Injecting CO2 into oil wells is not real carbon sequestration
Capturing CO2 and injecting it into a well to squeeze more oil out of the ground is not real carbon sequestration. Why? When the recovered oil is burned, it releases at least as much CO2 as was stored (and possibly much more). Therefore, CO2 used for such enhanced oil recovery (EOR) does not reduce net carbon emissions and should not be sold to the public as a carbon offset.
Yet a company, Blue Source, LLC, proposes to do just that: to capture the CO2 from a fertilizer plant, pipe it to an oil field, and inject it into wells for EOR :
The company hopes to profit from the project by earning credits for the carbon reductions in voluntary carbon markets and by selling carbon dioxide to energy companies.
The deal will cut CO2 from the plant by about 650,000 tonnes per year by permanently storing the emissions in the oil fields, he said. The U.S. Department of Energy says that capturing CO2 from power plants for enhanced oil recovery could greatly boost U.S. oil reserves while permanently keeping CO2 from reaching the atmosphere.
Uh, no. To repeat, if the captured CO2 is used to extract oil that releases CO2 when it is burned, then how is that offsetting anything?
The key ratio is CO2 injected vs. CO2 released from recovered oil. Fortunately, BP and UCLA did that life-cycle analysis ($ub. req’d) in 2001 and concluded “the EOR activity is almost carbon-neutral when comparing net storage potential and gasoline emissions from the additional oil extracted.” And that may be optimistic. The study notes:
The results presented reflect only gasoline consumption but do not take into account the additional emissions that would originate from the refining process, nor the emissions arising from the combustion of the other products of crude oil such as diesel, bunker or jet fuels.
In short, the CO2 used to recover the oil is less than the CO2 released from that oil when you include the CO2 released from (1) burning all the refined products, and (2) the refining process itself. D’oh!
But wait. The study has a different conclusion: “utilizing captured and recycled CO2 instead of using CO2 exclusively from natural reservoirs reduces greenhouse gas emissions to the atmosphere from EOR.” Well, yes, most CO2 used for EOR today comes from “natural reservoirs.”
But the nation and the world have barely touched the full potential of EOR, even though it can potentially double the oil output from a well that has undergone primary and secondary recovery. Why? As a Department of Energy press release on an EOR-sequestration project noted, “much of the CO2 used in similar U.S. EOR projects has been taken at considerable expense from naturally occurring reservoirs” (tip of the hat to The Energy Blog and The Oil Drum, which has a good discussion of the EOR-climate issue).
Cheap, widely available CO2 would be a game-changer. The DOE has studied EOR a great deal and come to an amazing conclusion. In the U.S. alone, “next generation CO2-EOR technology” and “widespread sequestration of industrial carbon dioxide” could add a stunning “160 billion barrels of domestic oil recovery.” The combustion of that oil would produce more than 60 billion tonnes of CO2, equivalent to ten times annual U.S. CO2 emissions.
Nothing could be closer to genuine greenwashing then charging the public for offsets that are essentially subsidies of oil production.
Some environmentalists have said to me that allowing CO2 for EOR in a few demonstration projects could jumpstart the carbon capture and storage market. But we don’t need to waste time demonstrating how to store CO2 in an oil well — we know how to do that and it isn’t very useful for mitigating climate change, as we’ve seen.
We urgently need to begin demonstrating permanent injection into large deep underground repositories such as a saline aquifers [PDF] — and we need to start identifying and certifying dozens of those repositories around the country and around the world. That could take a decade or more — and so we’d better start now if we want carbon capture and storage to make a major contribution to avoiding catastrophic global warming.
We need to get busy with real sequestration and not subsidize the production of more greenhouse-gas-generating fossil fuels with the sale of phony carbon offsets.