Turning Water To Power. Tech Talk Column 372.

Many people find beauty in various forms – be it paintings, sculptures, or the splendour of natural landscapes. I find beauty in the elegant simplicity of science and technology. Take the phenomenon of gravity as an example. If you knock a coffee cup off a table, you can be certain it will accelerate towards the ground at 9.8 metres per second squared. This law of physics is consistent, predictable, and, with miniscule variations, true anywhere on Earth.

As we usher in a new era of the global economy, Australia finds itself in an enviable position, ready to capitalise on emerging opportunities we’ve not yet even imagined. Nowhere is this more apparent than in the renewable energy sector. Australia is rich in three pivotal resources: sunlight, wind, and open space. Yet, harnessing these elements effectively presents a logistical challenge, particularly when it comes to energy storage. The sun doesn’t shine all day, and the wind is often capricious, making it crucial to have a reliable method of storing generated energy.

Traditionally, the solution to this storage dilemma has been batteries. But these are far from perfect. Batteries are expensive to manufacture, and their production process requires mined resources. They also have a finite lifespan and are prone to slow energy leakage – losing up to two per cent of their stored power each month.

Innovation, however, is alive and well, and as we explore Australia’s regional areas, an alternative solution comes into view: pumped hydro storage. Hydroelectric power is not new; it was first utilised in England in 1878 when Lord Armstrong used hydro to illuminate an arc lamp in his art gallery. The first commercial hydroelectric plant came into existence in Wisconsin, USA, in 1882. Many people would be familiar with the Niagara Falls hydroelectric project, involving innovators Nikola Tesla and George Westinghouse, which commenced operations in 1895.

While most hydroelectric initiatives concentrate on generating electricity via falling water, my focus is on the possibilities it offers for energy storage. The concept of pumped hydroelectric storage systems started to take shape in the 1940s. These systems are beautifully simple in design, relying on two key parameters: the volume of water and the height from which it falls. For instance, to achieve 1 GWh of energy storage, you’d need 1 GL of water falling from a height of 400 metres.

However, who says that storage solutions need to be grand in scale? Small reservoirs can be just as effective and versatile. Indeed, much of the essential infrastructure already exists. Researchers at the University of New South Wales have identified that Australia’s farmlands contain 30,000 pairs of dams suitable for small-scale pumped hydro storage. Each of these setups would involve two dams situated within 500 metres of each other, on a land slope of at least 17 per cent. This configuration allows for a height drop of 84 metres over a 500-metre pipeline. Just one megalitre of water could store up to 180 kWh of energy at 80 per cent efficiency. The researchers were conservative and looked for reservoir pairs that could store at least 30 kWh – equivalent to a day and a half’s energy usage for a typical household.

Of course, there are complexities involved in actual implementation. You’d need to construct pipelines, install generators and pumps, and ensure connectivity to the existing electrical grid. Yet, despite these challenges, it’s hard to deny the promise that pumped hydro storage holds. In whatever form it takes – be it large-scale or small – pumped hydro will undoubtedly play a significant role in shaping Australia’s renewable energy landscape in the years to come.

Mathew Dickerson

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