RePercussion Section: The Rebranding of EOR—Same Old Wine, Same Old Bottles, Different Label
Adapted from the August 2024 report “The False Promise and Potential Health Harms of Carbon Dioxide Enhanced Oil Recovery (CO2 EOR) as a Tool of Climate Mitigation,” prepared by SEHN and the Bold Alliance
by Sandra Steingraber, SEHN senior scientist and writer in residence
The goal of carbon dioxide enhanced oil recovery (CO2 EOR) is to squeeze out the veritable last drop of recoverable oil from an oilfield. The assumption is that the injected CO2 will either remain within an escape-proof underground location or will be re-captured and reused if it rises to the surface with the oil it liberates.
Indeed, U.S. gas and oil companies have seized on carbon capture as a means to partially offset, on paper, their greenhouse gas emissions without ending fossil fuel extraction or combustion. CO2 EOR is, in fact, the only currently existing commercially available market for millions of tons of captured CO2.
All the evidence to date indicates that no regulatory framework or system of economic incentivization can transform CO2 EOR into a meaningful tool of climate mitigation. To the contrary, and for three fundamental reasons, CO2 EOR contributes to the climate problem rather than serving as a climate solution.
CO2 EOR suffers from incomplete emissions accounting.
The simple bottom line is that burning the oil recovered using CO2 EOR generally emits two or more times as much CO2 as is kept underground during CO2 EOR operations.
Even if every CO2 EOR operation were entirely leak proof, with all the captured carbon eternally sequestered in the spaces into which they are injected, those molecules of CO2 serve to displace molecules of crude oil, which, by nature, do rise to the surface. The downstream carbon emissions from burning the oil so extracted, which would otherwise remain in the ground, are not accounted for in industry models.
As noted by the two co-founders of the first privately funded company to make use of carbon capture in the United States, every dollar invested in renewable energy eliminates far more carbon emissions than CO2 EOR operations and does so less expensively. In sum, CO2 EOR harms the climate by incentivizing rather than impeding the continued extraction of fossil fuels.
Even if CO2 EOR could be made to work perfectly, renewable energy alternatives are cheaper and more effective at preventing greenhouse gas emissions. Although the oil and gas industry continues to hail CO2 EOR as an emissions-reductions strategy, this technology is more likely to increase total emissions rather than reduce them.
As noted by the Institute for Energy Economics and Financial Analysis in a July 2024 report, “CCS was originally devised to support oil and gas extraction and has a long history of under-achievement in combatting emissions, which is unlikely to change in the foreseeable future.”
Evidence that CO2 EOR can offer permanent CO2 sequestration is lacking.
CO2 EOR operations do not, in fact, work perfectly. The potential for leaks is real. As a supercritical fluid, CO2 has the dissolving properties of a liquid but the ability to move through porous solids like a gas and can migrate quickly through microscopic fractures in the rock.
Depending on small shifts in temperature and pressure, supercritical CO2 can behave more like a liquid or more like a gas, and its behavior can change dramatically, as, for example, when smooth, laminar flow suddenly becomes turbulent with a slight change of physical condition.
CO2 can help drive oil out of the pores within geological formations where it would otherwise not flow. But this same property allows it to easily slide through microscopic fractures in the rock where it is buried.
As noted by geologist and science historian Naomi Oreskes, “We all know the saying that what goes up must come down, but the opposite is also largely true”; that is, what goes up tends to keep going up. Pressurized supercritical CO2 is buoyant and tends to rise.
The ideal site for its permanent containment would be a permeable rock layer—with abundant pore spaces for the CO2 to fill—overlaid by thick cap rock without any pores or fissures in it. Additionally, there should be no unmapped or abandoned wells in the area to serve as a fast highway to the surface. And the formation should not be vulnerable to seismic activity.
Oreskes emphasizes that there might well be places on earth that meet these qualifications and could serve as a maximum-security facility for the permanent sequestration of CO2, but depleted oil wells likely are not these places.
A search for appropriate geological storage for CO2 also would require years-long site characterization research.
Old wells, boreholes, and naturally occurring faults are the most common pathways for free-form CO2 to escape to the surface. However, even absent significant seismic activity, carbon sequestration and CO2 EOR can create pressure build-up great enough to break through cap rock, releasing the stored CO2.
CO2 is not only buoyant but also converts to carbonic acid in the presence of moisture. Both of these qualities enable its ability to corrode well casings, dissolve rock formations, and rise to the surface.
There is no empirical data to suggest that depleted oil fields can serve as an eternal, escape-proof storage unit for pressurized, liquefied CO2.
Unable to scale rapidly, CO2 EOR is not a feasible tool for meaningful decarbonization within agreed-upon timelines.
CO2 EOR has been in use for a half century and yet has not succeeded in capturing carbon at a scale anywhere close to the levels required to hit agreed-upon climate targets that would limit warming to 1.5 degrees by 2050.
The International Energy Agency (IEA) has warned that incorporating carbon capture into ongoing oil and gas extraction operations is at odds with a net zero future and that carbon capture deployment of all kinds, including CO2 EOR, is well below what is required in the net zero scenario.
A 2024 analysis led by a geoscience team at Imperial College London notes that all the pathways for limiting warming to 1.5 degree assume massive amounts of geological carbon storage. However, these projections are wildly unrealistic. Currently, around 9 million tons of CO2 are stored underground, included in depleted oil and gas reservoirs. To stay below 1.5 degrees, the study forecasts the rate of storage would need to increase by 1000-fold in less than three decades, a rapid scaling that is “fanciful.”
As costs of renewable energy fall further, capturing CO2 from coal- or gas-fired power plants to serve as a feedstock for CO2 EOR operations for oil extraction becomes ever more uneconomical, especially when compared to the lower cost of renewable energy anddemand management programs.
Further, most of the CO2 EOR projects currently operating use CO2 extracted from natural underground deposits, not CO2 captured from industrial operations that would otherwise end up in the atmosphere. This practice represents a subsidized transfer of already sequestered CO2 from one site to another. As the IEA notes, “such practice is neither beneficial to the climate nor for the development of CCS.”
Privately, the oil and gas industry itself admits that carbon capture technologies are unscalable and of limited use in reaching climate targets. In April 2024, a joint bicameral staff report from the House Committee on Oversight and Accountability Democrats and Senate Committee on the Budget, “Denial, Disinformation, and Doublespeak,” revealed the fossil fuel industry’s campaign to misinform and deceive the public about its commitments to mitigate the climate crisis.
Notably, these efforts include statements made about carbon capture. Internal documents show that the industry publicly celebrated carbon capture technologies as a helpful tool for reducing emissions even while privately acknowledging that it is expensive, unscalable without massive investment by the federal government, and of very limited use.
According to the report, “the fossil fuel industry recognizes that the rollout of [carbon capture technologies] at scale is moving too slow to reach net zero emissions by 2050 and that the reason is their own extremely modest investment, but their public claims conceal this reality....The industry’s true goal is to prolong, perhaps indefinitely, the abated use of fossil fuels.”
In short, CO2 EOR is not a good-faith climate mitigation strategy and instead is an expensive, taxpayer-funded scheme—with a thin veneer of greenwash—to extract the last drop of oil from the ground. It may be the oil industry’s last, best hope for survival.