A new study published in Nature Energy has underscored a concerning trend with energy-from-waste (EfW) plants, a type of waste management system that could replace landfill sites.
EfW plants convert waste into energy through thermal treatments like combustion, thermal oxidation, gasification, or pyrolysis, burning waste to generate steam and produce electricity.
While widely regarded as cleaner and more environmentally friendly alternatives to landfill waste centres, some EfW plants produce more carbon per unit of electricity than coal-fired power plants, the new study has revealed.
The research points to an increase in plastic as a percentage of the waste content being processed at these plants as the main culprit, coupled with a lack of energy efficiency improvements and innovations.
Are EfW facilities a practical solution?
The study looked at almost 600 EfW facilities over a period of about 20 years in China, which has seen a rapid expansion in these types of waste management facilities in recent times – the sector processed some 700,000 tonnes of waste per day in 2020.
The researchers found that while EfW plants do reduce landfill emissions, the effectiveness of the plants differed greatly depending on the composition of waste and technological level of the facilities.
“Energy-from-waste has great promise, but there is still room for improvement,” said Dr Jenny Zhou, from the Monash University Nature, Urban and Human (NUH) Lab.
“In areas with high levels of plastic waste and older technology, EfW plants can be less efficient and produce higher emissions.”
Study co-author Ben Liu, a PhD candidate in the Monash Department of Civil and Environmental Engineering, said Australia had much more established waste classification practices than China, meaning its waste had a heating value potentially twice that of China’s.
“If Australia builds EfW plants with advanced equipment, we can leverage on these experiences and create a good balance between energy, environment, and sustainability,” Liu said.
On the path to sustainable waste management
The study recommended several pathways to achieving that goal, including:
- Improving waste segregation in the waste management chain and designing appropriate end-point treatments for separated waste streams with different attributes.
- Enhancing energy conversion efficiency, which offers greater long-term benefits despite the higher initial capital costs for high-efficiency modules.
- Implementing carbon capture when viable, as EfW has proven to be suitable platforms for potential Carbon Capture, Utilization, and Storage (CCUS) practices.
Monash Deputy Head of the Department of Civil and Environmental Engineering, Professor Victor Chang, said the data shows that while China’s EfW facilities have made great strides, there’s still potential to improve their efficiency.
“We’ve created a roadmap for integrating better waste classification and upgraded equipment to optimise EfW plants,” Professor Chang said.
“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.
“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.”