A look inside a combustion chamber, where the wood is burnt at 900 degrees. Photo: RNZ/ Niva Chittock
A new boiler system has cut Christchurch Hospital's carbon emissions by more than 50 percent, Te Whatu Ora Waitaha says.
In 2021, the health sector was identified as the largest emitter of carbon emissions in the public sector.
Globally, health made up five percent of total emissions.
The new Christchurch Hospital boilers run off woody biomass, such as wood chips and forestry slash.
It is burned at 900 degrees to create steam that is converted into heating.
Te Whatu Ora Waitaha and Te Tai Poutini executive director infrastructure Dr Rob Ojala said the old coal boilers were the hospital's single biggest source of emissions.
"From a carbon emissions point of view, this takes around 7200 vehicles off the road, in terms of equivalent carbon dioxide emissions. So it's a substantial change," he said.
The wood chips being sent into a boiler. Photo: RNZ/ Niva Chittock
The new system cost $45 million, and replaced the diesel boiler system damaged in the Canterbury earthquake.
It was mostly paid out of the hospital's earthquake insurance settlement fund, Ojala said.
The boilers were saving the hospital millions of dollars per year in running costs, he said, but could not give an exact figure due to commercial sensitivities.
The system began operating last month and supplies hot water heating and steam sterilisation to the hospital via underground pipes.
The pipes run under Tuam Street to deliver the steam across to Christchurch Hospital. Photo: RNZ/ Niva Chittock
A Canterbury public health physician Dr Anna Stevenson said it was also likely to benefit people's health.
Poor air quality has been known to cause higher than normal levels of respiratory illness in the region, she said.
"Air pollution in Canterbury, Christchurch particularly, has been a really big problem and has caused lots and lots of people to need care from primary care, general practitioners and admissions to hospital.
"For us to be contributing to [the poor air quality] was not a great look but we have fixed that now," Stevenson said.
Dr Anna Stevenson Photo: RNZ/ Niva Chittock
The new boiler system emitted 60 times fewer emissions than the old coal burners.
The system was able take poor quality biomass, such as slash, because it could handle loads with a moisture level of up to 60 percent, Ojala said.
"From our point of view, we'd be looking around the South Island to predominantly feed the boilers. A lot of the [slash] seen in the [aftermath of Cyclone Gabrielle] would be harder to access."
A number of feasibility studies had been done to identify a variety of woody biomass supplies that could be sustainably sourced for years to come, Ojala confirmed.
The new boilers had an estimated lifespan of 30 to 50 years.
The building still contained one diesel boiler in case the four biomass ones failed, Ojala said.
The boilers are located above the combustion chamber. Photo: RNZ/ Niva Chittock
The region's public health system should be nearly carbon neutral by the end of next year.
"We started off with the Burwood [Hospital] facility [rebuild in 2017] where we have one of the earliest biomass energy centres in the New Zealand health sector. The Christchurch Hospital biomass system is now coming online to bring Canterbury up to being almost completely carbon neutral," he said.
Two existing burners in Ashburton and Christchurch were still being converted to ground source heat pumps.
In a statement, Te Whatu Ora said decarbonisation and other sustainability measures have been a key focus for its infrastructure teams "for some time".
In 2021, there were 26 coal boilers across the public hospital estate nationally.
"Fifteen coal boilers have either already been replaced or have a replacement plan in progress. Nine of those have been replaced by fossil fuel free alternatives such as biomass boilers or ground sourced heat pumps over the past three years through the State Sector Decarbonisation Fund," it said.
"Once the final 11 coal boilers have been upgraded, Te Whatu Ora will see a reduction of carbon emissions by more than 7,000 tonnes [of carbon dioxide] per annum."
It expected all boiler upgrades would be completed by June 2025.
Dr Rob Ojala Photo: RNZ/ Niva Chittock
