The next generation of solar energy collectors could be rocks

Date:
May 30, 2023
Source:
American Chemical Society
Summary:
The next generation of sustainable energy technology might be
built from some low-tech materials: rocks and the sun. Using a new
approach known as concentrated solar power, heat from the sun is
stored then used to dry foods or create electricity. A team has
found that certain soapstone and granite samples from Tanzania
are well suited for storing this solar heat, featuring high energy
densities and stability even at high temperatures.


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FULL STORY ==========================================================================
The next generation of sustainable energy technology might be built
from some low-tech materials: rocks and the sun. Using a new approach
known as concentrated solar power, heat from the sun is stored then used
to dry foods or create electricity. A team reporting in ACS Omega has
found that certain soapstone and granite samples from Tanzania are well
suited for storing this solar heat, featuring high energy densities and stability even at high temperatures.

Energy is often stored in large batteries when not needed, but these can
be expensive and require lots of resources to manufacture. A lower-tech alternative is thermal energy storage (TES), which collects energy as
heat in a liquid or solid, such as water, oil or rock. When released,
the heat can power a generator to produce electricity. Rocks such as
granite and soapstone are specifically formed under high heat and found
across the globe, which might make them favorable TES materials. However,
their properties can vary greatly based on where in the world they were
formed, possibly making some samples better than others. In Tanzania,
the Craton and Usagaran geological belts meet, and both contain granite
and soapstone. So, Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande
and Thomas Kivevele from Nelson Mandela African Institution of Science
and Technology and Ardhi University wanted to investigate the properties
of soapstone and granite found in each of these belts.

The team collected several rock samples from the belts and analyzed
them. The granite samples contained a large amount of silicon oxides,
which added strength. However, the Craton granite contained other
compounds, including muscovite, which are susceptible to dehydration
and could make the rock unstable at high temperatures. Magnesite was
found in the soapstone, which conferred a high density and thermal
capacity. When heated to temperatures over 1800 degrees Fahrenheit,
both soapstone samples and the Usagaran granite had no visible cracks,
but the Craton granite fell apart. Additionally, the soapstone was more
likely to release its stored heat than the granite. In all, the Craton soapstone had the best performance as a TES, able to absorb, store and
transmit heat effectively while maintaining good chemical stability and mechanical strength. However, the other rocks might be better suited
for a lower-energy TES application, such a solar dryer. The researchers
say that though further experiments are needed, these samples show good
promise in being a sustainable energy storage material.

* RELATED_TOPICS
o Matter_&_Energy
# Thermodynamics # Solar_Energy # Energy_Technology #
Energy_and_Resources
o Earth_&_Climate
# Energy_and_the_Environment # Renewable_Energy #
Sustainability # Environmental_Science
* RELATED_TERMS
o Renewable_energy o Solar_power o Solar_cell o Wind_power o
Geothermal_power o Distributed_generation o Greenhouse_effect
o Hadley_cell

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Lilian Deusdedit Kakoko, Yusufu Abeid Chande Jande, Thomas Kivevele.

Experimental Investigation of Soapstone and Granite Rocks as
Energy- Storage Materials for Concentrated Solar Power Generation
and Solar Drying Technology. ACS Omega, 2023; 8 (21): 18554 DOI:
10.1021/ acsomega.3c00314 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230530125428.htm

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