Carbon Capture and Sequestration (CCS): A Primer

Carbon capture and sequestration (or storage)—known as CCS—has attracted congressional interest as a measure for mitigating global climate change because large amounts of carbon dioxide (CO 2) emitted from fossil fuel use in the United States are potentially available to be captured and stored underground and prevented from reaching the atmosphere. Large, industrial sources of CO 2 , 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. CO 2 emissions from fossil fuels. Currently, U.S. power plants do not capture large volumes of CO 2 for CCS. Several projects in the United States and abroad—typically associated with oil and gas production—are successfully capturing, injecting, and storing CO 2 underground, albeit at relatively small scales. The oil and gas industry in the United States injects nearly 50 million tons of CO 2 underground each year for the purpose of enhanced oil recovery (EOR). The volume of CO 2 envisioned for CCS as a climate mitigation option is overwhelming compared to the amount of CO 2 used for EOR. According to the U.S. Department of Energy (DOE), the United States has the potential to store billions of tons of CO 2 underground and keep the gas trapped there indefinitely. Capturing and storing the equivalent of decades or even centuries of CO 2 emissions from power plants (at current levels of emissions) suggests that CCS has the potential to reduce U.S. greenhouse gas emissions substantially while allowing the continued use of fossil fuels. An integrated CCS system would include three main steps: (1) capturing and separating CO 2 from other gases; (2) purifying, compressing, and transporting the captured CO 2 to the sequestration site; and (3) injecting the CO 2 in subsurface geological reservoirs or storing it in the oceans. Deploying CCS technology on a commercial scale would be a vast undertaking. The CCS process, although simple in concept, would require significant investments of capital and of time. Capital investment would be required for the technology to capture CO 2 and for the pipeline network to transport the captured CO 2 to the disposal site. Time would be required to assess the potential CO 2 storage reservoir, inject the captured CO 2 , and monitor the injected plume to ensure against leaks to the atmosphere or to underground sources of drinking water, potentially for years or decades until …