The CAD facilities themselves will need to evolve as quickly as possible. To be able to remove just 2 to 2.5 gigatons of carbon per year by 2050 – a fraction of the amount that will help us meet the Paris targets – we would need about 800. But to really do it a breach in the surge of CO2 levels, we would need to build them much faster. We’re talking about 4,000 to 9,000 plants by 2075, and over 10,000 by the end of the century, in which case we could theoretically sequester up to 27 gigatons of carbon per year. “It shows, in effect, that you have a very long, slow, and gradual scale up as the industry grows through 2050,” Hanna says. “Then once it gets to massive size, it’s really easy to add lots of plants quickly, because you have this huge industrial base for the industry.”
But there are a few important caveats to be aware of, as Hanna and her colleagues model nascent technology teeming with unknowns. For example, they need to make educated assumptions about how much energy future plants could use, which determines their operating costs. “The other big unknown,” says Hanna, “is how system performance might actually improve and how systems costs would decrease over time, given the experience of companies in building the system. technology.”
Additionally, global politics could disrupt the deployment of DAC: if all humans share the same atmosphere, why would a country pay to research and deploy the technology if its neighbor doesn’t pay a dime? “It’s good to approach things about climate change like it’s just technological issues – if we get the right cost, if we have the right technology,” says Brian Snyder, environmental scientist at Louisiana State University, which did not participate in this new work. “But they are inherently Politics problems, and we must solve them simultaneously. (In their article, Hanna and her colleagues ask for help from political scientists to explore the challenges of international cooperation here.)
Yet another open question: what do you do with this carbon once you’ve captured it? One option is to pump it underground, to seal it forever. Economically it’s a little tough because you spend the money to run your facility, but then you throw away your product instead of selling it. This means that the DAC will demand that government grants are economically feasible. A nation might ascribe intrinsic value to capturing carbon and slowing climate change, and devote some of its own funding to bear financial loss – at least in the short term – for an environmental good.
Researchers are also working on transform the captured carbon into new fuels, which could make this initial government investment in DAC lucrative. It seems, well, counterproductive, as we would burn the fuel and put the carbon right back into the atmosphere. But the idea is to use such a fuel to make industries difficult to decarbonizeneutral. Airliners and freighters, for example, are too massive to operate with current solar technologies. By essentially having them recycle fuel that is on its second life, there is less demand for fossil fuels taken out of the ground.
If these industries burn fuels made from captured CO2, they will still pollute, but at least they will pollute with carbon that was previously in the atmosphere. “The real effective role of negative emissions is for this long tail of hard-to-decarbonize sectors,” says Zeke Hausfather, climatologist and director of climate and energy at the Breakthrough Institute, which advocates for climate action. (He was not involved in this new research.) “Aviation, agriculture – things where we’re still going to emit carbon in the 2050s, and maybe after that.