The solar energy hitting Earth each year exceeds the total energy consumed by humanity by more than 20,000 times. But once the sun sets, or clouds fill the sky, our supply of solar energy is cut off. So how do we store solar energy to provide electricity at night?
The obvious solution of storing the energy in batteries is presently not economical at the massive solar power plant scale. Other options, of compressing and uncompressing air, or pumping water up a slope to use the energy it generates when it flows downhill, are all energy intensive themselves and require large storage areas or riverbeds.
The best answer today lies in thermal energy storage (TES) and heat transfer – using the sun’s energy to heat a material up and then using that heat to create steam on demand that can power a turbine and so generate electricity. In concentrated solar power (CSP) plants, molten salts have been the material of choice to store solar energy since the 1980s.
Image credit: The Masdar Institute
The Masdar Institute of Science and Technology, an independent, research-driven graduate-level university focused on advanced energy and sustainable technologies, announced that its researchers have successfully demonstrated that desert sand from the UAE could be used in concentrated solar power (CSP) facilities to store thermal energy up to 1000°C.
The research project called ‘Sandstock’ has been seeking to develop a sustainable and low-cost gravity-fed solar receiver and storage system, using sand particles as the heat collector, heat transfer and thermal energy storage media. Desert sand from the UAE can now be considered possible thermal energy storage (TES) material. Its thermal stability, specific heat capacity, and tendency to agglomerate have been studied at high temperatures.
Dr. Behjat Al Yousuf, Interim Provost, Masdar Institute, said, “The research success of the Sandstock project illustrates the strength of our research and its local relevance. With the launch of the MISP in November, we have further broadened the scope of our solar energy research and we believe more success will follow in the months ahead.”
A research paper on the findings developed under the guidance of Dr. Nicolas Calvet, Assistant Professor, Department of Mechanical and Materials Engineering, was presented by PhD student Miguel Diago at the 21st Solar Power and Chemical Energy Systems (SolarPACES 2015) Conference in South Africa. The paper was co-authored by alumni Alberto Crespo Iniesta, Dr. Thomas Delclos, Dr. Tariq Shamim, Professor of Mechanical and Materials Engineering at Masdar Institute, and Dr. Audrey Soum-Glaude (French National Center for Scientific Research PROMES CNRS Laboratory).
Replacing the typical heat storage materials used in TES systems — synthetic oil and molten salts — with inexpensive sand can increase plant efficiency due to the increased working temperature of the storage material and therefore reduce costs. A TES system based on such a local and natural material like sand also represents a new sustainable energy approach that is relevant for the economic development of Abu Dhabi’s future energy systems. (Source: The Masdar Institute)
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