Sitting somewhere between the politically fraught world of the electricity market and the dysfunction of Australia's recycling industry, waste-to-energy technology is on the verge of being developed across the country.
There are more than 30 proposed projects in Australia, primarily based on the combustion of waste materials to generate electricity.
Large proposals include a $300 million facility in Ballarat, a $400 million facility at Swanbank west of Brisbane, and the country's first — a $668 million plant in Western Australia, due to be completed in 2021.
But while it is gaining momentum, environmental and engineering consultants say the ultimate success of waste-to-energy depends on whether governments, local councils and the public clearly understand the technology's purpose in both the energy and resource recovery market.
'It's like baking a cake'
UK-based engineering and environmental consultancy firm, Ricardo, operates in 40 countries and recently opened an office in Australia.
Technical director, Darren Perrin, said there was "big potential" in the Australian market for waste-to-energy but, "like baking a cake", multiple ingredients were needed to make it work.
"What's in the waste and the security of that supply? How long will that supply of material be there?" Dr Perrin said.
"Having clarity around what technology is going to be used to generate the energy from waste — so is it a proven technology? Is it reliable? Will it perform against the performance guarantees?
"Where will the energy or heat that you can make from that facility, or the resulting materials like ash for example, where will that go? Where is the uptake for that product?"
Dr Perrin said new and improved ways of collecting information was needed to help in the design and management of waste-to-energy facilities.
"Collect appropriate data on the composition of waste so that an informed decision can be made, which is different data than you would typically collect to inform a waste strategy."
A 2018 report from the Senate Environment Committee stated that "data around waste generation and diversion remains notoriously poor" while the subsequent 2018 National Waste Policy gave, in principle, support to "improve information on where Australia's waste comes from and where it goes".
It's more about the waste than the energy
Australia generates 67 million tonnes of waste per annum, around half of which is recycled.
It is estimated that the proposed waste-to-energy facility in Ballarat would use 60 per cent of the city's waste while the plant at Swanbank could generate power for 50,000 homes.
Dr Perrin said the quantity of waste going to these facilities depended largely on whether households were reliably and consistently sorting their kerbside recycling, general waste, and organics.
"Whilst some materials claim to be recyclable they may be difficult because they're composite packaging," he said.
"Sweet wrappers around a chocolate bar; that's quite a hard material to go and recycle but it has energy associated with it so, rather than that material ending up in landfill, it's better to try and generate and recover energy."
As for the output, Dr Perrin said electricity was "not the main endgame of an energy from waste facility" with its broader purpose being to avoid waste going into landfill..
"You can't close down a coal mine and a coal-fired power station and put in an energy from waste facility and say 'that's now the solution to our energy problem'," he said.
"If you're only generating energy from coal … then an energy from waste plant actually helps you to decarbonise your energy supply … if you're generating energy from 100 per cent renewable sources, then it wouldn't help you to decarbonise your energy supply."
Just how sustainable is waste-to-energy?
Director of Melbourne-based consultancy firm Blue Environment, Bill Grant, said waste-to-energy can "absolutely" be considered sustainable today but may not fit that criteria in decades to come.
"At present a lot of waste-to-energy proponents compare themselves to landfill and to brown coal energy, and these facilities stack up quite well compared to those," he said.
"You avoid methane from landfill, which is a potent greenhouse gas, and you obviously miss out the fossil carbons from brown coal energy.
"In the future, hopefully, we'll be getting most of our energy from renewable sources so you won't have that offset and you'll be burning a lot of plastic in your waste, which is fossil carbon."
Mr Grant said it was vital that facilities being built today were considering what the energy market would look like decades from now and that "we're locking ourselves into that as a long-term future".
"We need to design whatever system we've got that allows the fossil carbon to get diverted out of the waste stream and focus on getting our energy from biomass — the garden, the food waste, potentially agricultural and forestry residue," he said.
"It might be for the first 10–15 years of whatever energy facility we build, we do burn the plastic because it is offsetting coal but, over time, as we get more renewable energy, we have the systems in place that we can extract that plastic."
Mr Grant said if a high enough quantity of rubber, plastics and other synthetics were used, the emission standards of waste-to-energy facilities could be on par with black coal.
There are around 450 waste-to-energy facilities in Europe, which have the capacity to process 73 million tonnes of waste a year, according to the Confederation of European Waste-to-Energy Plants.
But if taken too far, a dependence on rubbish as a fuel source could create an incentive to produce more waste, rather than recycle it.
Mr Grant said it was yet to be seen if its economic potential stacked up in an Australian context and that its viability, in part, "depends if the users have got year-round use for the heat".
In Europe, much of the excess heat generated in waste-to-energy facilities is used to warm homes but, with its own climate and economic conditions, Australia could be different.
Mr Grant also said gate fees charged to councils or businesses looking to dispose of their waste tended to be higher in Australia, reducing the economic incentive to change current practices.
"It is new territory in Australia and I think people are going to need more information on what the options are," he said.
"Landfill is a bad option but, unless we design this right, we might be stuck with a poor option in the decades to come."