Sand Batteries For Solar Energy Storage

Sand batteries

Researchers from Masdar Institute have successfully demonstrated that desert sand in the United Arab Emirates (UAE) could be utilised as an alternative to molten salts for concentrated solar power (CSP) thermal energy storage.

Using the sand could be a cheaper and more sustainable approach for CSP facilities in the UAE. Instead of importing salts from elsewhere; developers could just use the plentiful materials around the facilities.

The researchers have been able to heat the desert sand, which is rich in quartz and carbonate materials, to temperatures of 800-1000 °C; indicating it may also be a more efficient material than molten salts.

Molten salt materials commonly used are a mixture of 60% sodium nitrate and 40% potassium nitrate, able to achieve temperatures of 260-550°C.

The Masdar Institute research is part of ‘Sandstock’, a project seeking to develop an environmentally friendly and low-cost gravity-fed solar receiver and storage system; using sand particles as the heat collector, heat transfer and thermal energy storage media.

“The availability of this material in desert environments such as the UAE allows for significant cost reductions in novel CSP plants, which may use it both as TES material and solar absorber,” said Dr Nicolas Calvet; project lead. ” The success of the Sandstock project reflects that usability and practical benefits of the UAE desert sand.”

A paper on the findings was presented at the 21st Solar Power and Chemical Energy Systems (SolarPACES 2015) Conference in South Africa in October

Next steps for the researchers include testing an improved pre-commercial scale prototype at the Masdar Institute Solar Platform’s (MISP’s) beam down concentrator.

Closer to home, Adelaide-based Latent Heat Storage (LHS) is also working on a sand-based thermal energy storage system (TESS).

The LHS system stores thermal energy by heating and melting containers full of silicon derived from sand. LHS’s TESS device is small enough to fit inside a 20-foot shipping container, but is readily scalable and suitable for small scale 500kW applications through to large scale applications in the hundreds of megawatts.

LHS was awarded a $400,000 commercialisation grant earlier this year under the Australian Government’s Entrepreneurs’ Programme, which will assist the company in bringing the system to market.