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Confused by Footprinting? Carbon Capture and Storage (CCS)
Carbon capture and storage (CCS) is a broad term referring to processes that may be employed to reduce CO2 concentration in the atmosphere. The capture part of CCS involves trapping CO2, either at the emission source or by “scrubbing” CO2 out of the ambient air. Once the CO2 is captured, it can be compressed and transported by pipeline. CCS involves finding a stable long-term location to store CO2, such as pumping it into a depleted oil reservoir, the deep ocean or binding it within mineral deposits. The terms carbon storage and carbon sequestration are often used interchangeably, though carbon storage generally refers to the process of geologic storage through CCS while carbon sequestration generally refers to the protection and growth of natural carbon sinks such as trees or other biomass.
Technique
CCS can occur along with any process that produces CO2 emissions, though it is more economically feasible when CCS efforts are targeted to a large point source of CO2 emissions. CCS technology is being implemented at large, dirty sources like coal-fired power plants and industrial facilities. CCS allows for emissions reductions while keeping fossil fuel burning infrastructure in place. This could help industries such as refining, steel and cement manufacturing, chemical production, and electricity generation to stay viable while reducing their carbon footprint. Some have suggested that the use of CCS technology can reduce emissions at power plants by 80-90%. Still, CCS would require significant additional fuel use and energy costs thus reducing overall efficiency.
EOR
Some have argued that integrating CCS with enhanced oil recovery (EOR) can boost domestic oil production while providing ample opportunities for carbon storage. The relevant EOR technique involves injecting a gas -- i.e., CO2 -- into an oil reservoir. The gas expands, pushing oil to a production wellbore. Gas dissolves in oil, which lowers its viscosity and improves its flow rate. Some have argued that the oil produced by EOR is 70% "carbon free," based on the difference between the carbon content of incremental EOR oil and the volume of CO2 stored, and therefore the use of the technique represents additional emissions reductions. At present, EOR technology is used primarily to generate profit from oil sales and not as an emissions reduction technique. Unifying these two goals is an important objective of some analysts. EOR is sometimes cited to argue against concerns that CCS is untested and unproven.
Sites
GHGs can be stored in deep geological formations, in the oceans, or reacted to produce mineral carbonates. Oceanic sequestration includes both injection into deep areas of the ocean and increased stimulation of ocean surface waters to grow phytoplankton and take up carbon dioxide. Because of the threat of oceanic acidification, geological sites are considered more promising for CCS. Other options include the use of microbes and plants to sequester carbon in biomass. The IPCC estimates that there are sufficient sites worldwide to store as much as 1,100 gigatons of CO2 through CCS.
Concerns
The prospect of CCS raises some concern, since it increases energy consumption and is expensive to implement. Some environmentalists are skeptical of CCS and worry that it is not an acceptable substitute for the development and use of renewable energy technology or that it unjustifiably extends the lifespan of coal-burning technology. According to this perspective, development of CCS preserves the coal industry at a time when it is more important to move away from dirty energy sources. A potential counter-argument could focus on the need for a wide portfolio of options when attempting to counter climate change. CCS might be seen not as a true "solution" but as a transitional technology that smooths the path from a brown to a green energy economy. Other concerns about CCS include the potential for leakage and contamination, including ocean acidification from marine leaks.
Presence
19% of the 2007 U.S. carbon offset supply came from CCS projects that capture emissions in geological formations. The UNFCCC and Kyoto Protocol do not mention CCS, but there are proposals to add it to the portfolio of accepted techniques. If these proposals are accepted, CCS will likely become another source of credits under the flexible mechanisms. The EU 'opt-in' created by the Linking Directive may lead to increased European funding of CCS activities. Norway has become a leader in CCS technology; there are projects being developed in North Dakota, Algeria, Australia, China, and Germany.
See also:
Legal issues surrounding CCS (includes overview of existing legislation)
North American Carbon Capture and Storage Association
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Carbon Registry
