2023-06-05 12:45:31
A new generation of technology for solar energy could be based on a very crude and primitive class of materials: stones.
Solar power is often stored in large batteries when not needed, but these can be expensive and resource intensive to manufacture. A less technological alternative is to store it in the form of thermal energy. For the latter, a liquid or a solid is used, such as water, stones or other material, in which the excess solar energy is used to heat them up to very high temperatures. Then, when their power is needed, the heat they retain is released and this can power a generator to produce electricity.
Rocks like granite and soapstone form specifically under high temperatures and are found all over the planet, which can make them suitable materials for storing thermal energy. However, their properties can vary greatly depending on where in the world they were bred, possibly making varieties from some regions much better than others.
The Tanzania craton and the Usagaran belt, also in Tanzania, host significant amounts of granite and soapstone.
Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande and Thomas Kivevele, the three of the Nelson Mandela African Institution of Science and Technology in Tanzania, have investigated the properties of granite and those of steatite hosted in each of these areas.
The team collected several rock samples from those sites and analyzed them. The granite samples contained a large amount of silicon oxides, which added strength. However, the craton’s granite contained other compounds, including common mica, which are susceptible to dehydration and could make the rock unstable at high temperatures. Magnesite was found in soapstone, which gave it a high density and good thermal capacity.
Granite (left) and soapstone (right) samples. The right varieties of these stone materials can be of great help in storing heat from the Sun for later use in the generation of electricity. (Image: adapted from ACS Omega, 2023, DOI: 10.1021/acsomega.3c00314. )
When heated to temperatures above 1000 degrees Celsius, both the soapstone samples and the granite from the Usagaran belt did not show visible cracks, but the granite from the craton fragmented.
Taking this and other differences into account, craton soapstone turned out to have the best performance as a material for storing thermal energy, being able to absorb, store and transmit heat efficiently, while maintaining chemical stability. and good mechanical resistance. However, the other rocks might be more suitable for a low-power thermal energy storage application, such as for a solar dryer.
The study is titled “Experimental Investigation of Soapstone and Granite Rocks as Energy-Storage Materials for Concentrated Solar Power Generation and Solar Drying Technology”. And it has been published in the academic journal ACS Omega. (Fountain: NCYT de Amazings)
#Collect #solar #energy #simple #stones