ORNL is a leader in DOE studies of carbon sequestration.

Capturing a Role
in Carbon Storage Studies

The quantity of carbon in the earth's atmosphere — currently 780 billion tons — has been rising by roughly 3.3 billion tons per year over the past 10 years. Three approaches are being considered in an attempt to reduce the buildup of carbon dioxide in the atmosphere because of concerns that it may be contributing to global warming and potentially devastating climate change.

One approach is to trim emissions of carbon dioxide by using energy more efficiently. A second is to burn fuels (e.g., hydrogen) or produce energy in systems (e.g., hydropower, solar power, or nuclear power plants) that emit little or no net carbon dioxide. This approach would include burning woody biomass and producing liquid fuels from renewable resources, such as ethanol from corn. A third approach is both new and not yet well understood. This approach entails capturing carbon dioxide from the atmosphere and from stack emissions of fossil-fuel combustion facilities, converting some of it into useful products, and transferring most of it to above-ground and below-ground terrestrial ecosystems — such as forests and underground coal seams — and to the ocean. The process of long-term storage of captured carbon is called carbon sequestration.

As part of its climate change technology initiative, the U.S. Department of Energy's Office of Science in 1999 formed two centers to study carbon sequestration: one focusing on terrestrial ecosystems and the other on oceans. The centers will conduct research and help focus and coordinate research across a wide range of disciplines. The goal is to find environmentally acceptable ways of keeping atmospheric carbon dioxide from reaching concentrations that could cause unacceptable climatic changes.

The DOE Center for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSITE) is led by a consortium comprising DOE's Oak Ridge, Pacific Northwest, and Argonne national laboratories. The center's co-leaders are Gary Jacobs of ORNL and Blaine Metting of Pacific Northwest National Laboratory (PNNL).

Structure of a leaf that is less efficient than some grasses at fixing carbon.

This center will receive $6 million over three years. Collaborating in center studies will be researchers from Colorado State University, North Carolina State University, Ohio State University, the Rodale Institute in Pennsylvania, Texas A&M University, the University of Washington, the Joanneum Research Institute in Austria, and the US Department of Agriculture.

From the viewpoint of terrestrial ecosystems, carbon sequestration is the removal of carbon dioxide from the atmosphere by enhancing natural absorption processes and storing the carbon for a long time in vegetation and soils. Carbon sequestration may be accomplished by fixing more carbon in plants by photosynthesis, increasing plant biomass per unit land area, reducing decomposition of soil organic matter, and increasing the area of land covered by ecosystems that store carbon.

Research to date has shown that one way to increase carbon sequestration is through better land management. If modest changes in farming and forestry practices are made, plants and soils may more efficiently remove carbon dioxide from the atmosphere and store it in long-lived "pools" such as forest reserves, wood products, or soil organic matter. The longer that carbon is sequestered, the slower the rate of increases in atmospheric carbon dioxide.

Mac Post (left) and Don Todd take soil samples on the Oak Ridge Reservation for later analysis to determine their carbon content.

Field research will be conducted at several sites, including DOE's national environmental research parks at ORNL and the Fermi National Accelerator Laboratory, as well as US Department of Agriculture sites in Alabama and South Carolina, the Rodale Institute Research Center in Pennsylvania, and forestry industry research sites in the Pacific Northwest and the Southeast.

The second center, which is focusing on ocean carbon sequestration, is led by a consortium of DOE's Lawrence Berkeley and Lawrence Livermore national laboratories. The DOE Center for Research on Ocean Carbon Sequestration (DOCS) will receive a total of $3 million over three years. DOCS will have collaborators from the Massachusetts Institute of Technology, Moss Landing Marine Labs, the Pacific International Center for High Technology Research, Rutgers University, and the Scripps Institution of Oceanography. Center co-leaders are Jim Bishop (Lawrence Berkeley) and Ken Caldeira (Lawrence Livermore). DOCS will study the feasibility, effectiveness, and environmental acceptability of injecting carbon dioxide into the ocean and fertilizing marine organisms on the ocean's surface.