Question mark over Direct Air Capture tech’s viability

An emissions busting technology backed by several large oil and gas firms could be a “non-starter” in the short term.

Direct Air Capture (DAC) involves extracting carbon from the atmosphere by moving air using a “solid sorbent or liquid alkaline solvent”.

The sorbent or solvent is heated to release the carbon, which can be used or stored.

Business models are being drawn up that would let companies or individuals pay to remove CO2 from the atmosphere to offset their emissions.

Storegga, which is behind the Acorn carbon capture and storage project, and Carbon Engineering (CE) is forging ahead with plans for a north-east facility, which could remove up to one million tonnes of carbon dioxide from the atmosphere a year.

But DAC has been served a reality check by Westwood Global Energy Group, which claims the technology might only make financial sense for firms in a handful of countries.

The research body said problems stem from the fact that the “concentration of carbon dioxide” in the air is “very dilute”, so the amount of heat required to extract CO2 from a DAC plant is “considerable”.

One estimate found DAC could need up to 2.6 terawatt-hours to remove a million tonnes of CO2 a year.

Westwood Global said: “Based on research from 2018, historic cost estimates for DAC can range from USD$50 to $1,000 per tonne of CO2. Further analysis indicates the cost is likely to fall between roughly $95 and $230 in the next decade, depending on design options and economic assumptions.

“If carbon costs were above this range, then DAC really would make money out of thin air. As it stands, though, the average price for carbon worldwide is just $3 per tonne, according to the International Monetary Fund.

“Only in some sectors in Sweden, Switzerland or Liechtenstein would the carbon price be sufficiently high to support DAC today. So, the technology looks like a non-starter for now.”

However, Westwood Global noted the cost “hasn’t put developers, governments and the research community off”, with expectations of future rises in carbon pricing.

In addition to the Storegga and CE project, Aberdeen’s Net Zero Technology Centre (NZTC), formerly the Oil and Gas Technology Centre, aims to develop “technology to bring the cost of DAC down to £100 ($139) per tonne of CO2”.

Elsewhere, the US Department of Energy said in June it would put £8.7m into six DAC research and development projects.

And several large oil and gas firms are interested.

Chevron and Equinor are co-investors in DAC technology developer Carbon Clean, which is carrying out design services for the Acorn project.

And ExxonMobil is linked to Global Thermostat, aiming to remove up to 40 giga-tonnes of CO2 a year.

Nevertheless, Westwood Global said that, even if the DAC cost barrier is overcome questions remain over whether it could scale up fast enough. As such, it said DAC seems likely to be an “energy transition negative emissions technology also-ran”.

But it doesn’t write the technology off, saying there is “one emerging trend” that could be a lifeline.

It said: “In January, DAC firm Climeworks revealed its technology was being used as part of IT behemoth Microsoft’s efforts to become carbon negative by 2030. And Climeworks is also partnering with fintech company Stripe on a venture called Stripe Climate.

“This allows businesses using Stripe to put a fraction of their revenues towards carbon removal efforts. For rich tech companies such as these, the ability to pull carbon out of the air is worth more than the cost of DAC today.

“In the future, other hardto-abate sectors, like aviation, may have no choice but to use DAC if alternatives to current fuels are slow to develop. These may well be markets worth keeping an eye on.”

Engineers at a DAC pilot facility in British Columbia.