The concept of CO2 capture and utilisation (CCU) sounds promising: capturing CO2, from industrial flue gases for example, and using it to produce chemicals, fuels and other materials. "We know, however, that the involved chemical processes also use energy, and that captured CO2 is often emitted soon after it has been used in a product. We therefore wanted to assess the real reduction in CO2," says environmental scientist and first author Kiane de Kleijne.
CO2 utilisation often leads to insufficient emission reductions
Most forms of industrial CO2 utilisation do not reduce emissions sufficiently to comply with the Paris Agreement. And forms that would be able to halve emissions by 2030 are often not market-ready, conclude environmental scientists from Radboud University. The researchers published their findings in the academic journal One Earth on February 18th.
With her colleagues, De Kleijne calculated which CCU methods are consistent with the Paris Agreement, whose temperature limits imply halving CO2 emissions by 2030 and reaching CO2-neutrality by 2050. To carry out this assessment, the team used information on the CO2 emissions associated with the use of different CCU technologies and their current level of technological maturity.
They concluded that it is impossible for most CCU methods to sufficiently reduce industrial CO2 emissions in time. "Some technologies do not reduce CO2 emissions enough throughout their life cycle, and others will not be ready in time. There are only a few that are good enough for a carbon-neutral world," says co-author Heleen de Coninck.
Different utilisation routes
There are various routes for capturing and utilising CO2. For example, it can be captured from gases released during fossil fuel combustion in a power plant or a factory, but it can also be taken directly from the atmosphere or from the combustion of biomass. Subsequently, the CO2 can be used, for example in greenhouse cultivation, or it can be converted into products like a fuel. While CO2 is re-emitted when such fuels are combusted, the captured CO2 can also be used in materials that never return the CO2 to the atmosphere, such as certain building materials. "The idea here is that you produce products with reused CO2 instead of using virgin materials, which may result in a net reduction of emissions," says De Kleijne.
No long-term solution
"Our calculations show that some CCU methods can achieve the 2030 target, but many will run out of steam after that," says co-author Steef Hanssen. "The requirements get stricter after 2030 - total emissions reduced to zero, and we see that most CCU routes cannot achieve this long-term goal. By 2050, CCU has to meet at least two of these three criteria: the CO2 must be permanently stored in a product, the capture and conversion processes themselves are carbon-neutral, and the CO2 must come directly from the atmosphere or from sustainable forms of biomass."
"A great deal of innovation is necessary to further develop CCU methods that are fully carbon-neutral," says de Kleijne. "But money is still being spent on CCU methods that will come too late or inherently will not be able to reduce emissions enough to contribute to the Paris goals."
One Earth, de Kleijne et al., 'Limits to Paris compatibility of CO2 capture and utilization' DOI: 10.1016/j.oneear.2022.01.006
More information? Please contact
- Kiane de Kleijne, Kiane.deKleijne [at] ru.nl
- Radboud University Science Communication, media [at] ru.nl, +31 24 361 6000
- Kleijne, K. de (Kiane)