Conversion of landfilled waste-to-electricity (WTE) for energy efficiency improvement in Shenzhen (China): A strategy to contribute to resource recovery of unused methane for generating renewable energy on-site

Abstract

Recent growth of population and rapid urbanization have increased the generation of municipal solid waste (MSW) in Shenzhen (China). As a result, the city strives to implement circular economy (CE) by converting its landfilled waste into electricity. As a primary component in landfill gas (LFG), methane (CH4) emissions need to be mitigated to deal with climate change. This exploratory study investigates the utilization of LFG based on CH4 formation at a waste-to-energy (WTE) plant in Shenzhen (China) by converting landfilled waste into electricity. This work also explores the scheme of incorporating a combined cooling, heating, and power (CCHP) system into the WTE power station by utilizing the waste heat of a LFG power generation process. To maximize LFG utilization efficiency and optimize the return on investment (ROI) in the city's WTE, an economic viability of energy generation that incorporates a CCHP system into the plant is presented. The WTE's capacity for power generation and total energy provided by waste heat utilization are estimated. The benefits to local community and the project's long-term impacts on the environment are elaborated. It was found from modeling study that about 2.22E+11 kg of landfilled MSW during a 15-year period yielded 1.34E+10 kg of CH4, while 90% of CH4 production still occurred about 20 years after landfilling. During the 20-year of timespan, when harnessing the waste heat from power generation, the landfilled MSW in 2021 could generate 9.68E+8 kWh of electricity and 1.75E+13 kJ of heating, or 1.17E+13 kJ of cooling. The outputs can meet the energy demands of Shenzhen's urban buildings and its population for electricity, cooling, and heating. This implies that incorporating technological values to the landfilled waste for electricity generation not only promotes a CE, but also facilitates resource recovery from unused waste, thereby contributing to the UN Sustainable Development Goals (SDGs) by 2030.