Scientists from Stanford University have found a way to use carbon dioxide and plant waste to make plastic. Their discovery could provide a low-carbon alternative to plastic bottles.
Many of today’s plastic products are made from polyethylene terephthalate (PET). Around 50 million tonnes of PET are produced worldwide each year and used in items such as fabrics, electronics, beverage containers and personal-care products.
But PET has a heavy environmental footprint: its two components are derived from petroleum and natural gas, and manufacturing PET releases significant amounts of CO2 into the atmosphere.
“The use of fossil-fuel feedstocks, combined with the energy required to manufacture PET, generates more than four tonnes of CO2 for every ton of PET that’s produced,” Matthew Kanan of Stanford University said in a press release.
Together with colleagues, he set out to replace petroleum-derived products with plastic made from CO2. “If you could do that without using a lot of non-renewable energy, you could dramatically lower the carbon footprint of the plastics industry.”
To accomplish this, his team set its sights on polyethylene furandicarboxylate (PEF), which is made from ethylene glycol and a compound called FDCA, which can be sourced from biomass instead of petroleum.
But despite its promise as a PET alternative, PEF is expensive to manufacture at scale because of the difficulties in producing FDCA in a sustainable manner. Some researchers have tried to convert fructose from corn syrup into FDCA, but fructose production has a substantial carbon footprint. It also requires a lot of land and water, which would compete with food production.
The Stanford team decided to experiment with furfural, a compound made from agricultural waste that has been widely used for decades in resins and solvents.
Their results were successful: after just five hours at an extremely high temperature, they were able to turn nearly 90 per cent of their CO2 and agriculture waste mixture into FDCA by adding carbonate to it.
As Kanan explains, their approach could significantly reduce greenhouse gas emissions because the CO2 required to make PEF could be obtained from fossil-fuel power plant emissions or other industrial sites. And products made of PEF can be recycled or converted back to atmospheric CO2 by incineration.
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