Improving urban ecosystem holistic sustainability of municipal solid waste-to-energy strategy using extended exergy accounting analysis

Jianrui Liu; Harn Wei Kua; Chi-Hwa Wang; Yen Wah Tong; Jingxin Zhang; Yinghong Peng

doi:10.1016/j.scitotenv.2023.166730

Improving urban ecosystem holistic sustainability of municipal solid waste-to-energy strategy using extended exergy accounting analysis

Sci Total Environ. 2023 Dec 15:904:166730. doi: 10.1016/j.scitotenv.2023.166730. Epub 2023 Aug 31.

Authors

Jianrui Liu¹, Harn Wei Kua², Chi-Hwa Wang³, Yen Wah Tong³, Jingxin Zhang⁴, Yinghong Peng⁵

Affiliations

¹ Department of Mechanical Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
² Department of the Built Environment, College of Design and Engineering, National University of Singapore, 4 Architecture Drive, Singapore 117566, Singapore. Electronic address: bdgkuahw@nus.edu.sg.
³ Department of Chemical and Biomolecular Engineering, College of Design and Engineering, National University of Singapore, 4 Engineering Drive, Singapore 117585, Singapore; Energy and Environmental Sustainability Solutions for Megacities (E2S2), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 138602, Singapore.
⁴ China-UK Low Carbon College, Shanghai Jiao Tong University, 138602, China.
⁵ Department of Mechanical Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Energy and Environmental Sustainability Solutions for Megacities (E2S2), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 138602, Singapore.

PMID: 37659547
DOI: 10.1016/j.scitotenv.2023.166730

Abstract

Waste-to-energy technologies play a crucial role in integrated waste management strategies to reduce waste mass and volume, disinfect the waste, and recover energy; different technologies have advantages and disadvantages in treating municipal solid waste under urban conditions. This paper applies the extended exergy accounting method to develop an analytical framework to identify the optimal waste-to-energy strategy from an urban ecosystem holistic sustainability perspective. In the analytical framework, urban ecosystem costs and revenues are formulated as a multi-criteria cost-benefit quantitative model. The urban ecosystem cost is divided into five categories, and the urban ecosystem revenues consist of direct and indirect parts. The direct part is the chemical exergy of the waste-to-energy plants produced product, and the indirect part includes equivalent exergy content of power generation substitution, human health risk elimination, disamenity impact removal and environmental degradation avoidance. Proposing an indicator system to evaluate the waste-to-energy strategy impact on the sustainability of the urban ecosystems and social, economic and environmental sub-ecosystem. Detailed analysis of food waste treatment scenarios of a food center in Singapore was done as a case study to illustrate this analytical framework. Base scenario is current practice that food waste disposal in incineration plant. Anaerobic digestion and gasification are proposed as potential technological solutions for on-site food waste treatment in scenario I and II respectively. In different scenarios, the urban ecosystem costs are estimated to be 71,536.01, 61,854.87 and 74,190.34MJ/year respectively, and the urban ecosystem revenues are estimated to be 135,312.66, 405,442.53 and 298,426.81MJ/year respectively. We show that the scenario where food waste is treated by anaerobic digestion outperforms both the base scenario and scenario II in terms of urban ecosystem costs and revenues, technical energy conversion efficiency, contribution to urban ecosystem holistic sustainability, and natural, social, and economic subsystems improvement, making it the optimal municipal solid waste-to-energy strategy choice.

Keywords: Cost-benefit model; Extend exergy accounting; Municipal solid waste; Sustainability indicator; Urban ecosystem; Waste-to-energy.