Meet the giant mechanical stomach turning food waste into electricity

Tonnes of food scraps collected from restaurants and supermarkets are being converted into electricity under a green energy initiative powering thousands of homes in Perth.

The City of Cockburn has made the waste to energy service a permanent fixture of its general duties, collecting rotting food waste from local businesses and feeding it to a mechanical ‘stomach’ at a nearby fertiliser plant.

The anaerobic digester heats the food, traps its methane gas and feeds the energy into the electricity grid, powering up to 3,000 homes.


Key points:

  • A giant mechanical stomach is turning tonnes of food waste to energy
  • The electricity is being fed into the grid, powering 3,000 homes
  • The City of Cockburn has made the initiative part of its general duties


“Food waste really shouldn’t be thought of as a waste, it should be thought of as a resource,” said the city’s waste education officer, Clare Courtauld.


“It’s really important to take food waste out of landfill because it produces harmful greenhouse gases.

“If global food waste was a country, it would actually be the third-highest greenhouse gas emitter in the world.”


Food scraps are fed to the mechanical stomach around the clock.(Flickr: Taz, CC BY 2.0)


Ms Courtauld said the City had so far recycled 43 tonnes of food waste and saved 81,000 kilograms of CO2 equivalent gasses that would have otherwise entered the atmosphere rotting in landfill.

The $8 million mechanical stomach sits at the Jandakot headquarters of fertiliser company RichGro.

It was the first bio-waste plant of its kind to operate in the southern hemisphere when it opened in 2016.


“Their trucks come in … they tip off the food waste.

“It then goes through a piece of machinery which removes any packaging that might be in with the food waste and any contamination.

“It pulps the food waste up into like a porridge consistency and doses it into a big tank.


The food waste is pulped into a rich slurry and pumped into the digester.(ABC News: Gian De Poloni)


“This tank then feeds the two digesters … they’re getting fed 24 hours a day.

“As it breaks down, it generates methane gas. We’re capturing that gas and we’re running large generators that combined can produce up to 2.4 megawatts of electricity.”

The plant powers the company’s entire operations and up to 3,000 neighbouring homes, all from food waste.


What goes in, must come out

“Out the back end comes a liquid that is actually certified organic as a liquid fertilizer,” Mr Richards said.

“We sell a percentage of that to farmers and the remaining percentage of it we add into our compost piles.”


The bioenergy plant converts the methane gas from food waste into electricity to feed into the local power grid.(ABC News: Gian De Poloni)


Some foods are better than others.


“Certainly, you can overdo a good thing — you wouldn’t want too much fats, oils and greases.

“A lot of fruit and vege, starchy, sugary products are good. They produce a lot of energy.”

The City’s waste manager, Lyall Davieson, said there was community appetite for these sorts of initiatives.

“I’ve been in waste for about 25 years,” he said.

“Not so long ago, all we could really do was just recycle a few cans and a bit of steel.

“But now we really have at our disposal lots of options to divert waste from landfill and to recycle.”


The energy created from food waste is fed into the existing electricity grid, powering up to 3,000 homes.(ABC News: Gian De Poloni)


Frank Scarvaci, who owns a longstanding independent supermarket in Hamilton Hill, was one of the first businesses to sign up for the service.

He said it was a natural progression for his grocery store after embracing a plastic bag ban and installing solar power.

“I’ve been surprised [at] how the community has accepted the change,” he said.

“I thought [there] was going to be much more resistance in regards to when they scrapped plastic bags, for example — but there was virtually no resistance at all.”


Contamination causes indigestion

While common in Europe, the plant is just one of a few of its kind to be built in Australia.


People living close to the plant in Perth’s southern suburbs wouldn’t even know their homes are being powered by food waste.(ABC News: Gian De Poloni)


The City of Cockburn said it was not a waste service it would expand to households, because the risk of contamination disrupting the process was too high.

“We do have a machine that does have a certain ability to remove a level of the contamination,” Mr Richards said.

“Can it remove everything? No, it can’t.

“We’ve even had bowling balls come through — you can’t process things like that, in a system like this. It does damage our machinery.”


Bio-energy has a bright future

The bio-energy technology is growing in Australia, with the next logical step in the process to convert the bio-waste into biomethane, which could be fed into the gas grid.

The Federal Government is co-funding a biomethane production facility at a wastewater treatment plant in Sydney’s southern suburbs.

Once online in 2022, the $14 million plant is expected to pump biomethane derived from biogas created by a similar ‘mechanical stomach’ that would meet the gas needs of more than 13,000 homes.



By Gian De Poloni

Source ABC News Australia

March 30, 2021