Projects Suggest Underground Carbon Storage May Help Limit Greenhouse Gas Emissions, Researchers Say
Much of the carbon dioxide produced by power plants and factories can be pumped underground into safe, long-term storage, at reasonable cost, according to new research presented at the AAAS Annual Meeting.
Based on early tests of large-scale “carbon-dioxide sequestration” technology, members of a symposium panel agreed that pumping the carbon-dioxide directly underground and hiding it beneath “tight” geological formations such as shales seems to offer a solution to a global problem.
That problem, of course, is the constant flow of carbon dioxide, a heat-trapping greenhouse gas, into the Earth’s atmosphere. Based on measurements that began in the 1950s, it’s clear that carbon dioxide is accumulating inexorably, faster than it can be removed naturally by plants via photosynthesis, and by other natural processes. Considerable evidence demonstrates that the Earth has already begun to warm as a result.
The consequences of global warming may be dire. They include rising sea levels, shifting agricultural patterns, expanding deserts, stronger storms, worse droughts and more floods, plus tropical diseases such as malaria and dengue fever spreading into higher latitudes.
Ambitious CO2 capture and storage projects were the focus of a 90-minute symposium  on Monday 20 February, the closing day of the AAAS Annual Meeting in Vancouver, British Columbia.
Ideally, said Carlos Saraiva Martins, global energy production will shift to renewable power sources such as solar energy and wind energy, plus nuclear energy. But Martins, director of energy research for the European Commission, emphasized that “the age of fossil fuels is far from over.”
He explained that major developing nations such as China and India increasingly rely on coal for power generation, while the United States and other developed countries will still be burning natural gas, as well as coal, for the foreseeable future.
As “worrying trends,” Martins pointed to coal output being increased in India, Poland, Russia, and China. “Coal production has increased by 30% in Russia. Nuclear power is uncertain—several countries are shutting down their nuclear plants,” he added, and the nuclear plant disaster caused last year by Japan’s earthquake and tsunami has seriously dimmed enthusiasm for nuclear power in many areas.
Thus, between the years 2000 and 2010, global coal consumption increased by about 50%. And right now people in the United States speak of “a new future for gas, a new ‘golden era’ for natural gas,” Martins said, because of a massive increase in gas availability based on new gas extraction technology. Although gas is cleaner, in terms of carbon dioxide, than coal, it is still a fossil fuel.
All of these factors point to an increasing load of atmospheric carbon dioxide, making it increasingly apparent, and desirable, that some way be found to capture and store carbon dioxide before it leaves the smokestack, Martins said.
Two major experiments that involve pumping large amounts of carbon dioxide into the ground are currently under way. One, in Germany, is led by Michael Kuehn, head of the Center for Carbon Dioxide Storage, in Karlsruhe. That effort is looking at “the why and the how,” Kuehn told the AAAS audience. “We’re trying to get answers. Is long-term and safe storage possible? My conclusion is that carbon dioxide storage is a solution to this global challenge.”
The targets for such experiments are deep basins of sedimentary rock. The carbon dioxide is transported to the storage sites and then pumped far underground into the hidden basins. “It’s pumped into porous rocks, which take up the carbon dioxide like a sponge takes up water. The carbon dioxide is trapped—and we have to make sure it stays where we put it.”
Still, “it is not a silver bullet” that will solve the whole global warming problem quickly, he said. Carbon sequestration might be able to reduce carbon emissions by 25%, and even that will require emissions from power plants and many industrial facilities to be captured before being emitted. Also, so much carbon dioxide is produced from fossils fuels that the only logical reservoir for storage is underground, either on-shore or deep under the seabed, he said.
In any case, there’s plenty of room for carbon storage; “the global capacity is really huge,” Kuehn said, with estimated space for something like 11,760 gigatons of carbon dioxide.
The pilot project in Germany has already demonstrated successful carbon dioxide storage on a research scale—58,000 tons of carbon dioxide injected underground—showing it is safe and reliable. Monitoring for small leaks is continuing. “There has been no detectable leakage,” Kuehn said. “It has to behave as expected. We need long-term stability.”
That European experiment is now almost over, he added. “It’s still an operating site, but we are able to go from operation into the closure phase, and storage.”
A similar U.S. Government-funded experiment in Decatur, Illinois, is also under way, said geochemist Sallie Greenberg, who works for the Illinois State Geological Survey. Carbon dioxide injection was started recently, with a goal of pumping 1 million tons of the gas into the 17,000 square-mile wide underground reservoir.
“The carbon dioxide is coming from an ethanol (alcohol fuel) project” owned by the Archer-Daniels-Midland Corp, Greenberg said. The gas is going into a hole 5500 feet deep, forced into a 1600-foot-thick deposit of rock capped by a thick layer of impermeable shale called the Eau Claire shield. As this is being done, she added, scientists are collecting “real time temperature and pressure data.”
Such data also include surface and near-surface monitoring for leakage, as well as testing shallow groundwater for changes. And, Greenberg said, all the data collected are shared worldwide. A little more than 75,000 tons of carbon dioxide has been injected into the Illinois reservoir so far, she added. The cost runs to about $25 per ton of carbon dioxide injected.
Greenberg emphasized that intense effort is going into public education, making sure all questions for local citizens are promptly answered, that all information is complete and clear.
The symposium audience also heard Mark Weaver describe Australia’s effort to develop the world’s biggest carbon dioxide sequestration project. Weaver, of the Clean Energy Division in the government of Australia’s Department of Energy, Resources, and Tourism, said the government is developing a project to store 120 million metric tons of CO2 two kilometers below Barrow Island, an environmentally sensitive area about 30 miles off the nation’s western coast.
See full coverage  of the 2012 AAAS Annual Meeting in Vancouver, British Columbia.