Washington, DC - A field test sponsored by the U.S. Department of Energy (DOE) has demonstrated that opportunities to permanently store carbon in unmineable seams of lignite may be more widespread than previously documented. This finding supports national efforts to address climate change through long-term storage of CO2 in underground geologic reservoirs.
Lowering the core barrel at the PCOR Partnership lignite site.The PCOR Partnership, one of seven partnerships in DOE’s Regional Carbon Sequestration Partnership Program, collaborated with Eagle Operating Inc. (Kenmare, N.D.) to complete the field test in Burke County, N.D. In March 2009, approximately 90 tons of CO2 were injected over 2 weeks into a coal seam 10-12 feet thick at a depth of approximately 1,100 feet. Testing demonstrated that the CO2 did not significantly move away from the wellbore and was contained within the coal seam for the duration of a 3-month monitoring period.
The partnership also evaluated a variety of carbon storage operation conditions to determine their applicability to similar coal seams. While the results did not change the initial regional storage capacity estimates at nearly 600 million tons for lignites in the U.S. portion of the Williston Basin, they do suggest that suitable lignite seams are potential targets for CCS.
The study also investigated the feasibility of combining CO2 storage with enhanced methane production. When CO2 comes in contact with coal, including low-rank coals like lignite, the CO2 molecules physically attach to the coal. In many cases, the CO2 displaces methane, the primary component of natural gas, making it easier to recover. This combination potentially offers both a near-term economic return and a long-term environmental benefit.
The successful injection and storage of CO2 in the PCOR test opens the door for the conduct of similar CO2 injection tests at a larger scale and longer duration to confirm an optimal injection regime, investigate the economics of this carbon storage option, and adapt monitoring tools.
The Regional Carbon Sequestration Partnerships Program is a government-industry effort determining the best approaches for capturing and storing gases that can contribute to climate change. The PCOR Partnership brings together approximately 100 partners--consisting of public agencies, utilities, oil and gas companies, engineering firms, nonprofit organizations, and universities--in a region that includes all or part of nine U.S. states and four Canadian provinces. Led by the Energy & Environmental Research Center at the University of North Dakota in Grand Forks, North Dakota, the PCOR Partnership has completed four small-scale validation tests and is currently conducting two large-scale development tests. The National Energy Technology Laboratory manages the partnership program for DOE’s Office of Fossil Energy.