Comparative Life-Cycle Assessment of Biochar and Nickel Catalysts for CO ₂ -Free Hydrogen Production via Methane Decomposition

Growing concerns about global warming from fossil fuel combustion underscore the need for sustainable hydrogen production. Catalytic methane decomposition (CMD) offers a CO2-free pathway by generating hydrogen and solid carbon. This study performs a cradle-to-gate life-cycle assessment of CMD using two catalytic systems, including Ni/Al2O3 (metal-based) and biochar (renewable carbon-based), for producing 1 kg H2 under physical and economic allocation approaches. The physical allocation results demonstrated biochar’s superior environmental performance, with 26% lower fossil fuel depletion (11.30 vs 15.32 MJ) and 31% lower global warming impact (3.04 vs 4.38 kg CO2 eq) compared to Ni catalysts. In contrast, economic allocation results showed smaller improvements for biochar compared to the Ni catalyst (reductions of 17.21 and 25.07% for fossil fuel depletion and global warming impact, respectively). These findings highlight biochar’s promise as a sustainable catalyst for CMD and support the broader transition toward low-carbon hydrogen technologies.