AWARDS FINALIST: Ecogas – closing the food and energy loop

Ecogas says anaerobic digestion is an important tool to help deal with the significant challenge posed by the country’s food waste.

The company opened its flagship, state-of-the-art organics processing facility in Reporoa in October. It is the country’s first commercial-scale anaerobic digestion facility and can process up to 75,000 tonnes of food waste and organic residue annually.

Ecogas says large facilities like Reporoa can process waste traditionally difficult to compost, such as meat and dairy products, alongside waste containing contaminating materials such as packaging.

Not only is the food waste processed at a lower emissions rate than either landfill disposal or composting, but the anaerobic digestion can supply renewable products to nearby industries, such as CO2, heat, pipeline-ready biomethane, electricity and regenerative biofertiliser.

Reporoa

The Reporoa plant is fully contained and self-sufficient, charging the company’s electric vehicles and powering processes and machinery. Residual water from truck washes and processing is recycled back through the plant in a semi-closed loop.

The biogas generated is converted to heat and piped to the adjacent glasshouses used to grow tomatoes by T&G. Along with Firstgas, Ecogas is co-investing in upgrading equipment which will refine the raw biogas into biomethane and food-grade CO2. Once operational, the CO2 will also be piped to the glasshouses to enhance growth.

The remaining biofertiliser is applied to farmland surrounding the facility, returning nutrients to the fertile farms. By keeping application local, the associated transport and manufacturing emissions are minimised.

The refined biomethane will be injected directly into the national gas grid. The conversion from biogas to pipeline-ready gas ensures that no other changes are required by end users. This transformation process is the first of its kind in New Zealand.

Long term

The plant was designed with long-term sustainability in mind and the partnership has been contracted by Auckland Council to process the city’s kerbside food scrap collections for the next 20 years. It will receive additional waste from commercial, industrial and institutional suppliers.

Across commissioning and operations, the OPF has already processed almost 7500 tonnes of food waste, ahead of forecast volumes. By processing that waste at Reporoa, the venture has prevented the equivalent of up to 13,000 tonnes of CO2 being released into the atmosphere.

By closing the food and energy loops, Ecogas hopes to create a more circular and sustainable future for New Zealand.

The Low Carbon Future Award category is sponsored by Energy Resources Aotearoa