Ellen Phiddian
Cosmos science journalist
Concentrated solar thermal has long promised to roll both solar power and energy storage into one technology.
Another feature is being dangled by a newer version of the technology: the provision of high heat.
This could help to power emissions-intensive industrial processes that can’t electrify easily, like steelmaking.
The CSIRO has just launched a new startup company, FPR Energy, to scale up a new style of solar thermal power.
The researchers successfully piloted their solar thermal technology at a 1-megawatt plant in Newcastle, and the company now has plans to build a 50-megawatt demonstration plant.
The company has $15 million in seed funding from funds management firm RFC Ambrian and Japanese gas company Osaka Gas.
“One of the reasons why we’ve been able to raise the sort of capital that we have is that [our technology] is just very different to what they’ve heard before about solar thermal,” Dr Gregory Wilson, a principal research scientist at CSIRO and senior technical advisor to FPR Energy, tells Cosmos.
“It’s targeting the sort of energy demand that they have.”
Like all concentrated solar thermal plants, the technology uses mirrors to concentrate sunlight onto a specific material, heating it up.
“The material we use is effectively a synthetic type of sand,” says Wilson.
FPR’s material is black ceramic spheres, each a third of a millimetre in diameter, made from alumina and iron oxide. They’re sold for use as “proppants” in the fracking industry, to prop open gaps for oil and gas to flow through.
“They use so much of them in the oil and gas industry that they’re really cheap,” says Wilson.
“We’ve used them in our system because they’re spherical, and they’re really low abrasive, in comparison to sand.”
This lets them flow smoothly through the solar thermal receiver.
“They cascade down our receiver, much like a waterfall,” says Wilson.
“They fall down the back wall of the receiver, and they’re caught on these little ledges that slow down the particles and mix them at the same time that the sunlight is impinging on them.”
The black particles absorb heat quickly.
“Each pass through the receiver, they can heat up by about 200°C,” says Wilson.
“We circulate them through the receiver about 3-4 times, until we get up to about 800°C. Then, as they fall through the receiver, they’re stored in what we call the hot storage bin.”
From there, the particles can store heat energy for more than 10 hours. The planned demonstration plant aims to have 16 hours of energy storage on hand, with temperatures reaching up to 1200°C.
This heat could be used to generate electricity, by making steam to power a turbine. But the heat itself could also be used directly.
“You can quite literally just use them as hot rocks if you wanted to,” says Wilson.
“Or you could, for instance, pass a gas across them – like air or a nitrogen stream. It will take on that heat.”
Another option is a heat exchanger CSIRO has adapted from industry uses, which could use water to generate industrial steam – or other liquids for further chemical use.
“It’s practically the Swiss army knife of thermal energy systems,” says Wilson.
Wilson says that FPR Energy plans to have the 50-megawatt demonstration plant deployed within 5 years, with commercial systems ready in high-solar Australian regions “over a 10 year period”.
“These are in areas more remote from the major population centres, where land use is typically underutilised and not for primary production,” says Wilson.
