Abstract: Carbon capture and sequestration (or storage)—known as CCS—has attracted interest as a measure for mitigating global climate change because large amounts of carbon dioxide (CO2) emitted from fossil fuel use in the United States are potentially available to be captured and stored underground or prevented from reaching the atmosphere. Large, industrial sources of CO2, such as electricity-generating plants, are likely initial candidates for CCS because they are predominantly stationary, single-point sources. Electricity generation contributes over 40% of U.S. CO2 emissions from fossil fuels.

Congressional interest has grown in CCS as part of legislative strategies to address climate change. On February 13, 2009, Congress passed the American Recovery and Reinvestment Act of 2009 (ARRA, P.L. 111-5), which included $3.4 billion for projects and programs related to CCS. Of that amount, $1.52 billion would be made available for a competitive solicitation for industrial carbon capture and energy efficiency improvement projects, $1 billion for the renewal of FutureGen, and $800 million for U.S. Department of Energy Clean Coal Power Initiative Round III solicitations, which specifically target coal-based systems that capture and sequester, or reuse, CO2 emissions. The $3.4 billion contained in ARRA greatly exceeds the federal government’s cumulative outlays for CCS research and development since 1997.

The large and rapid influx of funding for industrial-scale CCS projects may accelerate development and deployment of CO2 capture technologies. Currently, U.S. power plants do not capture large volumes of CO2 for CCS, even though technology is available that can potentially remove 80%-95% of CO2 from a point source. This is due, in part, to the absence of either an economic incentive (i.e., a price for captured CO2) or a regulatory requirement to curtail CO2 emissions. In addition, DOE estimates that CCS costs between $100 and $300 per metric ton (2,200 pounds) of carbon emissions avoided using current technologies. Those additional costs mean that power plants with CCS would require more fuel, and costs per kilowatt-hour would be higher than for plants without CCS.

After CO2 is captured from the source and compressed into a liquid, pipelines or ships would likely convey the captured CO2 to storage sites to be injected underground. Three main types of geological formations are being considered for storing large amounts of CO2 as a liquid: oil and gas reservoirs, deep saline reservoirs, and unmineable coal seams. The deep ocean also has a huge potential to store carbon; however, direct injection of CO2 into the deep ocean is still experimental, and environmental concerns have forestalled planned experiments in the open ocean. Mineral carbonation—reacting minerals with a stream of concentrated CO2 to form a solid carbonate—is well understood, but it also is still an experimental process for storing large quantities of CO2.

The increase in funding for CCS provided for in ARRA and by other economic incentives may lead to less expensive and more effective technologies for capturing large quantities of CO2. Without a carbon price or a regulatory requirement to cap CO2 emissions, however, it will be difficult to predict or evaluate how the technology would be deployed throughout the U.S. energy sector. By comparison, transporting, injecting, and storing CO2 underground may be less daunting. A large pipeline infrastructure for transporting CO2 could be very costly, however, and considerable uncertainty remains over how large quantities of injected CO2 would be permanently stored underground. To help resolve these uncertainties, DOE has initiated large-scale CO2 injection tests in a variety of geologic reservoirs that are to take place over the next several years.

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Topics: Energy, Science & Technology