Environmental Life Cycle Assessment of Hydrogen Energy Production for Fuel Cell Buses: A Review

This review synthesises the life cycle environmental performance of hydrogen production pathways for fuel cell bus applications based on a core systematic dataset of 19 peer-reviewed studies from the 2001–2020 review period, supplemented by recent literature to assess subsequent developments in the field. The reviewed literature shows that hydrogen produced using fossil-intensive electricity and coal gasification generally results in higher environmental impacts, whereas renewable-powered electrolysis provides substantially lower life cycle greenhouse gas emissions. Steam methane reforming remains an important hydrogen production pathway, and the reviewed studies indicate that carbon capture and storage can reduce its associated greenhouse gas emissions. Recent studies further indicate that the relative sustainability of hydrogen fuel cell buses is context- and scenario-dependent, with outcomes influenced by hydrogen production pathways, regional electricity systems, operational conditions, infrastructure, and economic factors. Considerable variation is observed among the reported environmental impacts, mainly because of differences in system boundaries, electricity generation mixes, geographical conditions, functional units, passenger loading assumptions, and LCA methodologies. Overall, the environmental performance of hydrogen fuel cell buses is strongly dependent on the hydrogen production pathway and the energy source used. Greater methodological standardisation and the increased use of low-carbon energy sources are therefore important for improving both the environmental performance and comparability of hydrogen-based bus systems.