Dynamic model of a power-to-gas system: Role of hydrogen storage and management strategies

Tackling climate change requires a drastic decarbonization of the energy system through the introduction of renewable energy technologies. However, a greater penetration of intermittent renewables requires large-scale flexible energy storage. This need, combined with the growing interest in the use of hydrogen in mobility and industry, makes tangible the prospect of including this energy vector in our daily lives. However, the problems related to the development of dedicated infrastructures make its positioning in the market complex. In a transition phase, power-to-gas systems constitute an emerging solution that allows the use of existing structures for natural gas and, at the same time, solves the problem of hydrogen storage. In this study, a power-to-gas system producing synthetic methane from wind energy was modeled. Management strategies for both the electrolysis system and the hydrogen storage were implemented. In particular, the impact of the storage on the mitigation of the operating condition fluctuation of the methanation unit was analyzed. To verify the influence of the sizing of the subsystems over the system performance, a sensitivity analysis on the sizes of the methanation unit and hydrogen storage was carried out. The conducted sensitivity analysis suggested selecting the smallest size of the hydrogen storage and the size of the methanation unit equal to 80% of the electrolysis system nominal production to achieve good performances of the power-to-gas system. However, the sizing of the subsystems depends on the context in which the power-to-gas system is integrated (i.e., characteristics of wind source), the possibility to valorize the hydrogen surplus (i.e., proximity to hydrogen users), and the specific objective for which the system has been designed.