Companies are sucking carbon from the atmosphere using 'direct air capture'. How does it work?

direct air capture: CO2 written in the sky as clouds
Direct air capture can reduce the amount of CO2 in the atmosphere
Image: Unsplash/Matthias Heyde
  • Direct air capture involves removing CO2 from the air and storing or reusing it.
  • The world’s first large-scale plant is being built in the United States.
  • Companies such as Microsoft, Shopify and Swiss Re are buying into direct air capture to offset their emissions.
  • But a massive scale-up in facilities is needed to help the world reach net zero by 2050, says the International Energy Agency.

The world’s journey towards net zero emissions is taking us down many new roads when it comes to technology. Electric vehicles and renewable energy are among those helping us to stop emitting carbon, but direct air capture takes another approach – sucking CO2 we emit back out of the atmosphere.

Direct air capture could be a solution for combatting carbon emissions that are hard to avoid – like those from certain industries – and for removing carbon that has been emitted over past decades.

Here’s a quick explainer.

Mining and Metals Blockchain Initiative

What is the World Economic Forum doing to help companies reduce carbon emissions?

Corporate leaders from the mining, metals and manufacturing industries are changing their approach to integrating climate considerations into complex supply chains.

The Forum’s Mining and Metals Blockchain Initiative, created to accelerate an industry solution for supply chain visibility and environmental, social and corporate governance (ESG) requirements, has released a unique proof of concept to trace emissions across the value chain using distributed ledger technology.

Developed in collaboration with industry experts, it not only tests the technological feasibility of the solution, but also explores the complexities of the supply chain dynamics and sets requirements for future data utilization.

In doing so, the proof of concept responds to demands from stakeholders to create “mine-to-market” visibility and accountability.

The World Economic Forum’s Mining and Metals community is a high-level group of peers dedicated to ensuring the long-term sustainability of their industry and society. Read more about their work, and how to join, via our Impact Story.

What is direct air capture?

Direct air capture – DAC for short – involves capturing carbon dioxide directly from the air. The CO2 can then be permanently stored, meaning that it stops contributing to global warming.

A direct air capture plant in Iceland is capturing 4,000 tonnes of carbon dioxide a year and storing it in basalt, a type of volcanic rock. The CO2 then mineralizes over around 20 years, turning into stone in a natural reaction with the rock.

The captured CO2 can also be reused in other industries. In food processing, it can be used to carbonate drinks. And in aviation, it is being combined with hydrogen to create synthetic low-carbon fuel.

A chart showing direct air capture global operating capacity, 2010-2021
The amount of direct air capture capacity in the world is rising fast, but it needs to rise even faster to help the world reach net zero emissions.
Image: IEA

Two technologies are used in direct air capture – liquid and solid DAC. Liquid DAC involves passing air through a chemical solution to remove any carbon dioxide. In solid DAC, the CO2 is captured in a filter system.

Where is direct air capture today?

There are 19 direct air capture facilities in operation worldwide, the International Energy Agency (IEA) says. Of these, 18 are in Canada, Europe and the United States, according to the IEA report Direct Air Capture: A Key Technology for Net Zero.

New plants are also being built. The world’s first large-scale plant is in development in the US. It will be able to capture up to 1 million tonnes of CO2 a year and is expected to be operating by the mid-2020s.

Big companies such as technology firm Microsoft, e-commerce company Shopify and reinsurance firm Swiss Re are starting to invest in DAC removal as a way to offset their carbon emissions.

What is DAC’s potential?

To help the world reach net zero emissions by 2050, direct air capture technologies need to be capturing more than 85 million tonnes of CO2 in 2030, and then 980 million tonnes in 2050, the IEA estimates.

A chart showing Global CO2 capture from DACS and DAC with use in the Net Zero Scenario
The IEA has put numbers on where direct air capture needs to be.
Image: IEA

However, this means a “large and accelerated scale-up” is needed, as DAC plants currently only capture around 10,000 tonnes of CO2, the IEA says.

The good news is that momentum is building. Governments have committed almost $4 billion to develop and deploy DAC plants since the start of 2020, according to the IEA. Australia, Canada, Japan and the United Kingdom are among the countries investing in DAC research and development.

Direct air capture technology pioneers

Two companies already capturing CO2 from the air are Climeworks and Carbon Engineering.

Both are World Economic Forum Technology Pioneers – early-stage and growing companies from around the world who are leading the way on new technologies and innovations.

Switzerland-based Climeworks opened its first DAC plant in 2017 and now has 15 machines in operation. It runs the Iceland plant mentioned above – currently the world’s biggest – and employs a form of solid direct air capture using filters.

Climeworks is helping companies including jewellery brand Swarovski and online grocer Ocado to reduce, offset and remove CO2 emissions.

Canada-based Carbon Engineering uses a form of liquid direct air capture and is working with partners to develop the world’s first large-scale DAC facility. This is in the US Permian Basin, a shale oil and gas producing area between Texas and New Mexico, and is designed to permanently lock away between 500,000 and 1 million tonnes a year of CO2 in rocks deep underground.

Engineering has started on another DAC plant of the same scale planned for Scotland.

Meanwhile, US start-up CO2Rail has partnered with University of Toronto researchers to explore adding DAC technology to trains, potentially sequestering gigatonnes of carbon in the future.

The technology works by capturing air as the train moves, putting it through a chemical process to separate out the carbon dioxide, and storing it in special chambers onboard. The captured CO2 can then be delivered to underground sites or used as feedstock, while the CO2-free air is re-released into the atmosphere.

The researchers believe 6,000 tonnes of CO2 could be captured by each train each year, and that by 2050, a rail-based DAC system could remove 2.9 gigatonnes of CO2, making it almost carbon-neutral.

“Everybody wants to fix the climate crisis, but few are happy to have it done in their proverbial ‘backyard’,” Professor Geoffrey Ozin, one of the researchers, told University of Toronto News. “Rail DAC does not require special zoning, surveys or building permits and would be transient and generally unseen by the public,” he added.

Prototypes are already being worked on and the first railcar is expected to be ready in 2023.

Net zero technologies

To accelerate the development of emerging technologies that will help the world reduce emissions to net zero by 2050, the World Economic Forum and partners in the US government have set up the First Movers Coalition.

This is a public-private partnership that is working across sectors and companies. The coalition says that about half of the technologies the world needs to get to net zero are still under development or in prototype stages.

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