Going full circle – Tamahere Forum

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By Gord Stewart

We’re addicted to fossil fuels and we’ve long enjoyed the convenience of plastics. They’re part of our ‘take-make-waste’ economy, more formally known as the ‘linear’ economy. This way of living has helped to bring on our current climate crisis. And it has led to a world where, we’re told, there will be more plastic than fish in the ocean by 2050.

But a u-turn is still possible. Leading scientists, businesses and policymakers are showing the way to a ‘circular’ economy – or better yet a circular bio-economy. ‘Borrow, use, return’ it is, which nicely differentiates it from the traditional way of doing things.

Researchers at Scion, one of the country’s crown research institutes, are hard at work on this. In the orchard, in the vineyard and out in the forest, they are finding materials normally discarded in production that can be put to very good use. Here are just a few examples.

Cut, scoop and compost

Zespri’s signature ‘spife’ (spoon-knife) is included in boxes of kiwifruit shipped to happy customers around the world. Spifes have traditionally been made of polystyrene (a petroleum-based plastic).

Zespri’s spife, made from recycling kiwifruit skins [Photo: Scion]

Scion researchers found a way to use kiwifruit skins leftover from pureeing in a process they call ‘masterbatching’ (eliminating the need for polystyrene). The resulting concentrated kiwifruit mixture is added to a compostable bioplastic before being injected into the spife moulds. Voilà, the biospife!

Christchurch-based Alto Packaging was the production partner for this innovation. The biospife has the required mechanical properties and meets food safety standards. Zespri appreciates its inherent sustainability features and its organic look, clearly different than the old polystyrene spife.

Kiwifruit skins are normally sold as animal feed or composted directly, so the biospife was a great way to put them to a higher-value use.

Clip and go

Birds are not a winemaker’s best friend. For six to eight weeks each season, vineyards around the country are covered with netting to protect ripening grapes from the feathered ones. Until recently the nets were held in place by polystyrene clips. When the nets are removed, the clips break, fall to the ground and stick around as micro-plastic pollution. Not so bad if it’s just a few, but not good when it’s over 15 million of them a year.   

The bio-degradable vine net clip [Photo: Scion]

Scion helped put an end to it. Scientists there first looked at using pomace – a material in the seeds and skin of grapes and a waste by-product in winemaking – to produce an alternative-to-plastic vine net clip. Pomace was considered for its strength and because it would increase the speed at which the clips break down in soil.

Another Christchurch-based manufacturer, EPL, was brought on to explore ways to improve the clip and ready it for production at scale. Other biodegradable materials were subsequently found to perform better than pomace (science works like that sometimes – start down one path, move on to a better one). The finished clips have been sent to vineyards around the country for real-life testing.  

Recognised for their efforts, the Scion-EPL partnership won the 2020 Sustainable Business Awards ‘Outstanding Collaboration Award’.      

Peel, make and burn

Bark has been called the tree’s ‘suit of armour’. Compounds in bark that help protect and keep trees healthy are known to include valuable biochemicals offering antioxidant, antibacterial and waterproofing properties. These and other applications are now under close study in the Bark Biorefinery Project, a five-year Scion-led and Ministry of Business, Innovation and Employment (MBIE) funded research programme.

One product in a pine bark extraction trial, carried out with Nelson-based Pharmalink, is a mixture of soft, natural waxes much like petroleum-derived paraffin. Scion is working to separate and purify these natural waxes. Possible uses include waterproof or water-repellent surface coatings and as a moisturiser in cosmetics and skin care products.

There are further investigations into bark-derived water-repelling materials as a sustainable alternative to petroleum-based ones used in the likes of paper coffee cups, rainwear and touchscreen coatings. Another avenue of study is the extraction of natural tannins to treat leather. Success here would mean chromium, which is toxic to humans and to the environment, could be eliminated from the process.

Once the good stuff is recovered from bark and gone on to greater glory, the residue can be processed into ‘bio-coal’ briquettes. This renewable fuel source could replace coal in boilers for industrial process heat (CO2 emissions from burning bio-coal is about 2 percent of that of coal). Along with bark, other source materials include waste products from sawmilling, papermaking and other wood processing operations.

Scion researchers are perfecting heat and pressure combinations to transform all this wood waste into what is a high-energy, high-density fuel (close to that of sub-bituminous coal). The briquettes are durable, moisture resistant and handle like coal. Their use would cut into the one million tonnes of coal burned around the country every year, an amount which leads to some two million tonnes of greenhouse gas emissions.

“Effective use of renewable materials is a crucial part of the circular bioeconomy,” says Dr Florian Graichen, General Manager, Forests to Biobased Products at Scion. “It’s all part of a critical transition needed to meet the Government’s goals for an environmentally and economically sustainable future New Zealand.”

  • Gord Stewart is a sustainability consultant with a background in environmental management and economics.

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