Carbon abatement technologies (CATs) offer options for using fossil fuels during the transition to a low carbon energy system. Carbon Capture and Storage (CCS) is the most innovative of these but also offers the potential for the deepest cuts in CO2 emissions. It involves the deployment of a chain of technologies for CO2 capture, transportation and storage, rather than developments focused on the combustion plant alone. Most of the technologies needed to implement CCS are currently available through other applications but there is an urgent need to validate the operation of the whole CCS technology chain.
CCS involves capturing the carbon dioxide in fossil fuels either before or after combustion, and storing it for the long-term in formations such as depleted natural gas fields, deep saline aquifers and unmineable coal seams. CCS technology can reduce carbon dioxide emissions from large industrial sources and coal-fired power stations by approximately 85% depending on the type of non-capture plant displaced1.
CCS has the potential to be an essential technology to significantly reduce greenhouse gas emissions and allow the continued use of fossil fuels for energy security, without damaging climate security.
There are three generic process routes for capturing CO2 from fossil fuel combustion plants:
Each of these processes involves the separation of CO2 from a gas stream. There are five main technologies available for doing this, with the choice depending on the state (i.e. concentration, pressure, volume) of the CO2 to be captured:
There are several options for the long-term storage of CO2 in geological formations including injection into depleted oil reservoirs, depleted natural gas fields, deep saline aquifers and unmineable coal seams. Together these are estimated to have a global storage capacity of 1000-10,000 GtCO2, therefore with current world energy-related CO2 emissions of about 27GtCO2 per year there is sufficient storage capacity for CCS to play a major role in emissions abatement. For further details see the IPCC Special Report on Carbon Dioxide Capture and Storage 2005, available from the IPCC webpage. Both a Technical Summary and a Summary for Policy Makers is available.
The Technical and Policy Makers Summaries are also available in Chinese here.
Major international collaborative projects are continuing to monitor existing CO2 injection sites, notably at Sleipner, Norway, Weyburn, Canada, and Salah, Algeria and similar work is planned for Gorgon, Australia.
1Review of the feasibility of carbon dioxide capture and storage in the UK, DTI, September 2003.