Aucklanders’ food scraps now provide renewable energy to help power the tomatoes that may very well end up on their plates thanks to a technology called anaerobic digestion.
Anaerobic digestion extracts the powerhouse of energy and nutrients locked inside food scraps and other organic waste, with the EcoGas facility in Reporoa leading the way in implementing this technology in New Zealand.
The facility collects food scraps and other organic waste from a range of sources, including Auckland Council’s food scraps collection, and produces enough heat from the waste to keep a neighbouring five-hectare glasshouse at ideal temperatures to grow its tomatoes – the equivalent of heating about 2,000 homes. Soon, the glasshouse will also gain bio-carbon dioxide produced by the food scraps to enhance tomato growth, as excess energy generated from the food scraps is fed into the national gas grid.
The residual material that remains after biogas is extracted is transformed into liquid fertiliser, replacing synthetic fertilisers in New Zealand’s agriculture, which is much better for soil health.
Auckland Council GM Waste Solutions, Justine Haves says diverting Auckland’s food scraps from landfill to be turned into clean energy and other resources helps move Auckland towards its goal of Zero Waste by 2040.
“Sending waste to landfill is the most expensive way to dispose of a community’s waste from an environmental perspective,” Ms Haves says.
“The more waste we have going to landfill, the more harmful emissions we have and the more landfill capacity we need, which comes at a significant cost to communities.
“With our finite resources, it makes sense to use the best environmentally sustainable technologies available to us to recover valuable resources from food scraps, and by diverting Auckland’s food scraps away from landfills towards processing for beneficial uses, the cost of the food scraps service is reduced.
“The food scraps sent from Auckland to Reporoa travel in aggregate trucks that were previously heading back there empty, so this is a truly circular initiative.”
Chair of the Policy and Planning Committee, Councillor Richard Hills adds anaerobic digestion can capture 99% of the biomethane that exists in organic waste such as food scraps for renewable energy.
“Instead of sending tens of thousands of tonnes of food waste to landfill, Auckland’s food scraps contribute to solving many of the big issues Auckland faces including waste minimisation, energy scarcity, and climate change. Aucklanders who use the food scraps service are helping this change – reducing emissions from food scraps by keeping them out of landfills, and turning this waste into energy,” Cr Hills says.
