Carbon Capture and Storage (CCS)
Carbon Capture and Storage (CCS), also known as Carbon Capture and Sequestration, is a process that collects carbon dioxide that would otherwise be emitted into the atmosphere by industrial and power generating sources, and pumps it deep underground for long term storage. Because carbon dioxide is a greenhouse gas that traps heat in the atmosphere, CCS is often discussed as a potential solution to climate change. However, the technology is still in the development stage and has not yet been proven safe and effective at commercial scale over the long term. The first pilot CCS project at a U.S. coal power plant commenced operations at the Barry Electric Generating station in 2012.
Carbon dioxide can be captured either pre- or post-combustion. In integrated gasification and combined cycle power plants, carbon dioxide is removed pre-combustion in the gasification process. In conventional coal-fired power plants, carbon can be captured post- combustion using a chilled ammonia solution, which seizes the pollutant from flue gas before it is released into the atmosphere. It is then compressed to a near-liquid state and transported to storage sites via pipeline, train, or truck. There are several types of underground storage sites. In sandstone formations, the near-liquid carbon dioxide flows into the tiny pores in the sandstone and is trapped by a dense rock layer immediately above the sandstone layer. This dense upper layer keeps the carbon dioxide from migrating to the surface. Alternatively, carbon dioxide can be dissolved into the briny waters of saline aquifers. Finally, carbon dioxide can be injected into depleted oil and natural gas wells to force the less accessible oil and natural gas to the surface -- a process known as “enhanced oil and gas recovery.”