The PLA puzzle

Finding the most suitable final destination for packaging made from polylactic acid (PLA) can feel like trying to make your way out of a maze. A maze with more than one exit, and where the PLA players find it hard to agree on the right path to the finish.

Near to PLA’s roots in the US Mid-West is Eric Lombardi, who runs a recycling operation in Colorado and is also president of the GrassRoots Recycling Network (GRRN). He and a loose alliance of recycling groups have thrown down a challenge to Cargill-owned NatureWorks, which manufactures PLA in Nebraska: provide a viable end-of-life solution for PLA containers – specifically bottles – or impose a moratorium on new applications until you have one.

Most PLA bottles are difficult to distinguish from PET or HDPE. Where more sophisticated equipment is used, PLA can be separated from other polymers. The real issue, says Lombardi, is the additional cost this imposes on sorting and recycling organisations. As a residue, these PLA bottles are likely to end up in landfill, without the benefit of recovery in any form.

Earlier this year, NatureWorks said it was in “active discussions” with environmental groups about PLA’s final destination. The company also said it had not developed any new bottle applications for several months. In fact, as its latest newsletter informs us, Canadian brand +1 Water added one new application at the beginning of January.

But is this anything more than a local duel between NatureWorks, which Lombardi likes to call “the world’s largest private corporation”, and a disaffected materials recycling facility operator (and one which, by the way, could be thought to have vested commercial interests in traditional polymers)?

UK concerns

Well, it certainly looks a lot bigger than that, and the debate has come a lot closer to home. In March, a workshop run jointly by the Green Alliance, Wrap and the National Non-Foods Crop Centre highlighted similar concerns in the UK.

The consensus was that many applications of biodegradable and compostable polymers should be encouraged. But Green Alliance policy officer Hannah Hislop says: “There were concerns that bottles were not a desirable application for biodegradables, because they are indistinguishable from other polymers.” Nor do the potential problems end there. When Peter Skelton of Wrap’s retail innovation team outlines the pros and cons of PLA in particular, there are plenty of positives. These include high-clarity grades, and comparable cycle times and energy requirements to other polymers in converting operations.

But many performance limitations still remain. Skelton highlights the water vapour and oxygen transmission rates, its unsuitability for carbonates and the fact that it deforms at high temperatures.

At least one UK retailer has chosen not to give preference to PLA because of the risk of genetically modified maize content. This is despite the fact that, according to Wrap, only some 10% of consumers think this is an issue.

But even those retailers that have come out publicly in favour of PLA have no illusions about the difficulties it presents. Marks and Spencer, which uses the biopolymer for packs such as yoghurt pots, has admitted that PLA is technically very difficult. Its susceptibility to static and its brittleness are just two of the challenges it presents. And claims, such as the availability of effective peelable grades, are difficult to substantiate.

The question marks remaining over many of PLA’s performance criteria are reasons why those with access to the polymerisation technology have not invested in more production, the retailer suggests.

It has been estimated that M&S currently uses only around 2,000 tonnes of PLA a year, despite the prominence given to the material in its hierarchy of preferences. But even in small volumes, availability of supply can be a thorny issue.

Zain Okhai, managing director of film converter Rockwell Solutions, admits that having to rely on limited global supplies, and most of those still from a single supplier, causes real problems. While some material is becoming available in the Far East, there is no likelihood of European supply in the near future. (See Growing PLA in the UK below.)

End-of-life issues

Wrap’s long-awaited lifecycle analysis (LCA) for PLA was due for publication early in June this year. But an LCA carried out by Germany’s Institute for Energy and Environmental Research, which was commissioned by NatureWorks itself and published last year, came up with some interesting observations. Much of what the report said was positive. But end-of-life issues again loomed large. “Composting should not be the standard treatment for PLA packaging waste as it cannot be expected to provide the environmental benefits achievable by chemical recycling and energy recovery,” it said. Anaerobic digestion, it added, was another good option.

But wasn’t compostability supposed to be a – if not the – key benefit of biodegradables such as PLA? It is understandable that oil-based polymers, which have been used for decades, should only recently have started to work hard at recovery options. But isn’t it rather strange there should be so many concerns about the best final destination for materials so firmly rooted in the new millennium?

John Williams, technology transfer manager at the National Non-Food Crops Centre, is pragmatic about the level of final destination preparation done for PLA plastics. He says: “We are still in the early days with PLA. If you go back to the early 1950s when petrochemical plastics were coming on to the market then there would not have been an answer to questions about feed stock or waste management.”

Recoup, an authority on waste management for traditional plastics, says there is still work to be done on the processing of eco-polymers. “If there were more PLA packs in the supply chain, would the composting facilities be prepared to deal with it?” asks Stuart Foster, project manager at Recoup.

The effectiveness of the traditional plastics recycling system, which deals with one in five bottles used, could be compromised by the increasing use of PLA in packaging, he warns: “As the use of bioplastics increases, we feel there should be more research done to understand the impact on existing recycling and composting systems. There’s a need to make sure it doesn’t jeopardise what’s there already.”

As the current system stands, says Foster, PLA bottles are “unlikely to be removed because of the cost to the reprocessors.” At the moment, the amount of PLA in use remains at a safe level for reprocessors looking to reuse batches of plastic. But, says Foster: “If you speak to reprocessors, they really don’t want PLA in the bottle stream. If the amount rises, they might have to look at rejecting whole batches of waste plastic.”

Growing PLA in the UK

As some converters of PLA manufactured by NatureWorks report shortfalls of supply, UK users might have to look elsewhere for their PLA.

Farmers in the UK aren’t yet aware of the potential for their crops to be feedstock for polymers as well as feedstock for humans or animals, according to the National Union of Farmers. The Home Grown Cereals Authority (HGCA) has done more research into the potential packaging applications for UK-grown crops. Mairi Black, industrial uses product manager, says that the HGCA has been working with Green Light Products to develop a wheat-based alternative to polystyrene block packaging.

The success of their work shows that high-volume production of eco-friendly materials is possible in the UK. Green Light Packaging’s product has taken one-third of the market for loosefill packaging since its design.

The HGCA also has an R&D contract with the Department of Trade and Industry’s Technology Programme, led by Brunel University, into eco-composites based on renewable materials, due to be completed in December 2007.

Black says there isn’t the same level of financial incentive to develop PLA production in the UK as there was in the US, where it was a good solution for excesses of cheap corn.

John Williams from the National Non-Food Crops Centre says that the UK public might have ethical concerns about using wheat or corn, that could be food, to produce packaging materials. But he says around 45% of crops produced in Europe already go in to non-food applications and that there is suitable waste produced from corn or wheat plants after the food parts have been removed: “The technology is coming along to produce products out of this waste. If you use the agricultural feedstock effectively then there should be enough in the supply chain to meet both food and other needs.”

Williams’ concerns about producing PLA in Europe regards the intellectual property rights. It is likely any producer keen to manufacture PLA in the UK would have to licence the technology from NatureWorks, says Williams. “My personal view is that this will change,” he says. “Someone or other will find another way of doing it and then NatureWorks won’t control the supply chain.”

There are other eco-polymers already in production in the UK. Innovia supplies Nautreflex, a cellulose film, to the global market from its manufacturing site in Wigton, Cumbria. “PLA is the one people talk about, because it was the first on the commodity market to be produced in any reasonable volume,” says Williams, but with products like NatureFlex already produced in large quantities from renewable resources in the UK, it may be time to look at alternative eco-polymers.