Could waste-to-energy plants be more polluting than coal?
Generating energy from waste is often considered a cleaner alternative to landfills. However, a new study suggests that some waste-to-energy (WtE) plants in China may emit more CO₂ per unit of electricity produced than coal-fired power stations. According to researchers at Monash University, the increasing presence of plastic in waste streams is a major driver of these high emissions.
Waste-to-energy emissions: A data-driven analysis from 2000 to 2020
Researchers analyzed nearly 600 waste-to-energy plants across China over a two-year period, observing a rapid expansion of the sector, which processed about 700,000 tons of waste per day by 2020. While these plants have reduced landfill emissions, the study found that their effectiveness varies significantly based on waste composition and the technologies used.
Co-author Ben Liu highlighted the need for improved waste separation and recycling. Cities that invest in better waste sorting methods and modern equipment could potentially halve waste-to-energy emissions, bringing them closer to the cleaner levels of natural gas by 2060.
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How do waste-to-energy plants work?
Waste-to-energy plants burn municipal solid waste at high temperatures, generating heat that produces steam to drive turbines and generate electricity. Some facilities use alternative methods, such as pyrolysis or gasification, to convert waste into combustible gases.
Advantages of waste-to-energy plants
- Landfill waste reduction: Significantly decreases the volume of waste that ends up in landfills.
- Energy recovery: Generates electricity from non-recyclable waste.
- Methane emission reduction: Prevents methane production, a potent greenhouse gas emitted by landfills.
Disadvantages: When do waste-to-energy plants pollute?
- High carbon emissions: Particularly when burning large amounts of plastic waste.
- Air pollution risks: Combustion can release harmful pollutants into the atmosphere.
- High investment costs: Advanced technologies are required to mitigate environmental impacts.
Strategies to reduce emissions from waste-to-energy plants
Professor Victor Chang, deputy director of the Department of Civil and Environmental Engineering at Monash University, emphasizes that optimizing WtE plants requires improved waste sorting and technological upgrades. According to Chang, expanding these facilities must align with clean energy goals to avoid replacing one high-emission source with another.
The study outlines several strategies to improve waste-to-energy efficiency and reduce emissions:
- Better waste sorting: Separating different waste components for specialized treatment.
- Higher energy efficiency: Investing in advanced high-efficiency systems despite higher initial costs.
- Carbon capture integration: Implementing Carbon Capture, Utilization, and Storage (CCUS) to mitigate CO₂ emissions.
With stricter policies and technological advancements, waste-to-energy plants could shift from being a major emissions source to a sustainable energy solution.