Source: Auckland Council
Thanks to a technology called anaerobic digestion, Aucklanders’ food scraps now provide renewable energy to help power the tomatoes that may very well end up on Aucklanders’ plates, contributing to New Zealand’s circular economy and reducing waste disposal costs.
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,” she says.
“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.”
Separating food scraps from rubbish is an easy way to reduce a household’s carbon footprint and provide a renewable resource for energy and fertiliser, so if you haven’t yet made use of your food scraps bin, it’s never too late to start! Simply put your food scraps bin out each week and it will be picked up as part of Auckland Council’s kerbside collection.
From your kitchen to an Ecogas facility – the food scraps journey
Watch the Journey of Food Scraps video below.
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Food scraps bins go out weekly, on council collection day. The small bins are emptied into food scraps collection vehicles – a third of which are electric – and the food scraps are transported to a facility in Papakura before being transferred into trucks bound for Reporoa.
The food scraps are loaded into vehicles which have delivered gravel and aggregate to Auckland from Taupō. Instead of returning to Taupō empty, they make the return trip south carrying food scraps. We are using an existing trip that would still happen without food scraps.
Food scraps arrive at the Ecogas Organics Processing Facility where they begin the process of anaerobic digestion.
Turning food scraps into clean energy and fertiliser – what is Anaerobic Digestion?
Imagine a huge tank. You mash up all your food scraps, like banana peels, corn cobs, and bones until it looks like a thick soup and pour it into the tank. Inside it, there are tiny, invisible helpers – the bacteria. These helpers love to eat the food scraps, but they don’t need any air to do it.
As they munch away, they make two special things: bio-gas for energy use and a liquid fertiliser that can be applied onto pasture to help grass thrive. This whole process is called anaerobic digestion because it happens without any oxygen.
The huge tanks turn Auckland’s food scraps into renewable energy and fertiliser which is spread on neighbouring farms. The energy helps to grow tasty tomatoes and the fertiliser helps grow grass to feed cows. Both the tomatoes and milk end up in your supermarket and on your plate. This energy is also used to run the facility itself making it self-sufficient and supplying renewable gas to the local gas grid.
Place your food scraps bin at the kerbside on your collection day and rest assured that you’re making a difference now and for the future.
