Questions are being raised over Queensland's pumped hydro plans. What is it and are there alternative options?
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.
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 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.
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.
Powerlink CEO Paul Simshauser said the route had been designed to run through as much state-owned land as possible, but that some impacts on landholders were unavoidable.
"We've come up with what we think is the lowest-cost solution for Queenslanders," he said.
But the former CEO of Powerlink, Simon Bartlett, warned that the current plans would come at an exorbitant cost because Pioneer-Burdekin was so far away from the main population centre of South-East Queensland.
"A basic rule of planning is: build your generation, if you can, as close as you can to the load centre. That reduces what you spend on transmission, and it reduces the risk of long-distance transmission," Professor Bartlett said.
"But the plan doesn't do that, the plan wants to build it 1,000 kilometres from the main load centre [Brisbane] – it just makes no logic to me, I'm afraid."
Professor Bartlett also says it is high risk for Powerlink to connect the pumped storage schemes by only one new line of 500kV towers that carry a double circuit, due to the risk of fires or vandals bringing down towers.
"What they're proposing is just a single transmission line, that's a major flaw in the design because that can come down, and every half a kilometre there's a tower, and all the wires are on the one tower. So that can come down and totally blackout a large part of the state," he said.
Mr Simshauser refuted that, arguing two lines of towers were not needed.
"We believe at this point in time anyway, [it] will be a cost that we won't need. We believe we can manage it in other ways," Mr Simshauser said.
"There are always risks in running a transmission network, any of our system plans will always take into account the most probable and credible contingencies that we can envisage and make sure that the balance of the network is, you know, available to deal with those contingencies."
Queensland's Energy Minister Mick de Brenni said he considered the state's plan to be "the best path possible" to transition to renewables.
Professor Bartlett is urging the government to re-think the scale of the two schemes, in favour of emerging grid-scale batteries.
"They say it's the world's largest scheme. As soon as someone says that: watch out. There's a reason that others haven't gone that big," Professor Bartlett said.
"There are other ways of getting storage besides pumped storage, and there's been incredible developments in chemical batteries, the costs have just come down dramatically.
"[Australian Energy Market Operator] AEMO's own report shows that 8-hour batteries are about half the cost of an 8-hour pump storage scheme.
"Pumped storage is expensive because of the civil engineering, the concrete, the steel, the labour … and while pumped storage has getting dearer, batteries are getting cheaper."
However, Powerlink CEO Paul Simshauser said that it needed to make decisions based on current market conditions.
"At this point in time, the only serious battery proposals that we've got on our book are lithium-ion batteries, and all of them have congested around a 2-hour storage time, which tells us that that's what the market deems as economic at this point," he said.
"In terms of long-duration storage, really the only long-duration storage project proponents we've seen are pumped hydro," he said.
Similarly, Mr de Brenni said the government had closely considered the alternatives.
"We've worked for a number of years considering all of these options, and pumped hydro energy storage is the proven technology that will enable us to reach our renewable energy targets," he said.
The construction industry is sounding the alarm that there are too many projects in the infrastructure pipeline, and Australia simply does not have the workers to complete them.
Engineers Australia CEO Romilly Madew said governments around the country were not learning from major infrastructure delays on other big projects.
"When you take into account the infrastructure pipeline that's already in place, you've got the Queensland Olympics coming up in 2032.
"You also have AUKUS now been added into the mix from the federal government. And then you add in energy transition. The capacity isn't there," Ms Madew said.
"If we say it's going to take 10 years, let's say it's going to be 15. There are so many unknowns at the moment and we really need to make sure we have contingencies on these projects,"
"We must remember it's taxpayer money — so are we reporting transparently on the time frames, on the delivery and on our commitments, and being really realistic about those?"
Mr de Brenni agreed there were workforce issues but was not concerned the state would not be able to attract workers.
"Whilst there are challenges in the infrastructure market, today, we're confident that we'll be able to attract the very best workers so that it's delivered, and it will be a quality outcome for our state for generations," he said.
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