Earlier, I mentioned a related technology called direct air capture. It involves exactly what the name implies: capturing carbon directly from the air. DAC is more flexible than point capture, because you can do it anywhere. And in all likelihood, it’ll be a crucial part of getting to zero; one study by the National Academy of Sciences found that we’ll need to be removing about 10 billion tons of carbon dioxide a year by mid-century and about 20 billion by the end of the century.