Power-to-Gas in gas and electricity distribution systems: A comparison of different modeling approaches

Power-to-Gas (P2G) has been one of the most frequently discussed technologies in the last few years. Thanks to its high flexibility, it can offer services to power systems, thereby fostering Variable Renewable Energy Sources (VRES) and the electricity demand match, mitigating the issues related to VRES overproduction. The analysis of P2G systems used at the distribution level has only been dealt with in a few studies: however, at this level, critical operation conditions can easily arise, in both the electrical infrastructure and in the gas infrastructure. The choice of appropriate modeling approaches for a P2G plant, as well as for the electricity and gas distribution grids is necessary to avoid overestimating or underestimating the potential flexibility that P2G plants connected to distribution networks can offer. The study presents a methodological analysis on the impact of different simulation approaches when P2G is installed at a distribution system level. The aim of this paper has been to understand the impact of different modeling approaches in order to determine whether, and under what conditions, they could be adopted. An illustrative case study has been developed to perform this analysis. The results show that the flexibility of the P2G technology can also be used at the distribution level; nevertheless, a correct modeling approach is necessary to properly evaluate the potential of this solution. The placement of P2G systems within the electricity network can affect the performance of the plant to a great extent. Therefore, it is necessary to use a model that takes into account the topology and energy flows of the electrical network. It was found, in the analyzed case study, that the use of an inappropriate electricity network model can lead, depending on the conditions, to either an overestimation or an underestimation (of 50 % and 40 %, respectively) of the ability of P2G plants to absorb VRES over-generation. The accuracy of the gas network and of the P2G plant models also plays an important role. In conditions of low gas consumption, it is necessary to consider the gas flows and the line-pack potential of the gas network, as well as the interactions between the components of the P2G plant in order to avoid underestimating the flexibility of the entire system. In the analyzed case study, the use of a simplified model of the gas network led to an underestimation of the accumulation potential of the overgenerations of VRES of about 30 %, while the use of a simplified model for the simulation of P2G plants led to a 10 % underestimation of the storage potential.