Pumped hydro: the missing link for clean energy success

RPS’ National Onshore Renewables Lead, Simon Pollock explains why Australia should pay more attention to the water battery option - pumped hydro.

We all know that the success of a fully renewable energy system rests on a guarantee of supply.

In the past, this was rarely a problem as coal-fired generation operates on a baseload power model. But as we move into the era of renewables where the supply of sources like sun and wind is inherently intermittent, the investments we make in our network must incorporate both diversity of input, and effective storage solutions.

Storage means we don't lose excess electricity generated from renewable sources and ensures supply when the wind isn't blowing and the sun isn't shining.

It also has a role to play in reducing the need for large new - and often unpopular - transmission lines. A system that incorporates micro grids and effective storage to capture electricity from nearby renewable sources, allows more control over when and how much electricity is transmitted for wider use. And this means we could build smaller and leaner transmission lines.

The industry is making huge leaps with battery storage technology, but there is another option that should be receiving more attention and investment – and that’s pumped hydro.

Pumped hydro: a water battery

Pumped hydro is a closed system made up of two dams – one sitting higher than the other – that utilises gravity via a turbine tunnel. Water is pumped from the bottom reservoir to the top when power from another connected source - like solar - is readily and cheaply available.

While the solar energy is used for pumping, its potential is stored in this ‘water battery’.

When demand for energy from the solar (or other renewables) component of the network outstrips supply, water from the top reservoir is released back into the lower one, turning turbines and creating hydroelectricity on the way down. Supply is therefore maintained. 

Pumped hydro can help solve the intermittency challenges that still exist for maturing renewable generation asset classes like solar and wind.

Untapped potential of the dam system

Pumped hydro has untapped potential in this country.

The Australian National University has created a global pumped hydro atlas. It has identified 616,000 potential sites around the world suitable for pumped hydro energy storage, with 3,000 or so low-cost potential sites around Australia.

The Australia Government has stated that the number of potential sites in this country offers an opportunity for developers: “The potential pumped hydro energy storage resource is almost 300 times more than required. Developers can afford to be very selective since only about 20 sites (the best 0.1% of sites) would be required to support 100% renewable electricity generation.”

Addressing pumped hydro challenges

One of the challenges or potential barriers for investment in pumped hydro is the long lead time needed to bring a project online. Like planning for an offshore wind farm, there needs to be considerable environmental impact assessments and studies. Pumped hydro projects also need sustainable water sources to fill and maintain the dam system.

However, it would be short-sighted to dismiss pumped hydro for these reasons. 

Pumped hydro is a relatively low cost, natural battery solution. Also, as pointed out by the Australian National University, the water requirements of a renewable system – with pumped hydro, wind and solar – is far less than for a similar coal-based system as renewables do not need cooling towers.

And, where evaporation might be an issue, suppressors (covers) can be used, and again, topping up the system is still less water-intense than a coal-based system.

An integrated approach for renewable energy

Some smart developers are looking to pumped hydro as a mechanism for ‘smoothing’ their energy offer or powering their businesses and projects. Some are beginning to work together to develop solar, wind, pumped hydro and green hydrogen in close proximity to one another to effectively build a ‘green’ industrial power plant, of sorts.

This integrated approach must be front of mind as we plan our transition to a renewable energy system.

As each state and territory moves quickly to meet net zero targets, there must be clever and systematic planning for how each piece of the renewables puzzle intersects and complements the others.

Whether through private innovation or government set-ups (or a combination of both), collaboration is needed to ensure we have the right mix of renewables feeding into the system.

There is a lot to like about pumped hydro. It can store a lot of energy, its renewable, and it can be called on when needed. Now is the time to talk about it more.


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