Storing renewables in the gas network: modelling of power-to-gas seasonal storage flexibility in low-carbon power systems

The power-to-gas (P2G) process, whereby excess renewable electrical energy is used to form hydrogen and/or synthetic natural gas (NG) that are injected, transported, and stored in the gas network, has the prospect to become an important flexibility option for the seasonal storage of low-carbon electricity. This study is the first to model and assess the potential of P2G when combined with gas seasonal storage operation accounting for the two networks' characteristics and constraints (including the amount of hydrogen that can be blended with NG under different gas network conditions). Power system operation with P2G is analysed via a two-stage optimisation based on DC power flow to assess the gas production from otherwise curtailed renewables, also considering impact of P2G on short-term and long-term gas prices. Additionally, impact of P2G on gas network operation and its potentially required re-dispatch are evaluated with a steady-state gas flow model. Case studies conducted on the Great Britain gas and electrical transmission networks quantify benefits and limitations of the integrated usage of P2G with seasonal gas storage under different scenarios. The proposed model thus sets the fundamentals for further development of this emerging technology as a seasonal storage option in low-carbon power systems.