The drop in emissions brought about by coronavirus lockdowns is likely to be temporary. As economies start to reopen, the need for a global focus on the climate will grow ever stronger.

The world is approaching a point where simply cutting the volume of CO₂ emissions will not be enough to meet climate targets. To reach net-zero, we also need to remove CO₂ that already exists to counteract the impact of rising industrial and energy demand, effectively removing more emissions than we generate.

Direct Air Capture (DAC) technology offers one way of doing this – and it could help slow, or even reverse, rising emissions. Although still in its infancy, the technology could be used to filter carbon from the atmosphere, closing the carbon loop by utilizing the captured CO₂ in industry. One example of this is enhanced oil recovery which produces “green” oil.

The idea of removing CO₂ from the air is nothing new – the technology has been used to purify the confines of submarines for many years. What is new are attempts to scale up the technology for commercial operations.

In 2017, a company called Climeworks pioneered a project in Iceland that captured carbon from the air, mixed it with water and injected it below ground where a geological reaction turned the gas to stone. Its capacity to capture emissions, though, was modest – at 50 metric tons a year, about the equivalent released by an average U.S. household.

But carbon capture costs have fallen dramatically, from around $600 per metric ton in 2011 to less than a third of that figure in some cases. As a result, this experimental technology has been applied to several projects and is now ready to be scaled up for commercial operations.

The oil and gas industry was an early investor, with projects backed by energy majors including ExxonMobil and Occidental.

For DAC pioneers Global Thermostat, a decade of environmental research resulted in two functioning pilot projects, each with capacity to capture up to 4,000 metric tons of CO₂ per year. In 2019, ExxonMobile began a partnership with the start-up to launch this research at scale, investing money and expertise to build additional facilities that will boost the current modest carbon capture capacity to 1 billion metric tons (one gigaton) annually.

Global Thermostat’s system draws in air, which is pushed through narrow channels over a large surface area containing a substance that extracts the carbon. Taking high volumes of air over a short period of time allows it to operate quicker than rival systems, reducing capture costs.

The plant uses large fans to draw huge volumes of air, which pass over corrugated sheets doused with a chemical solution that filters out the CO₂. Once drained, the carbon-rich solution is exposed to quicklime to form limestone pellets.

When heated to around 1,000°C the limestone pellets create quicklime – which can be reused – and release a gas stream of pure CO₂, ready to be stored or utilized in various industrial processes.

Occidental intended to pump captured carbon from the plant deep below ground into its Texas oil fields, releasing trapped oil deposits. As the carbon then stays below ground, the oil recovered using this method is carbon-negative. However, the COVID-19 pandemic and other market shocks have rocked the energy market, causing a drop in prices that would make the “green” oil promised by these ventures unviable until the market recovers.

There are many other uses for the vast volumes of CO₂ a scaled-up DAC sector could potentially harvest. The market for CO₂ is expected to reach $9.3 billion by 2025, with applications including oil and gas, medical, and food and beverage.

Carbon is used to manufacture synthetic fuels such as methane, which provide alternatives to fossil fuels like petrol and diesel, and could help decarbonize hard-to-electrify sectors such as aviation, shipping, and other modes of transport. Elsewhere, the petrochemicals sector utilizes carbon in the production of plastics, fertilizers, and industrial gases.

While no one ‘silver bullet’ technology can reverse the impact of climate change, innovations that help close the carbon loop take us a step closer to realizing a net-zero future. The challenge for DAC projects moving forward is to scale up the technology while bringing down costs.