Carbon dioxide removal (CDR) systems put more greenhouse gases into the air than they take out.
Carbon dioxide removal (CDR) systems – touted as techno-fixes for global warming – usually put more greenhouse gases into the air than they take out, a recent study has confirmed.
Carbon capture and storage (CCS), which grabs carbon dioxide (CO2) produced by coal or gas-fired power stations, and then uses it for enhanced oil recovery (EOR), emits between 1.4 and 4.7 tonnes of the gas for each tonne removed, the research shows.
Direct air capture (DAC), which sucks CO2 from the atmosphere, emits 1.4-3.5 tonnes for each tonne it recovers, mostly from fossil fuels used to power the handful of existing projects.
If DAC was instead powered by renewable electricity – as its supporters claim it should be – it would wolf down other natural resources.
And things get worse at large scale.
To capture 1 gigatonne of CO2 (1 GtCO2, just one-fortieth of current global CO2 emissions) would need nearly twice the amount of wind and solar electricity now produced globally. The equipment would need a land area bigger than the island of Sri Lanka and a vast network of pipelines and underground storage facilities. (See endnote 1.)
Claims made that CCS could be “green” – by generating the energy from biofuels, and/or storing the carbon instead of using it for oil production – do not stand up to scrutiny either, the article shows.
The paper – Assessing Carbon Capture: public policy, science and societal need, by June Sekera, a public policy analyst, and Andreas Lichtenberger, an ecological economics researcher – is free to download on the Biophysical Economics and Sustainability web site.
Sekera and Lichtenberger demolish the case put by governments and fossil fuel companies for investing in CDR systems – and show how research methods are slanted to avoid discussion of the full resource costs.
They also challenge the way that so much CDR research focuses not on its extremely dubious worth as a tool to combat climate change, but on whether it can make money. Economists envisage the CO2, in a gaseous or solid form, being marketed as a commodity – but this, too, could operate at scale only in the world of techno-fantasy and/or late-capitalist dystopia.
Sekera and Lichtenberger write that “market actors seeing avenues for profit [and] seeking government support” are the main promoters of CDR by mechanical and chemical methods (such as CCS and DAC), as opposed to natural methods such as planting trees.
Fossil fuel producers are keen too. They falsely claim that CCS can help produce “green” electricity from coal or gas. Moreover, the main use to which sequestered carbon is currently put is for enhanced oil recovery (EOR), an oil and gas production technique: the carbon is pumped into underground reservoirs containing oil and gas, helping to push these products to the surface.
Governments have long backed industrial CDR, and that has intensified since the Intergovernmental Panel on Climate Change (IPCC) reports of 2014 and 2018, which pointed to negative emissions technologies, in particular, Bioenergy with CCS (BECCS) – producing electricity from biofuels, and sucking back the carbon emitted with CCS – as a way to meet decarbonisation targets.
Climate scientists have slammed the scenarios in these reports that rely on unrealistic and dangerous assumptions about using a vast proportion of the world’s land to grow crops for bioenergy. (See e.g. here, here or here.) But that has not stopped state backing for CDR.
The US government alone sank $5 billion into the research of CDR in 2010-18, Sekera and Lichtenberger point out. The UK Committee on Climate Change says CDR is a “necessity”, and the European Commission has incorporated industrial CDR into its “green deal”. The trough of development funding is getting bigger.
Humanity’s “collective biophysical need” to reduce the amount of CO2 in the atmosphere is the standard by which Sekera and Lichtenberger judge CDR technologies.
This helps them to cut through mountains of hype about CDR, including articles focused on how “cost-effective” it is, or claiming it is “carbon reductive” compared to a hypothetical “business as usual” case.
They reviewed more than 200 scientific papers and analysed what they said about: the impact of each CDR technology on the total carbon balance; the resource usage required for it to be used at scale; and the biophysical impacts, especially at scale.
In the case of CCS, Sekera and Lichtenberger point out that it “can not reduce the stock of atmospheric CO2 since it can not store more than it captures”. In order for the CO2 to be captured by this method, it has to be added to the stock in the first place, almost always by a power station or industrial process.
If the carbon is stored, rather than used for oil production, “the process could avoid being net [CO2] additive”, Sekera and Lichtenberger concede. But renewable electricity generation linked to storage would be much more energy-effective, as a research team led by Sgouris Sigouridis at Khalifa University, Abu Dhabi, calculated recently – so why would you invest in fossil fuels plus CCS in the first place?
Furthermore, in the real world, now, CO2 captured by CCS is not stored, but used for EOR – that is, to produce more oil. All five of the largest CCS projects recently listed by an oil industry journal (one of which, Petra Nova, is currently mothballed) send the captured CO2 for EOR. (See endnote 2.)
Other CCS facilities, that take the carbon out of natural gas without the gas being burned, e.g. in the manufacture of hydrogen, also very often send the CO2 produced for use in EOR.
The Global CCS Institute, an industry body, says that, of ten new projects it recently listed, three will send CO2 for EOR, two are “considering” it and only two plan dedicated geological storage. No information is provided for the other three.
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