Waste not

by Rebecca Macfie / 05 May, 2016
Forest residue could be turned into a vast renewable energy source.
Man on a mission: Christian Jirkowsky. Photo/Sam Brett
Man on a mission: Christian Jirkowsky. Photo/Sam Brett

This article is an excerpt from our May 7, 2016 special report on how our lives will change as the world heats up and we move to limit greenhouse gas emissions.

The huge new boiler house at Christ­church’s Burwood hospital is ­crawling with workers in high-vis gear in the final stages of commissioning the largest operation of its type in the country. In the midst of a labyrinth of pipes and ducting are two clean-burning wood combustion chambers that will produce all the heat and hot water needed for the hospital – energy previously supplied by two coal-fired boilers. Overseeing the project is mechanical engineer Christian Jirkowsky, a man on a mission to wean our industry off fossil fuels. Though this country can boast about its electricity being 80% renewable, often overlooked is the commercial heat and industrial processing sectors, which are heavily reliant on coal.

About 2.8 million tonnes of coal are burnt a year in New Zealand, of which about 54% goes to electricity and steel-making, with the rest going to such users as schools, rest homes, hospitals, milk-drying plants, meat works and timber kilns. Each tonne of coal burnt produces roughly two tonnes of CO2.

The replacement of Burwood hospital’s coal-fired boilers with the new wood-fired system will save 7000-10,000 tonnes a year of CO2 emissions, says Jirkowsky. When the plant swings into full operation in coming weeks, it will consume the branches, roots, bark and other residue from forests near the South Canterbury town of Geraldine – waste material that would otherwise be left on the ground after logging – which will be chipped on site and trucked to the hospital. The boilers can handle wood with moisture content of up to 60% – the chips are dried in the boiler before being gasified and combusted.

Jirkowsky estimates that 3.4 million tonnes of logging residue are going to waste each year in New Zealand plantation forests, a vast untapped renewable fuel stream that could do the job of coal. “You have the resources here,” he says.

Photo/Sam Brett
Photo/Sam Brett


Jirkowsky, a mechanical engineer, has 25 years’ experience as a renewable-energy specialist, including advising the Austrian Government. In 2011, he set up a New Zealand-based branch of Austrian company Polytechnik Biomass Energy. He says Austria has perfected wood-based energy systems over the past 50 years, with 800,000 households heated by wood-fired energy plants in that country alone. The Austrian wood-energy sector is worth NZ$2.3 billion and employs more than 14,000 people.

Jirkowsky has overseen the installation of 12 wood-fired boilers in Australasia over the past three years, including at Christchurch’s energy award-winning K&L Nurseries, and Zealandia Nurseries, where the systems heat vast glasshouses.

Ralph Sims.
Ralph Sims.

He laments New Zealand’s failure to make better use of its wood waste and sees the emergence of entire new suburbs in post-quake Christchurch that could have been heated by distributed wood-fired energy as a lost opportunity. And though the new Burwood hospital has gone with wood, the rebuild of the city’s main hospital will most likely include coal-fired boilers.

Jirkowsky blames the continued predominance of coal-fired boilers on a lack of awareness among consultants about wood energy systems, lax standards governing the likes of sulphur dioxide emissions and the failure of New Zealand’s emissions trading scheme to put a serious price on greenhouse gases.

Renewable energy specialist Ralph Sims, who led the Royal Society report on low-carbon options for New Zealand, says the availability of cheap coal in the south and cheap gas in the north has also blocked the uptake of wood energy.


Like former Green Party co-leader and Coal Action Network activist Jeanette Fitzsimons, Jirkowsky has been campaigning hard against Fonterra’s continued heavy use of coal. According to the latest Government data, the dairy industry as a whole is the country’s biggest industrial coal burner, and a third of Fonterra’s sites run coal-fired boilers (the other two-thirds use gas and biogas). The company is seeking consent for a massive expansion of its Studholme dairy factory near Waimate, with two coal-fired milk driers – although Fonterra says they will be capable of burning up to 20% wood biomass. However, as the Listener was going to print, the company indicated some of these details may change when it responds to a request from the resource consent hearings panel for further information in the coming week.

Robert Spurway.
Robert Spurway.

Robert Spurway, Fonterra’s managing director global operations, says the company wants to “transition away from coal” and is trialling renewables such as miscanthus – a tall grass with high biomass properties – geothermal, wind, solar, biogas and wood biomass. But he says there are “no viable alternatives” to coal in the South Island at present. The sheer volume of energy needed to dry milk into powder is such that shifting from coal to wood in its South Island plants would require “an area the size of Belgium” – about three million hectares – to be planted in trees, he claims.

Jirkowsky, by contrast, suggests the job could be done with just 30% of the wood residues that lie rotting on the ground after forests are felled.

Whoever is right, the Paris agreement means the days of burning coal are numbered. The European coal industry group, Euracoal, recognised as much when its secretary general predicted late last year that in the wake of the agreement, the sector would be “hated and vilified in the same way that slave traders were once hated and vilified”.

Read more: 

  Special climate report: New Zealand could buy time by planting trees – lots of them.
 Special climate report: Reducing demand for animal protein is crucial, but challenging for a country like New Zealand.
•  Environmental philosopher Dale Jamieson says to get action on climate change we must first understand human psychology.
 Rising seas will have profound effects on coastal towns and cities – and nowhere more so than Dunedin.
•  Transition to a Low-Carbon Economy for New Zealand”, Royal Society of New Zealand. 
 “New Zealand’s Low Emissions Future: Transformational Pathways to 2050”, Motu Economics. 
•  New Zealand Energy Scenarios: Navigating Energy Futures to 2050”, BusinessNZ Energy Council. 

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