The term “carbon capture and storage,” or CCS, refers to the process by which carbon dioxide (CO2) gases are separated from other material in emissions from fossil-fuel (coal and gas) power plants, industrial processes, and other stationary sources of CO2 and converted to forms that allow the CO2 to be transported to a site where it is stored without being able to be released into the atmosphere, often a subsurface geologic formation. The purpose is to reduce the amount of CO2 being released into the atmosphere as CO2 emissions are one of the major contributors to global climate change. The process is key to efforts to reduce or eliminate the emissions attributable to coal-fired power plants in particular as coal remains an abundantly available and inexpensive source of energy in a number of countries, including the United States and China. Coal is also one of the most carbon-intensive, or dirtiest, sources of energy.
The CO2 is most often captured after the fossil fuel is burned but can be removed before combustion. One major problem with CCS is that the capture of the CO2 requires a lot of energy, is therefore expensive and unless that energy source is low-carbon the process merely exacerbates the global climate change risk.
After capture, the gases can be compressed or turned into liquids in order to transport the CO2, usually by a pipeline, to wherever it is going to be stored. While storage in the ocean has been considered, many believe this option presents too many risks as the concentrations of CO2 can kill ocean organisms and increase the acidity of the ocean. More typically, the CO2 can be stored in geologic formations, such as deep saline formations, oil and gas reservoirs, and unmineable coal seams. For years it has been the practice of oil companies to inject CO2 into oil fields that are declining as a means of enhancing production. One problem with storing CO2 in oil fields or coal seams is that more oil is produced or methane escapes from the coal seams, and so any benefit from storing the CO2 from one source simply creates more greenhouse gases from the storage process.
Some further ideas to explore on Carbon Capture and Storage:
Identify existing CCS projects and evaluate whether they are successful.
What government policies, if any, are necessary to support the development and expansion of CCS.
Identify the environmental and health risks, if any, associated with CCS.
European Enviornmental Agency, “Capturing Carbon: A new front in the fight against climate change,” www.eea.europa.eu/themes/climate/multimedia/capturing-carbon-a-new-front-in-the-fight-against-climate-change/view
US Environmental Protection Agency, Report of the Interagency Task Force on Carbon Capture and Storage (August 2010) www.epa.gov/climate/climatechange/policy/ccs_task_force.html
Green Facts, “Scientific Facts on CO2 Capture and Storage”