An oil drilling rig in Californias Central ValleyAshley Cooper / AlamyFossil fuel companies are experimenting with using carbon dioxide captured from the air in oil extraction to usher in a new era of planet-friendly net-zero oil but the idea is an illusion, according to researchers.In enhanced oil recovery (EOR), crude oil is extracted by injecting CO2 underground to squeeze out any remaining oil from a depleting reservoir. Combining EOR with CO2 sucked out of the air by direct air capture (DAC) plants will result in net-zero oil, some oil firms claim, a process they hope can