By James Thornhill, 17 April 2019

  • Recent project collapse cast doubt on solar thermal’s future
  • Vast Solar seeks to improve the technology, reduce risks

Vast Solar’s 1MW pilot project in Jemalong, Australia. Source: Vast Solar

An Australian energy startup says it has found a solution to the problem that has dogged some thermal solar technology projects, removing instability in the process of storing the generated electricity.

Vast Solar’s technology differs from rivals because it uses liquid sodium as a heat transfer agent, improving control of the sunlight bouncing off specialized mirrors, according to Chief Executive Officer Craig Wood. The mirrors focus the light on liquid sodium receivers placed on the top of a tower, with the sodium then used to transfer heat to molten salt storage tanks. Other projects typically also use molten salt as the transfer agent.

“Across the industry there has been a number of issues people have had with failures with heat exchanges and also with the hot salt tanks,” Wood said in an interview. “These failures have been caused to a greater or lesser extent by inadequate control of the heat transfer fluid temperature out of the solar receiver.”

Vast Solar may help shore up confidence in the technology after rival SolarReserve Inc. failed to arrange financing for its A$650 million ($463 million) Aurora Solar Energy project in South Australia. That project was seen adding a crucial new supply to the state’s troubled grid amid global efforts to transition to cleaner power generation. California-based SolarReserve didn’t respond to a request for comment.

Thermal solar technology’s attraction lies in firming up solar generation — utilizing thermal storage to keep the power flowing when the sun isn’t shining. However, operational issues have cast doubt on its reliability.

Vast Solar’s use of liquid sodium allows it to move away from the central tower design used at most existing solar thermal plants, instead using multiple receiving towers which Wood says can unlock efficiencies and reduce the risk of system outages.

Wood’s company has had a pilot project in operation since 2017 and plans to have a so-called 30 megawatt “reference plant” online in three years.  (Accessed, 18/04/2019)