Towards a bark biorefinery

27 September 2018

There is huge potential for converting bark into value-added products including water-repelling polymers, green chemicals and biofuel.

Around 2.3 million tonnes of bark is produced annually by the New Zealand forestry industry. Pine bark is a rich source of polyphenols, polysaccharides, terpene and resin acids that each have unique functional and structural properties.

Developing methods that can extract and refine these high value chemicals and other products using green chemistry and sustainable technologies in a ‘Bark Biorefinery’ is at the heart of a five year Scion research programme supported by the Endeavour Fund.

The bark biorefinery promises to deliver significant quantities of water-repelling (hydrophobic) polymers. Hydrophobic polymers are used in items from paper coffee cups and rainwear to touch screen coatings. The market is dominated by petrochemical-based polymers but bio-based hydrophobic polymers are part of a rapidly growing market niche.

The Scion research team plans to a combination of extraction techniques to yield high value products, as well as a hot water treatment to extract tannins. The remaining solid waste with its high residual lignin content could be processed into bark briquettes, for example, and used as a renewable biofuel.

Available bark volumes will increase due to a ban on methyl bromide use from 2020 onwards which will mean only de-barked logs are able to be exported. Bark biorefinery technology provides a new economic opportunity to convert a waste stream into a range of high value materials that will earn an estimated value of $400-600 million per annum, contribute $1.8 billion to New Zealand’s GDP, and add several thousand new jobs by 2050.