Filtering CO₂ from the air remains more expensive than hoped

Filtering CO2 from the air on a large scale will become cheaper in the medium term, but not as cheap as previously assumed. Researchers have reached this conclusion based on a new estimate. Efforts to avoid CO2 emissions should therefore under no circumstances be scaled back, they write.

A team of researchers at ETH Zurich has calculated that by 2050, it could cost between 230 and 540 dollars to remove one tonne of CO2 from the air. Previously, costs were estimated to be half that amount. The researchers compared the potential costs of three technologies already in use today: that of the ETH spin-off Climeworks, as well as CO₂ capture in aqueous solution and using calcium oxide.

The process developed by the Swiss company Climeworks, in which a solid filter material with a large surface area captures CO₂, could cost between $280 and $580 per tonne by 2050. The estimated costs of the other two DAC technologies are in similar ranges: For the capture of CO₂ as an aqueous solution using potassium hydroxide – a process commercialised, for example, by the Canadian company Carbon Engineering – the researchers cite a range of $230 to $540 per tonne. And for capture using calcium oxide, which is extracted from limestone, the estimated costs range from $230 to $835. This process is offered, for example, by the US company Heirloom Carbon Technologies.

In view of the potential costs, none of these technologies currently offers clear advantages over the others. According to the researchers, all three should therefore be developed further.

Source: ETHZ