By Guest Author 26/07/2019

Elspeth MacRae

If you could name the packaging material that is close to being public enemy number one at the moment – it would have to be plastic.

We’ve all seen the tragic images of marine life entangled in plastic – the dead whales with stomachs of plastic, the list goes on. As a result of this continuous exposure to images of plastic damaging marine life, consumers are rightly concerned. We know plastic is bad, but, there is a great deal of confusion about what alternatives there are, and where we are headed.

I see the main issue with current plastics – which are derived from petroleum – is that they damage the environment because they don’t degrade in the same way as historical packaging (such as paper, leaves, baskets from plant materials and untreated leathers).

Our current plastics, as many people know, take hundreds of years to break down and do so by breaking in to smaller and smaller pieces, known as microplastics. These microplastics infiltrate all parts of our environment – which became clear in a study we published earlier this month that found plastic microparticles on 29 Auckland beaches and waterways.

So – what’s the answer? Can we produce packaging that isn’t going to profoundly damage the environment? The answer may lie with bioplastics.

Unlike conventional plastics that are made from petroleum, bioplastics are made from plants or other biological material. But it’s worth having a good look at the different types – as some have greener credentials than others.

The most well-known bioplastic is made by extracting sugar from plants like corn to convert into polylactic acids (PLAs). PLA plastic is mostly used in food packaging, plastic bottles, utensils, and textiles. We already have this type of packaging in New Zealand – that’s what the so-called compostable coffee cup is made of.

But PLA plastic doesn’t solve all the environmental problems associated with plastic. Unfortunately, PLA plastic won’t reliably biodegrade in home composts, and if it ends up in the ocean, it won’t biodegrade and will float around until it breaks into tiny pieces similar to petroleum-based plastics. Instead, it needs to go to an industrial composter running at temperatures of at least 60C in order for microbes to work on the plastic. In New Zealand, the main problem is that we don’t have adequate infrastructure (i.e. enough industrial composts) set up to process the amount of PLA plastic we use.

At Scion, we are working on innovative ways to move industry away from a reliance on PLA. For example, we created PLA based clips for vineyard nets.

Our winemakers use millions of plastic clips every year to secure the vineyard nets that protect the ripening grapes from birds. These are typically made from polystyrene and end up scattered on the ground after use. We’ve developed an alternative type of bio clip from a mix of PLA and bio waste – in this case, red grape pomace – a waste by-product from wine making. Unlike the current plastic clips, after use, these bio clips biodegrade where they fall.

We’ve also been working on another type of bioplastic called polyhydroxyalkanoate (PHA) which is a sound alternative to fossil fuel-derived plastics. (Not to be confused with PLA – and apologies for the potential acronym fatigue!) PHA plastic is made by bacteria feeding on plant material – including waste – which is pretty incredible when you think about it. These microbes store the plastic to use it as energy, like we store glycogen or plants store starch. The promising thing about PHA plastics is that they are biodegradable, both in industrial composts and in the soil, freshwater and seawater.

Essentially, they biodegrade into carbon dioxide and water, which plants use to make sugars which can then be fed back into being the source material for microbes to make more PHA.

Globally, PHAs can be found in packaging, food service, agriculture and medical products. They are being used in both low value, high volume markets – such as compost bin liners – and high value markets – such as absorbable surgical film. At Scion, we are working on various aspects of PHA plastics. There are many different ways you can change this form of bioplastic to give different properties for a final plastic.

I think New Zealand has a real opportunity here. We could manufacture PHA here and be able to control the whole lifetime of the plastic.  Given this plastic’s biodegradable credentials, I think it fits well with the country’s ‘clean, green’ export image. We just need investment and backing to make it happen.

At the moment, there is a sizeable initial development overhead for pilot scale manufacturing facilities, yet this is a real growth market and the rewards could be significant. This kind of facility would allow industry to try out possible new bioplastic products to replace those currently made from petroleum.

Let’s seize the opportunity, New Zealand!

Elspeth MacRae is the Chief Innovation & Science Officer at the New Zealand Forest Research Institute (Scion), the Crown Research Institute for forestry, wood and biomaterial products. 

0 Responses to “Bioplastics – a major opportunity for New Zealand”

  • “As a result of this continuous exposure to images of plastic damaging marine life, consumers are rightly concerned.”

    Why should it only be consumers that should be concerned? It’s the authorities’ business to implement sensible policies.

  • This sounds awesome, I 3D print decoys in PLA and would really like to work with a plastic that melts at a higher temperature but will biodegrade. Would happily pay 3x the price.