Multi-objective assessment of hydrogen energy systems for residential PV integration in power-to-power and power-to-gas applications: A comparative life cycle assessment across european energy mixes

The building sector is one of the most energy-intensive sectors globally, and photovoltaic (PV) energy is widely adopted to meet residential energy demand in a low-carbon manner. However, the mismatch between PV production and household demand often leads to periods of surplus energy. This study aims to evaluate the potential of hydrogen-based energy systems to capitalize on this excess energy. To achieve this, a model that generates consistent, continuous, and diverse electrical and thermal load profiles for low-carbon residential buildings is coupled with a multi-energy system simulation. The simulation computes the performance of hydrogen components for different hydrogen utilization (Power-to-Power and Power-to-Gas) and energy mix configurations. The systems' energy, economic, and emission performance are analyzed using a multi-objective optimization process to evaluate their competitiveness and identify optimal sizing strategies. The results show that system performance varies significantly depending on the criteria, usage, and energy mix of the electrical grid. For Power-to-Power applications (using hydrogen to produce electricity and heat), the system excels in providing renewable energy but is not cost-competitive with the French electricity grid, nor does it significantly reduce emissions. However, it proves competitive in terms of life-cycle emissions considering most European energy mixes. For Power-to-Gas applications (producing hydrogen for sale), the hydrogen production is not economically competitive without subsidies but shows potential for reducing emissions, especially in carbon-intensive sectors like transport and industry.