A Big Step for the Sky Vacuums

Companies are bringing down the cost of a controversial weapon against climate change

- By Peter Coy

Halting global warming by sucking carbon dioxide out of the air strikes many people as a dumb idea. It’s complicated and energy-intensive. Why not focus on keeping more greenhouse gases out of the atmosphere in the first place—say, by installing more solar and wind power? Stanford engineering professor Mark Jacobson told the Israeli newspaper Haaretz in early December that “carbon capture is the Theranos of the energy industry,” referring to the company that built false hopes for blood diagnostics.

Some critics even argue that “direct air capture” of CO2 is a form of greenwashing—i.e., putting a gloss of environmentalism on the dirty business of hydrocarbon production. They point to the involvement of oil companies Chevron, Exxon Mobil, and Occidental Petroleum, which intend to use captured CO2 to recover more oil from their fields.

The companies leading the commercialization of direct air capture—Carbon Engineering of Canada, Climeworks of Switzerland, and Global Thermostat of the U.S.—say the technology is meant to supplement, not replace, shifts to solar and wind power. They reject the charge of greenwashing, saying the use of CO2 in oil fields is a transitional step in the decarbonization of the global economy. One longterm plan is to inject the captured gas into basalt rock formations to remove it from the atmosphere.

Most important, the companies are trying to prove that direct air capture can be cheap enough to be deployed widely and soon. An influential study published in 2011 by the American Physical Society estimated it would cost $550 to capture a metric ton of carbon dioxide using one leading method. But in 2018, Harvard applied physicist David Keith and others wrote an article for the journal