Environmental Impacts and Life Cycle Assessment of Biohydrogen

Biohydrogen is increasingly recognized as a promising alternative to fossil fuels for meeting global energy demands and addressing climate change. Hydrogen is recognized as an environmentally friendly energy carrier but it needs to be proven by LCA. In this paper, the environmental impacts of hydrogen were evaluated by using Life Cycle Assessment (LCA) of both biological and thermochemical routes. The midpoint impacts of global warming potential (GWP), eutrophication potential, acidification plus energy demand (ADER), system boundaries (SB), functional unit (FU) and allocation are presented. Existing literature and reported cases from industries were employed as LCIA data sources. Sensitivity analysis was also applied to validate uncertainty and regional differences. Based on LCIA, it was found that biohydrogen routes have lower GWP compared to conventional fossil fuel hydrogen production. The environmental impact still depends on where it is produced, what kind of raw material is used and how efficient the technology is. Valorization of waste and optimization of processes were found to be the key influential steps to better the LCIA of biohydrogen production. Lastly, more contextual and dynamic LCA approaches are needed to support future technology applications. The methodology for LCIA of biohydrogen needs to be agreed upon internationally. More comprehensive studies that combined environmental, economic, and social impact assessments are also required. Future research should focus on expanding data availability, refining impact models and embedding life cycle thinking into energy policy frameworks to fully realize the environmental benefits of biohydrogen.