How could pumped hydro energy storage power our future?

Reservoirs of water are poised to play a key role storing renewable energy to bolster the grid.

By: ARENA

How could pumped hydro energy storage power our future?

Like the hydroelectric power stations that have powered Tasmania for a century, a new generation of pumped hydro plants will play an important role in Australia’s future energy mix.

Pumped hydro operates within a closed system, storing energy as gravitational potential in water pumped uphill to an elevated reservoir when electricity is cheap and plentiful. When demand and electricity prices rise, the water is released to power a turbine and produce electricity.

Unlike traditional pumped hydro energy storage power stations that largely rely on motion from flowing or dammed rivers, pumped hydro plants cycle water within a closed system.

The amount of energy that can be stored is determined by the size of the upper reservoir – the world’s largest example is in Bath County Virginia, with 3003 MW of generation capacity and 24,000 MWh of storage.

Pumped Hydro Storage - How does it work infographic
Pumped Hydro Storage – How does it work infographic.

Back in Australia, approvals have been granted for the Snowy 2.0 project, which will link two existing dams in the New South Wales Snowy Mountains to provide 2,000 MW of capacity and 350,000 MWh of storage.

Why pumped hydro?

Now that renewables provide the most affordable form of new electricity generation, storage will be needed to keep the grid stable and ensure enough energy is available at all times.

Pumped hydro is able to store excess energy from windy and sunny periods to be used when renewable generation falls. The new Snowy 2.0 facility is forecast to be able to power approximately three million homes over the course of a week from its six generation units that will be installed deep underground within the Snowy Mountains.

Shoalhaven
The upper reservoir and pipelines at Origin’s Shoalhaven pumped hydro power station

With the Australian Energy Market Operator forecasting that 15 GW of large-scale storage will be needed by the early 2040s, pumped hydro is well-positioned to provide energy storage over long durations.

It is expected to operate alongside other storage technologies like large-scale batteries, which are emerging as a particularly effective way to inject electricity into the grid quickly to arrest frequency imbalances.

Unlike batteries, pumped hydro plants operate synchronous generators, contributing to the stability of the electricity grid in a world with more asynchronous wind and solar power.

Read more about ARENA’s pumped hydro energy storage projects.

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