Fossil fuel companies are experimenting with using carbon dioxide captured from the air in oil extraction to usher in a new era of planet-friendly 鈥渘et-zero oil鈥� 鈥� 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, , a process they hope can allow oil production to continue even as the need to lower carbon emissions gets stronger.
Studies looking at the impact of this聽usually But the technique can only be used on reservoirs that have already been significantly depleted. Once the emissions from earlier exploitation are accounted for, the oil is no longer net zero, says at ETH Zurich in Switzerland.
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Mazzotti and his colleagues conducted a full analysis of EOR using DAC, assessing the emissions and fluid dynamics across a reservoir鈥檚 lifespan. 鈥淲e want to understand the impact on the climate of the exploitation of the whole reservoir, because we feel that you cannot decouple what happens when you produce oil from what happens when you inject CO2,鈥� says Mazzotti.
By this measure, all EOR projects are significantly carbon-positive once a reservoir鈥檚 entire life cycle is accounted for. It is impossible to produce net-zero oil from a reservoir because the injected CO2 needed to offset the emissions from the oil that is removed and burned would take up three times as much space as would be available in the reservoir, says Mazzotti. 鈥淭here is a mismatch between the capacity of the reservoir in terms of CO2 storage and the amount of CO2 that is generated when the reservoir is emptied by producing oil,鈥� he says.
鈥淚f you take the boundaries of the reservoir during its entire lifetime, there is no such thing as doing carbon-neutral oil,鈥� says team member , also at ETH Zurich.
Later this year, the world鈥檚 largest DAC plant is due to open in Texas. The Stratos plant, ultimately owned by the US oil firm Occidental Petroleum, will be able to capture up to half a million tonnes of CO2 per year from the atmosphere. Occidental Petroleum has said it may use the captured CO2 from Stratos to produce 鈥渘et-zero oil鈥� via EOR.
When invited to comment on the new study, Occidental Petroleum referred New 杏吧原创 to claiming that EOR using captured CO2 has the . However, these analyses don鈥檛 consider a reservoir鈥檚 entire life cycle.
at the campaign group Carbon Market Watch dismisses the concept of net-zero oil as 鈥淧R spiel鈥�. 鈥淲e don鈥檛 want to spend too much attention on this type of gimmick,鈥� he says. 鈥淚鈥檇 rather focus on real solutions.鈥�
Oil firms also sell oil labelled as 鈥渘et zero鈥� by buying nature-based carbon credits to offset the pollution caused by their products, he says. 鈥淚t鈥檚 the same idea: you say that you are pulling from the atmosphere and therefore it doesn鈥檛 matter what you are putting into it. We are too far into the climate crisis for this to have any validity.鈥�
For decarbonisation, what is ultimately needed is an overall reduction in fossil fuel use, says Mazzotti. 鈥淲e can capture and store the CO2 as much as we want, but if we want to really reduce net emissions, we need to reduce the production of oil and gas, otherwise we will never manage,鈥� he says.
EarthArXiv
