1.0 Energy from Waste in the Sunshine State
The QLD regulator (DES) recently released a discussion paper on Energy from Waste (EfW) policy, and also held a workshop. So, just for fun, lets dive into the topic at bit, with a Queensland focus.
1.2 How much energy?
When we say energy, let us assume a thermal treatment of MSW (see below for a typical SEQ composition) with of course, best-practice electrical generation efficiency (say 29%, i.e. grate incineration), but not combined heat and power (CHP), as there is less demand for heat in QLD.
600,000t/a of MSW is the right ballpark for a large-scale thermal plant to be economical in Australia, with about a $130/t gate fee (Hitachi Zosen), so let us run with that, for now. Of course, the current QLD levy doesn’t drive those kind of landfill gate fees yet, but, give it time, plus, the SEQ landfill market will soon enough be almost entirely provided by the private sector.
600,000t/a of current QLD MSW potentially equates to around a 50MW thermal plant.
Thermal relies on the plastic & paper fraction of MSW.
Now, what about… if we put the same mixed MSW through an anerobic digestor (and all the green-bin waste too), and burnt the methane to generate energy?
Potentially equates to only around 9MW anaerobic digestion plant.
Also, the residue (digestate) would not be clean enough for agriculture, and would likely go to landfill, attracting the levy. This is why thermal treatment of mixed MSW can be economical, while anerobic digestion of the same MSW is typically not, unless processing of the MSW occurs and the digestate can be used for non-landfill purposes (e.g. Veolia Woodlawn).
Perspective
- On average, Australian households use 6,570Kwh/pa of electricity, so, 50MW powers around 66,000 homes.
- However, 50MW is only 0.36% of current QLD generating capacity (14,415MW), so can’t replace coal. It would however, be largest ‘bio-energy’ generator in SEQ, overtaking Rocky Point Co-gen, which burns Council green-waste and bagasse.
1.3 Does the waste exist?
Consider, for example, the 2018 combined LGA’s of Brisbane, Redlands, Logan and Ipswich.
- Population, approx.: 1.7million people
- MSW landfilled in recent years, approx.: 650,000t/a – the resource stream exists! without even considering the C&I generation, which is about the same again, or, MSW and C&I from NSW, or – the yellow-top recyclable fraction.
- This also shows that outside SEQ, the resource stream does not exist (for thermal).
1.4 ‘Moving Toward’ a Circular Economy
The QLD waste management and resource recovery strategy talks about moving toward a circular economy for waste, away from our current ‘take-make-use-dispose’ linear system. This is going to require imposing cost to make recycling more economic than taking new resources. However, in doing so there will many more jobs and also hundreds of millions in economic opportunity. Note that more bins is not the answer.
Now, residual waste that goes to landfill or thermal processes, is really ‘leakage’ from the circular economy ideal. Like any leak, we should be working to fix and reduce it, if at all possible.
In particular, burning plastic is no different to burning oil, a fossil fuel, while landfilling plastic is actually carbon sequestration. Landfill is not always the least circular option for some wastes.
I include refuse derived fuel (RDF), sold for co-generation in cement kilns, as ‘leakage’. However, like landfill, RDF is flexible, as it is a commodity. Processers would quickly switch to supplying a more ‘circular’ plastics-to-oil plant as opposed to cement kilns, if that was more beneficial to them. RDF is ‘moving toward’ a circular economy.
Energy generated from anerobic digestion from green bin collections, with residual digestate to agriculture, or oil from re-processed plastic, are part of the circular economy.
Burning green waste (which already occurs in SEQ) and/or non-recyclable paper with best-practice energy recovery is also circular.
Queensland is not northern Europe, or Japan, with massive existing MSW thermal investment to protect. Remember, thermal economic viability requires not only a landfill levy, but also a contracted, committed and consistent MSW waste supply for 20+ years. Given that, can we honestly say that committing our waste stream to thermal treatment is ‘moving toward’ a circular economy in QLD?
1.5 What was the question again?
If the questions are:
- How do I minimise my 600,000+ tpa MSW landfill volume? A good answer is: ‘thermal treatment’ with best-practice technology, regulatory oversight, and efficient energy recovery.
- Would such a facility buy my mixed recyclables my MRF can no longer export? A good answer is: Absolutely. Plastic and paper make very good fuel. And probably yes, even if you are outside SEQ…including NSW and VIC.
- I’m in NSW, our levy is really high, but we can’t get social licence for thermal…can we do a deal? A good answer is: Let’s run the numbers…
However, if we were to ask:
4. What is the highest and best use of our QLD MSW? A great answer is: not thermal treatment no matter how energy efficient. In fact, it is possible thermal could become an opportunity cost that ‘captures’ the waste resource for 30+ years, and so stifle the emergence of a much more circular economy, plus associated jobs in new re-processing industries. It might also encourage the interstate waste trade to continue, if QLD builds too much thermal capacity.
1.6 Highest and best use?
A MSW vision (for all of QLD in the levy zone). A version of this also works for C&I waste as well.
Energy from waste
- Anerobic digestion of food and garden (FOGO)
- Green-waste co-generation
- RDF
- Plastic/ tires to oil plants
- Maximise landfill gas capture
- Solar on/around landfill
Rowan Cossins is a principal at ATC Williams, a specialist engineering consultancy focusing on effective client solutions in the waste management and mining sectors. Contact 07 3352 7222 or rowanc@atcwilliams.com.au
