Thanks to new findings and successful demonstrations we could be storing solar energy using desert sand from the United Arab Emirates. According to researchers, the UAE sand is particularly useful when it comes to keeping heat energy up to 1000°C stored in concentrated solar power (CSP) facilities.
Scientists from the Masdar Institute of Science and Technology focused on advanced energy and sustainable technologies developed an affordable and sustainable solar receiver and storage system with sand as a heat collector, transfer and energy storing agent.
What is concentrated solar power? Its a system generating electricity by using mirrors or lenses to concentrate a large area of sunlight onto a small area. When the concentrated light becomes heat, it drives a heat engine connected to an electrical power generator or enables a thermal chemical reaction.
Currently the process is costly since it requires thermal energy storage (TES) materials as well as a solar absorber, let alone their transportation to the solar plants, usually located in the world’s deserts. But the UAE sand could work as both. This is why its thermal specific heat capacity, stability and tendency to collect and store energy have been tested at high temperatures.
Today the usual heat storage materials in current TES systems are synthetic oil and molten salts. Replacing them with cheap sand can make solar plants much more efficient.
Since there is plenty of sand around Dubai and Abu Dhabi, this poses a local and natural solution, which, in fact, goes hand in hand with the economic development of the UAE’s energy systems.
The analyses showed that it is possible to use desert sand as a TES material up to 800-1000 °C. The sand chemical composition has been analyzed with the X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques, which reveal the dominance of quartz and carbonate materials. The sand’s radiant energy reflectiveness was also measured before and after a thermal cycle, as it may be possible to use the desert sand not only as a TES material but also as a direct solar absorber under concentrated solar flux.
“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. The success of the Sandstock project reflects that usability and practical benefits of the UAE desert sand,” believes Dr Nicolas Calvet, a scientist on the project.
The university is currently looking for a business or industry partner to support their next step – test an improved prototype at the pre-commercial scale at the Masdar Institute Solar Platform (MISP) using the beam down concentrator.