To allow recovery of the atmosphere, storage of CO2 is necessary for 10,000 years
Reducing global carbon dioxide (CO2) emissions from 40 gigatonnes / year to "net zero" by 2050 is modelled by the Intergovernmental Panel on Climate Change (IPCC) as essential, not optional.
The technologies of capture from industries, and recapture from the atmosphere are proven to work across the globe. Cleanup does use additional energy and costs more than dumping polluting CO2 into the atmosphere. But benefits include cleaner air, a stable climate and creation of high value jobs.
Clean concentrated gases (from gas power plant, or cement works at 4-8 per cent CO2), are much easier to capture than dirty gases (coal combustion at 2 per cent CO2) or dilute gases (normal air from the atmosphere, CO2 0.04 per cent).
To allow recovery of the atmosphere, storage of CO2 is necessary for very long timespans —10,000 years. Geological storage is similar to oil accumulations, where a porous reservoir rock is needed, overlain by an impermeable shale seal. This pairing of rock types occurs with hydrocarbons — for example, the North Sea east of the UK could store 200-400 years worth of emissions. Similar rocks for CO2 storage exist offshore on the northwest and east of India.
CO2 can also be stored in chemically reactive basalt, where growth of new minerals can lock up CO2 at very low cost. Abundant basalts in central India could be investigated for their suitability. The applications of CCS are not restricted to power plants.
In the UK and Europe, most large industries emit CO2. The UK plans for net zero are now being made to capture CO2 where industries are grouped together as "clusters" to gain the benefits of sharing pipes and storage sites.
The EU has established a "taxonomy" which will guide sustainable investment into clean industries. It is expected that carbon tariffs will soon emerge to penalise imports of high carbon goods into Europe. Change has started and is inevitable. CCS will be essential to that.
(The author is Professor of Carbon Capture and Storage, University of Edinburgh, UK)
This is part of Down To Earth's print edition dated December 1-15, 2019
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