Cost of carbon capture by 2050 ‘twice as high as previously estimated’

The cost of removing one tonne of carbon dioxide from the atmosphere by 2050 will be twice as high as previously estimated, new research has found.

Using one of three carbon capture techniques will cost $230-540 per tonne, according to the work at ETH Zurich in Switzerland. Researchers compared technologies used by ETH spin-off Climeworks, carbon capture using aqueous solutions, and carbon capture using calcium oxide, all of which are already in use.

The Intergovernmental Panel on Climate Change (IPCC) estimates that up to 13bn tonnes of CO₂ will need to be removed from the atmosphere every year from 2050.

Direct air capture (DAC) will become “significantly” cheaper as the technologies are scaled up, the ETH announcement said, but not as cheap as some stakeholders currently anticipate. Some previous figures estimated costs of $100-300.

“Just because DAC technologies are available, it certainly doesn’t mean we can relax our efforts to cut carbon emissions. That said, it’s still important to press ahead with the expansion of DAC plants, because we will need these technologies for emissions that are difficult or impossible to avoid,” said Bjarne Steffen, ETH professor of climate finance and policy. He developed the new method for estimating the cost with Katrin Sievert, a doctoral student in his research group, and ETH Professor Tobias Schmidt.

Findings suggest that the process developed by Swiss company Climeworks, in which a solid filter with a large surface area traps CO₂ particles, could cost $280-580 per tonne by 2050.

The estimated costs of the other two DAC technologies fell within a similar range. The researchers calculated a price of $230-540 using an aqueous solution of potassium hydroxide, a process that has been commercialised by Canadian company Carbon Engineering and others. The cost of carbon capture using calcium oxide derived from limestone, offered by US company Heirloom Carbon Technologies and others, was estimated at $230-835.

The ETH researchers focused on the individual components of the different DAC systems and estimated their cost one by one. They then asked 30 industry experts to assess the design complexity of each technological component and determine how easy it would be to standardise.

The researchers based their work on the assumption that the cost of less complex components that can be mass-produced will fall more sharply, while the cost of complex parts that must be tailored to each individual system will fall only slowly. DAC systems also include mature components such as compressors, which cannot feasibly be made much cheaper. Once the researchers had estimated the cost of each individual part, they then added the cost of integrating all the components and the costs of energy and operation.

“At present, it is not possible to predict which of the available technologies will prevail. It is therefore crucial that we continue to pursue all the options,” said Sievert, lead author of the study that recently appeared in Joule.

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