Molten salt pushes reach of rooftop solar

Molten salt pushes reach of rooftop solar

Fast-melting salts could solve solar power’s big challenge: the mismatch between peak sunlight hours and peak, evening electricity use.

Researchers from the University of South Australia have developed a new phase-change system that provides energy storage at a tenth of the cost of batteries. By melting and solidifying an inexpensive liquid salt solution, energy can be stored and released quickly and cheaply.

As well as extending the potential reach of renewable energy, the system also allows Australian produce companies to reduce multibillion-dollar refrigeration electricity costs by ‘charging’ the system – freezing the solution – during off-peak hours and ‘discharging’ – remelting – during high-cost peak times.

For their development of the unorthodox energy storage system, the university’s Associate Professor Frank Bruno, Dr Martin Belusko and Dr Steven Tay were awarded the ANSTO Eureka Prize for Innovative Use of Technology.

The phase-change system resolves the mismatch between generation hours and electricity use, so solar and wind power can form an even larger slice of the national generation grid. It also smooths out electricity use, reducing the need for expensive, peak-driven infrastructure and for extra fossil-fuel generation of power during daylight hours.

The notion of using salts for energy storage is not new. Molten salt batteries are used at a number of large-scale solar thermal farms, including the world’s biggest solar tower and storage plant, the 110MW Crescent Dunes facility in Nevada, US. But the use of salt as a phase-change material for smaller-scale, rapid-discharge batteries for residential and commercial use is unprecedented, according to RenewEconomy.

The awards also recognised Professor Martin Green and Dr Mark Keevers from the University of New South Wales for splitting a single light beam to generate power from two different types of solar.