Direct air capture: new technology will speed up net zero

Cutting emissions is not enough. Stabilising the climate also requires the removal of carbon from the air, the UN warned recently. The technology is, for now, too small-scale and costly. But some of the world’s biggest companies want to accelerate development. In April, Stripe, Alphabet, Shopify, Meta and McKinsey pledged to spend nearly $1bn doing just that over the next nine years.

Their advance market commitment aims to promote innovative technologies by guaranteeing future demand for them. The money will be spent on direct air capture (DAC) projects that have the potential to be low cost — less than $100 per tonne — and high volume in the future. The goal is to store carbon permanently, or at least for over 1,000 years. That avoids the risks of natural carbon sequestration projects like tree planting, which are vulnerable to fire and decay.

Costs for DAC are currently at least $250 per tonne of CO₂ removed, says the World Resources Institute. CO₂ makes up just 0.04 per cent of air and so trapping a tonne of the gas means processing as much air as would fit in about 525 Olympic swimming pools. That makes it far more expensive than capturing carbon from industrial processes or power plants, where emissions are more concentrated.

Hence cheap renewable energy plays an important role in DAC. Swiss start-up Climeworks, which raised $650mn in an April fund raise, and Iceland’s Carbfix are using geothermal power to power the fans at the world’s largest DAC plant in Iceland. Once the air is sucked in, the carbon dioxide is captured on a chemical filter. It is then injected underground where it is turned into rock by mineralisation, a natural process.

The capacity of a plant planned by Occidental Petroleum in the Permian Basin will be 250 times bigger, capable of removing 1mn tonnes of CO₂ a year. It will cost up to $1bn; the goal is to build 70 by 2035, the US company said in March. Investors are unlikely to attribute value to the opportunity, as yet. There is a lot of uncertainty: over funding, government support, cost reductions and the size of the voluntary offset market.

There is a lot to do before the technology comes of age. The proportion of carbon emissions currently being captured has been compared with bailing out the Titanic using an eyedropper. DAC is not an alternative to cutting emissions. But scaled up, it could make a crucial contribution.

The Lex team is interested in hearing more from readers. Please tell us if you think direct air capture technology has a future for climate mitigation in the comments section below.