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This paper evaluated steam and CO2-enhanced gasification of spent coffee ground (SCG) biomass, including energy and exergy aspects focusing on hydrogen production. The waste-to-hydrogen (WTH) conversion was performed via gasification (1000 °C) with a drop-tube-reactor investigating six different steam to biomass (SBR of 0.5, 0.8 and 1.2) and CO2 to biomass (CO2BR 0.09, 0.18 and 0.27) ratios. The syngas production indicated clear improvement against O2/N2 with an H2 yield increase up to 69.21% and 18.32% for steam and CO2 mediums. The energy and exergy analysis points out the 0.8 SBR as the optimum condition with 210% CGE and 48.05% exergy efficiency for H2 production. As a strategy for carbon capture and usage, the medium with 0.27 CO2BR provided a 28.52% exergy efficiency for H2 production and reduced soot formation, showing a potential gasification medium for SCG. Results encourage waste-to-hydrogen prospection within circular economy principles, boosting circular economy principles in urban districts.

This study applied Life Cycle and Risk Assessment (LCRA) to characterize a sugar-energy refinery's operation, considering greenhouse gas emissions. The introduction of disturbances in mass or energy flows within LCRA enabled the simulation of accidental hypotheses, with the estimation of their environmental impacts from an approach oriented to the final damage. A risk value was assigned to each transient scenario (10, 30, and 100% leakage), and criteria was defined for accepting losses, calculating probabilities and identifying other associated tangible and intangible damages. The method provided a consistent theoretical basis that reduces ambiguity in estimating environmental impacts associated with transient events.