Denise M Palmer

Carbon Capture and Storage

Keeping in view the dangers of global warming, it is imperative to limit the levels of CO2 in the atmosphere; there are three means of achieving this;

Carbon capture and storage (CCS) is an approach to mitigating climate change by capturing carbon dioxide (CO2) from large point sources such as power plants and subsequently storing it away safely instead of releasing it into the atmosphere. Technology for capturing of CO2 is already commercially available for large CO2 emitters, such as power plants. Storage of CO2, on the other hand, is a relatively untried concept and as yet (2006) no power plant operates with a full carbon capture and storage system. Currently, United States government has approved the construction of world's first CCS power plant, FutureGen, while BP has indicated that it intends to develop a 350 MW carbon capture and storage plant in Scotland, in which the carbon from natural gas will be stripped out and pumped into the Miller field in the North Sea.

CCS applied to a modern conventional power plant could reduce CO2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS. Capturing and compressing CO2 requires a great deal of energy and would increase the fuel needs of a plant with CCS by 10-40%. These and other system costs are estimated to increase the cost of energy from a power plant with CCS by 30-60% depending on the specific circumstances.

Storage of the CO2 is envisaged either in deep geological formations, deep oceans, or in the form of mineral carbonates. Geological formations are currently considered the most promising, and these are estimated to have a storage capacity of at least 2000 Gt CO2. IPCC estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100.

Capturing and compressing CO2 requires much energy, significantly raising the costs of operation, apart from the added investment costs. It would increase the energy needs of a plant with CCS by about 10-40%. This, the costs of storage, and other system costs are estimated to increase the costs of energy from a power plant with CCS by 30-60%, depending on the specific circumstances.

The costs of CCS are dominated by costs of capture. The storage is relatively cheap, geological storage in saline formations or depleted oil or gas fields typically cost $0.5-8 per ton of CO2 injected, plus an additional $0.1-0.3 for monitoring costs. However, when storage is combined with Enhanced oil recovery to extract extra oil from an oil field, the storage could yield net benefits of $10-16 per ton of CO2 injected (based on 2003 oil prices).

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