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Composting reduces GHG emissions compared to landfill

 

Back in 2018, Mike Ritchie wrote an article comparing landfill GHG emissions to transport emissions. Prompted by a meeting with Local Government Mayors and CEO’s (where a claim was made that transporting organics by truck to a compost facility 150km away would emit more greenhouse gases than landfilling it locally), Mike did the maths and was startled to discover that that was far from the truth, in fact, 13,100km away.

We found ourselves in a similar situation recently, when a client brought up that article and quizzed us on the assumptions. It turned out that Mike’s calculations warranted an update, especially since the accepted global warming potential of methane in Australia has increased from 25 in 2018 to 28 now. Our key assumptions and calculations are shown in the table below.

Value Description/Source
Type of truck Articulated truck Motor vehicles constructed primarily for load carrying, consisting of a prime mover having no significant load carrying area, but with a turntable device which can be linked to one or more trailers. Source: ABS survey of motor vehicle use
Tonnes of FOGO (t) 25 Average FOGO load of articulated truck
CH4 GWP 28 Source: National Greenhouse Accounts factors 2021
FOGO landfill emission factor (t CO2-e/t ) 1.85 Assuming 50/50 FO & GO and using National Greenhouse Accounts factors 2021
LFG capture (%) 50% Lifetime capture
Transport emission factor (kg CO2-e/km) 1.5 Source: Calculated based on National Greenhouse Accounts factors 2021 and ABS survey of motor vehicle use
Landfill GHG emissions of 25t FOGO 23.1t CO -e FOGO deposited in well run landfill with 50% lifetime gas capture rate

In short, and to shamelessly copy Mike’s original story, we found out that a truck filled with 25 tonnes of Food and Garden Organics (FOGO) can be driven 15,444km to a composting facility before it emits the same amount of greenhouse gases as that same truckload put in a landfill with 50 per cent gas capture (typical of whole of life gas capture).

Or put another way, you could circumnavigate Australia (14,500km) and then drive some more and you would still have not emitted as much as if you’d just buried that same FOGO locally, in a standard landfill with gas capture.

If the landfill had no gas capture, you could drive that truck for twice as long before the CO2-e emissions from the truck were equal to the landfill’s emissions. To put that in context, you could drive the truck from Sydney to Perth and back four times before you generated the same amount of emissions.

How stark is that?

Organics belong in our soils, not in landfill, and dedicated FOGO services are the best way to recover organics from the municipal and commercial waste streams. FOGO has grown since 2018 and organics collections have grown significantly. The Victoria and NSW Governments have mandated FOGO across the state while WA mandated FOGO in the Perth Peel regions.

However, more needs to be done in order for source separated FOGO collections to become the standard waste service for all Australian households and businesses. Especially since there is evidence that we are underestimating emissions from landfill.

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