Hydrogen blending in Italian natural gas grid: Scenario analysis and LCA

In this paper, a detailed analysis of the impact of hydrogen blending in the natural gas grid in terms of potential increase of Intermittent Renewable Energy Source (IRES) penetration, increase of electrolyzer power installed, reduction of CO2 emission and environmental footprint, is provided formulating models in EnergyPLAN and OpenLCA software. The Italian energy system is taken as case-study. Three scenarios have been analysed: BASELINE scenario represents the current energy system; MID-SCENARIO foresees a total IRES capacity of 158.17 GW (x5 compared to 2019 capacity) derived from the capability to convert intermittent electricity surplus in hydrogen and inject it in the natural gas grid; in the END-SCENARIO, the IRES capacity is pushed up to 272.1 GW. The main outcomes of the study attest that blending of hydrogen in the natural gas grid leads to beneficial impacts in terms of environmental footprint. Considering the global energy system, hydrogen production and blending in the natural gas grid leads to a maximum decrease of 15% in CO2 emissions compared to 2019. The impact is significant but limited by a threshold in the maximum hydrogen amount that the gas distribution infrastructure can currently accept (hydrogen molar fraction <20%). Focusing the study on the electricity generation sector, the reduction of CO2 emissions reaches −66% in the END-SCENARIO. The LCA index “Fossil resource scarcity” is reduced by up to −77% due to the replacement of fossil fuels, starting from coal. On the other hand, the LCA category “Mineral scarcity” undergoes an increase (x3.03 in MID-SCENARIO, ×2.73 in END-SCENARIO) due to the large amounts of materials needed to manufacture the photovoltaic plants, wind farms and electrolyzers, such as copper, aluminum, platinum, nickel, titanium and silicon, exacerbating the critical materials issue.