  To move towards a low-carbon society by 2050, understanding the intricate
dynamics of energy systems is critical. Our study examines these interactions
through the lens of hydrogen storage, dividing it into 'direct' and 'indirect'
hydrogen storage. Direct hydrogen storage involves electrolysis-produced
hydrogen being stored before use, while indirect storage first transforms
hydrogen into gas via the Sabatier process for later energy distribution.
Firstly, we utilize the PyPSA-Eur-Sec-30-path model to capture the interactions
within the energy system. The model is an hour-level, one node per country
system that encompasses a range of energy transformation technologies,
outlining a pathway for Europe to reduce carbon emissions by 95 percent by 2050
compared to 1990, with updates every 5 years. Subsequently, we employ both
quantitative and qualitative approaches to thoroughly analyze these complex
relationships. Our research indicates that during the European green
transition, cross-country flow of electricity will play an important role in
Europe's rapid decarbonization stage before the large-scale introduction of
energy storage. Under the paper cost assumptions, fuel cells are not considered
a viable option. This research further identifies the significant impact of
natural resource variability on the local energy mix, highlighting indirect
hydrogen storage as a common solution due to the better economic performance
and actively fluctuation pattern. Specifically, indirect hydrogen storage will
contribute at least 60 percent of hydrogen storage benefits, reaching 100
percent in Italy. Moreover, its fluctuation pattern will change with the local
energy structure, which is a distinct difference with the unchanged pattern of
direct hydrogen storage and battery storage.
