Direct air capture technology as the path to emissions reduction targets

As Australia and the world grapple with the challenge of reaching ambitious emission reduction targets, one emerging solution for carbon dioxide (CO₂) removal is direct air capture (DAC). With billions in fresh research dollars and tax incentives (particularly in the U.S.) available, DAC technologies are being accelerated through global laboratories and into scaled field deployments at speed.

Dr. Claudia Echeverria is the Newcastle-based Research Group Lead of our Sustainable Carbon Technologies team, which is progressing some of our efforts in this space.

"Direct air capture is a really hot topic worldwide at the moment. As technologies advance and diversify around carbon capture, utilization and storage, it's attracting more and more global scientific research and commercial interest," Claudia said.

DAC works to gather and capture CO₂ directly from the atmosphere, which can then be either stored or used to produce carbon-based products.

The International Energy Agency (IEA) 2022 Direct Air Capture Report states, "DAC is not an alternative to cutting emissions or an excuse for delaying action but is part of a comprehensive strategy for net zero—where emissions being released are ultimately balanced with emissions removed."

Some also see the bigger promise of DAC. The allure of realizing negative emissions instances if it can be fully powered by renewables and effectively used in combination with a variety of carbon storage and utilization initiatives.

Current state

The first DAC unit was operational in 2010, but field deployment really took off around 2017. According to IEA's 2022 Report, there are 18 DAC facilities operating in Canada, Europe and the U.S. Fifteen of these have been commissioned by Swiss based Climeworks, and the majority have CO₂ utilization as an end use. All are small scale, with some capturing single digit CO₂ tons per year. The biggest, located in Iceland, is capturing 4,000 tons of CO₂ a year.

An industry game changer came in 2021. 1PointFive (a subsidiary of U.S. oil independent, Occidental) announced the engineering and design phase for the world's most ambitious DAC project to date: Strato. Based on Carbon Engineering technology, initial construction works started this year with the 500,000 ton Texas-based facility to be operating by 2025. It plans to expand capacity to extract one million tons of atmospheric CO₂ annually. It's the first of 100 same-sized DAC facilities the company envisages to have globally by 2035. All with the combined carbon removal equivalent of about four billion trees.

It's an ambitious project and will need to navigate the practicalities of facility performance, access to operating environments, policy conditions, available resources and market demand. If realized, its 100 million tons of atmospheric CO₂ removal per year would be a step towards the gigatons-per-year proportions required by DAC. This is informed by net zero emissions scenarios outlined in the sixth assessment report by the Intergovernmental Panel on Climate Change (IPCC).

How much CO₂ must the world remove?

An MCG full... every four seconds!

The Melbourne Cricket Ground (MCG) 's volume is 1,574,000 cubic meters, which is equivalent to about 2,901 tons of CO₂.

IPCC analysis found up to 20,000 million tons per year (MTPA) of CO₂ will need to be removed from the atmosphere to achieve global climate targets by 2050. This means removing an MCG full of CO₂ every 4.37 seconds.

Directly working on DAC

Our project-focused teams of chemists, engineers, economists and business developers are collaborating across Australia, the U.K. and the U.S. on a range of DAC technologies. These are investigated in the lab and through demonstrators, aiming to increase their technology and commercial readiness level.

Dr. Paul Feron is a Senior Research Principal Scientist who has been leading work on Carbon Capture, Utilization and Storage (CCUS) solutions globally for more than 20 years.

"Direct air capture is an accelerating area of interest within CCUS research. CSIRO has diverse technologies under development as one would expect at this early stage where deployment options and integration with carbon storage and utilization are being assessed in a technological and economic sense," Paul said.

"Some DAC's use solid absorbents, some use a combination liquid/solid absorbent, and some use liquid absorbents. Basically, these absorbents saturate themselves in CO₂ captured from airflow and are then heated to release and secure the gas for piping to geologic storage or use in a manufacturing process," he said.

"All have a focus on producing a level of purity CO₂ as needed for permanent storage or utilization points and for efficiently regenerating and recovering the absorbent material so that it can be reused in a continuous process."

Liquid absorbent-based technology: ACOHA

Our researchers initially explored the suitability and applicability of amine liquid capture technology for DAC in 2018. This work built on earlier laboratory research and demonstration of the technology for flue gas treatment, and it led to the development of the Ambient CO₂ Harvester (ACOHA), which has the potential to capture millions of tons of CO₂ from the atmosphere annually.

Key advantages of the ACOHA technology are its basis in commercially available technologies, potential to drive down costs through process and equipment innovation, and potential to be scaled up quickly to have a real impact in terms of climate change mitigation. There is an opportunity for the CO₂ captured using ACOHA to be used as a renewable feedstock in the beverage industry, directly in greenhouses, for fuels synthesis or locked into long-lived mineral products.

The Newcastle-based research team is also supporting a technology demonstration in the U.K. in 2024. This is at a scale of at least 100 tons per year through a project led by Rolls Royce Plc.

Solid/liquid absorbent-based technology: CarbonAssist

In Perth, Western Australia, another research team is collaborating with Santos on the development and deployment of carbon assist technology. This is through a partnership that encompasses a robust framework for future technology commercialization.

CarbonAssist uses an innovative sorbent material—a combination of 30% solid sorbents and 70% liquid amines—that is highly selective for CO₂ from the atmosphere. It significantly exceeds current industry benchmarks of utility, economy, and efficacy.

Amir Aryana, a Research Group Leader in our Energy team, said CarbonAssist was developed as part of our strategy on decarbonization and transition in fuels.

"The project wanted to achieve a technology that could capture CO₂ directly from the air at a very low cost and be applied to different industries," Amir said.

The research team is currently finalizing a pilot plant for field testing at Santos' Moomba operations in South Australia. The pilot plant is capable of removing 90 tons of CO₂ from the atmosphere per annum, but work has already started on a second, larger unit that will capture 365 tons per year.

Research is also being conducted as part of the new CarbonLock Future Science Platform. This work is investigating how to rapidly increase our capacity for permanent carbon removal from the atmosphere. Our researchers currently exploring DAC techniques, along with other biological, ocean-based and mineral-based solutions.

What's next?

The main challenge for researchers working on DAC is upscaling the technology to a point where it becomes a feasible, cost-effective means for carbon dioxide storage or utilization.

Claudia said approaching this problem from the perspective of a circular carbon economy also means seeing CO₂ in the atmosphere as an untapped resource rather than just a pollutant.

"Assessing the most effective way to do that is as much about economics as it is about the environment," she said.

Irrespective of the different approaches being progressed, DAC is a technology focused on tackling legacy and residual emissions as other technologies and practices work to reduce current and future emissions to the lowest level achievable.

With a multidisciplinary approach, two decades of research expertise, and a strong track record of establishing effective partnerships with government and industry, we're well positioned to help drive the enormous potential of this work.

Provided by CSIRO