Towards decarbonizing gas: A generic optimal gas flow model with linepack constraints for assessing the feasibility of hydrogen blending in existing gas networks

Hydrogen blending into natural gas networks is a promising pathway to decarbonize the gas sector but requires bespoke fluid-dynamic models to accurately capture the properties of hydrogen and assess its feasibility. This paper introduces a generalizable optimal transient gas flow model for transporting homogeneous natural gas-hydrogen mixtures in large-scale networks. Designed for preliminary planning, the model assesses whether a network can operate under a given hydrogen blending ratio without violating existing constraints such as pressure limits, pipeline and compressor capacity. A distinguishing feature of the model is a multi-day linepack management strategy that engenders realistic linepack profiles by precluding mathematically feasible but operationally unrealistic solutions, thereby accurately reflecting the flexibility of the gas system. The model is demonstrated on Western Australia's 7560 km transmission network, using real system topology and demand data from several representative days in 2022. Findings reveal that the system can accommodate up to 20 % mol hydrogen, potentially decarbonizing 7.80 % of gas demand.