Presented as part of Technology Transfer Seminars 2025

Stuart Walker, Ecogas, Director

Stuart Walker has a diverse career background and can claim to have literally worked at all ends of the agricultural/food industry from pasture to plate. After 15 years in the animal health/nutrition and veterinary sectors, Stuart went onto run the Hansell’s Food Group from 1999-2006. This was followed by successful ownership of two niche food manufacturing companies whilst also taking on the Acting CEO role in 2011 during the establishment phase for ‘The Food Bowl’ as part of a $20m investment by local and central government in promoting new food technologies to the industry. Stuart continues to consult to numerous food and non-food business over the last 20 years including a very close association with Ecostock Supplies and as a Director of Ecogas, New Zealand’s first large scale waste to energy plant based at Reporoa. Stuart also has an interest in the baking field as an owner of a dedicated factory in Auckland producing around 5 ton of specialist breadcrumbs per day.

Extracting value from waste

How do we extract value out of waste? Not just commercial food waste, but also household waste. This is the question Ecogas aims to answer by supporting the development of a sustainable circular organic waste to energy solutions (sustainable biogas and biofertilizer) by utilising Anaerobic Digestion technology.

Ecogas is a 100% New Zealand owned joint venture between Ecostock (commercial waste food for dairy and pigs) and Pioneer Energy. Stuart describes Ecogas as a commercial operation for public good.

Their Anaerobic Digestion (AD) Facility is on 2 Ha of farmland adjacent to Turners &Grower’s 5Ha tomato growing glasshouse. The AD Plant can process up to 75,000 t per annum of organic food wastes. Renewable biogas is used to power a 1.2 MWeCHP, onsite utilisation of heat, and surplus electricity is exported. Excess biogas will be separated into methane for injection into natural gas grid and CO2 for glasshouse fertilisation. Soil conditioning bio-fertiliser is now being spread onto more than 1,500 Ha of neighbouring farmland.

Organic waste is sourced from farms, households, factories, and food services, transported to digesters, and turned into biogas which is used on site for energy, growing tomatoes in glasshouses as part of their circular business model. Very little process energy is required, only for mixing and contact. Methane is captured as a key energy source. Nitrogen and key nutrients are retained in the liquid digestate.

Ecogas is in the process of developing another facility on the outskirts of Christchurch.

Presented as part of Technology Transfer Seminars 2025

Jess Broun, Kai Commitment

Jess Broun is the Programme and Account Manager for Kai Commitment, a voluntary agreement for leading food businesses to reduce their food waste led by New Zealand Food Waste Champions. Jess has an extensive Partner and Operation management background with many years spent in the food sector. She works to empower businesses to see the opportunity in their surplus and take a leadership role in reducing their food waste.

Everybody’s Responsibility, Every Business’s Opportunity

“When you look at the food it was meant to be, not the waste it became, you realize the true cost.” There are opportunities to not only reduce food waste, says Jess, but to innovate, create value and empower people. If you know why you are wasting food, you can change it.

Food waste contributes to global climate change, the cost of living, and food insecurity crises. It has economic, social, and environmental impacts. In New Zealand, 45% of land is used to grow food or farm animals, equivalent to the entire North Island. A third of this food goes to waste. Waste occurs across the supply chain, including the energy, water, manufacturing, and resources used to produce food. 80% of New Zealand’s exports go to countries with mandatory climate-related disclosures. Reducing food waste and diverting food waste from landfills would significantly help New Zealand achieve its methane reduction target.

So, where do we start? Business/ industry can drive significant change across the food system chain, but better collaboration is needed to reduce food waste faster. Jess notes that while a lot of good work is being done, collective efforts are essential for greater impact.

Voluntary food waste agreements are emerging globally. “Kai Commitment,” New Zealand’s food pact launched in 2022, focuses on identifying waste, understanding its drivers, and taking action. The program encourages businesses to set targets, measure food waste, plan and act to reduce it, and collaborate to innovate and share best practices.

Every business should ask itself the cost of unsold or wasted food. Viewing it as surplus rather than waste can help see it as an asset that can be reused and create value. Considering waste at the product design stage can prevent it occurring.

Managing food waste according to a food recovery hierarchy helps businesses reduce their emissions and disposal costs and ensures their surplus goes to the best destination possible.  The preferred outcome is preventing food waste or redistributing it commercially. This is closely followed by donating to people in need or to stock feed. Next, businesses should seek waste destinations that enable nutrient or energy recovery; the least preferred outcome is food waste ending up in landfills.

A collaborative project involving several large commercial bakeries identified food waste destinations and drivers across the bread supply chain. The resulting map highlights the need for coordination and collaboration between supply chain stages to address systemic food waste drivers. It also captures end destinations for food waste and barriers and enablers for each.

The Working Group is consolidating findings and deciding how best to disseminate the resource and project outcomes. Businesses involved are working together on root cause analysis and piloting projects to reduce food waste. Detailed findings and analysis from this project will be published shortly and will be accessible on KaiCommitment.org.nz

In recognition of Food Waste Action Week, Kai Commitment has launched a free resource, The Food Waste Rapid Review tool. The tool offers actionable steps to:

• Identify areas where food waste occurs within your operations.
• Implement strategies to reduce waste effectively.
• Measure progress to ensure continuous improvement.

The tool is designed to help businesses achieve significant benefits, including cost savings, enhanced operational efficiency, and strengthened sustainability practices.

Reducing food waste is also a great way to contribute to a more efficient, resilient, and sustainable food system that benefits everyone.  Regardless of where you are in the supply chain, we can all do something, but we achieve the best results by working together.