IOP Groups

Carbon Capture

Jon Gibbins (Energy Technology for Sustainable Development Group, Mechanical Engineering Department, Imperial College, London)

Abstract

Fossil fuels, although a dwindling resource, are not dwindling fast enough for the climate. The IPCC estimate that another 5000 Gt of fossil fuel carbon could still be emitted, ten times the amount since the start of the Industrial Revolution. It is likely that, to avoid dangerous climate change, significant amounts of desirable fossil fuels will either have to be left unused, essentially for ever, or that they will have to be used in such a way that the resulting carbon dioxide doesn’t do any harm – with CO2 capture.

Carbon dioxide can be captured from conventional power plants by washing the flue gases with CO2-specific solvents before they are vented to the atmosphere, or other post-combustion methods. Alternatively, the fuel can first be gasified and reformed, to produce hydrogen and carbon dioxide. The CO2 is then removed and the hydrogen burned in a conventional gas turbine power plant (instead of natural gas) to generate 'decarbonised' electricity. Fuel may also be burned in oxygen to generate a CO2 stream with minimal additional processing. Decarbonised electricity and hydrogen can replace oil and gas in the transport and building sectors; biomass+CCS can put aircraft CO2 safely underground.

Initial designs for capture plants, based on conventional power and chemical plant technologies, are expected to add an extra 1-2 p/kWh to the average cost of electricity generation – in the long run. Getting there from here may be challenging, with the first plants involving much higher costs and risks. Sharing these pains – and the gains – is important though, because we engineers and scientists may have only a short opportunity to gain competence in this field before atmospheric and political pressure to act becomes overwhelming.

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