overtaken the United States as the world's largest coal consumer. Coal fuels 90 percent of China's electricity demand. That demand is increasing so rapidly that China expects to expand its generating capacity over the next 30 years by 300,000 MW, or almost half of America's current consumption. As matters now stand, nearly all of China's projected new capacity will use standard pulverized coal technology.

These projections are alarming enough to convince some environmentalists that coal simply has no acceptable future as a major energy source. "Coal is the enemy," says Roel Hammerschlag, a widely respected energy analyst who runs the Institute for Lifecycle Environmental Assessment in Seattle. "It's worse than oil. We're going to run out of oil in the next century, but it's easy to synthesize methanol and other liquid fuels from coal. So coal will replace oil. And there's at least 300 years' worth of coal still in the ground. That's enough to raise atmospheric CO2 to insanely high concentrations -- 10 times preindustrial levels."

Before the Industrial Revolution, the atmosphere contained about 270 to 280 parts per million (ppm) of CO2. That level has risen to more than 380 ppm today. With polar ice caps and arctic permafrost melting, ocean levels rising, and climate patterns changing at the present atmospheric CO2 concentration, what might happen at 450 ppm, 600 ppm, or higher still? "We cannot put the world on hold while we figure it out," Hawkins says.

In spite of this grim outlook, Hawkins is far from ready to concede defeat. He's among the most prominent and outspoken advocates of a bold scheme that would take advantage of the nation's abundant coal resources while at the same time curbing CO2 levels in the atmosphere. This scenario relies on a combination of technologies that would enable a new breed of coal-fueled power plants to "capture" CO2 and other pollutants efficiently and economically. The captured CO2 gas would then be piped deep below the earth's surface for permanent storage. This concept, often referred to as "carbon capture and sequestration" (CCS, for short), has in recent years gained a great deal of currency in the halls of Congress, in the boardrooms of utility companies, and nearly anyplace else -- even the White House -- where energy policy and responses to global warming are discussed.

The National Commission on Energy Policy, a bipartisan panel of 16 energy experts from industry, academia, government, and nonprofit groups, released a landmark report last December that includes carbon capture and sequestration among its key policy recommendations. "In addition to our own domestic coal reserves, which are the largest in the world, China and India have enormous resources of low-cost coal," says Sasha Mackler, a senior analyst with the commission. "It's hard to imagine them not using it. Developing systems with which these countries can continue to utilize their coal, but in a way that does not increase carbon emissions, is a huge priority. Carbon capture and sequestration is the most viable pathway for that."

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> Letters to the Editor

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Craig Canine, a former editor and writer for Newsweek, often writes about technology from his home in Palo Alto, California. His work has also appeared in The Atlantic, Reader's Digest, and Discover.

The work of Guggenheim fellow Mitch Epstein adorns the walls of New York's most distinguished museums: the Metropolitan, the MoMA, the Whitney. His photos have appeared in magazines such as the New York Times Magazine and Conde Nast Traveler.

Photos: Mitch Epstein
Map: Blue Marble Maps
Illustration: Jim Kopp

OnEarth. Fall 2005
Copyright 2005 by the Natural Resources Defense Council


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