Wood-based biomass beating climate change

Wood-based biomass beating climate change
 November 2021   

Wood-based biomass is now recognised as a vital resource to mitigate climate change. And the mainstream media is at last becoming aware of forestry as a sustainable energy resource. But it’s taken the likes of New Zealand’s mega business, Fonterra, to make media headlines.

Earlier this year Fonterra announced the establishment of an 11,000kW (11MW) wood chip boiler for its Stirling dairy processing plant in South Otago. The company has been tinkering with replacing coal-fired boilers over the past few years, but had originally been concerned with consistency of supply. Dairy units, fibreboard plants, paper mills and garden centres, all compete for available pulp and low grade logs, which is still worth more in export values.

Further down the road near Balclutha, the French-owned Danone milk treatment plant is also soon to commission a similar sized Veolia chip boiler.

This is all going to take considerable volumes of forest harvest residue available within Otago/Southland forests. Tree planting, however, is supposed to be ramping up due to current government policy to cut greenhouse gases under New Zealand’s commitment to the Intergovernmental Panel on Climate Change (IPCC) and recommendations of the Climate Change Commission.

The Fonterra boiler is to be installed by Polytechnik Biomass Energy which is in the process of installing, five boilers – three for the Ministry of Health Christchurch Hospital steam boilers, one for Wood Engineering Technology in Gisborne, as well as Stirling.

Polytechnik’s General Manager, Christian Jirkowsky, explains that the total thermal output of all those biomass boilers would be around 50MW (50,000kW). 

“In using over 100,000 tonnes of forest residues, thereby replacing global warming fossil fuel, those boilers will reduce   emissions by 75,000 tonnes every year –equivalent to taking about 30,000 to 40,000 cars off the road,” he figures.

Throughout the country there has been a steady increase in installation of wood chip boilers which has taken place with little attention from the mainstream media. Instead, hitting the headlines for climate change have been electric vehicles and shiny metal structures such as wind turbines, green hydrogen plants and acres of photovoltaic solar energy plants requiring high   emissions to produce the materials.

Currently on the market are a variety of biomass boilers ranging from under 1000kW to 40,000kW output. Within the mix of conversions from fossil fuels are tertiary institutions, schools, universities, public utilities, aqua centres and a variety of commercial businesses. But the elephant in the room has recently been electricity supply, having to import coal partly due to drought conditions, demand through an increasing population, infrastructure and housing development. Which begs the question: Why are some dams spilling water while Huntly Power Station is under pressure to increase supply with increasing tonnage of coal imports? However it is understood that development of other forms of biomass conversion could solve the problem in the longer term. Water turns the turbines. So does steam from burning wood and other low emission materials, which can drive generators. One kilojoule of wood burnt in boilers emits only a little over 2kg compared with coal which emits...

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