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Carbon dioxide (CO2) capture and geological storage (CCS) (also formerly known as carbon dioxide geosequestration) is a technology with the potential to reduce emissions of CO2 and/or other greenhouse gases to the atmosphere. This technology involves the combined processes of capture, transport and geological storage of CO2 and/or other greenhouse gases as shown in the diagram below.

Source: CO2CRC

The greenhouse gases may be produced by the combustion of fossil fuels, or co-produced as a result of oil and gas extraction or some industrial processes. Instead of allowing the gases to be released into the atmosphere, they are captured at the emission site where they are separated from other substances. The separated stream is then compressed into a concentrated volume and transported from the source location (emission site) to the injection location. Geological storage comprises:

• the injection of the compressed stream into geological formations in the deep sub-surface
• its migration away from the immediate vicinity of the injection point
• its subsequent trapping in geological formations.

CCS offers the potential for Australia to reduce its greenhouse gas emissions while maintaining its international competitiveness through its competitive advantage in low cost and abundant fossil fuels (coal and gas). It is one of a suite of technologies Australia is considering to meet its future greenhouse objectives.

The electricity generation sector, which represents 35 per cent of net national greenhouse gas emissions, is potentially well placed to take advantage of CCS technologies given it is dominated by relatively few large emission sources, although there is a need to improve capture technologies and reduce associated costs.

Some of Australia’s major natural gas reserves contain significant proportions of CO2 and gas projects may also be well placed to utilise CCS technology, given the capture and separation of CO2 is part of the gas processing system.

Technically, individual elements of CCS are well understood through international and domestic experience, however, geological storage of CCS streams over the long term has not been fully demonstrated. As with any large scale industrial process, there are environmental and health and safety issues (both occupational and public safety) associated with CCS. However, experience with some facets of CCS technology indicates these can be managed with appropriate safeguards.

Further information on the technical aspects of CCS can be found in the Government submission to the House of Representatives Inquiry on Geosequestration Technology.