Plastics under fire

The take-away

  • Contrary to popular belief, many bioplastics are not biodegradable and must be incinerated, buried or recycled – just like conventional plastic.
  • Discarded fishing nets and ropes can either be used as construction material in reinforced concrete or as raw material for new products.

Our love affair with plastics appears to be on the rocks: plastic waste is being condemned from all sides, some countries have banned plastic bags, supermarkets have launched plastic-free aisles and the European Commission has proposed measures to slash plastic use.

The possibility of banning single-use products like straws or picnic cutlery may prompt some to ask, “Are we living at the end of the plastic era?” Or is it more a matter of rethinking our century-plus relationship with plastic? As Jyrki Katainen, one of the Commission’s vice-presidents puts it: “Plastic can be fantastic, but we need to use it more responsibly.”

Plastics are seriously useful materials. Their lightness, low cost, strength, and ability to be shaped into any form imaginable have influenced our lives, allowing innovations from war-time aircraft plexiglass to today’s affordable computing. Production has leapt from 15 million metric tonnes in 1964 to 311 million metric tonnes in 2014. And there’s no end to the trend, with McKinsey & Company consultants predicting production to double by 2036. However, petrol-based plastics (petroplastics) come with serious negative environmental impacts, and the development of organic alternatives – bioplastics – is generally considered a positive step. But the reality is not so simple.

One downside of bioplastics is that their production can compete with food supply since crops like corn and sugar beets largely provide the raw inputs. Many bioplastics are not biodegradable and, like petroplastics, must be incinerated, buried or recycled. Also, environmentally conscious consumers can easily become confused: some bioplastic waste is compostable at home, some is biodegradable only in recycling plants, and some is non-biodegradable. Moreover, frustratingly, most bioplastics can be broken down only if separated from other plastics.

Coming full circle

Ironically, the world’s first plastic, created in 1869, had organic origins: cellulose derived from cotton. But the 1907 arrival of Bakelite, the first petroplastic, trumped this with its suitability for mass production. Now a plethora of new bioplastics are under development or already on the market, ranging from high-profile pilots like Lego’s sugarcane ethanol-based building blocks to the joint Portuguese-Irish Seabioplas pilot, which is looking to scale production of bioplastics from sustainable seaweed. Ikea is even planning to use fungus-based biodegradable packaging as an alternative to polystyrene.

While recyclable PET plastics, like Coca Cola’s partially bio-sourced plantbottle, top the bioplastic industry at a quarter of all production, the sheer volume of new plastics being developed and groomed for commercial production is set to make it anyone’s game.

Jeremy Luterbacher of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, heads a team of researchers attacking the issue of fossil fuels by transforming lignin, a bulky, largely-unusable component of wood and other rigid plant material, into molecules for biofuels or bioplastics.

Despite making up almost a third of all biomass, this complex polymer is normally destroyed during biofuel processing and burnt for energy. But Luterbacher’s team found that adding formaldehyde allows 80% of the lignin to be extracted as substitute building blocks for plastic.

While the process is now being scaled up for production, the first lignin products won’t be conventional plastics but high-value pharmaceutical and flavour intermediates. “Petroplastics is a highly optimised industry after 150 years, so it’s very hard for new technologies to compete,” says Luterbacher. “But we hope we can build the process for high-value products, financially de-risk the technology and then become competitive in the bulk plastic industry.”


Closing the loop

Even as bioplastics producers strive to become financially competitive and bioplastics carve out a pioneering market – about 1% of all plastic – there is pressure to use petroplastics more responsibly. The EU-funded Circular Ocean project is tackling this challenge in Europe’s waters.

The project looks to turn discarded fishing nets and ropes in the region between Europe and the Arctic from a hazard into a valuable economic opportunity and a source of plastic materials. An estimated 640,000 tonnes of fishing gear go missing every year, whether lost or dumped, and disposing of waste like fishing nets is difficult and costly for many small, remote communities in the region, where sophisticated recycling infrastructure is often lacking.

Ida Bertelsen coordinates the efforts of Artek DTU Civil Engineering, a project partner of the Technical University of Denmark, in reusing disposed nets or even ghost nets in construction materials. “One successful approach has been shredding the nets into plastic fibres, which are then included in reinforced concrete,” said Bertelsen. “This reduces the number of cracks forming in the concrete and thus prevents water from entering and corroding its steel reinforcement.”

But even this approach is problematic. The EU’s strategic goals for plastics in a circular economy essentially require that plastics be kept in circulation, with products never becoming waste but instead being turned into new resources in biological and technical loops at the end of one lifecycle. The reuse in concrete reinforcement means the plastic fibre cannot be used again because no one yet knows how to re-extract fibres from end-of-life concrete.

The pan-European PlastiCircle project, on the other hand, plans to reduce plastic waste before it can get anywhere near the ocean. By using smart waste containers for better waste separation, data-optimised waste collection, high-tech waste sorting, and plastic upcycling, it hopes to boost the amount of pure, sorted plastic collected and redirect it into the economy.

The long transition

Circular Ocean’s concrete-use case could still be important as virgin petroplastic is used as fibres in concrete reinforcement worldwide. Not having to pay for virgin plastic could provide motivation to reuse nets in remote communities with limited recycling infrastructure.

As a mainland alternative, DTU’s Danish industrial partner Plastix can recycle the nets into high-quality raw plastic for new plastic products, cutting CO2 emissions, marine pollution, landfilling and resource loss. If such value can provide an incentive to stop nets being lost or dumped in the ocean, this is an important step towards a technical circular economy loop.

And biological circularity? The VTT Technical Research Centre of Finland, a winner of the 2018 Circular Materials Challenge, has created a multi-layer plastic suitable for food packaging that is made from agriculture and forestry by-products – and is compostable.

Back at EPFL, Luterbacher says they are not yet working on making lignin bioplastics biodegradable. It’s possible but adds extra challenges. He argues that competing directly with the fossil fuel-based market should be the first priority within an overall plastics transition. Next to this, learning how to best collect, sort, and recycle non-biodegradables in a circular loop would aid our ability to successfully transition to biodegradable plastics.

“We’re in the transition already and if we have a signal like a global carbon price, that will pick up rapidly,” says Luterbacher. “The desire to replace petroplastics is there, and the technology is almost there. No matter how quickly it starts, the shift will be gradual, with the low-hanging changes occurring rapidly and bioplastics popping up everywhere. A full transition to renewable plastic could take up to a century.