Even if IGCC offers no solution to the dangers of pulling coal from the earth, it at least provides a way to control some of the most hazardous by-products of burning (or gasifying) the coal. For some of the captured contaminants, like fly ash, this is a straightforward matter of burying the waste in a landfill. Carbon dioxide is a much trickier proposition. The research of how and where to store it safely for essentially forever is just starting.

In September 2005, the Intergovernmental Panel on Climate Change, a United Nations organization that includes scientists from nearly every country in the world, released a report estimating that 2 trillion tons of carbon dioxide could be stored in old coal mines, abandoned oil and gas fields, and in various other geologic formations around the world. That's a huge reservoir, even compared to the rate at which humans are now burning fossil fuels. "The estimated storage capacity equals about 80 times the total rate at which we make carbon dioxide from everything per year," Robert Socolow, a Princeton University physicist who coheads its Carbon Mitigation Initiative. Coal-power plants account for about 25 percent of that carbon dioxide, so it's 320 years of coal-power emissions."

Courtesy of Kent Kessinger/SouthWings
Three large-scale carbon storage, or sequestration, projects are testing ways to bury carbon dioxide effectively. The world's oldest carbon-sequestration experiment began in the North Sea oil fields in 1996. Statoil, the Norwegian national oil company, extracts carbon dioxide from natural gas and pumps 2,800 tons of it every day 3,000 feet below the North Sea floor, trapping it in sandstone. A 250-foot-thick layer of shale covers the entire sandstone formation, and it seems to be leakproof. Statoil estimates that all the carbon dioxide emissions from every power plant in Europe for the next 600 years could be stored in the formation.


EnCana Petroleum of Calgary, Alberta, is conducting North America's first big sequestration project. The company buys carbon dioxide from an American utility and pumps the gas underground in southern Saskatchewan to force out oil that would otherwise be unrecoverable. During the six years that the project has been running, there have been no signs that any of the gas is escaping. EnCana ultimately expects to store about 20 million tons of carbon dioxide underground. A third project, in Salah, Algeria, expects to store 1.2 million tons of carbon dioxide per year in natural gas wells.

"We're going to get more ideas on where to put this stuff," says Socolow. "In a few decades, I think we'll have a sense of the formations we can access, and the numbers will go up. Conceivably, we may find that we were optimistic, and the numbers will go down. But we've got to get going and learn the subject. It's like prospecting; you'll get some unsuccessful ones and some good ones. It's 'learn as you go'—but we're ready to start." All the storage capacity in the world won't matter, however, if we don't have the kind of power plants that can siphon off the carbon dioxide (and other pollutants) so it can be buried. Nine new IGCC plants over the coming decade will make only a minuscule dent in the problem.

Most in the coal industry argue that market forces will sort out the problem, a dubious view shared by the Bush administration, but that seems improbable unless IGCC technology gets cheaper or the cost of emitting carbon goes up. The Department of Energy is aiming to kick-start the technology with a project called FutureGen, a $1 billion pilot IGCC plant that will have integrated carbon-capture and storage technology—a true zero-emissions plant. But the department has not yet even chosen FutureGen's construction site, and the plant will probably not be completed before 2012.



Artist conceptions of FutureGen, the world's first zero-emissions fossil-fuel power station (above). The proposed plant would combine cutting-edge coal gasification technology, emissions control, carbon dioxide sequestration, and hydrogen production in a single integrated facility. The billion-dollar initiative, approved by President Bush in February 2003, is intended to demonstrate the feasibility of clean coal and serve as a model for future power plants. When completed, FutureGen is expected to produce enough electricity for 275,000 homes, while capturing 90 percent of its carbon dioxide emissions—a total of 2.2 million tons of greenhouse gas each year—all at costs comparable to those of traditional plants. It will also produce highly enriched hydrogen gas, which can be burned as fuel or used in fuel cells to produce electricity. Nevertheless, FutureGen is not purely green: The plant would still obtain its coal from high-impact mining operations. The project, spearheaded by the Department of Energy and a nonprofit consortium of coal and power companies, will take at least six years to complete. The department will not even select a site for FutureGen until next year.

Courtesy of the Department of Energy
Some companies aren't waiting for FutureGen to get off the ground. Vattenfall, a Swedish firm, is backing a technology called oxyfuel combustion, which burns coal in a nitrogen-free atmosphere. By August 2008, the company expects to complete a 30-megawatt plant near Berlin that will capture and store carbon dioxide in an aquifer outside Berlin. BP is planning a hydrogen-fueled 500-megawatt plant 20 miles south of Los Angeles. When completed in 2011, the plant will make hydrogen from petroleum coke, an oil-refining by-product, in the process storing as much as 4 million tons of carbon dioxide a year in California's oil fields. Still, these also amount to just a drop in the bucket of human-generated carbon emissions.

So what will it take for emission-free coal technology to go mainstream? Holdren thinks the mounting evidence of climate change will spook the world into action. "I believe that right across the industrialized nations there will be mandatory economy-wide approaches in place by no later than 2010, and in the major developing countries by 2015," he says. James Hansen of the Goddard Institute for Space Studies argues that China and India will make this decision out of pure self-interest, since rising sea levels could place large portions of their coastal populations at risk. China has already committed to a 43 percent increase in industrial energy efficiency by 2020.

"Things could change overnight," agrees Daniel Schrag, a Harvard University geochemist who studies both ancient climate and carbon sequestration. "Think of being involved in airport security in August of 2001. You couldn't have gotten a meeting with the Undersecretary of Transportation. And now it's a month later and you're meeting in the Oval Office."

Schrag suggests that the costs of cleaning up coal are surprisingly modest. "Right now we put about 2.5 billion tons of carbon from coal burning into the atmosphere each year. An order-of-magnitude estimate for capture and storage is something like $100 a ton. That 2.5 billion tons is only $250 billion dollars a year—about half a percent of global GDP. It's a lot of money—it requires political will—but it's not a ridiculous amount of money."

For context, Schrag compares that cost to other ways we willingly pay for security. "Solving the climate problem altogether—completely rebuilding our energy infrastructure—is something like a $400-billion-a-year program. The U.S. share is maybe $100 billion. That's not that much compared with defense outlays. It's small compared to Iraq. If we really got scared, we could do a lot in a hurry."

What if we never run out of oil? Read a 1999 perspective on world oil supplies—and how they may bolster the pace of global warming.

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