Few credible experts see how the world will reach net-zero emissions without actively removing carbon dioxide out of the air, perhaps through direct air capture technologies. This has become an active research area over the past two decades, but most existing work doesn’t consider how ambient environmental conditions—temperature, humidity, pressure, and carbon dioxide concentration—affect these engineered systems, which need to process massive amounts of atmospheric air to remove the carbon dioxide. Faculty and students affiliated with the Sustainable Energy program recently published a paper in PNAS—the first to model how these plants would actually perform across the globe, considering different weather conditions, different emissions from electric power systems worldwide (some of which are dirtier than others), and different emissions from natural gas systems (some of which are leakier than others).
The work is intended to stimulate serious discussion of the role of direct air capture technologies in nationally determined contributions submitted to UNFCCC. For nations that are making large bets on carbon dioxide removal despite having poor or fair conditions for the deployment of direct air capture, the research should stimulate discussion of cross-border carbon accounting mechanisms that would allow these nations to subsidize deployment in regions with more appropriate climatic conditions.