Can we bury CO2 in North Dakota prairie?

  • Article by: Bill McAuliffe
  • Star Tribune
  • November 3, 2007 - 6:10 PM

Not long ago, the North Dakota prairie hid missiles that were key weapons during the Cold War. Now, it's a proving ground for a new high-tech attack on global warming.

A partnership that includes Minnesota corporations and state agencies is testing whether it can pump carbon dioxide -- the key pollutant linked to climate change -- deep into the ground. That would not only remove it from the atmosphere, but also free up inaccessible oil and gas deposits.

Winning crucial federal money last month, the "Plains CO2 Reduction Partnership" is part of a nearly $300 million program underway in three regions of North America.

Together they constitute the largest experiment in the world to capture carbon dioxide produced by power plants and other major sources and seal it away underground, perhaps for thousands of years.

"The primary goal of the whole project is to find a way to put the CO2 in a place where the cork's in the bottle," said Gerry Groenewold, director of the Energy and Environment Research Center at the University of North Dakota.

Meanwhile, researchers in Minnesota, backed by nearly $500,000 approved by the Legislature this year, have determined that limited underground carbon dioxide storage may be possible here. But more promising is the prospect of "storing" carbon in stems, trunks and leaves by planting more trees, grasses and cover crops and restoring wetlands.

"The state is increasingly focusing on an environmental agenda, and a climate-change agenda, and we need to consider all options, all possibilities," said state geologist Harvey Thorleifson.

Making it pay

The Plains CO2 Reduction Partnership is launching one test that will inject 1 million tons of CO2 annually into a remnant of an ancient sea about 10,000 feet below the North Dakota prairie.

Carbon dioxide from a coal-fired power plant near Beulah, N.D., will be compressed into a fluid and pumped into the earth where it will remain, said associate research director John Harju, "in perpetuity." (For comparison, Minnesotans produce about 115 million tons of carbon dioxide every year.)

But the test doesn't end with storage. The carbon dioxide also will be used to recover oil out of deep rock formations. A smaller test is about to inject carbon dioxide gas into a 1,000-foot-deep seam of inaccessible coal in northwest North Dakota, where it may force trapped methane to the surface for use in home heating and electricity generation.

But doesn't taking carbon dioxide out of the atmosphere and using it to produce more fossil fuels only reinforce the global-warming cycle?

"That's oil we were going to go get anyway," said Bill Grant, a member of a Minnesota panel drawing up climate-change strategies to bring to the Legislature in February.

The overall process, Grant emphasized, can help slow or reverse carbon dioxide emissions. Plus, the economic potential can broaden the political support for anti-global warming measures.

"Unless you can persuade coal-state senators that there's a path forward for coal in a carbon-constrained world, they're going to be very hard to move on the question of how steeply we should regulate carbon emissions," Grant said.

"There's no magic bullet laying around," Harju said.

Race against time

In Minnesota, burying CO2 underground might be possible only on the edges of a narrow geologic rift that meanders from Lake Superior southwest through eastern Minnesota and central Iowa into eastern Nebraska and Kansas. A more likely alternative, Thorleifson said, might be a process of combining carbon dioxide with minerals to create rocks that could be used in construction. "It's all a question of costs," he said.

Instead, what's now turning heads in Minnesota is the so-called "terrestrial sequestration" in plants, wetlands and soils. It wouldn't be as long-lasting as the geologic version but could play several roles, said Rep. Kent Eken, DFL-Twin Valley, who sponsored a bill authorizing $475,000 to study terrestrial sequestration and $90,000 for geological sequestration.

Carbon storage in the landscape, which would in large part require a return of cropland into grasslands and wetlands and deforested lands back into forest, would have its own environmental benefits, Eken said. But it could also have strong economic value if and when policy-makers attach a price to carbon emissions; then carbon-holding lands could be bought and traded or used as credits by big CO2 emitters.

At the same time, crops such as grasses might be harvested and used for energy while their roots remain to hold carbon in the soil. Studies have shown that up to 60 percent of the carbon-holding material in the soils of the Great Plains has been lost to plowing.

Indeed, researchers agree that carbon storage, while helping meet carbon dioxide emissions reduction goals, is also a way to buy time -- time for low-carbon alternatives to fossil fuels to emerge in a significant way. Fossil fuels now account for about 85 percent of the world's energy sources, Harju said. Finding a storage place for carbon will have to happen faster, Grant noted.

"Climate scientists say we need to achieve 70 to 80 percent reduction in CO2 release into the atmosphere by, say, the middle of the century," Grant noted. "That's an extremely ambitious time frame."

Bill McAuliffe • 612-673-7646

Bill McAuliffe •

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