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Episode 40 of the Factor This! podcast features Craig Wood, CEO of the Australian next-gen concentrated solar power company Vast, which thinks it can change CSP's fortunes in the US. Subscribe wherever you get your podcasts.

The story behind concentrated solar power is complicated. But that's not because it's a poor resource.

Using mirrors and towers, CSP can cleanly generate electricity, provide long-duration thermal energy storage, and decarbonize heavy industry by producing heat. Its attributes only increase in value with higher penetrations of intermittent renewables, like solar photovoltaics and wind.

CSP has a less-than-sunny history in the U.S, though. Installed solar PV capacity dwarfs that of CSP 113 GW to 2 GW. High costs associated with construction have led to bankruptcies and shuttered projects. The story isn't much rosier for international markets either.

So why, then, is the Department of Energy investing millions in CSP research, as international players circle the U.S. as an untapped opportunity?

Vast, an Australian CSP company, is preparing to list on the New York Stock Exchange at a value of up to $586 million. The company's next-gen technology aims to overcome CSP's limitations by combining modularity with a novel approach to thermal energy storage.

Vast CEO Craig Wood joined the Factor This! podcast from Renewable Energy World to break down CSP's partly cloudy past and why it may be poised for a resurgence.

Two generations

Concentrated solar power plants have been deployed for more than 40 years, with some of those pioneering projects still in operation today.

At its core, CSP uses mirrors to concentrate and capture the sun's energy in the form of heat. In most systems, that heat is stored through a medium, typically molten salt, to become a large thermal battery. The energy can be dispatched in the form of process heat or electricity when needed.

The evolution of CSP technology can be grouped into two generations.

Generation 1

The most widely deployed CSP technology uses a series of linear collectors called parabolic troughs. These focus the sun's energy on a pipe filled with thermal oil. As of 2020, parabolic trough systems represented 4,000 MW of the 6,128 MW of total installed CSP capacity.

The thermal oil does have limitations, though, as it can only heat up to 400 degrees Celsius. By the time that heat passes through a storage medium and is ultimately used to create steam and spin an electric turbine, the power cycle operates between 330-350 degrees Celsius, which is relatively inefficient.

The power cycle limitation raises the cost of the energy, though the systems are still widely deployed. A significant portion of Spain's overnight energy comes from parabolic trough systems.

Generation 2