Waste carbon dioxide from burning fossil fuels could be used to make valuable products such as plastics, fuels and cement, suggests new research.

If done correctly, using waste carbon dioxide (CO₂) to make useful products would also help offset the costs of mitigating climate change, argue scientists in a review published today in Nature.

To avoid adding to carbon to the atmosphere, these pathways should use atmospheric CO2 as their raw material. Dr Niall Mac Dowell

The authors of the study, led by the University of Oxford and including Imperial College London researchers, looked at the potential uses for CO₂ captured from the burning of fossil fuels or drawn from the atmosphere, or even captured biologically by photosynthesis.

They looked at ten ‘utilisation pathways’ for this CO₂, including using it in fuels, chemicals, plastics, building materials, soil management and forestry. For example, CO₂ could be used to replace petroleum during the manufacture of materials like plastics or cement, or it could be used to enhance crop yields in agriculture.

These pathways could store waste CO₂ by locking it away in products, or replace the use of fossil fuels to power processes, leading to fewer emissions in the first place.

Keeping global warming to 1.5 degrees

According to the Intergovernmental Panel on Climate Change, keeping global warming to 1.5 degrees and avoid catastrophic climate change will require the removal of CO₂ from the atmosphere on the order of 100–1000 gigatonnes (billion tonnes) of CO₂ over the 21st century. Currently, fossil CO₂ emissions continue to grow by over one percent annually and reached a record high of 37 gigatonnes of CO₂ in 2018. 

The promise of CO2 utilisation is that it could act as an incentive for CO2 removal and could reduce emissions by displacing fossil fuels. Professor Cameron Hepburn

The new research found that on average each utilisation pathway could store or remove around 0.5 gigatonnes of CO₂ per year, and that a top-end scenario could see well over 10 gigatonnes of CO₂ used per year at theoretical costs of under $100 per tonne of CO₂.

However, the researchers also cautioned that significant investment in both research and industry was needed for the pathways to reach a sufficient scale in time to help fix the climate.

Professor Cameron Hepburn, Director of the Oxford Smith School of Enterprise and Environment, said: “Greenhouse gas removal is essential to achieve net zero carbon emissions and stabilise the climate. We haven’t reduced our emissions fast enough, so now we also need to start pulling CO₂ out of the atmosphere.

“Governments and corporations are moving on this, but not quickly enough. The promise of CO₂ utilisation is that it could act as an incentive for CO₂ removal and could reduce emissions by displacing fossil fuels.”

Scaling up successfully

The various utilisation pathways also require consideration of the industries they sit within, to ensure that scaling up the industry would not add to CO₂ emissions.

Dr Niall Mac Dowell, Reader in Energy Systems at Imperial College London, said: “If CO₂ utilisation is to contribute meaningfully to climate change mitigation, the first and foremost priority is to decarbonise the energy system within which these industries will be located. To avoid adding to carbon to the atmosphere, these pathways should use atmospheric CO₂ as their raw material.”

Some CO₂ utilisation technologies are likely to be adopted early simply because of their attractive business models:  in certain kinds of plastic production, using waste CO₂ as a raw material is a more profitable and environmentally cleaner production process compared with using conventional hydrocarbons, and can displace up to three times as much CO₂ as it uses. 

In other areas, utilisation could provide a ‘better choice’ alternative during the global decarbonisation process. One such pathway is the use of CO₂-derived fuels, which could potentially find a role in sectors that are harder to decarbonize, such as aviation.

No magic bullet

The authors stressed that there was no ‘magic bullet’ approach or perfect pathway. Professor Hepburn explained: “Each faces their own unique challenges and not all methods will be effective. That means that we need sensible and joined-up approaches to investment in carbon capture, utilisation and storage.

“Policymakers need to think like investors and fund a portfolio of options. That also means taking a hard look not only at regulatory barriers and incentives, but also into R&D investment for enabling technologies like green hydrogen.”

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‘The technological and economic prospects for CO2 utilization and removal’ by Cameron Hepburn, Ella Adlen, John Beddington, Emily A. Carter, Sabine Fuss, Niall Mac Dowell, Jan C. Minx, Pete Smith, and Charlotte K. Williams is published in Nature.

Based on a press release by the University of Oxford.