illustration by pete ryan

Big Idea: Capture Carbon From the Air

Companies need to stop their emissions from polluting the skies. Direct air capture can help absorb what’s already up there.

BY PHIL DE LUNA

June 3, 2024

I was a curious kid, always drawn to science. I mainlined episodes of The Magic School Bus, and even though I came from an immigrant family with little money, I begged my parents to buy me chemistry kits filled with test tubes and colour-changing pH strips. Those early chemistry lessons were the gateway to my understanding of climate change. I couldn’t yet grasp complex concepts like greenhouse gases and the carbon cycle, but I did know that the tools and technologies humans created had an impact on our environment. We could make messes, but we could also help clean them up.

I was in university when I first heard about direct air capture, or DAC—the idea that you could collect carbon dioxide that had already reached the atmosphere, instead of at sources of emission, like factories or power plants. The world’s first DAC technology was developed by research groups at the University of Calgary and ETH Zurich about a decade ago. I was in grad school at the time and started researching it myself. After completing my Ph.D. at the University of Toronto in 2018, I became the youngest-ever director at the National Research Council Canada, in charge of a $60-million program to find ways to convert captured carbon into plastic.

Direct air capture involves a multi-step process: first, large fans mounted on the sides of steel or aluminum cooling towers pull in the air. It then passes through a filter, made of a liquid (like potassium hydroxide) or a solid (like metal organic frameworks, which are similar to the activated carbon in Brita filters). Clean air goes back out into the atmosphere, but the CO stays behind. It is removed from the filter using energy—heat, electricity or steam—then compressed into a liquid, pumped and stored two kilometres underground, in ancient ocean beds made of porous sand. 

Complex, maybe, but Earth needs all the help it can get: 2023’s record-breaking high temperatures were caused by emissions from 10 to 50 years ago. Even if we were able to end all emissions tomorrow, we’d still have 10 to 50 years of warming to go. We’re going to need to tackle the CO problem in several ways at once: electrifying everything, reducing emissions in hard-to-clean industries like cement and steel, protecting natural resources and investing in newer solutions, like DAC. 

Currently, there is only one active commercial DAC plant in the world: Mammoth, built in Iceland by a company called Climeworks. It will remove 40,000 tonnes of CO a year. In Texas, Occidental Petroleum is close to unveiling a DAC facility that’s expected to capture 500,000 tonnes a year. Here in Canada, there’s Deep Sky, where I work as the chief carbon scientist and head of engineering. We’re the country’s first project developer for DAC, or, as I like to call us, an oil-and-gas company in reverse.

At our first facility, set to open later this year, we’ll be testing out 10 different DAC prototypes, made by startups from around the world. They’ll look similar from the outside—like shipping containers covered in fans—but each will filter carbon differently. I can’t say right now how much our operation will cost, but generally speaking, a DAC plant that removes 500,000 tonnes a year costs between $800 million and $1 billion to build today. Of course, one plant will barely make a dent. To get to net zero by 2050, we’ll need to remove 10 billion tonnes of CO from the air every year leading up to that deadline. That’ll require thousands of DAC plants worldwide.  

Canada is well positioned to be a world leader in DAC. The technology requires two main ingredients: plenty of that porous geologic storage and renewable energy infrastructure. Canada has an immense amount of storage capacity. There’s enough space underground in Western Canada to hold all of the emissions produced by humanity since the dawn of the Industrial Revolution. Many provinces also have incredibly clean grids. Quebec, Deep Sky’s HQ, operates on roughly 99 per cent hydroelectricity.

Another of Canada’s advantages is its wealth of experienced energy workers. Out in Alberta, oil and gas workers already know how to move liquids and gases, calculate heat and mass balances, and install pipes and compressors. The same skills that are required to take carbon out of the ground are the same ones needed to put it back in. From a job-creation standpoint, DAC could be a boon: Carbon Removal Canada, a project launched by the non-profit Clean Prosperity Foundation, has estimated that our growing DAC industry will create 89,000 Canadian jobs by 2050.

For all DAC’s potential, there are some roadblocks to making it more widespread. The technology is still in its early stages, and some critics have deemed it too expensive. But the same was said of every revolutionary technology in its development phase. Currently, some DAC pilots are being built by hand or in scientists’ garages. If we still built cars this way, each unit would cost a million dollars to make. Once a manufacturing and supply chain has been established, DAC can scale and its costs will rapidly decrease. 

DAC projects also need to reduce their energy requirements. Right now, a large commercial plant needs 200 to 300 megawatts to run, an energy load similar to those of some oil refineries. Canada is investing in clean energy sources like EVs and heat pumps, which means there’s going to be a lot of competition for limited green power. Improvements in DAC technology will reduce our electricity consumption. 

DAC has already received support from the Canadian government. In 2021, it unveiled the Investment Tax Credit for Carbon Capture, Utilization, and Storage, which offers a 60 per cent rebate on all expenditures on DAC projects. DAC companies can also generate carbon credits, which they can sell to companies. Many of these firms are Fortune 500 corporations interested in offsetting the emissions they can’t prevent.

The story of DAC is one of overcoming skepticism. To the people who say building thousands of DAC plants is impossible, I’d say that the world has thousands of coal-fired power plants and water desalination plants. We can clearly build big. And remember COVID? If you’d told me in 2019 that we’d be able to produce and distribute a novel vaccine in the span of 10 months, I would have laughed. But when humanity’s back is against the wall, we make things happen. For a long time, even scientists thought pulling carbon from the air would be inefficient. And here we are. 

It’s unlikely that, as a country, we’ll ever stop emitting altogether. Concrete production will always produce carbon dioxide, for example. The good news is that whether we pull emissions from the skies in Canada, Europe, Africa or elsewhere, we all benefit. DAC isn’t a silver bullet—it’s one part of a bigger strategy to save the planet. After I die, I want my Wikipedia page to say, “Phil De Luna was responsible for removing x tonnes of CO from the atmosphere.” I want that number to be as large as possible.


Phil De Luna is the chief carbon scientist and head of engineering at Deep Sky in Montreal.

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