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Pumped hydro-energy is coming to Walpole in WA. But there are a number of different types of hydroelectricity systems. We explain the difference.

Hydroelectricity continues to be a renewable energy game changer – able to generate and store vast amounts of clean, stable energy.

As well as generating power, it’s also become the most common form of energy storage, acting like a battery, through pumped hydro energy storage (PHES).

In Australia, the use of hydro power has traditionally been on the east coast.

In NSW, home to the 70-year-old and high-profile Snowy Hydro scheme, there are around 35 large to medium pumped hydro-electric power stations along rivers and dams using PHES technology.

Hydro is seen in NSW as the forerunner to replacing ageing coal stations. However it’s not without debate. Hydroelectricity requires elevation and a dam for water to flow and be stored, meaning there can be environmental impacts.

New to the mix is mini-pumped hydro, an exciting new technology being installed in Walpole.

Mini-hydro has fewer environmental impacts and can be used in many more locations, making it a tantalisingly viable option for future energy generation.

So what is the difference between hydro power, pumped hydro and mini-pumped hydro?

What is hydroelectricity?

Hydro power uses the movement of water to create energy. It’s not a new technology – water wheels, used since ancient Grecian times, are examples of early hydropower.

In those simple examples, water flowing from a stream would hit a turbine with blades, causing the turbine to spin. This would then drive the action of other machinery, such as milling grain, or lifting water to irrigate crops.

Those ancient technologies were reliant on the flow of a stream or river to keep the turbine turning.

What is pumped hydro energy storage?

Pumped hydro energy storage (PHES) is a form of hydroelectricity, but its purpose is more to store rather than generate energy. This means it has more in common with a battery than a traditional hydro plant.

In a PHES system, excess energy generated from wind or solar is used to pump water up to a reservoir or dam at a higher elevation/point where it is stored.

When that stored water is released to flow back down through a turbine, the movement of this stored water generates energy. That means the water stored in the dam becomes ‘stored energy’, like a battery, ready to be used when needed.

This is how PHES can help with the fluctuations of renewable energy. It uses the surplus solar or wind power - when there is too much being generated - to pump water. Then, when the sun is not shining or wind not blowing, the stored water is released to create energy that smooths over energy generation lulls.

PHES accounts for more than 90 per cent of all the world’s installed energy storage capacity, more than lithium batteries.

Pumped hydro is therefore seen as a great option to create steady baseload energy.

What is mini-pumped hydro?

Mini-pumped hydro is like the equivalent of how the computing capacity of a 1950s mainframe now sits inside your smartphone.

While large-scale pumped hydro operations require a large dam or reservoir to be constructed, mini-pumped hydro is a much smaller operation, typically using existing ‘infrastructure’ like an old mining pit or farmer’s dam – as long as the water has sufficient height to create energy.

The smaller infrastructure means mini-pumped hydro has a significantly reduced environmental footprint, making it more versatile in where it can be located, particularly in the south west of WA.

The new mini-pumped hydro facility in Walpole only requires a 90m incline or drop, and doesn’t require major augmentation to connect to the grid, making it more economical as a grid solution to increase reliability and sustainability.

Although mini-pumped hydro generates less energy than larger scale operations, typically from 1 to 30MW, it is effective at generating or storing energy for a local area like Walpole.

It means mini-pumped hydro has the potential to make very big waves in the energy landscape, offering flexible and accessible tool to generate and store localised energy.

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