Exergy and Environmental Analysis of a Bio-Hydrogen Supply Chain Using Data Envelope Analysis

Abstract

Hydrogen is a promising fuel for fuel cell (FC) mobility use, given its high energy density and the lack of CO₂ emission from its use during the operating stage of mobility. In addition, biomass-derived hydrogen, which is carbon neutral, is an attractive fuel because its use can mitigate CO₂ emission during the hydrogen production stage. However, because of the low energy density of biomass feedstocks, they first must be effectively converted to hydrogen; an effective hydrogen use path, including hydrogen storage and mobility and FC utilization for different scale mobility, that takes into consideration the environmental impacts and exergy is needed. In this study, the entire hydrogen path (hydrogen production, hydrogen storage, and mobility) was investigated using life cycle assessment and exergy analysis to determine the corresponding environmental and exergy hotspots and an effective hydrogen path. To compare various types of functional mobility, data envelope analysis was used. It was found that metal hydride (MH) utilization was an important factor in the mitigation of environmental damages caused by using hydrogen as fuel and in the effective use of biomass feed feedstock. Also, it was indicated that the reduction of precious metals in MH and FC would be necessary to mitigate environmental impacts.