How pumped storage hydropower is unlocking broader renewable energy developments

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Pumped storage is key to smoothing the intermittent energy delivery of renewable power projects. We are leading the way with a pioneering project that is repurposing a redundant gold mine in Queensland – including the development of new digital tools to minimise lifetime carbon.

With the worldwide push for renewable energy generation comes a major hurdle. Because solar and wind generation is by its nature intermittent, we must develop ways to smooth out the peaks and troughs of supply. It’s a challenge that is seeing countries across the globe looking to pumped storage as part of the answer.

Pumped storage works like a giant battery, where water from an upper reservoir generates power, when required, as it flows through turbines to a lower reservoir. The water is pumped back to the upper reservoir during a low-cost energy period.

Ground engineering support

A design joint venture in which we joined forces with Australian based consultant GHD undertook geotechnical work for the project. This included the design of the overall project layout as well as the intake canal, water conveyance tunnels and shafts lining, underground powerhouse structure and equipment integration and various associated structures.

Reflecting the global reach of our business, the team in Australia have been supported by experts in these sectors from across the world.

It’s a technology that has existed for over a century for projects that focussed more on fiscal management than sustainability. Many larger plants date from the 1970s, when they were built to pump and thereby store electrical potential during off-peak tariff times, for use during expensive peak demand periods. Now the focus has shifted to renewables, bringing a resurgence of interest since pumped storage can plug energy troughs in a national grid when there has been a shortfall of energy from solar or wind generation.

The International Hydropower Association says pumped storage is already the world’s largest battery technology, accounting for 94% of energy storage capacity, with 9000GWh of electricity stored worldwide. But with the resurgent use of this technology, the association now forecasts a 50% leap in total installed capacity by 2030.

Australia is one country showing an enthusiasm for pumped storage, and one where our team has been providing engineering design services in the development of a 250MW facility in Queensland able to dispatch eight hours of on-demand energy – enough to power 140,000 homes. It is the first pumped-storage project to be built in Australia for 40 years, but many more are in the pipeline globally.

Solar, wind and hydro: a balancing act

The three elements of the Kidston energy hub – solar, wind and pumped hydro storage – will complement each other to maximise reliability and minimise risk. On cloudy days that provide less solar energy, the breeze is often stronger meaning wind power can compensate; days with little wind, on the other hand, tend to be sunnier. When both sun and wind are weak, the stored energy in the hydro comes into play. “Your first call is either solar or wind, and you use the pumped storage as your insurance to fill in the gaps,” explains Brian.

Not only does this mean more consistent energy for consumers, it also ensures the energy off-taker, EA (Energy Australia), can fulfil its precise time-slot supply commitments to the grid, avoiding the punitive financial penalties companies face when they do not. But crucially, pumped storage also enables the development of other renewables projects.

The Kidston pumped storage project is a critical component of a renewable energy hub being developed by energy supplier Genex and delivered by McConnell Dowell and John Holland in joint venture. In an innovative move, it is repurposing a redundant gold mine into a pumped-storage facility to support co-located solar, and planned wind generation. The project, now under construction, will help Queensland achieve its target of 50% electricity from renewable resources by 2030.

Optimised design means lower cost and carbon

By drawing on experience and expertise in hydro storage, we found ways to adjust the client’s strategy for Kidston that reduced capital outlay while increasing the project’s efficiency. The new plan uses both the available former goldmine pits rather than just one as had been originally planned. And because this required less construction, it also meant a lower carbon footprint.

Carbon twin boosts environmental efficacy

Renewables bring obvious environmental benefits, but there are still operational and embodied carbon issues that require complex analysis. We have developed a tool to achieve this and trialled it at Kidston to demonstrate its effectiveness. Called the Carbon Twin, it can visualise in detail an infrastructure project’s carbon intensity, including carbon hotspots. By combining carbon data and pricing with 3D design, it enables more informed decisions. With Kidston being used as a template to develop the tool, the amount of carbon saved will become apparent during operation since it has been developed as a whole-life assessment.

Energy and carbon consultant Lindsay Speyers, began development of the carbon twin last year, drawing in experts from across the business. He then coordinated and tested the tool’s development, engaging with our clients to ensure it provided value for them.

The tool works by leveraging BIM models, while factoring in the government carbon emission factors specific to the locality. By automating the calculation of embodied carbon, it allows work that would otherwise take months to be cut to mere days.

For owners and managers, the carbon twin offers a way of tracking their assets against critical environmental, social and governance (ESG) metrics, all the way through from design and construction to operation and eventual decommissioning.

Temporary water pumps transfer water into the upper reservoir so that the tailrace tunnel and outlet can be built at the lower reservoir

It is also the first project of this type in Australia to be almost entirely privately funded, with the government’s renewable energy agency ARENA contributing just AUS$47M of the AUS$777M total project cost. For the high-capacity transmission line to link the hub into the grid, however, the Queensland state government is paying most of the cost, contributing AUS$147M of the AUS$258M total.