Direct Air Capture with CO2 Storage - a backstop technology for achieving net-zero

Technologies that can use machinery rather than natural systems to permanently remove CO₂ from air are an essential ‘backstop’ for achieving net zero emissions. Whatever the cost of this direct air carbon capture and storage (DACCS) turns out to be, this value effectively defines the real cost of emitting CO₂ to the atmosphere. So bringing this cost down as fast as possible could be the deciding factor in getting serious global commitment to the necessary finite national, and hence global, CO₂ emission budgets.

So far most non-government venture capitalist and similar support has been for direct air capture (DAC) to produce CO₂ to make products such as synthetic fuels for boutique markets, as we are seeing now. This has been very valuable to get things moving, but in any serious emission reduction programme large amounts of storage of CO₂ from the air as an offset for other emissions will be required. Some examples will be discussed.

DACCS is not ‘geoengineering’, just the equivalent of picking up litter; the key is to get the litterer to pay, not pass the cost on to future generations. If DACCS can be driven through the same type of cost reduction process as solar power, then no-one can claim that net-zero emissions is impossible for any process.

For hard-to-avoid emissions, DACCS is likely to be faster and cheaper to implement than radical changes in the way we do things. For example, if DACCS costs can be brought down to even £200 per tonne of CO₂ permanently removed from the atmosphere (and developers hope to do much better than this) then pump prices for the ultimate cut in emissions to net zero fossil petrol and diesel would need to go up by only about 50p/litre. DACCS could also be the best way to offset infrequent CO₂ emissions from natural gas central heating systems used to top up hybrid heat pumps.