Fully electric dairy process wins praise

The electric boiler is dropped into its site at the Mataura Valley Milk factory. PHOTOS: SUPPLIED
The electric boiler is dropped into its site at the Mataura Valley Milk factory. PHOTOS: SUPPLIED
The engineering firm behind New Zealand’s first dairy factory powered by 100% steam-generated renewable electricity has won gold at the national consulting and engineering awards.

Aurecon worked with Mataura Valley Milk (MVM) on the ambitious goal of completely electrifying its dairy processing site in Gore by replacing its coal-fired boiler with a high-pressure electrode boiler. This will reduce greenhouse gas emissions of 22,000 tonnes of carbon dioxide equivalent per year — a significant milestone for industrial energy transition.

Called Project Recharge, the initiative plays directly into New Zealand’s Emission Reduction Plan, which aims to establish a sustainable, secure and affordable energy system for a low-emissions economy.

Association of Consulting and Engineering New Zealand chief executive Helen Davidson said awards judges were impressed with Aurecon’s work to identify and apply the technology, develop the business case and provide project management and governance support during construction.

"Aurecon should be exceptionally proud of its work with Mataura Valley Milk, especially navigating the challenges around technology, timelines and risk. This was an impressive project that will have a significant environmental impact — huge congratulations to the Aurecon team."

In 2021, Mataura Valley Milk became part of the a2 Milk Company when a2 acquired a 75% shareholding, with China Animal Husbandry Group retaining 25%. Project Recharge was the first major asset investment in MVM after the a2 acquisition.

Aurecon was engaged to help MVM assess the feasibility of converting the coal-fired boiler to biomass.

The team acquired access to funding under the former government’s Investment in Decarbonising Industry (GIDI) fund, the decision was made to "go electric". Project Recharge was born.

For dairy companies worldwide, transitioning to full electrification has been almost impossible. It is only recently that electric boiler technology has evolved enough to reliably produce the large volumes of high-pressure steam required for drying milk powder. The transition to electrification has therefore required companies to take a risk on one of their critical components for operation.

Luckily Southland had a reliable source of power.

The installation of the high-pressure electric boiler encountered a number of challenges. The project team worked together to solve problems such as safe access to potentially high-voltage environments, design for longevity of switchgear under cyclic loads and management of the unique water chemistry requirements.

The boiler feedwater supply required extensive review, leading to a full upgrade of the site’s demineralisation plant.

It was a huge risk to be a first-mover in this space.

At 20MW, this project is the largest electric boiler installation in Australasia, and the first in Australasia which can produce steam at a high enough pressure to dry milk powder.