In discussing how to counter global warming, it’s pretty easy to argue that nuclear should be the major electricity source and heat producer to replace fossil fuels. At 6 grams per kilowatt-hour, it has the lowest carbon emissions of any energy source, according to the United Nations, and is objectively the safest form of energy for humans and the environment alike, again from a recent UN report.

Given how much carbon dioxide has been released into the atmosphere from fossil fuels, replacing those fuels with clean options like nuclear energy is urgent, but could be likened to shutting the barn door after the proverbial horse has bolted. But what if you could also round up excess CO₂ already in the atmosphere? That’s the goal of direct air capture (DAC) and other so-called negative emission technologies—to capture climate warming CO₂ for use in products or processes or for permanent storage.