Short-Term Off-River Energy Storage (STORES) is a breed of pumped hydro energy storage which incorporates closed-loop pumped hydro systems located away from rivers. Compared with conventional river-based hydroelectric projects, the STORES facilities consume modest volume of water and have little impacts on the environment and natural landscape. A significant feature of STORES is the large altitude difference between upper and lower reservoirs (typically > 300 metres), which enables large amounts of electrical energy to be stored in pairs of medium-sized reservoirs. STORES is capable of large-scale energy time shifting and a variety of ancillary services such as frequency regulation and voltage control, which can facilitate high penetration of photovoltaics and wind in electricity systems. This study investigates the potential for STORES to be deployed in Australia supporting large-scale photovoltaics and wind developments in the Australian electricity markets. The study is comprised of two aspects: 1. Grid integration modelling of photovoltaics, wind and pumped hydro with a focus on the analysis of energy supply and demand balance in 100% renewable electricity systems. Hypothetical scenarios for 100% renewable electricity in the Australian National Electricity Market (NEM) and 90-100% renewable electricity in the South West Interconnected System (SWIS) of Western Australia are modelled. An energy balance model is used to determine the least-cost configuration of generation, storage and transmission facilities based on the hour-by-hour analysis of historical solar and wind data and electricity demand in 2006-2010 (NEM) and 2007-2014 (SWIS). The levelised costs of electricity normalised to 2016 Australian dollars are $75-93/MWh for the NEM and $103-129/MWh for the SWIS, which can be competitive with new-build coal or natural gas-fired power stations in Australia. Importantly, the levelised costs of balancing are only $25-$28/MWh in the NEM and $37-$41/MWh in the SWIS, which are significantly lower than the ...