Lithium–sulfur battery technology presents a promising pathway for advancing the electrification of sustainable public transportation systems

Abstract

Public transportation plays a crucial role in reducing traffic congestion, greenhouse gas emissions, and social inequalities in urban systems. However, selecting the most sustainable transit bus technologies remains challenging because socio-economic conditions, geographic characteristics, and energy infrastructures vary across regions. This study aims to develop an integrated sustainability-based decision-making framework to evaluate and optimize alternative-fuel bus technologies across different urban contexts. The study proposes a novel sustainability-integrated multi-objective decision-making (SI-MODM) framework that uniquely combines three integrated components: 1) an activity-based life-cycle sustainability assessment model incorporating a battery upscale cost model for an emerging and understudied advanced solid-state battery technology, 2) systematic embedding of region-specific operational and socio-economic context across different dimensions (e.g. driving cycles, urban geography, etc.), and a multi-objective optimization model for strategic fleet planning. This integrated approach enables the first comprehensive evaluation of advanced solid-state lithium sulfur (ASSLiS) batteries for urban transit applications alongside conventional alternatives (diesel, hybrid, compressed natural gas (CNG), and battery electric buses (BEBs) powered by ASSLiS and lithium-ion nickel manganese cobalt oxide (NMC-LIB) batteries). Real-world driving cycles from four major U.S. cities, such as Atlanta, Chicago, Denver, and New York, were incorporated to capture region-specific operational conditions. The results indicate that BEBs powered by ASSLiS batteries demonstrate the lowest life-cycle carbon emission intensity among all alternatives. In addition, ASSLiS-powered BEBs achieve, on average, 2.5% lower life-cycle costs compared to BEBs powered by conventional LIB batteries. Across all cities analyzed, the ASSLiS BEB consistently appeared in the optimal fleet composition solutions generated by the multi-objective optimization model. The findings also reveal that urban geographic and demographic characteristics significantly influence the life-cycle sustainability performance of alternative-fuel bus technologies. The proposed framework provides a robust analytical tool for policymakers and transit agencies to support sustainable fleet planning decisions. The results suggest that advanced solid-state lithium–sulfur battery technologies offer significant environmental and economic advantages for urban bus electrification. Moreover, the study highlights the importance of incorporating region-specific operational and socio-economic factors when evaluating sustainable public transportation technologies.