Life Cycle Impacts and External Costs for Various Hydrogen Pathways

Hydrogen is an energy vector of considerable recent interest because of its perceived environmental benignity. Aspects of the hydrogen economy are addressed in this article by quantifying associated impacts and costs. For the first time, important questions are addressed in a comprehensive way. Impact assessments and external cost analyses investigate whether hydrogen should replace standard fuels and which production technologies are preferred. Finally, the life cycle stages of that contribute the largest impacts are identified. If external costs are to be minimized in the operation of a U.S. hydrogen economy, it is recommended that hydrogen (H₂) be produced from solar thermochemical (STC) cycles and wind electrolysis, with the possible use of steam methane reforming (SMR). The external costs associated with biomass gasification are shown to be comparable with those for wind electrolysis. Thus, biomass-produced hydrogen could also be a viable alternative, especially in areas ideally suited to the growth of energy crops. Finally, the most influential life cycle stages are the Construction of the Fuel Cell Vehicle (FCV) and Hydrogen Production (except for the environmentally benign wind electrolysis). For the wind/electrolysis case, the majority of impacts come from plant construction.