Repowering Port Augusta for superior concentrated solar power storage

Like a phoenix rising from the ashes, Port Augusta’s concentrated solar power plant is back from the dead.

Vast Solar’s pilot concentrated solar thermal plant in Jemalong, near Forbes, NSW. Credit: Vast Solar.

While it’s ten years too late for a smooth transition from coal-fired power to the solar-heated variety in the ‘Crossroads Town,’ it might be just in time for other coal towns approaching their own uncertain futures.

Travellers to Port Augusta these days marvel at the solar concentrator which is powering Sundrop Farms’ massive greenhouse on Highway One just south of the town. Sundrop grows 15% of all Australia’s tomatoes.

The main attraction, however, of concentrated solar thermal power is the potential to store and dispatch energy on demand.

Energy from the sun is captured and stored as heat, which can be later used to power turbines.

Storage of 4-to-12 hours’ duration is “the most pressing utility-scale need in the next decade”, according to the Australian Energy Market Operator (AEMO).

In the Integrated System Plan For the National Electricity Market (June 2022), AEMO describes this time frame is required “to manage stronger daily variations in solar and wind output, and to meet consumer demand, also during more extreme days, as coal capacity declines.”

AEMO predicts Australia will need to “treble the firming capacity from dispatchable storage, hydro and gas-fired generation to firm renewables.”

The plan is that by 2050, the market will provide 46 GW/640 GWh (gigawatt hours) of “dispatchable storage, in all its forms” to add to the 7 GW of existing hydro generation, and 10 GW of gas-fired generation for peak loads and firming.

If the original plan for Port Augusta had come to fruition, a massive concentrated solar power plant about 30 kilometres north of the town, built by US company SolarReserve, would have been producing 495 GWh annually.

In 2017, the South Australian Government announced a 150MW solar thermal power plant would be built in Port Augusta, with then-Premier Jay Weatherill awarding the $650 million contract to SolarReserve. Construction was to begin in 2019. But that project was cancelled when SolarReserve failed to secure finance.

Now, the Australian company Vast Solar is developing VS1 in Port Augusta, after the Australian Government announced $110 million in concessional financing.

The 30 MW concentrated solar thermal power plant will use Vast Solar’s modular technology and will be based at the Aurora Energy Project site.

VS1 will generate clean, low-cost, dispatchable power available on demand for up to 12 hours, even when the sun is not shining.

A joint venture with 1414 Degrees will also see Vast Solar co-develop a 140 MW battery energy storage system on the Aurora site.

Vast Solar chief executive Craig Wood says 30MW is still “subscale”, but it’s a step up from the company’s 1.1MW pilot plant, operating five hours west of Sydney, near Forbes.

What is concentrated solar thermal technology?

Most people are more familiar with solar photovoltaic (PV) panels, which use semiconductors to turn sunshine directly into electricity.

Concentrated solar is different. Curved mirrors focus sunshine onto a central tower, where receivers absorb and store the heat in liquid. That heat is later used to power a steam turbine.

In the original project, SolarReserve planned to use a circular field of computer-controlled curved mirrors (heliostats) to reflect sunlight onto a target at the top of a lofty 227 metre tower. There it would then heat up a liquid referred to as salt — not table salt, but an inert mixture of sodium nitrate and potassium nitrate, traditionally used as garden fertiliser.

The initial melting of the salt is a one-time process, after which the liquid salt is recirculated and used for the life of the plant.

In Vast Solar’s modular design, deployed at the Jemalong Pilot Plant in central western New South Wales, there are five separate arrays, each concentrating solar radiation onto their own 27m thermal receiver tower.

The company says this unique design is more efficient and therefore cost-effective, with the capacity to produce cheaper dispatchable renewable energy.

Vast Solar uses liquid sodium, molten metal, as the receiving heat transfer fluid, borrowing technology from the nuclear power industry. Heat from the sodium is then exchanged with molten ‘solar salt’, the storage medium.

“We then have a loop for the sodium,” Wood says. “The sodium passes the heat, through a heat exchanger, into the salt.

Wood explains how the system works: “At the start of the morning, all the salt’s in the ‘cold’ tank, at 304 Celsius. During the day it passes through the heat exchanger and ends up in the hot tank at 550 Celsius.

“And then when we need to, we take the hot salt, put it through – essentially it’s a glorified industrial kettle, a steam generator – and produce steam that goes into the turbine at 538 Celsius.”

The turbines will be similar to those already found in traditional coal and gas power plants, “meaning jobs are ideally suited to former fossil fuel power plant workers,” Wood says.

Vast Solar says the project will employ hundreds of people during construction, with several dozen permanent operational positions.

“A skilled workforce is required onsite to operate that equipment,” Wood says.

“So in terms of a transition for displaced power station workers, it’s really the best technology there is.”

An electric history

It’s been a long journey. Port Augusta was home to South Australia’s last coal-fired power stations, which were collectively known as the “Northern Power Station.” The station was powered by brown coal from Leigh Creek which was hauled by train.

One of the generators, named Playford (B) after the SA Premier who is often given credit for industrialising the state with cheap, subsidised power, was mothballed in 2012 and shut down in 2015. The other generator, Northern Augusta, closed in 2016.

In 2010, the Beyond Zero Emissions think tank identified Port Augusta as the ideal place to build a solar thermal power plant. The Repowering Port Augusta report was published in 2012.

That’s when former power station worker Gary Rowbottom first heard of solar thermal power, courtesy of the Australian Youth Climate Coalition (AYCC).

Young activists came to town spruiking a plan to Repower Port Augusta that sounded too good to be true.

So the mechanical technical officer and self-confessed “energy nerd” started looking into their claims.

He was very pleased with what he found.

Solar thermal technology was already operating in Spain and the US. And it was just what Port Augusta needed.

Rowbottom said he recognised the need to decarbonise and especially liked the mechanical nature of this particular solution, which offered a neat pathway for power station workers.

“Wind and to a greater degree, the more normal solar panel type systems doesn’t give that, that’s sort of weighted towards people who push dirt around, and the electricians,” he said.

“For us poor mechanical guys, it’s harder to get a look in there. And the job density is relatively higher with these sorts of [solar thermal] facilities as well, so that was part of the reason why I liked solar thermal way back in 2012.”

Rowbottom joined the Repower Port Augusta Alliance. He gave rallying speeches, fronted the media and met politicians at local, state and federal levels.

In 2017 when the South Australian Premier Jay Weatherill announced a 150 MW solar thermal power plant would be built in Port Augusta, Rowbottom felt vindicated: “For a year and a bit we thought we had the job done.”

Daniel Spencer was campaign manager for Repower Port Augusta at AYCC from 2012-16. He moved north for the job at the age of 21.

“Oh, it was incredibly disappointing when everything fell over,” Spencer says, looking back.

“It was not the ideal transition we were hoping for, all those years ago.”

But the Mid-North town’s solar story is not over yet.

“I think that the campaign still made a big difference,” says Spencer.

“The community’s efforts highlighted the fact that we need to have a fair transition for existing workers and the broader community when we’re closing down fossil fuel power stations.

“It also put Port Augusta on the map as a place to build renewable energy, which I think was a significant achievement. The fact so many projects have gone ahead in the area is a byproduct of that.”

He’s now Senior Campaigner for the SA and NT Branch of the Australian Services Union, which looks after power station workers.

Twelve coal-fired power stations have closed in the past decade and many more have flagged intentions to close in coming years.

Unions are calling on the Albanese Government to establish a National Energy Transition Authority tasked with ensuring affected workers and their communities are fully supported.

A Greens Bill to establish such an Authority has been referred to the Economics Legislation Committee for inquiry and report by 14 March 2023.

The Bill establishes the National Energy Transition Authority as a statutory authority to plan, coordinate and provide advice on the transition to renewable energy, focusing on the facilitation of new economic opportunities for workers and communities who are currently involved in fossil fuel production and associated industries.

John O’Brien, a Deloitte Partner in Decarbonisation, believes “the role of government is now to make that inevitable transition more orderly, more efficient and more equitable”.

“I remember when the power station at Port Augusta shut, to everyone’s horror and amazement, and they said ‘Oh, my goodness, no one would have seen that coming, let’s set up an Emergency Task Force,’ when it was obvious the thing was going to close, it was just [a matter of] when.”

He says what’s needed now is what’s called a “radical collaboration” to get big industry, community, government and investors “all trying to work out what the win-win-win kind of arrangement will be, how can everyone do things differently and enable that change”.

“It requires a fair bit of thinking and often, different people doing that thinking, to enable that to come to reality.”

Effectively that’s now happening in Port Augusta, O’Brien says, but happening by default, rather than through preparation and good planning, and it’s taking longer because of that.