Richard Musgrove
Zoologist, Dr Richard Musgrove is a science journalist based in Far North Queensland.
In a surprising finding researchers say energy from waste (EfW) facilities in some parts of the world may emit more carbon per unit of electricity output than coal-fired power plants.
The researchers from China and Australia, led by PhD student Ben Liu, analysed 20 years of data on waste used, energy produced and carbon emitted for almost 600 EfW plants in China. A third of the plants surveyed accounted for 18.4 Mt CO2 equivalent in 2020, 42% of China’s emissions for that year.
The problem is the plastic content.
Methane and carbon dioxide are released during plastic incineration. Zero Waste Europe (ZWE) estimates that about 580g of CO2 equivalent is given off per tonne of plastic burned in waste incinerators, depending on the type of plastic. This compares to 340g CO2 equivalent for electricity generated through conventional means, such as fossil gas (340g CO2 equivalent per kWh).
Burning plastic also gives off toxic gases and chemicals — dioxins and furans, polychlorinated biphenyls and volatile organic compounds, including hydrogen chloride, an acid which can cause serious inflammation,— says Susan Kosher of the National Institute of the Environmental and Health Science in the USA. The remaining ash can get into the lungs, potentially causing respiratory disease, heart problems and early deaths.
All good reasons for reducing the burning of plastic.
China processes at least 700,000 tonnes of waste per day through EfW plants, but, says Liu, plant effectiveness varies enormously, depending on waste composition and equipment available. Improved waste sorting and recycling would reduce carbon emissions from Chinese EfWs processing increasing amounts of plastic waste, he says.
“In areas with high levels of plastic waste and older technology, EfW plants can be less efficient and produce higher emissions,” says Dr Jenny Zhou, from Monash University Nature, Urban and Human (NUH) Lab.
Energy conversion efficiencies for Chinese EfW plants are often lower than those in many other countries — usually due to technological issues. Shanghai’s EfW plants generate around 280 kWh per ton, whereas in Europe and the US the range is generally 500–700 kWh per ton with more advanced technology.
Australia doesn’t have any EfW plants yet, but two are planned, both in Western Australia, at East Rockingham and Kwinana, to reduce landfill dependence. The $696 million Kwinana EfW plant is expected to generate around 500 kWh per ton, comparable with Europe, processing 460,000 tonnes of non-recyclable waste per year.
China is making progress, though, says co-author, Professor Victor Chang
“We’ve created a roadmap for integrating better waste classification and upgraded equipment to optimise EfW plants. By focusing on improved waste sorting and modernising technology, the roadmap highlights how these steps can boost efficiency, enhance energy recovery, and reduce GHG emissions from EfW facilities,” Professor Chang said.
Chang says the study shows there is a role for EfW in cleaner waste management and electricity supply.
“To ensure EfW remains a sustainable part of urbanisation in major cities worldwide, its expansion must be carefully balanced with clean energy goals to prevent merely substituting one high-emission source for another,” Chang says.
Liu says that improved waste classification and investment in modern equipment, could cut EfW emissions by half.
“Energy-from-waste has great promise, but there is still room for improvement,” says Zhou.
The paper was published in Nature Energy.
Where is the waste coming from?
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