Integrated Environmental and Economic Life Cycle Assessment of Urban Bus Technologies: A Methodological Framework for Fleet Transition

Keywords:

Abstract:

Purpose:
The energy transition in the urban public transport sector is a critical component of global strategies to reduce greenhouse gas (GHG) emissions and improve local air quality. Various propulsion architectures—ranging from conventional diesel to natural gas, renewable fuels, and battery electric vehicles—are being deployed in cities worldwide. However, the comparison among these alternatives is often fragmented. Environmental Life Cycle Assessment (LCA) studies typically focus on quantifying impacts from resource extraction to end-of-life, often neglecting the direct economic implications for operators and society. Conversely, Total Cost of Ownership (TCO) and Life Cycle Costing (LCC) analyses primarily emphasize the financial perspective of the operator, such as capital and operational expenditures, while marginalizing environmental externalities. The purpose of this study is to propose and develop an integrated methodological framework that simultaneously evaluates the environmental and economic performance of diverse urban bus architectures (Diesel S10, Biodiesel, CNG, LNG, Biomethane, and Battery Electric). By monetizing environmental impacts and aggregating them with private costs, this research aims to provide a comprehensive, systemic Life Cycle Costing (LCC) metric to support decision-making processes for public managers and transport operators, particularly in the context of fleet renewal and decarbonization policies in emerging economies like Brazil.
Design/Methodology:
The proposed methodology is structured into five interconnected modules to ensure a holistic evaluation. Module 1 (Environmental LCA) assesses the environmental performance of the targeted bus architectures using a well-to-wheel boundary, quantifying impacts such as climate change, particulate matter formation, and acidification per functional unit (passenger-kilometer). Module 2 (LCA Radar) normalizes these multi-criteria results into a dimensionless scale, allowing for a visual representation of the trade-offs between different impact categories for each technology. Module 3 (Monetization of Environmental Impacts) converts the characterized environmental damages into monetary values based on the ISO 14008 framework and external cost factors, adapting international references to the local economic context. Module 4 (TCO - Operator's Perspective) calculates the private costs borne by the transport operator, including vehicle acquisition, infrastructure investment, fuel, and maintenance over the asset's lifespan, discounted to present value. Finally, Module 5 (Systemic LCC) integrates the operator's TCO with the monetized environmental externalities to generate a consolidated societal cost indicator. This framework is designed to be tested and calibrated using secondary data from international literature, followed by an empirical application using primary operational data from the public transport system of Campinas, Brazil.
Findings:
The preliminary development of this methodological framework demonstrates that integrating LCA and LCC through the monetization of externalities provides a robust and comprehensive metric for comparing transport technologies. The approach reveals that while certain architectures, such as battery electric buses, may present higher initial capital expenditures (CAPEX) within the traditional TCO perspective, their systemic LCC can be highly competitive when the monetized benefits of reduced GHG emissions and local air pollutants are accounted for. Conversely, technologies based on natural gas and biomethane exhibit intermediate profiles, where the balance between infrastructure investments, fuel costs, and environmental performance heavily depends on the local energy matrix and operational context. The methodology also highlights significant methodological challenges, particularly the sensitivity of the systemic LCC to the unit factors used for monetizing environmental damages, which require careful calibration to reflect the specific socioeconomic realities of the application area.
Practical and Theoretical Implications:
Theoretically, this study contributes to the literature on Life Cycle Sustainability Assessment (LCSA) by operationalizing the integration of environmental and economic dimensions into a single, monetized framework applicable to heavy-duty urban transport. It bridges the gap between engineering-focused LCA and economics-focused TCO, offering a structured approach to internalize environmental externalities. Practically, the proposed framework serves as a vital decision-support tool for public policymakers and transport authorities. By translating complex environmental impacts into a unified monetary metric (cost per passenger-kilometer), it enables a more transparent and rational evaluation of technological alternatives for fleet renewal. This systemic perspective is essential for designing effective public tenders, structuring subsidies for renewable fuels and electrification, and ultimately guiding the transition towards more sustainable and economically viable urban mobility systems.

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