CO2-derived plastics could reduce the greenhouse gas footprint of plastics under a clean energy grid scenario and reduce pressure on biomass resources, which will become increasingly in-demand as the world pivots towards a more circular economy, say plastic experts.

Demand for waste biomass such as used cooking oil, agricultural residues, and forestry residues is set to rise substantially in a greener economy, driven by the growing market for sustainable aviation fuel (SAF), and new uses in textiles, chemicals, and other materials, leading to a potential shortage of waste biomass for some sectors like bioplastics.

CO2-derived plastic technology could step into this gap, offering a low-carbon alternative to fossil-based plastic and alleviating pressure on biomass resources otherwise needed to produce bioplastics, according to research from Radboud University in the Netherlands.

The researchers undertook a a life cycle assessment (LCA) of the GHG footprint of CO2-derived polylactic-co-glycolic acid (PLGA), which can be used to substitute some of the most widely used plastic polymers, and found it could reduce the GHG footprint of plastics, particularly in a future energy grid scenario much cleaner than today’s.

Dutch startup Avantium’s Volta technology captures CO2 and uses it as a carbon source for the chemicals and plastics industry, producing carbon-negative PLGA that is degradable, home compostable, and recyclable, its website says.

The technology works by producing glycolic acid (GA) out of CO2 molecules, which is then copolymerized together with (biobased) lactic acid (LA) to obtain PLGA.

The captured CO2 can come from a variety of different sources including the flue gas of fossil fuel power plants and direct air capture (DAC), though the former could face the critique of prolonging the life of fossil fuel assets, said Sara Gonella, PhD candidate at Radboud University, and one of the study’s authors.

Avantium’s Volta technology is still at laboratory scale, however, while its other bio-based plastic technologies are at more advanced stages of development.

The researchers also found the PLGA produced by Volta technology to have better barrier properties than some other plastics like PET, including for uses as food film in multi-layer packaging, thereby reducing the overall amount of material needed.

It’s important to take a “holistic perspective” to tackling the plastic crisis, as focusing too much on one area such as bioplastics can lead to unwanted effects elsewhere in the value chain, Gonella told Carbon Pulse.

For example, even though scaling up bioplastics reduces fossil fuel dependency, it requires increased supply of biomass, which can have negative impacts on land use and the environment, she said.

PLASTIC IMPACT

Global plastics production doubled from 2000 to 2019 to reach 460 million tonnes, and by 2060 could as much as triple, mainly driven by economic growth, according to the OECD.

Plastics account for 3.4% of global greenhouse gas emissions, with estimates that this will double by 2060 under business as usual.

Just 9-10% of plastics today are recycled, with around 50% ending up in landfill, and the remainder either being leaked to the environment or incinerated.

The environmental impact is incredibly damaging, whether from the impact of microplastics on wildlife, which feeds into the food value chain, or from the CO2 emitted by the petrochemical industry.

Currently available options to reduce this impact including recycling, producing more durable plastic products, and biodegradable or bio-based plastic, often compete with one another and disrupt each other’s potential to be sustainable, said Gonella.

For example, “biodegradable plastic mixed with recyclable plastic generally hampers the overall quality”, while designing a durable plastic product often requires adding substances to the plastic that ultimately make it more difficult to recycle, she said.

“Probably the best solution is to adopt a different approach according to the application”, such as using biodegradable plastic in agriculture, she said.

Chemical recycling technologies offer a lot of potential as they break down plastics to their building blocks, meaning they can accept a plastic mix that is more varied and lower quality than mechanical recycling, said Delphine Largeteau, global sustainability consulting director for energies and chemicals at Schneider Electric.

However, chemical recycling is energy-intensive and so needs scaling up alongside clean energy supply, together with the right infrastructure to properly collect, sort, and segregate plastic according to its suitability for either mechanical or chemical recycling, she said.

The latest round of negotiations on the UN plastic treaty wrapped up at the end of April with shy steps forward on a draft text, due to be finalised by the end of the year, though observers levelled criticism over the lack of progress on production cuts and funding mechanisms.

Countries weighed the proposal of a target for 40% reduction for plastic production by 2040, but this faced strong opposition by petrochemical lobbyists, and a final agreement was not reached.

BIOMASS FOR BIOPLASTICS

Bioplastics offer an alternative to fossil fuel production, but pose the key risk of diverting land use away from agricultural production if first-generation (edible) biomass is used as a feedstock, and still potentially have adverse environmental effects even if second-generation (non-edible) biomass is used, said Largeteau.

“The increasing need for sustainable aviation fuel in future will also require a lot of the biomass residue being produced, meaning there could be a shortage for other industries like bioplastics,” she told Carbon Pulse.

Indeed, almost all of the estimated supply of used cooking oil and animal fat is forecast to be used for biofuel production alone by 2027, and even with a broader range of waste biomass feedstock, the biofuel industry is expected to absorb about 65% of supply, according to the IEA.

The aviation, road transport, bio-chemicals, and bio-gas sectors will increasingly compete for the same bio-feedstock, with demand rising across the board due to regulations in some sectors to blend a certain quantity of biofuel into the fuel mix.

In 2020, less than 0.05% of total jet fuel demand in the EU was supplied by SAF, meaning that a huge ramp up is required to meet the 6% blending target by 2030 under the bloc’s ReFuelEU legislation for all flights departing from EU airports, estimated to require about 2.3 Mt of SAF.

Currently, the maximum potential SAF production capacity in the EU is estimated at around 0.24 Mt, just 10% of the amount required to meet the proposed mandate by 2030, according to the EU Aviation Safety Agency (EASA).

Annual jet fuel demand is expected to exceed 400 million tonnes by 2030 and 500 mln tonnes by 2045, and “given airline companies lobbying power, they will put enormous pressure to have access to [biomass] feedstock” for SAF, said Schneider Electric.

Biofuels aren’t the only sector clamouring for a piece of the biomass pie, with the demand for bio-based textiles, chemicals and other materials also rising as the world transitions to net zero.

“Current climate scenarios risk over-reliance on biomass, claiming 40-100% more than will be available,” finds a report by the EU-funded Climate-KIC innovation centre and the Energy Transitions Commission, alongside others.

“Decision makers thus need to prioritise the uses with the highest economic and societal value”, the report notes.

As “expanding biomass supply is not automatically carbon neutral” and unless carefully managed, can lead to unwanted CO2 emissions from disrupting natural ecosystems that would thereby negate the net climate benefit of replacing fossil-based materials with bio-based materials, it adds.

Source: Climate-KIC

One potential framework to ensure the effective use of biomass is to ensure that resources are used primarily for human consumption, secondly as animal feed, and thirdly as feedstock for fuel or materials, though there are often competing views on how land and resources should be used and it’s a fraught political topic.

Globally, about 30% of cropland dedicated to cereals is used to grow livestock feed, which would be more resource-efficient if consumed directly by humans, and about 13% of cropland is used to produce biofuels and textiles.

The trend for bio-based materials is unlikely to slow down any time soon, given growing consumer demand for natural products and pressure on the petrochemical sector to scale back its impact.

Companies capitalising on this trend include Bcomp with its flax-based composite material that can substitute plastic parts, and Afyren that produces a bio-based carboxylic acid from biomass residue for use in a wide range of markets.

However, given that “biomass is a highly demanded resource, it is still valuable to explore the possibility of using carbon sources other than fossil fuels and biomass for plastics production,” said Gonella.

Using residual material and energy flows that were previously considered waste or surplus is key to delivering a more circular economy, including the capture and use of CO2 for the production of chemicals, cites this scientific paper.

Avantium was approached to comment but did not respond by the time this article went to print.

By Bryony Collins – bryony@carbon-pulse.com