Harnessing forestry waste can drive down New Zealand’s coal dependency

Ever been into a commercial forest? The reality is that even though wood is a renewable product, essential to the modern way of life, generally the market dictates what is valued, and for forestry this means big logs. The remaining slash (branches, stumps and offcuts) is then considered a waste product.

Forestry company OneFortyOne believes that this wood waste is both a design and a market flaw, and is putting its collective minds towards finding useful applications for this wood fibre previously only viewed as a problem.

Mark Coghill, OneFortyOne Operations Manager, says the company has invested close to a million dollars into the biofuel project since late 2021. “The majority of the investment made has gone towards collecting, measuring and storing the wood fibre. Over the next five years we hope to reduce the amount of wood waste (or slash) in our forests by at least 75,000 tonnes. That’s enough wood to fill 2,000 logging trucks or cover 10 rugby pitches piled three metres high,” he explains.

In a recent breakthrough, the company has signed a new five-year agreement with Canterbury Woodchip Supplies which will see wood fibre previously left in the forest now turned into biofuel, a renewable resource which can displace environmentally damaging coal. The timing of this coincides with local company J.S. Ewers new biomass boiler upgrade, and some of the wood will be used in their new boiler.

With New Zealand committed to reaching net-zero carbon emissions by 2050, this development gives the Nelson Tasman area – where OneFortyOne manages its extensive forests – a path towards reducing its environmental footprint by choosing clean renewable fuel over environmentally damaging coal.

There’s plenty of headroom for this product, as OneFortyOne’s forests cover some 80,000 hectares in Nelson Tasman and Marlborough, with a harvest of more than 1.2 million cubic metres each year. Removing such a massive quantity of otherwise unvalued material from the forests and turning it into biofuel in the form of woodchips could help local businesses avoid burning more than 22 thousand tonnes of coal over five years, says Coghill, reducing carbon dioxide emissions by a whopping 50,000 tonnes.

With a good deal of New Zealand’s coal being imported, there is a multiplier effect achieved, by using a locally developed product as an effective coal substitute. Furthermore, as the forests from which the wood is removed are renewable resources – currently, OneFortyOne’s plantations are in their fourth rotation, being replanted with new seedlings after every harvest – the wood itself is a regenerating asset.

Coghill says slash is often regarded as a problem for the forestry industry generally, but notes that OneFortyOne decided to look at it as an opportunity instead. That led to talks with Canterbury Woodchips, a seasoned operator producing various processed wood products for use in parks, playgrounds, as animal bedding – and industrial boilers and other heating sources. Coghill notes ‘huge potential’ for the project if scaled up, adding that ‘it could be a game-changer for New Zealand in creating a sustainable source of bioenergy.’

Even as the ink dries on the contract with Canterbury Woodchips, Coghill says other avenues for turning trash into treasure are being explored. “We continually look for ways to improve slash management. Replacing fossil fuels with bioenergy alternatives can help meet emission targets and create new opportunities for the local economy,” he says.

As a result of that continued work and investment, another promising emerging use for slash is as feedstock for the production of biochar. This carbon-rich solid product is produced from the pyrolysis (heating in the absence of oxygen) of biomass residues. Biochar is agriculturally useful, as a supplement added into feedstock it can reduce the methane produced from cows, it can improve soil properties, while offering further potential by sequestering carbon and mitigating greenhouse gas emissions.

“As we look to the future and further innovation to help the environment, there is more wood fibre available and we are ready to work with other organisations to reduce the impact of slash, prevent climate damage, and create economic opportunities for the Top of the South region,” he says.

For more information, please email Kylie Reeves, OneFortyOne New Zealand’s Corporate Affairs Manager: kylie.reeves@onefortyone.co.nz