Short-Term Off-River Energy Storage to facilitate a 100% wind & photovoltaics scenario for the South West Interconnected System in Western Australia

In Australia, as renewable energy penetration in electricity markets increases along with closure of fossil fuel power stations at the end of their lives, the need for grid-scale, commercially available energy storage systems intensifies. To ensure a secure and reliable renewable power system, it is critical to deploy sufficient energy storage facilities in a costeffective way, balancing intermittent energy production from wind & solar PV farms with the varying demand for electricity in real-time. Short-Term Off-River Energy Storage (STORES) is a new breed of pumped hydro energy storage designed to assimilate short-term fluctuations in power system. Compared with conventional on-river pumped hydro energy storage (PHES) which requires the construction of dams on existing major water systems, no existing natural water body is required for the paired reservoirs for pumping/generation operation, and hence there is no flood control issues and no interaction with the ecology of river system. Moderately-sized pondage (1-10 ha) means low water consumption for initiating and operating the facilities, as well as low land use requirements. A GIS-based screening study for prospective STORES sites was conducted over the southwest of Western Australia (WA) on the basis of pre-defined search criteria (Table 1). Isolated from the National Electricity Market (NEM), the self-contained South West Interconnected System (SWIS) is a network where STORES systems can be of great value. The GIS searching process was designed as three sequential procedures: sites location, reservoir identification, and potential quantifying (Figure 1). GIS algorithms applied in the screening study showed improvements in productivity in searching process and yielded satisfactory results as required. The study proceeded to chronological dispatch modelling based on analysing half-hourly wind speed and direction data, gridded hourly solar DNI & GHI data, and half-hourly SWIS electricity demand, together with the results of searching process from the GIS screening study. The research showed STORES has a great potential to be deployed in the southwest of WA especially in the Darling Range area. A dozen prospective sites (Head ≥ 200m) with a total energy potential of 10 GWh were identified (Figure 2). This can provide sufficient storage to smooth short-term fluctuations and support a 100% wind & solar PV scenario for the SWIS network.