The CCS technology complex
CCS (Carbon Capture and Storage) is an umbrella term for a complex of technologies designed to reduce CO2 emissions from coal, gas and biomass. The technology has been used since the 1970´ies to increase the yield from oil and gas production (Enhanced Oil Recovery) EOR and (Enhanced Gas Recovery) EGR. in 1996 in Norway the stateowned company Statoil began to capture CO2 from the Sleipner field in the Norwegian part of the North Sea for underground storage. This was due to a natural content of CO2 in the gas that was too high for it to be used in a power plant. The technology has its greatest potential in energy production based on coal and to a lesser extent in energy intensive industries such as cement production, steel production and refining of petroleum products.
The CCS process covers four stages:
- capture of CO2,
- transport ,
- monitoring of storage.
Three different types of technologies are in principle available for the capture process:
- oxy-fuel combustion capture.
To date the post combustion technology has drawn the greatest attention mainly because it can be retrofitted on existing coal plants, which opens up to a - probably very large - export potential for the first commercial scale movers. Research and development, however, is carried out in all three versions of the technology. See this link for a description of the capture technologies.
Transportation of captured CO2 can be in pipelines, by train, by tanker or by ship. See this link.
If CCS is to be implemented on a billions of tons per year scale sources estimate that it would require a pipeline system twice as large as the existing world wide natural gas pipeline system for transport of captured CO2.
- Joseph Romm "For CCS to be even one of those would require a flow of CO2 into the background equal to the current flow of oil out of the ground. That would require, by itself, re-creating the equivalent of the planet's entire oil delivery infrastructure, no mean feat " Climate Progress Blog
INGAA Foundation (Interstate Natural Gas Association of America) "The major conclusion of the study is that while CCS technologies are relatively well defined, there remain technological challenges in the carbon capture and sequestration phases, and less so in transportation. Carbon capture is the most significant cost in the CCS process. The study forecasts that the amount of pipeline that will be needed to transport CO2 will be between 15,000 miles and 66,000 miles by 2030, depending on how much CO2 must be sequestered and the degree to which enhanced oil recovery (EOR) is involved. The upper end of the forecast range is of the same order of magnitude as the miles of existing US crude oil pipelines and products pipelines."
Storage of CO2 can be done in several ways. Predominant forms of storage will most likely be in saline underground formations (saline aquifers) and in depleted oil and gasreservoirs. Storage in the sea, as has been suggested is currently shelved because of foreseeable problems with CO2 effects on the marine environment. See this link for a description of storage methods.
For both environmental and financial reasons, it is essential that stored CO2 will stay put. The IPCC estimates that more than 99% of the stored CO2 is "very likely" to remain in storage after a 100 years and that over 99% of the stored CO2 "likely" will remain in storage after a 1000 years. " Observations from engineered and natural analogues as well as models suggest that the fraction retained in appropriately selected and managed geological reservoirs is very likely to exceed 99% over 100 years and is likely to exceed 99% over 1 000 years.... The vast majority of CO2 would gradually be immobilized by various trapping mechanisms and, in that case, could be retained for up to millions of years." IPCC Special Report on Carbon Dioxide Capture and Storage.
Obviously no guarantees can be issued, a wide range of monitoring -, measuring - and controlling technologies, however, makes it possible to successively monitor the state of the stored greenhouse gas. Such technologies also play a role in the accounting of cross-border CO2 - i.e. CO2 captured in one country but stored in another - and hence have implications for Annex 1 countries´ compliance with national targets and Kyoto commitments. See this link for details.