Scientists propose injecting carbon dioxide into earth for storage

Jan 27, 2003 01:00 AM

The plan to landfill air pollution might seem laughable. As a stopgap solution to global warming, scientists have proposed capturing several billion tons of carbon dioxide from the air and injecting it deep into the earth for long-term storage.
No one knows whether vast amounts of the greenhouse gas would stay put 2 miles below ground. Nevertheless, an increasing number of experts -- including some environmentalists -- believe the idea isn't as harebrained as it might sound.

With carbon dioxide emissions rising steadily in the US and around the world, countries are casting about for ways to reduce the heat-trapping pollution. In the meantime, scientists say it can be unloaded into dark reaches of the earth, including saline aquifers, depleted oil wells, coal seams and the ocean.
The sprawling Illinois Basin, which extends into Indiana and western Kentucky, offers an ideal location to study three of the methods, say Illinois State Geological Survey officials. They are leading a multi-state effort to bring up to $ 10 mm in federal funding to the region to study and, perhaps, begin testing the technique.

Last month, the US Department of Energy expanded funding to inspire state agencies, industries and universities to research and test the technique -- known as carbon sequestration -- on an unprecedented scale. The government wants to create four to 10 regional partnerships to study whether it is possible to capture emissions from coal-fired power plants and unload them into deep saline formations below 35 states, including Illinois.
Theoretically, the briny aquifers -- below those used for drinking water -- could hold all the carbon dioxide from coal burning power plants for the next 100 years, according to Secretary of Energy Spencer Abraham. Others say storage could last for hundreds of thousands of years. The technology exists, and though prohibitively expensive, the costs should decrease over the next decade with more research, experts say.

Environmental groups call storage "one viable option," as long as the captured carbon would not be dumped into the ocean, where it has unknown effects on marine life. Others believe carbon storage could not only boost the domestic coal industry, but also could help the world gradually transition from fossil fuels to renewables fuels.
Still, by most accounts, it would at least double the cost of energy, and there is little incentive for power plants to install expensive capture technology. Questions remain over the possible health hazards if the carbon escaped: In a bizarre catastrophe, Cameroon's Lake Nyos emitted a cloud of carbon dioxide in 1986, asphyxiating about 1,700 villagers. And environmental groups such as the Union of Concerned Scientists and the Natural Resources Defence Council, though supportive, warn against developing the technology at the expense of other solutions.

"It's promising, but there's more that needs to be done to make sure [carbon dioxide] stays where you put it," said David G. Hawkins, director of the NRDC's Climate Centre. "It fits very well with an issue before Congress: Whether to start regulating carbon dioxide from coal-fired power plants."
In some regions of the country, depleted oil and natural gas reservoirs or coal deposits could be used to hold carbon dioxide. For the last two decades, carbon dioxide has been injected into mature oil fields in west Texas to produce additional oil, a process known as enhanced oil recovery. Coal seams, meanwhile, are more experimental and may absorb carbon dioxide and release methane as a recoverable product to increase natural gas supplies. Both methods have advantages that could help offset costs.

"If we're successful with sequestration, we could continue to use coal resources as a major bridge to these new fuels over a period of decades," said Robert Finley, director of the Centre for Energy and Earth Resources at the State Geological Survey, who is working with state geological surveys of Indiana and Kentucky as well as Argonne National Laboratory, near Lemont, and several gas and electric companies. "At the same time, we could avoid the release of carbon into the atmosphere."
In a report, Finley added, "In fact, with certain innovative combustion technologies now under study, emissions of nitrogen oxide and sulphur oxide also might be economically sequestered along with a carbon dioxide-rich flue-gas stream."

Carbon dioxide, produced from burning carbon-containing fuels, including oil, coal, natural gas and wood, is largely blamed for trapping heat and causing climate change. Since the beginning of the Industrial Revolution, the amount of carbon dioxide in the atmosphere has increased by 33 %. Scientists are worried about it doubling by the end of the century, said Howard Herzog, of the Massachusetts Institute of Technology, who has been studying carbon disposal for more than a decade. Mounting evidence links that increase to the burning of fossil fuels.
Fossil fuels provide 85 % of the world's primary energy, however, and electricity use isexpected to grow by 2 % annually in the US and by 3 % internationally over the next two decades, according to Scott Klara of the National Energy Technology Laboratory. "In the last four years, carbon sequestration has really come into its own," said Ed Rubin, professor of environmental engineering and science at Carnegie Mellon University.

Carbon dioxide can be captured from a power plant's flue-gas stream -- the volume of gas after coal has been burned -- by scrubbing it with a chemical solvent that absorbs the carbon dioxide. Once it's regenerated into a concentrated stream, it can be pressurized until it becomes a liquid. Then it can be pipelined to a storage site.
The process works best in sandstone formations with a thick cap rock over them, said Sally Benson, deputy director of the Lawrence Berkeley National Laboratory, who is developing technology to monitor carbon once it's underground. "Carbon dioxide has to flow through pore spaces in the rock, and the rock underground is like brick, some is even like sand. It takes a lot of energy to wiggle through pore spaces, so a catastrophic failure is difficult to imagine." Still, the prospect of leaks will likely always haunt sequestration.
"Hopefully if it comes out, it will be so slowly that no one notices," Herzog said. "But you also have to look at whether it's out in the atmosphere and causing trouble. You want it down there until we're no longer worried about climate change. In reality, the bulk of it can stay down there thousands of years."

As part of the federal program, American Electric Power, one of the largest power plant operators and polluters in the nation, is collaborating on a $ 4.2 mm carbon sequestration project in the Ohio River Valley, which has the largest concentration of power plants in the nation. Over the next two years, researchers will conduct seismic surveys of the massive Mt Simon Sandstone in West Virginia, which extends as far west as Illinois and Wisconsin. The project also involves drilling a 10,000-foot exploratorywell.
"If we can't prove this could be a permanent repository, it will be a hard sell as a policy option for mitigating greenhouse gas," said Dale Heydlauff, AEP's senior vice president of government and environmental affairs.

Source: Chicago Tribune
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