Comparative life cycle assessment of hydrogen–natural gas blending in residential heating networks for cold climate regions

Purpose This study presents a technical and environmental assessment of decentralized green hydrogen production for blending into existing natural gas networks to meet residential heating demand in cold-climate regions. The proposed system integrates photovoltaic (PV) energy, a proton exchange membrane electrolyzer (PEMEL), reverse osmosis water purification, multi-stage compression, and seasonal hydrogen storage. Methods A dynamic model of the system is developed in MATLAB/Simulink using Simscape, enabling high-resolution simulations of hydrogen production, buffering, compression, and distribution processes over one year. Real thermal demand data from Ronzo-Chienis, a municipality in the Autonomous Province of Trento (Italy), are used as the primary case study. The hydrogen production plant is modelled using site-specific solar irradiance data and local thermal demand profiles, accounting for both daily and seasonal variability. Two hydrogen-blending scenarios (S1: 10% and S2: 20% by volume) are evaluated for system performance, technical feasibility, and environmental benefits. A Life Cycle Assessment is conducted following ISO 14040/44 standards using SimaPro Craft v10.2, comparing the hydrogen-based heating system with a conventional natural gas supply (business-as-usual scenario, 100% CH₄). Results and discussion The results show that increasing the share of H₂ up to 20% could lead to a reduction in 12 out of 18 impact categories, with benefits of 2–20%. Compared with the business-as-usual scenario, the scenario with 10% hydrogen would avoid 27.6 kg CO₂ eq/MWh, while the scenario with 20% hydrogen would avoid 54.9 kg CO₂ eq/MWh, showing a proportional and more pronounced reduction in the other impact categories as well. For example, S2 would lead to reductions in stratospheric ozone depletion and land use (− 18%), marine eutrophication and terrestrial acidification (− 17%), ionizing radiation and freshwater eutrophication (− 14%). Considering the energy demand of Ronzo-Chienis, the introduction of H₂ is estimated to result in an annual reduction of approximately 440–875 t CO₂ eq (435–865 kg per capita), accompanied by further reductions in overall environmental impacts. Conclusions Overall, the combined results of dynamic modelling and LCA indicate that the introduction of hydrogen into domestic heating systems in Alpine regions could represent a credible pathway for the decarbonisation of residential energy systems, particularly in contexts characterised by harsh winters and high heating demand. Under such conditions, integrating hydrogen into the domestic energy mix could significantly reduce emissions, as even modest improvements in efficiency may translate into substantial seasonal emission savings.