Life Cycle Assessment of a Chamotte–Nickel Oxygen Carrier: Hotspot Identification and Implications for Cleaner Hydrogen Production

Abstract Oxygen carriers (OCs) are essential materials in chemical looping technologies for low-carbon hydrogen production; however, the environmental implications of their synthesis remain insufficiently explored. This study presents a gate-to-gate life cycle assessment (LCA) of a chamotte–nickel OC produced via wet impregnation, following ISO 14040/44 guidelines. The functional unit was 1 kg of OC, requiring 0.8 kg of chamotte, 1.042 kg of nickel nitrate, and 0.66 kg of water. Environmental impacts were modeled using ReCiPe 2016 Midpoint (H). Transportation dominated 15 of the 18 impact categories, particularly toxicity and resource depletion, while wet impregnation contributed 38.9% to climate change and 55.6% to terrestrial acidification. Thermal treatments were major sources of N₂O and NOₓ, significantly affecting climate change and human toxicity. Hotspot analysis identified precursor selection, energy supply, and logistics as key drivers of environmental burdens. Mitigation strategies—including precursor substitution, renewable-energy integration, low-energy synthesis routes, emission abatement, and industrial symbiosis—could reduce CO₂-eq emissions by 30–50% and NOₓ by up to 90%. These results offer actionable guidance for sustainable OC design and highlight the importance of integrating LCA into early-stage materials engineering to support cleaner hydrogen production and circular resource flows.