Life cycle assessment of hydrogen and power production by supercritical water reforming of glycerol

• The environmental performance of the supercritical water reforming (SCWR) of glycerol was assessed.
• Biogenic CO2 emissions allowed quantifying a realistic GHG inventory of 3.8 kg CO2-eq/kg H2.
• The environmental profile of SCWR process was compared to those of other technologies.
• A good environmental performance of H2 and power production by SCWR of glycerol was obtained.

The environmental performance of hydrogen and electricity production by supercritical water reforming (SCWR) of glycerol was evaluated following a Life Cycle Assessment (LCA) approach. The heat-integrated process was designed to be energy self-sufficient. Mass and energy balances needed for the study were performed using Aspen Plus 8.4, and the environmental assessment was carried out through SimaPro 8.0. CML 2000 was selected as the life cycle impact assessment method, considering as impact categories the global warming, ozone layer depletion, abiotic depletion, photochemical oxidant formation, eutrophication, acidification, and cumulative energy demand. A distinction between biogenic and fossil CO2 emissions was done to quantify a more realistic GHG inventory of 3.77 kg CO2-eq per kg H2 produced. Additionally, the environmental profile of SCWR process was compared to other H2 production technologies such as steam methane reforming, carbon gasification, water electrolysis and dark fermentation among others. This way, it is shown that SCWR of glycerol allows reducing greenhouse gas emissions and obtaining a favorable positive life cycle energy balance, achieving a good environmental performance of H2 and power production by SCWR of glycerol.

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