According to a recent study published in ACS Omega, rocks, such as soapstone and granite, combined with solar power, may hold the key to sustainable energy storage.
Researchers from Tanzania have discovered that commonplace rocks, specifically soapstone and granite, have the potential to serve as efficient materials for thermal energy storage (TES). This innovative approach involves capturing and storing solar heat for later use.
The next generation of sustainable energy technology could rely on the fusion of low-tech materials, such as rocks, and the power of the sun. Through a technique called concentrated solar power, solar heat is harnessed, stored, and utilized for activities like food drying or electricity generation. The team behind the study, featured in ACS Omega, found that certain samples of soapstone and granite from Tanzania possess excellent attributes for storing solar heat. These rocks exhibit high energy densities and remarkable stability, even at elevated temperatures.
Traditionally, energy is stored in large batteries during periods of low demand. However, these batteries can be costly and resource-intensive to manufacture. A more accessible alternative is thermal energy storage (TES), which involves accumulating heat in a liquid or solid medium, such as water, oil, or rock. When released, this stored heat can power generators to produce electricity.
Rocks such as granite and soapstone, which are formed under intense heat, are widely available worldwide. This makes them attractive candidates for TES materials. However, the properties of these rocks can vary depending on their geographic origin, suggesting that some samples may be more suitable than others. In Tanzania, the meeting point of the Craton and Usagaran geological belts presents an opportunity, as both regions contain deposits of granite and soapstone. With this in mind, Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande, and Thomas Kivevele from the Nelson Mandela African Institution of Science and Technology and Ardhi University set out to investigate the properties of soapstone and granite from each of these belts.
The team collected multiple rock samples from these geological belts and subjected them to analysis. The granite samples exhibited significant silicon oxide content, which enhanced their strength. However, the Craton granite contained additional compounds, including muscovite, which are prone to dehydration and could render the rock unstable at high temperatures. On the other hand, the soapstone samples contained magnesite, contributing to a higher density and thermal capacity.
Upon heating the samples to temperatures exceeding 1800 degrees Fahrenheit, both soapstone samples and Usagaran granite displayed no visible cracks, while the Craton granite disintegrated. Furthermore, the soapstone demonstrated a greater propensity to release its stored heat compared to the granite.
Overall, the Craton soapstone exhibited the most favorable performance as a TES material. It effectively absorbed, stored, and transmitted heat while maintaining excellent chemical stability and mechanical strength. However, the other rocks may be better suited for lower-energy TES applications, such as solar drying.
Although further experimentation is necessary, these rock samples show promising potential as sustainable energy storage materials.
Reference: “Experimental Investigation of Soapstone and Granite Rocks as Energy-Storage Materials for Concentrated Solar Power Generation and Solar Drying Technology” by Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande, and Thomas Kivevele, 17 May 2023, ACS Omega.
DOI: 10.1021/acsomega.3c00314
The authors acknowledge funding from the Partnerships for Enhanced Engagement in Research under the National Academies of Sciences, Engineering, and Medicine, as well as the United States Agency for International Development.
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Frequently Asked Questions (FAQs) about sustainable solar energy storage
What is thermal energy storage (TES)?
Thermal energy storage (TES) is a method of storing energy in the form of heat. It involves collecting and storing heat in a liquid or solid medium, such as water, oil, or even rocks like soapstone and granite. This stored heat can be later released and used to power generators for electricity production or for other applications.
How do rocks like soapstone and granite contribute to sustainable energy storage?
Rocks like soapstone and granite have unique properties that make them suitable for sustainable energy storage. They can effectively absorb, store, and transmit heat, making them ideal for thermal energy storage (TES) applications. When combined with solar power, these rocks can capture and store solar heat for later use, such as drying foods or generating electricity.
Why are rocks considered a low-tech alternative for energy storage?
Rocks are considered a low-tech alternative for energy storage because they are naturally occurring and widely available materials. Unlike large batteries, which can be expensive and resource-intensive to manufacture, rocks like soapstone and granite can be found across the globe. This accessibility makes them a cost-effective and sustainable option for storing thermal energy.
Are all rocks equally suitable for thermal energy storage?
No, not all rocks are equally suitable for thermal energy storage. The properties of rocks can vary depending on their composition and origin. For example, the study mentioned in the text focused on soapstone and granite samples from Tanzania. These specific samples were found to exhibit desirable characteristics for energy storage, such as high energy densities, stability at high temperatures, and efficient heat release. It’s important to study and analyze rocks from different locations to determine their suitability for specific energy storage applications.
What are the potential benefits of using rocks for energy storage?
Using rocks for energy storage offers several potential benefits. Firstly, it provides a sustainable and environmentally friendly solution for storing renewable energy, such as solar heat. Secondly, rocks are abundant and widely available, reducing the need for resource-intensive manufacturing processes. Additionally, rocks can have good thermal properties, allowing for efficient heat storage and release. Lastly, utilizing rocks for energy storage can potentially lower the cost of energy storage systems, making them more accessible and economically viable.
More about sustainable solar energy storage
- ACS Omega: The journal where the study on rocks as energy storage materials was published.
- Partnerships for Enhanced Engagement in Research: Information about the funding program that supported the research.
- United States Agency for International Development: The organization that provided funding for the study.
