Turning waste to energy

The challenge

Australia is facing big waste and energy problems. How do we turn one project's problem into another's solution by helping the waste and energy sectors transition to the circular economy?

In this article

  • Australia's waste and energy problems - can circular economy principles solve them?
  • Creating a tool to model the economics behind a number waste-to-energy technologies, such as anaerobic digestion.
  • Helping utilities invest more confidently in waste-to-energy technologies by exposing tipping points and economies of scale.

Australia is facing a big waste problem. We're producing waste at a rate of over 600 kilograms per person per year. That's not our only challenge. Our nation’s energy supply is among the world’s dirtiest and is becoming increasingly costly and unreliable. Many municipalities are taking stock of this state of play and are looking for more sustainable ways to handle their waste and energy needs.

In this research project, we explore how one problem might solve the other. Michael Salt, an economist in our Canberra office, has created a tool to help municipalities identify more sustainable opportunities. It's part of our commitment to supporting Australia on its journey towards a pioneering circular economy capable of using waste as a resource.

Michael is working with a cross disciplinary team of waste, water and energy experts to build this functionality into an easy-to-use spreadsheet. The tool helps us recognising opportunities by taking key inputs about utilities - the volume of waste produced or amount of energy required for a particular process - and weighing them against the readiness of utilities to adopt a suite of technologies and economic drivers like the cost of waste disposal or the savings potential of generating power on site.

The outputs will help municipalities make decisions about whether or not a technology is appropriate for their specific set of circumstances. Even better, it will help users understand how and when existing and emerging technologies will become feasible from them, guiding future planning towards circular economy principles.

The ISOS Input for a Food Waste Anaerobic Digestion facility in Gowerton & Aberystwyth. Photo Arup.

Prototyping, Testing, Iterating, Collaborating

For the first iteration of the tool, the team has decided to focus on anaerobic digestion (AD) technology.

AD work by converting biosolids into a compostable digestate and methane gas. Waste goes in. Energy comes out. The technology is particularly valuable in regional contexts, where the digestate can be used locally as fertilizer.

That said, there’s no reason why this tool can’t be tweaked to suit the urban context as well. All it would take is a slight modification of certain inputs. For instance, while energy savings might be less in the city due to network access costs, waste disposal savings are likely be a lot higher due to the shortage of space. These simple tweaks will be rolled out as Michael and the team work to make sure that the tool will be relevant to as wide an audience as possible.

This video by the Ellen MacArthur Foundation does a great job of explaining the Circular economy.

Re-Thinking Progress: The Circular Economy by the Ellen MacArthur Foundation.

Translating Technology

Anaerobic digestion technology is not new.

The industrial use of anaerobic biodigestion has been around since the birth of the septic tank in the late 1880s. In 1897, the local government of Exeter used biogas captured from the city’s waster-water treatment facility for both heating and lighting.  The technology gained popularity in the 1970s, with the sharp rise in fossil fuel prices and increased understanding of and hence regulation around air pollution. Many technologies, like pyrolysis (thermal decomposition), share a similar history. Yet, widespread adoption has been minimal in Australia. Why? 

Historically, we've always had access to cheap and plentiful energy.  

Michael and his team are now applying these solutions to modern problems. Or, in this case, using modern economic modelling to apply new insights to old technology.  Often when we think of translating technology, we’re immediately drawn to big data solutions, robotics or algorithms. Yet the most effective - and in many cases democratic - uses of technology are those that are lo-fi, tried and true.

An example of biodigester technology being applied to a rural household context in Cambodia. Photo Jeff McAllister.


  • By understanding tipping points, and leveraging economies of scale, we can identify and plan for opportunities to turn our waste problems into energy solutions.
  • Old technology, like biogas and pyrolisis, can still offer new opportunities when applied to modern problems.
  • No waste to energy technology is a band-aid solution. Not all utilities have the same needs. By creating a tool that compares a suite of waste to energy solutions we can help utilities decide which option is best for their context.

This story was written by Jeff McAllister, as part of the Research Review. This series is produced by the Arup Australasia Research team; Alex Sinickas, Bree Trevena and Jeff McAllister with contributions from Sheda and Noel Smyth.

Lead Arup Researcher

Michael Salt
Michael is a senior Energy consultant with the Advisory, Planning & Design group in our Melbourne office

Ask Michael about

  1. How to determine whether a waste-to-energy solution is right for a utility. What are the key inputs and outputs his tool uses?
  2. The economic modelling and waste-to-energy plant design underlying his tool.
  3. What if a waste-to-energy solution isn't viable yet? What other steps can a utility take to work toward contributing to the circular economy.


Research TEAM

Mike leads our Australasian Environment and Resources team.
Giles is an environmental engineer.
Elise is a graduate engineer working across transport and resources
Alex is a chemical engineer working in our Environment and Resources team.
Shaun is an Associate Principal working in our Environment and Resources team.
Maria Caruda is a consultant working in our Environment and Resources team.
Barry is an Associate working in our Environment and Resources team.
Poyani is a civil engineer working in our Environment and Resources team.

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