Life Cycle Assessment of Hydrogen Use in Passenger Vehicles

This life cycle assessment (LCA) presents initial findings of potential environmental and human health impacts from fuel cell hybrid electric vehicles (FCHEV). The LCA is significant because it is based on the ecoinvent database of emissions and background processes, and it assesses a broad range of emission pathways. Although the paper highlights key areas in the life cycle of FCHEV, including the production of hydrogen (H2), it also highlights the need for additional and more accurate data on FCHEV production. Results are compared to internal combustion engine vehicles (ICEV). Introduction The environmental burdens associated with conventional road transportation extend much further than the combustion gases produced whilst driving; there are significant contributions from all other steps in the life cycle of the vehicle i.e. fuel supply, road infrastructures, as well as non-exhaust emissions from the vehicle (mainly from the tyres and brakes). Using hydrogen in fuel cell vehicles is seen as a possible solution to increase the security of transport-related fuel supply whilst offering the potential to reduce greenhouse gas (GHG) emissions. But hydrogen is an energy carrier which must be produced from other primary energy resources and means that the specific primary energy resource used and the method of conversion are highly influential on the overall environmental balance as has been shown in previous research. These studies have either focused on North American fuel chains and vehicle use or assess only specific greenhouse gas emissions (GHG) and energy demand. They may also be conducted within restrictive system boundaries which do not account for background processes and the demand for capital goods (e.g. production and transport infrastructures). An objective assessment of the environmental performances of conventional with alternative options of passenger transport therefore requires the inclusion of all direct and indirect processes and to compare them on the basis of a range of cumulative burdens on the environment and human health. Under the objectives of the THELMA project on electric mobility in Switzerland, the research presented in this paper is the life cycle assessment (LCA) of a fuel cell hybrid electric vehicle (FCHEV) running on gaseous hydrogen (H2) from different production pathways. The use of this passenger vehicle is compared with that of a gasoline internal combustion engine vehicle (ICEV). As a basis for comparison, all of the results refer to the functional unit of 1vkm (vehicle km). Inventory datasets for the FCHEV and H2 production pathways were modelled using the ecoinvent life cycle database of background processes. For the FCHEV H2 is produced by decentralised processes located at the fuelling station and representative of current (2010) technologies. The H2 is pressurised to 700 bar . The fuel cell technology is that of a polymer electrolyte membrane (PEM), also sometimes referred to as a proton exchange membrane. The results are shown in an impact assessment which considers GHG, non-renewable resource depletion (abiotic resources), acidification and eutrophication, ecotoxicity and respiratory inorganics the latter being related to human health. In comparison with the ICEV, the integration of fuel cells and other necessary drivetrain components in vehicles is a relatively new venture and still very much under development towards large-scale production volumes; a development which could still take at least another 10 to 15 years 12, . Also due to the lack of “reallife experience” regarding daily use, the performance parameters of the fuel cell as assumed in this study (e.g., system efficiency and lifetime) are therefore associated with relatively high uncertainties. A sensitivity analysis determines the influence of these factors on the LCA results. a Technology-centered Electric Mobility Assessment (THELMA). An inter-disciplinary project examining road transport technologies in the context of climate friendly policies. A collaboration between six laboratories of the PSI and ETH Zürich: www.thelma-emobility.net