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The Wood Fibre Solution to the world’s Plastic Problem

The world needs a replacement for plastic. But where would we find such a material? Is wood the answer? Separating wood into its constituent parts could be the future for other weird and wonderful applications. Lee Williams looks into the potential of wood fibres.
wood-fibre

June 13, 2018

Plastic is a problem. There are almost two trillion kilos of waste plastic on the planet, much of which – more than seven billion kilos a year – goes into the oceans where it breaks down, poisoning fish and making its way into the food chain.

All the plastic ever made still exists somewhere on the planet, yet we are still making huge amounts – over 300 billion kilos a year. That’s a tower stretching to the moon and back 25 times from plastic bottles alone. If we continue plastic production at this rate there will be more plastic than fish in the oceans by 2050 according to the Ellen MacArthur Foundation. And to top it off, plastic is derived from fossil fuels, driving the demand for oil and thus contributing to global warming.

Clearly we need a replacement for plastic. But where would we find such a super-material? What properties would it need? And what would it look like?

How about a tree? It may sound weird, but many experts believe trees could provide a viable alternative to plastic in all its guises. One such believer is Finnish pulp and paper manufacturer Stora Enso. “Our philosophy is that everything that is currently fossil-fuel based can eventually be replaced by a tree,” says Markus Mannström, head of biomaterials at Stora Enso.

That wood can replace plastics in some applications is already clear. You only have to purchase something online or buy a hot drink or burger from the high street to see how plastic wrappers have given way to wood-based packaging. This trend is likely to continue in the near future with more plastic wrapping giving way to wood. Coffee cups may be paper now but the lid is still plastic, as is the polyethylene coating that stops the liquid seeping through. These are the next targets. “We’re working hard to find a substitute where that same barrier would come out of something bio-based,” says Mannström, “maybe even biodegradable.”

Another aim being commercialised is wood-plastic composites where wood fibres are combined with polymers and broken down into tiny granules suitable for injection moulding. The resulting material has the mouldability and performance of plastic with the look and feel of wood. Its applications range from decking and furniture to any general household product previously made from plastic, like toothbrushes, dish brushers and toys. “The benefit is that if we mix 50% wood into the raw material, then of course we have 50% less fossil-fuel-based materials,” says Mannström.

Plastic bottles made entirely from natural fibres may be a bit further away. Yet Coca Cola showed it was possible in 2015 with its prototype PlantBottle made from 100% natural fibres. Since then it has sold more than 50 billion PlantBottles containing 30% bioplastics. The main barrier going forward is the cost of scaling up the processes involved. “You have to think how huge the industry is today,” says Mannström. “If you come in with new process technology, it will require enormous investments in the short term. It’s going to come but I think we need to speed up technology development.” Even so, use of bioplastics for use in bottles and other applications will grow at least 50% in the next five years, according to the European Bioplastics Association.

Carbon fibre is another product based on fossil fuels which wood could replace. Already a team of Swedish researchers have created a miniature prototype electric car in which the roof and battery were made from a material called lignin. Lignin is a component of wood with a complex polymer structure which, when chemically treated and carbonised under high temperatures, has the same properties as carbon fibre. Lignin is found in nearly all plants found on dry land and is the second most abundant natural polymer in the world (after cellulose – another plant material). It is also one of the waste products of the paper-making process. This makes it an attractive alternative to carbon fibre from fossil fuels in an economic as well as sustainable sense.

“Why aren’t we using so much carbon fibre in cars or in airplanes?” explains Engelbert Schrapp a corporate account manager for Siemens in the fibre industry. “It’s simply because it’s too expensive. The Carbon fibre industry is more or less an oligopoly. There are very few suppliers who are responsible for 95% of the production globally, therefore it is quite artificial high pricing. Now think about a new player coming into the game who can produce carbon fibre from natural materials – the same product with the same strengths and one third or two thirds of the cost.”

Separating wood into its constituent parts could be the future for other weird and wonderful applications. By removing the lignin and separating the fibres from the resulting pulp, researchers have been able to do some remarkable things, like create transparent wood. This could find a role in the construction industry creating semi-transparent windows. It could also be used in solar panels and even to create flexible LEDs.

And if all of that isn’t enough, how about clothes made from wood? Wood fibres from the pulp industry can be used as a replacement for fossil-fuel-based synthetic materials as well as cotton, which has negative environmental impacts due to its large water consumption. “During the last five to ten years this has received a lot more attention,” says Mannström. “The cellulosic fibre-based textile market is close to six million tonnes of pulp annually, so it starts to be a sizeable business.”

The applications look promising. But when might this vision of a world without fossil-fuel-based materials become a reality? Mannström sees it as an evolutionary process. The first step is food packaging where he expects to see huge developments within the next ten years. Then comes wood-based carbon fibre. Mannström thinks we could see it in aeroplanes within 20 years. Other applications may be further away, according to Mannström but all of them have the potential to be realised.

More trees are a good thing but just how many trees would such a world require? Perhaps Sweden and Finland, with their large paper and pulp industries, provide an indication. Both Nordic countries have seen their tree populations double in the last hundred years.

But Mannström sees it more in terms of overall sustainability than a pure numbers game. “We have to make sure that the recycling streams that exist today become so efficient that we recycle our materials through seven, eight, nine cycles,” he says. “Of course we need a lot more trees. But combining recycling and renewability – that is the real key.”

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