Quantifying the trade-offs: Energy potential and environmental impacts of municipal landfill mining in China

Abstract

Landfilling is a common method for municipal solid waste (MSW) management, and a significant amount of aged landfill waste (ALW) has accumulated over the last few decades. It is important to promote landfill mining to release land resources and utilize ALW. In many countries, screened combustible ALW is sent to MSW incineration plants for electricity generation. Yet it is controversial whether this method causes environmental pollution. Based on actual project data and long time-series city-level data in China, this study uses material flow analysis (MFA), life-cycle assessment (LCA), and geographic information systems (GIS) to systematically assess this workflow's energy and environmental aspects. The results show that ALW in Chinese cities exceeded 2000 million tons in 2022 and has the potential to generate about 400 million MWh of electricity, equivalent to 4.5 % of China's electricity production amount, close to the total nuclear power generation in 2022. However, trade-offs were observed among environmental impact indicators. Particulate matter formation, photochemical ozone formation, and terrestrial acidification potentials were reduced, while extra impacts on global warming potential, freshwater eutrophication, and human toxicity potentials were caused. Meanwhile, boosting energy conversion rate to 40 % could raise energy potential by 74 % and cuts carbon emissions by 14 %. The following is suggested: (1) improve energy conversion efficiency of combustible materials in ALW; (2) promote ALW utilization according to cities' MSW management ability, and explore new methods for future promotion.