 | The Capture and Sequestration of Carbon Dioxide |
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The Economics of Capture and
Sequestration
The cost of CO2 capture is due mainly to the increased capital cost of the plant. However, 20-50% of the increase in capital cost, expressed in US$ per kWe, is due to the reduced power output. Taking this into account, the efficiency loss and the capital cost of the capture equipment make about an equal contribution to the overall cost of capture.
The cost of avoiding CO2 emissions is ~US$30-50 per tonne of CO2 for most of the current range of fuel prices. The cost in US$ per tonne of CO2 is broadly similar for coal - and gas-fired power plant. This is higher than the avoidance costs associated with other technologies such as biomass and nuclear power, although rather lower than the offshore carbon tax levied in Norway (US$ 50 per tonne of carbon dioxide or US$ 150–170 per tonne of carbon).
The quantity of CO2 emissions avoided is less than the quantity captured, because the energy consumed during capture results in additional CO2 production. Cost per tonne of CO2 captured may be an appropriate measure if the aim to supply CO2 as a product but not if the aim is to avoid emissions of CO2 to the atmosphere. Utilisation of CO2 to enhance oil and gas production has some potential to provide additional revenue to help offset some of the cost.
As with most new technologies, costs of CO2 capture and storage are expected to decrease when they are applied on a large scale and technical improvements are made. An analogous situation has occurred with FGD. Capital costs of FGD plants have decreased by ~75% since they were first introduced on a large scale around 1970. FGD was originally regarded as an excessively expensive addition to power stations but is now usually seen as a relatively modest addition, fully justified by the environmental benefits.
The environmental side-effects of capture and storage are mostly quite small although storage in the deep ocean may have significant impact. The emissions reduction achieved by CO2 capture and storage could be verified accurately and at low cost, with available technology.