Plastics, proteins and plants key to reaching net-zero emissions

Electricity, transport, and heating together account for 80 per cent of greenhouse gas emissions, and are the priority for governments and businesses working to cut carbon emissions in line with their Paris Agreement obligations. However, reaching net-zero emissions also requires efforts directed at the remaining emissions.

The 'Final 25 per cent' of emissions refers to the remaining 20 per cent of emissions contributed by sectors such as agriculture, cement, waste, and plastics, in addition to the extraction of at least 5 per cent equivalent from the atmosphere to account for unavoidable emissions. These emitters come from a wide range of greenhouse gas emitters, making them trickier targets than, for instance, large centralised power stations.

Oxford’s Smith School of Enterprise and the Environment has published findings from its 'Final 25 per cent' project, which calls on experts to lay out roadmaps of investment in pursuit of net-zero emissions. These plans are contained in three reports which cover: use of polymers, nature-based solutions for carbon removal, and alternative proteins.

“The Final 25 per cent emissions identified in our three reports must be tackled if we are to achieve net-zero,” said Professor Cameron Hepburn, director of the business school. “Reducing or eliminating them is going to mean some real changes, though, and significant investment is needed in R&D to make sure these can happen. We can do this and the novel and imaginative solutions contained in these reports could get us there.”

One report highlights that the need for petrochemical-based materials – including not only plastics but also asphalt, pharmaceuticals, solvents, fertilisers, and lubricants – will not disappear anytime soon as they are indispensable in modern economies. Therefore, it says, new approaches are needed to manufacture sustainable plastics. It recommends using alternative sustainable feedstocks as an alternative to crude oil, such as captured carbon and biomass, increasing historically low recycling rates, and implementing policies which force sustainable polymer production to increase over time.

Another report examines the climate impact of proteins and notes that demand for animal products is on the rise; the contribution of these products to overall emissions is expected to grow from 16 per cent to 35 per cent by 2050. It recommends accelerating alternative sources of protein, including plant-based proteins, insects, mycoproteins (e.g. Quorn meat substitutes), algae, bacteria-derived protein, and cultured meat. These alternative proteins would not only aid decarbonisation efforts, they would also allow grazing land to be restored to support natural greenhouse gas removal.

The third report, which examines natural CO₂ sinks and sources of carbon feedstocks, calls for further research into how semi-arid and saline land could be treated to grow crops. It repeats calls for grazing land to be repurposed for reforestation, and suggests increasing soil carbon to provide a further carbon sink and potentially increase crop yields.

Leading report author Dr Katherine Collett commented: “Mitigating climate change demands more than a shift to renewable electricity generation; investment in harder-to-abate sectors is already required. To reach net-zero, intersections between plastics, proteins and plants – three seemingly unconnected systems – may hold the key. Our reports explore the potential of these systems in detail, pointing the way forward for research, policy development, regulation, and financing options.”

Brian O’Callaghan, another report author, added: “In the shadow of Covid-19, government investment in green innovation can both help to constrain climate change and seed new industries to stand as powerhouses of economic growth in the long-term […] the US invested big in renewable energy research and development during the global financial crisis. That investment has delivered many multiples. Governments could make similar progress in agriculture and industry today.”