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

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.

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.

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.

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.

Victoria Masterson, Senior Writer, Formative Content

This article was first published by the World Economic Forum.