Novel Waste-to-Energy and Sector Coupling Strategies Integrating Green Hydrogen for Urban District Decarbonization

This study investigates the energy, environmental, and economic performance of an integrated multi-energy system for the decarbonization of an existing urban district in Rome, Italy. The proposed configuration combines biogas-fueled combined heat and power, electric and gas absorption heat pumps, photovoltaic generation, green hydrogen production, methanation, and a fifth-generation district heating network. Three scenarios with hydrogen blending ratios of 10%, 15%, and 20% by volume were assessed against a conventional reference system. The analysis considers primary energy consumption, CO2 emissions, levelized cost of energy (LCOE), and carbon abatement cost (CAC), including the economic effects of ETS2. Results indicate that annual CO2 emissions decrease from 19,980 tCO2 in the reference case to 10,214 tCO2 at 20% hydrogen blending, with most of the reduction already achieved at 10%. Without ETS2, increasing hydrogen blending from 10% to 20% reduces the LCOE from 258 to 210 €/MWh and the CAC from 739 to 629 €/tCO2. When ETS2 is considered, the corresponding values increase to 276–225 €/MWh and 790–676 €/tCO2, respectively. A parametric sensitivity analysis, based on ±50% variations in technological and market parameters, identifies gas absorption heat pump (GAHP) and photovoltaic (PV) capital expenditures as the main drivers of both economic indicators. GAHP CAPEX variations produce changes of up to 43.0%, followed by PV CAPEX with variations of up to 28.3%. Overall, the 20% hydrogen scenario provides the lowest energy production and carbon abatement costs among the investigated configurations, although the relatively high CAC values indicate that further cost reductions are required to improve economic competitiveness.