Synergies between Power-to-Heat and Power-to-Gas in renewable energy communities

The deployment of intermittent renewables in distributed energy systems has to be managed so as to maximise local energy self-consumption. This paper deals with the application of sector coupling strategies to increase energy self-consumption and decarbonise urban energy districts. The aim of this work is to investigate the combined implementation of Power-to-Gas and Power-to-Heat strategies in Renewable Energy Communities. Power-to-Power, Power-to-Heat and Power-to-Gas systems, along with their combined adoption, have been implemented in a residential community under different renewable excess conditions. For each strategy, the storage system's size has been optimised and the configurations have been compared in energy, environmental and economic terms. The Power-to-Heat strategy is the most cost-effective solution, although it presents intrinsic limitations. The Power-to-Gas configuration involves the hydrogen injection into the gas grid, thus exploiting the local network as a free storage system. Higher self-consumption can be achieved; nevertheless, energy and emissions savings are lower due to the electrolyser poor efficiency. The combined application of the two sector coupling strategies allows the strategies individual advantages to be exploited and the limitations of both to be overcome. Furthermore, this solution leads to higher self-consumption and lower annual costs than conventional electric batteries.