When you are running a large dairy processing site, the boiler is critical infrastructure. It has to deliver consistent steam, every day, through peak season, without becoming a point of failure.
That is what makes moving away from coal difficult.
This project shows how Fonterra successfully transitioned from coal to wood pellet biomass boilers at scale, without compromising performance, reliability, or production output.
The Challenge: Replacing Coal in High-Demand Dairy Processing
Fonterra’s processing sites depend on a continuous supply of high-temperature steam for drying, pasteurisation, and cleaning. Unlike variable-load sites, demand here is steady, high, and non-negotiable.
Coal has traditionally been the preferred fuel because it is:
· Predictable under continuous load
· Capable of high heat output
· Well suited to large boiler systems
The challenge was not just reducing emissions. It was replacing coal with a renewable fuel that could maintain:
· Constant steam supply
· Plant stability during peak season
· No disruption to production throughput
At the same time, rising carbon costs and fuel price volatility made staying on coal increasingly untenable.
The Solution: Large-Scale Biomass Boiler Conversion Using Wood Pellets
Fonterra partnered with Nature’s Flame to convert existing coal boilers to run on wood pellets, a renewable biomass fuel suited to industrial process heat.
At Te Awamutu, this involved converting a 43MW coal boiler to operate entirely on wood pellets.
Key elements of the system include:
· Retrofit of fuel handling systems for pellet storage and delivery
· Controlled fuel feed for consistent combustion
· Combustion optimisation using staged air supply
· Bulk pellet storage sized for continuous operation through peak demand
Wood pellets offer a technical advantage in this context:
· Low moisture content improves combustion efficiency
· Uniform size supports controlled burn conditions
· Consistent energy density enables stable steam output
This was not a simple fuel swap. It was a full system conversion designed to replicate coal-level performance using renewable fuel.
Day-to-Day Operation at Scale
A key concern in any fuel switch is operational complexity.
At Fonterra sites, the system operates as part of normal plant conditions:
· Fuel is delivered in bulk and stored onsite
· Automated systems manage feed and combustion
· Steam output remains stable across full production cycles
· Minimal operator intervention is required during standard operation
From an operational perspective, the system behaves predictably. That consistency is critical in environments where downtime is not acceptable.
The Outcome: Proven Biomass Performance Under Real Operating Conditions
The system has moved beyond commissioning and into sustained, real-world operation.
Project Results
· Boiler capacity: 43MW converted from coal to wood pellets
· Emissions reduction: Up to 98 percent reduction at Te Awamutu
· Annual CO₂-e reduction: Approximately 89,000 tonnes avoided per site
· Network impact: Over 150,000 tonnes CO₂-e reduction targeted annually across sites
· Operational performance: Consistent steam output maintained across full production cycles
· Fuel supply: Locally sourced wood pellets with storage sized for peak demand
The key outcome is straightforward. Steam performance has remained in line with coal, while emissions have dropped significantly.
Why This Project Matters for Industrial Boiler Conversion
Many remaining decarbonisation opportunities sit in large, high-demand processing environments.
These are the most difficult sites to convert because they require:
· Continuous high-output steam
· Proven reliability under pressure
· No tolerance for operational disruption
Fonterra’s conversion demonstrates that wood pellet biomass boilers can meet those requirements at scale.
It confirms that biomass is not limited to small or low-demand applications. It is a viable solution for large industrial process heat.
The Takeaway: Coal-Level Performance, Renewable Fuel
This project comes down to a few critical outcomes:
· Coal has been replaced without compromising steam performance
· The system operates reliably under full production load
· Day-to-day operation remains predictable and low-intervention
· Emissions are significantly reduced using a renewable, locally sourced fuel
The benchmark is not the installation. It is sustained performance under real operating conditions.
Fonterra shows that biomass boiler conversion can meet that benchmark, even at industrial scale.
