At its very simplest, pumped storage hydro (PSH) can be thought of as a giant battery.  The concept is basic enough, pump water up-hill when electricity prices are low and use it to generate electricity when prices are high, arbitraging the price differences for revenue. How much energy can be stored and utilised depends on a combination of the volume of water available and the elevation difference in the circuit.

PSH can be either open cycle– where water is accessed from and released into large water sources such as a sea or ocean, or closed cycle – where water is moved between two reservoirs.

A key advantage of pumped storage hydro is that no rivers are dammed or diverted.  This ensures that sensitive ecosystems are protected from the electricity generation activities.  By using reversible turbines, water can be pumped from the lower reservoir to the upper reservoir.

Pumped storage hydro power is the largest form of grid energy storage available in the world at around 127 GW it represents approximately 99% of grid energy storage installed capacity.  Its appeal stems from its fast response times and excellent network support.

Despite the widespread appeal of pumped storage hydro power to electricity networks, its roll-out within Australia has largely been slowed by the limited suitable sites available.