See https://www.nature.com/articles/d41586-018-05357-w https://www.nature.com/articles/d41586-018-05357-w and https://www.economist.com/science-and-technology/

See https://www.nature.com/articles/d41586-018-05357-w https://www.nature.com/articles/d41586-018-05357-w and https://www.economist.com/science-and-technology/2018/06/09/extracting-carbon-dioxide-from-the-air-is-possible.-but-at-what-cost https://www.economist.com/science-and-technology/2018/06/09/... "Though that sounds thermodynamically bonkers, such fuel would, from a legal point of view, count as “zero carbon” because making and then using it involves no net release of CO2 into the atmosphere."