That was the question being asked at a conference held recently by the Waste Management Association of Australia in Melbourne which featured a dedicated stream on Energy from Waste (EfW). The general consensus seemed to be ‘no, not yet’, for a number of reasons least of which is the fact that we have three levels of government, all of which could potentially have an impact on such projects, and a number of complex and costly technologies in the market.
The Victorian Advanced Resource Recovery Initiative (VARRI) was designed to drive a “high-tech” makeover of the industry and see the construction of two new facilities by 2010. It was commenced in 2008 and delivered a report to former Labor government last year but the findings have not been made public to date.
It has been suggested that government entities delayed decisions on infrastructure until the report’s findings were released, as it was expected to provide a comprehensive business case for the best technological solutions to treat Melbourne’s waste.
Although there has been wide speculation on the contents of the VARRI report, industry sources have suggested that a thermal EfW process was considered as one of the options for treating residual waste as part of an integrated system.
What we know from international studies which have ranked various technologies on an environmental lifecycle basis is that landfill is at the low end of the scale and at the optimal end is often an EfW process which produces heat and power*.
Broadly, EfW can encompass mass combustion as well as thermal (gasification, pyrolysis, plasma arc) and non-thermal (anaerobic digestion, refuse derived fuel, mechanical biological treatment) technologies.
Minter Ellison’s Peter George, who described EfW as “a complex matrix or a tangled web”, presented at the WMAA conference on EfW from regulatory and policy perspectives. When asked if he could speculate on the conclusions reached by the VARRI, said, “It is difficult to speculate. The current state government is really struggling to come to terms with a whole lot of things, this being one of them. My suspicion is that it will take some time”.
SITA, which is hoping to roll out its PEF (process engineered fuels) process into other states after its success with the SITA-ResourceCo alternative fuel Advanced Resource Recovery facility in Adelaide, said its development would require some key decisions from the Victorian government.
“One is that the government sets emission thresholds and that they be applied to all industries and all sizes of facilities…we find it ludicrous that there’s not a level playing field.
“Secondly, that the government understands the different technologies available and once these threshold limits are set, deciding what is the best way to get value from high calorific materials.”
The Process Engineered Fuel produced by SITA – ResourceCo, from commercial waste, possesses significant calorific value and can be used as a fuel substitute for coal and gas in high combustion facilities.
Moltoni Energy is vying to be the first operator of a mixed technology EfW plant, with its Kwinana project in Western Australia. It is working on the conceptual engineering for the project which would treat MSW and compost residue with mass combustion and C&I waste with plasma gasification.
Anthony Douglas from Moltoni Energy told Inside Waste, “The Towards Zero waste strategy that was introduced by the Labor government in 2005 had a clause that said biological processes would be preferred over thermal processes [in Victoria] but I think the concern from people who offer thermal processes is if you exclude technologies from an assessment, it’s not a fair assessment”.
“All major economies, much more developed than ours, have utilised these technologies to respond to their reliance on landfill and have been very successful in doing so,” said Douglas.
He said the challenge was whether Victoria was ready for a step change in terms of waste diversion from landfill to around 65-70%.
“We believe that a technology led response is an important part of that step change and given the WA and NSW experience where biological processes have not produced the diversion from landfill we feel that thermal options should be considered.”
“Is Victoria ready for thermal processes? I don’t think we’re there yet and that’s primarily because there are many stakeholders involved in these types of processes because they cut across waste management and energy generation…I feel we’re at the stage where there’s a growing awareness of the needs and with the VARRI report and others there are questions being asked about what can be done.”
Douglas said with additional stakeholder engagement and education and awareness building with government and environmental groups he believes an EfW facility may be a reality in Australia within three to five years.
He said it was promising to see a number of policymakers and regulators in attendance at the conference who were interested in learning more about technologies for EfW.
Emissions from EfW – a reality check
Said ‘reality check’ was provided to WMAA conference delegates by Brian Stanmore, formerly with the Universities of Melbourne and Queensland.
He is so confident that air and land emissions from EfW plants are at acceptable levels that he has a house in France right next door to one.
“The techniques for the removal of acid gases, PAHs, dioxins, particulates and mercury are sufficiently developed to meet existing emission standards,” he said, “These standards should ensure that public health is safeguarded”.
Stanmore described the process of a modern EfW combustion facility in processing residual MSW where the recyclable and compostable materials have been removed.
“The most common type of furnace in service is the moving grate, on which the fuel gravitates in a thin layer down an open ‘belt’, helped by some form of mechanical transport,” he said.
Two solid ash streams are generated from the waste – the bottom ash which falls off the end of the grate, and flyash which is removed from the fluegas.
After being stored under cover for three months in order to stabilise, the bottom ash can be used as a construction material such as roadfill.
Even though the size of flyash is measured in microns, the cleaning devices operate at efficiencies above 99%, said Stanmore. Due to the solubility of its components and the presence of metals, this ash, which may represent only 1-2% of the waste feed, should be disposed of in a secure landfill.
The pollutants present in the fluegas include acid gases; PAHs (PolyAromatic Hydrocarbons) including dioxins; particulates; and metals.
“Any PAHs emerging from the bed are attacked by the overfire air, so that their concentration in the fluegas is extremely low,” said Stanmore, “Typical emission rates are 5-15 g t-1 of MSW, which should be compared with up to 1500 g t-1 for landfill”.
Dioxins, or polychlorinated dibenzo-p-dioxins and furans (PCDD/PCDF) are a series of chlorine containing, triple ring compounds, which are present in extremely low concentrations (nanograms Nm-3) in EfW flugas.
“The toxicity of dioxins has been overstated,” said Stanmore, “as demonstrated by the massive exposures experienced by inhabitants of Seveso in Italy. It was calculated that 30 kg of TCDD was released over two hours from a runaway reaction in a pesticide manufacturing plant, whereas the total emission of TCDD equivalent for 2002 in Australia was estimated at 1.79 kg. After 30 years of monitoring by a medical team, the only long term effect in Seveso is a slight increase in cancers to the lymph system”.
Over 95% of the human intake of dioxins is via food such as dairy products and meat, and the major source of dioxins in the environment is uncontrolled burning (bushfires), according to Stanmore. In his opinion, the major health concern posed by combustion processes such as EfW is the release of large numbers of fine particles into the atmosphere.
In looking at the example of a 100,000 tonne per annum EfW waste plant, Stanmore suggested that the emissions from a modern waste plant (in the range 1-2 x 105 cm-3) would be in the same order as ambient inner-city air.
“It’s all about risk isn’t it,” he said, “the output from dioxins would be equivalent to the output of 250 trucks…the output of particulates is equivalent to about 70 road vehicles”.
Mercury is extremely volatile and presents the greatest challenge to control in terms of metals. MSW is reported to contain 4 to 5 g t-1 of the element, and landfill gas, although extremely variable in trace element concentrations sometimes contains significant amounts.
“For a 10 hectare [landfill] site, the yearly emissions to air could be 2.5 kg,” said Stanmore, “The average emission from a WtE plant is around 15 mg t-1, which represents about 0.4% of the mercury in the incoming MSW”.
* IEA Bioenergy’s report from 2009 (Integrating Energy Recovery into Solid Waste Management Systems), used a lifecycle waste management software tool to see whether different types of options for managing residual waste offer particular environmental benefits and whether it is possible to establish a hierarchy of environmentally preferred options.
What it found was that all the treatment options considered had, for a typical coal/gas electricity mix, lower environmental impacts than landfill. They included energy from waste (combustion); combined heat and power (CHP) from combustion, a wide range of mechanical biological treatments (MBT); resource derived fuel (RDF); and landfill with energy recovery.
“While no treatment option performed best under all the cases and impacts evaluated, overall, the EfW plant had the best environmental performance, where there is no opportunity to utilise heat, and the EfW-CHP plant where there is an opportunity to supply heat,” the report stated.
However, if the energy recovered is displacing very low carbon electricity (eg. predominantly from hydro or nuclear), then there is much less differentiation between the waste management options, and the MBT-IVC (In-Vessel Composting) option performs best – where waste is sorted into an organic component that is composted and a fraction that is burnt in an EfW plant.
IEA Bioenergy is an organisation set up in 1978 by the International Energy Agency (IEA) with the aim of improving cooperation and information exchange between countries that have national programmes in bioenergy research, development and deployment. There are 23 countries plus the European Commission participating in IEA Bioenergy, including Australia.
