The Queensland government surprised many when it announced last year that the state would construct two new pumped hydro schemes, dwarfing the troubled Snowy Hydro 2.0 project in NSW.
At the core of the Energy and Jobs Plan, announced in September 2022 by Premier Annastacia Palaszczuk, is a commitment to turn off coal-fired power stations by 2035.
By the same year, Queensland would be running on 80 per cent renewable energy thanks to dozens of new solar and wind farms that would traverse the state.
To meet that target, the state needs a ready supply of stored power to draw upon when the sun is not shining and the wind is not blowing — enough to power the state for hours at a time.
That is where pumped hydro comes in as a large-scale storage option.
What is pumped hydro?
Pumped hydro works similarly to big batteries, filling in supply gaps when the grid needs a top-up of electricity.
The design involves two dams built at differing elevations, connected by a tunnel, with transmission lines then connecting it to the grid.
When there is plenty of sun and wind to power the grid, energy is in high supply, so water is pumped to the upper reservoir using surplus electricity.
When the sun goes down or there is no wind, water is released to the lower dam through the tunnel, generating electricity as it passes through a turbine.
That electricity is then injected into the grid via high-voltage transmission lines.
The debate
The criticism is broadly two-fold: firstly, that pumped hydro comes at a monumental cost and is being outpaced by other technologies (namely batteries), and secondly, that Australia simply does not have the workforce needed to construct such huge pieces of infrastructure by 2035.
The Energy and Jobs Plan proposed a 2-gigawatt pumped hydro scheme at Borumba Dam — west of Gympie — and another much larger plant called Pioneer-Burdekin, approximately 1,000 kilometres north of Brisbane, west of Mackay, offering an unprecedented 5 gigawatts.
The government has promised that the 2GW Borumba project would store enough energy to power 2 million homes continuously for 24 hours.
If constructed, the 5GW Pioneer-Burdekin project would be the largest energy storage (PHES) in the world.
Currently, the largest PHES schemes are in China and the United States, with plants of around 3 gigawatts each.
Pumped hydro is also expensive. The cost and delivery time frame for the Snowy Hydro 2.0 scheme bears little resemblance to what was originally announced by Malcolm Turnbull in 2017.
It was estimated to cost around $2 billion, not including power lines, and to be completed by 2021. Now, it is expected by December 2029 at a total estimated cost of $10 billion.
New transmission lines
The sheer amount of energy that will be stored in each of Queensland’s pumped hydro centres means that new high-voltage transmission lines need to be built, replacing the current mostly 275kV lines that connect the grid.
Powerlink, the state-owned company that constructs and manages the transmission lines, estimates the new 500kV lines will cost $6-8 million per kilometre and will become the backbone of a new “super grid” that will connect the state’s renewable energy network.
The company announced a compensation scheme for those that will be impacted by the new transmission lines surrounding Borumba at meetings and via letters earlier this year.
