plastic bottle waste

Net-zero CO2 plastic could be more affordable than expected

Image credit: DT

Researchers from the Institute for Technical Thermodynamics at RWTH Aachen University, Germany, have presented a sustainable model for plastics production and waste treatment which could achieve plastic production with net-zero greenhouse gas emissions at a much more feasible price point than expected.

The vast majority of plastics – one of the most ubiquitous human-made materials – use fossil fuels not only as feedstock but also to power their manufacture. The production of plastics currently accounts for 6 per cent of oil consumption. This is expected to rise to nearly 20 per cent by 2050. In order to meet climate targets in line with the Paris Agreement, the plastics industry must strive towards reducing its CO2 output to net zero.

Proposed strategies to cut carbon and other greenhouse gases in plastics manufacturing include decarbonisation of the plastics supply chain (such as using EVs for transport) and implementing circular technologies to reuse fossil carbon feedstock (such as chemical recycling, mechanical recycling, biomass, and carbon capture and utilisation).

While much research has focused on finding more sustainable building blocks for next-generation polymers, mitigating the greenhouse gas emissions over the lifetime of currently used plastics using circular technologies is perceived as energy-intensive and commercially unfeasible.

In a report published in Science, Raoul Meys and his colleagues have presented a bottom-up model for plastics production and waste treatment. The model – which is based on more than 400 technology datasets that represent the lifecycle of more than 90 per cent of plastics – allowed the researchers to lay out five different pathways for lifetime greenhouse gas emissions of plastics in the year 2050; the year by which the world must reach net-zero greenhouse gas emissions in order to maintain global warming within 1.5°C above pre-industrial levels and avert the most destructive impacts of climate change.

The models show that combining recycling, biomass utilisation and carbon capture and utilisation, net-zero emission plastics could be achieved with considerably lower energy demands and operational costs than those associated with current fossil fuel-based production technologies combined with carbon capture and storage. This would require an effective recycling rate of 70 per cent (at present, only nine per cent of plastic manufactured has been recycled) while saving 34 to 53 per cent of energy.

This pathway is feasible for the current varieties of currently monomers, meaning that net-zero plastic could be produced without depending on next-generation polymers.

According to the authors, realising the full cost-saving potential of $288bn would require a low-cost supply of renewable biomass and CO2, a high-cost supply of oil, and policies that incentivise large-scale recycling and lower investment barriers for technologies that use renewable carbon feedstock.

A recent study, also published in Science, found that current rates of plastic production, resulting in emissions into the environment, may be causing irreversible harm to the environment. In spite of growing consumer awareness of the environmental impacts of plastic waste, the quantity of single-use plastics produced annually is expected to grow by 30 per cent over the next five years, risking further damage to the marine environment as well as a rise in carbon emissions.

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