Food

How Auckland food waste is helping power NZ's electricity grid

17:54 pm on 8 May 2023

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In Auckland alone we send 100,000 tonnes of food waste to landfill every year.

Now food scrap bins are being rolled out across the city to help use that food for fuel, at the country's first large-scale "waste to bio energy" processing facility.

Food waste makes up about half of every household's general waste. Until recently in Auckland it has generally been rotting in landfills. 

General manager of waste solutions at Auckland Council Parul Sood said food waste was a resource we should be utilising. 

“If you take out and process it appropriately it has benefits, right. So you can make other products with it.

"So why would you want to put it in landfill? And it also creates greenhouse gases while its in there.”

In Auckland, the roll-out of green food scrap bins was now underway. Each household will receive theirs by November this year. 

A rubbish truck collects food waste in Auckland. Photo: RNZ / Nick Monro

Residents can fill them with banana peels, tea bags, bones and even tissues. 

The roll-out was a long time coming.

“We started probably 11 years ago, in terms of looking at what can we do, what does the city need, what is the processing end of it because if you imagine, the city is quite large so we needed a large processing plant to deal with the material."

Eco Gas in Reporoa was a two-hectare facility that processes 75,000 tonnes of organic waste a year into renewable energy. 

This plant was one of 9000 in the world and the biggest in the southern hemisphere.

It takes products from restaurants, businesses and now Auckland Council.

Director Andrew Fisher said the best aroma they get was from McDonald's hamburger buns. 

Food going to waste in Auckland. Photo: RNZ / Nick Monro

But he has been put off fizzy drinks, thanks to their sickly sugary stench. 

Fisher explained the process from food waste to bio gas, which then goes on to power the local tomato growers and more.  

Eco Gas' facility processing food waste. Photo: RNZ / Nick Monro

“We’ve got the bio gas coming off, its created by methane so you’ve got your cO2, you’ve got your gas-to-grid. We also run a generator here so we’re creating electricity.

"When you make electricity though, you actually lose 70 percent of the energy in heat, it’s the friction process. We capture that water, hot water then goes across to turners and growers to replace their use of gas.”

But he said New Zealand was behind other countries already using the fuel for vehicles. 

Eco Gas would like to take on several more council collections in the North Island and has plans for another facility in the South Island.