Greenhouse gas assessment of urban buses based on environmental product declarations – a review

The paper presents a review study about comparative life cycle assessment (LCA) of selected 12-meter urban buses powered by hybrid, battery-electric, and hydrogen fuel cell systems. The review is based on Environmental Product Declarations (EPDs) and follows ISO 14040/44 standards, using a cradle-to-grave approach and a functional unit of 1 passenger-kilometer. Environmental impacts are assessed across raw material extraction, production, operation, maintenance, and end-of-life stages. Results of the review show that the operation phase has the highest share of total greenhouse gas emissions, particularly when fossil-based energy is used. For electric and hydrogen buses, upstream processes also contribute significantly due to material and component complexity. The findings highlight the role of energy mix and vehicle structure in determining the total impact, stressing the importance of full life cycle assessment in evaluating sustainable transport solutions. EPD can be the first step for developing a Digital Product Passport (DPP) for the buses.