Filtering carbon: How will direct air capture help combat climate change?

To keep the earth’s average temperature from increasing by 1.5 degrees Celsius, the world needs to have halved its global carbon emissions by 2030, according to the United Nations. However, halving carbon emissions within the next seven years still only gives us a 50% chance of staying below that temperature.

Whilst the 50/50 chance of going above 1.5 degrees would be tragic, there’s still reason to believe that if we surpass 1.5 degrees, we can bring the temperature back down.

The UN’s Intergovernmental Panel on Climate Change (IPCC) says that staying below 1.5 degrees, or getting back down to 1.5 degrees, is only possible if the world reduces the number of coal plants, and starts taking carbon out of the atmosphere.

Whilst preserving existing forests, peatlands, and other natural carbon stores are still important in helping to remove carbon out of the atmosphere through photosynthesis, the latest IPCC report says that no amount of tree planting will make a significant enough impact on removing the continued output of fossil fuels.

Enter direct air capture (DAC) – great big machinery that takes carbon dioxide directly from the air, and generates a concentrated stream of the gas which is then either stored underground permanently or recycled for further usage.

With backers including Microsoft, Shopify, and a recent £54 million boost from the UK government, can direct air capture technology be the answer to net-zero ambitions for corporations and governments alike?

Car-bon voyage

One company currently at the forefront of DAC is Swiss carbon capture firm Climeworks, co-founded by Christoph Gebald and Jan Wurzbacher over a decade ago in 2009. Just last year, the company began operations on its first climate-positive DAC and storage plant in Iceland, named ‘Orca’, and is the first supplier of a long-term, technology-based carbon removal for Microsoft.

Since then, Climeworks has raised $650m in funding, and last month broke ground on its second, even larger DAC facility in Iceland – which it called ‘Mammoth’ last month. Mammoth is designed to have a CO2 capacity of 36,000 tons per year when fully operational, which will hopefully be within the next two years. If that’s the case, then Climework expects to capture and store multi-megatons worth of CO2 by 2030, and deliver a gigaton capacity by 2050.

The geological storage of CO2 Climeworks will be using at its plants means injecting the captured CO2 into the pores of rock formations deep underground, where carbon dioxide is physically trapped and permanently stored – a process called mineralisation.

Another company leading the way in carbon capture is Carbon Engineering, a Canadian firm founded by Harvard professor David Keith.

So far, Carbon Engineering has developed a system that captures one million tons of CO2 per year, which is the equivalent of annual emissions from 250,000 cars or the work of 40 million trees.

At the moment, Carbon Engineering is working with its development partner 1PointFive to engineer its first large-scale DAC plant in the Permian Basin in the US. It says that the technology can be located anywhere where low-cost, clean energy to power the system is available, or where it can permanently store the CO2 underground.

Whilst start-ups have been pioneering the technology, larger companies such as aerospace and car manufacturer Rolls-Royce, and energy firm EDF are now making movements to explore DAC after winning investment from the UK government.

In July, the UK acknowledged that greenhouse gas removal technology will be essential in helping it meet its climate target of net-zero emissions by 2050, and invested a shared amount of £54m into researching DAC.

EDF won £3m to fund a DAC plant that would be powered by using excess heat from its proposed Sizewell C nuclear plant in Suffolk, England.

The French energy firm plans to build a demonstration unit with engineers from Strata Technology, Atkins, the University of Nottingham, Doosan Babcock, and Sizewell C that’s capable of extracting 100 tonnes of CO2 from the air each year.

“If the demonstrator project being developed by the consortium is successful, a scaled-up DAC unit powered by heat from Sizewell C could one day capture 1.5 million tonnes of CO2 each year,” EDF said in a statement.

Rolls-Royce also secured £3m for a DAC demonstration unit, which could also capture 100 tonnes of carbon a year, with a full-scale version targeting one million tonnes a year of removals.

The demonstrator will be built in Derby, UK, and will be operational during 2023. Rolls-Royce plans to store and even recycle the carbon to make fuel for hard-to-decarbonise sectors such as aviation, enabling “the more rapid phase-out of fossil fuels”.

Jess Poole, direct air capture lead for Rolls-Royce said in a statement: “Our system combines our expertise in moving large quantities of air efficiently and integrating complex systems, which have been gained from designing world-leading jet engines, with novel DAC technology developed by CSIRO.”

Rolls-Royce and EDF are just two of 15 groups that received funding from the UK government, with others including the University of Exeter, which is developing a system to remove CO2 from seawater, and Scottish firm SAC Commercial, which is developing a technology to capture methane produced by cattle.

What’s up, DAC?

Last year, Canadian e-commerce company, Shopify invested 23% of its sustainability fund into DAC, and purchased a combined total of 15,000 tonnes of DAC from both Carbon Engineering and Climeworks.

Insurance company Swiss Re also signed a ten-year agreement with Climeworks, which it hailed as ‘the world’s first long-term purchase agreement for DAC and storage of carbon dioxide’, worth $10m.

In April, Microsoft released its latest Carbon Removal report that outlined where it was investing to offset its carbon emissions.

Interestingly, the update stated itself that technology-based carbon removal efforts are a better long-term solution (categorised as high-durability in their report) than nature-based efforts such as planting forests (categorised as low-durability.)

The tech giant categorised direct air capture as a high durability solution for carbon offsetting for its ability to store carbon for 10,000 years.

Microsoft’s update said that whilst technology-based solutions such as DAC are expensive to purchase for offsets, it’s on companies such as itself to sign multi-year purchase agreements with DAC to help jump-start affordable supply, as it has done so with Climeworks.