Recent Articles
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- Field to Flour: Can we reduce our footprint?
- Leading Action on Food Waste
- Bread bags from bread returns
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- Sustainability for the Baking Industry – Food without Footprint
- Better energy management for bakers
- Update on the Soft Plastic Recycling Scheme
- Good for the environment – Good for business
- BIRT Technology Transfer Seminars 2025 Evaluation
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.