Eco-Audit of MOFs as H₂ Storage Materials for Vehicle Applications, Using Novel Refueling Model

Abstract

Metal-organic frameworks (MOFs) are a heavily researched candidate for fuel-cell electric vehicle (FCEV) hydrogen storage. However, little analysis has been done on the environmental impact of potential MOF vehicles compared to established alternative vehicles, such as compressed hydrogen or battery-electric vehicles. In this work, a preliminary eco-audit was conducted for a FCEV using an MOF hydrogen storage system based the best current MOF Ni₂(m-dobdc) (Ni-MOF-74). (1) Cost and environmental impact analyses were performed for both the production and use phases of an MOF-FCEV. The cost and environmental impact of MOF production was compared to that of Lithium Nickel Manganese Cobalt Oxide (LiNMCO) batteries, the current state-of-the-art for BEVs. (2) Environmental impact was assessed using embodied energy estimates based on reported values for LiNMCO BEVs. These highlighted MOF vehicles as a competitor to current renewable energy vehicle technologies. For the use phase, a hydrogen refueling station that produces hydrogen onsite by proton exchange membrane (PEM) electrolysis from grid electricity was compared to an equivalent population of battery electric vehicles (BEVs) charged at distributed recharging stations. FCEVs using the proposed refueling model were able to compete with BEVs both in terms of electricity CO₂ footprint and cost in the simulated solar-dominated Californian grid, but not in the hydro- and nuclear-heavy Ontario grid.