Tanzanian researchers found that soapstone and granite rocks can be used to store solar heat for later use through thermal energy storage (TES). It is a simple cost-effective way to collect and use energy by using heat from sources such as rocks, oil or water, as an alternative to battery storage. Tanzanian soapstone and granite rocks store heat well at high temperatures because of their stability and high energy densities.
Researchers have found that Craton soapstone rocks can absorb, store, and transmit heat well, while also being chemically stable and mechanically strong. Although their potential as sustainable energy storage materials are promising, more experimentation is needed to fully explore their capabilities.
Recently, researchers from Tanzania found hidden sustainable solar energy storage in rocks. They discovered that common rocks may be ideal for Thermal Energy Storage (TES), which involves storing solar heat for use afterwards. Soapstone and granite are found to be the most ideal rocks among them.
Rocks can store solar heat and this could form the foundation of the upcoming eco-friendly energy technology. Through concentrated solar power, heat from the sun can be harnessed and utilized for drying food or generating electricity.
Soapstone and granite samples from Tanzania can store solar heat well at high temperatures due to their high energy densities and stability, according to a team from ACS Omega.
Storing batteries in large batteries can be expensive and requires a lot of resources to manufacture. Thermal Energy Storage is a lower-tech alternative that collects energy as heat in a liquid or solid such as rock, oil, or water. With energy stored as heat in such sources can be used to power a generator to produce electricity.
Granite and soapstone are specifically formed under high heat and are found across the globe. This feature possibly makes them a favorable TES material. But properties can vary based on the location they are formed which is why some samples of these rocks are better than others. The Craton and Usagaran geological belts meet in Tanzania and both contain granite and soapstone.
Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande, and Thomas Kivevele from Nelson Mandela African Institution of Science and Technology and Ardhi University decided to investigate the properties of these stones found in these belts. The team collected various rock samples from these belts and analyzed them. Granite samples showed a large content of silicon oxides that added to their strength.
The Craton granite also contains other compounds, including muscovite, that are susceptible to dehydration. This compound is capable of making the rock unstable at high temperatures. The soapstone containing magnesite provided exceptional thermal capacity and a remarkable density.
There were no visible cracks in both soapstone and Usagaran granite samples when heated to a temperature of over 1800° Fahrenheit. On the contrary, Craton granite fell apart. Also, it was expected that soapstone would release its stored heat more than granite. This is why the discovery of hidden sustainable solar energy storage in rocks is exciting.
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Overall, Craton soapstone had the performance as a TES as it was able to absorb, store, and transmit heat effectively. At the same time, it maintained good chemical stability and mechanical strength. However, it is possible that other rocks might be suitable for a lower-energy TES application like a solar dryer.
According to the researchers, further experiments are needed, but these samples show promising results in being a sustainable energy storage material. With this, it is expected that Tanzanian rocks are alternative to battery storage which is a groundbreaking discovery.
Source: ACS Publications
