For nearly 20 years, the Great Plains Synfuels Plant near Beulah, N.D., has turned tens of millions of tons of coal into synthetic natural gas. It also emits an irksome byproduct: nearly pure carbon dioxide, an atmospheric "greenhouse" gas.
Now, researchers around the world are watching as the plant's CO2 surges through a pipeline to the Weyburn oil field in Saskatchewan, where it's forced deep underground. Scientists and engineers are waiting to see: Will the CO2 stay put? What will it take to keep it locked underground?
The experiment is part of an intensifying project to capture and store carbon dioxide - and so reduce the climatic side effects of humanity's reliance on coal, oil, and natural gas. Monday, the Bush administration convened an international meeting - the Carbon Sequestration Leadership Forum - to launch such research, part of its climate-change program.
This week, experts with the UN's Intergovernmental Panel on Climate Change, which has so far given the issue scant attention, are set to meet in Oslo to begin work on a capture-and-storage special report, scheduled for completion in 2005.
Business, labor, and environmental groups have also seized on the concept. In a coalition chaired by former Sen. Timothy Wirth (D), now head of the United Nations Foundation, the group urged the building of more coal-fired power plants that funnel CO2 underground - part of a climate-friendly agenda pushed in its report last week.
Capture and storage of CO2 "is definitely getting more attention," says David Hawkins, director of the Natural Resources Defense Council's Climate Center in Washington. Other critical responses, he adds, are a focus on renewable energy resources and greater energy efficiency in homes, factories, and power plants.
The rising interest in carbon sequestration comes as the world waits for Russia to ratify the 1997 Kyoto Protocol. Under the agreement - from which the US withdrew in 2001 - industrial countries must reduce their collective greenhouse-gas emissions by an average of 5 percent from 1990 levels, and must do so between 2008 and 2012. If Russia ratifies the pact this fall, the protocol will take effect.
In fact, three commercial projects have long been in the works. Two, including the Weyburn oil-field project, are using CO2 to force more oil out of marginal fields. The third, under way in the North Sea, sequesters carbon in a salty aquifer beneath the ocean floor, in hopes of avoiding Norway's tax on industrial CO2 emissions.
But the technologies for such projects remain too expensive for widespread use, according to Carl Michael Smith, assistant secretary for fossil energy at the US Department of Energy. And therein lies the challenge, he told reporters last week
The need for sequestration - a broad term covering approaches from locking CO2 in plants, soil, and oceans to capture-and-storage techniques - is clear, according to Scott Klara, who heads the US Department of Energy's National Energy Technology Laboratory in Pittsburgh.
During the past 10,000 years or more, he notes, the concentration of atmospheric CO2 has remained relatively stable. But over the past century, those concentrations have grown by 30 percent - a byproduct of humans burning fuels.
Given the abundance of cheap fossil fuels, especially coal, Mr. Klara continues, underground deposits will probably remain the fuel source of choice - spurring further CO2 increases "if we don't do anything with regard to emissions," Klara says.
Though attention has focused on climate impact, burning more carbon-based fuels is unwise from a chemistry standpoint, too, say analysts. Carbon dioxide is an active ingredient in a range of biological processes, notes Klaus Lackner, a geochemist at Columbia University's Earth Institute, and "if you double the amount of carbon dioxide in the air, you start having other things to worry about beyond just climate." When oceans soak up CO2, he notes, their balance changes, stunting the growth of ecologically vital coral reefs.
As analysts weigh the range of sequestration options, choices grow increasingly narrow. "Fertilizing" the ocean with iron, for instance - to stimulate plankton's uptake of CO2 - is fraught with ecoperil, such as algae blooms, while pumping CO2 into the deep may shift water chemistry and endanger sea life.
Forests, grasslands, and cropland likewise have limited ability to absorb CO2. Although plants take it up in photosynthesis, they eventually reach a saturation point. Using plants and soils for carbon storage is a "no regrets" short-term strategy, says David Schimel of the National Center for Atmospheric Research in Boulder, Colo. "But it won't come close to solving the problem. It merely buys some time."
Thus, as analysts and environmentalists balance CO2 emissions with energy needs, capture-and-storage seems the most promising path. "There is increasing acceptance of the idea that this will have to be part of the mix," says Debbie Reed, head of the Environmental Trust's Global Warming Campaign in Washington.