Modelling hydrogen storage requirements to balance the future Western Australian grid

Increasing renewable energy technology penetration into electrical grids to meet net zero CO₂ emission targets is a key challenge in terms of intermittency; one solution is the provision of sufficient energy storage. In the current study we considered future projections of electrical demand and renewable energy (in 2042) for the Southwest Interconnected System grid in Western Australia. Required energy storage considered is a mixture of battery energy storage systems and underground hydrogen storage in a depleted gas reservoir. The Southwest Interconnected System serves as an excellent case study given that it is a comparatively large, isolated grid with substantial potential access to renewable energy resources as well as potential underground hydrogen storage sites. This work utilised a dynamic energy model that summates the wind and solar energy resources on an hourly basis. Excess energy utilised battery energy storage systems capacity first, followed by underground hydrogen storage. The relative size of the renewables and the storage options is then optimised in terms of minimising wholesale energy production costs. This unique optimisation analysis across the full, integrated system clearly indicated that both battery energy storage systems and underground hydrogen storage are required; underground hydrogen storage is predominately necessary to meet seasonal unmet energy demand that amounts to approximately 6% of total demand. Underground hydrogen storage costs were dominated by the required electrolyser requirements. The optimised levelised cost of electricity was found to be US$106/MWh, which is approximately 45% larger than current wholesale electricity prices.