Invercargill Prison replaces coal boilers with world's largest pellet heating system, cutting 700 tonnes of carbon annually

Invercargill Prison in New Zealand has switched on a new wood pellet boiler system that replaces its old coal-fired boilers. The system, built by Apricus Eco inside shipping containers, provides 1024kW of renewable heat for the prison's hot water, heating, kitchen, and laundry operations. The Department of Corrections says the switch will cut carbon emissions by 700 tonnes per year, a 99% reduction from the previous coal setup. The pellet system uses fuel from a sawmill just 10km away and can refill itself automatically. The modular container design meant only four hours of downtime during installation. The old coal boiler and its 21-metre smokestack will be fully decommissioned by November 2026. The project started in July 2025 and was driven by the need to comply with New Zealand's Zero Carbon Act and regional air quality rules. This is a concrete example of how large facilities with 24/7 heating demands can transition off coal using modular biomass systems. The key details are the emissions reduction figure, the local fuel supply chain, and the minimal disruption during the switch. For anyone tracking real-world coal phaseout projects, this one has numbers and timelines worth noting.