‘Bugs’ to boost solar energy storage underground in ‘soil batteries,’ new project claims
A new energy project in the U.K. has ambitious plans to create "soil batteries" to store solar power underground.
The design, one of the dozens of ideas that recently received a significant funding boost from the U.K. government, leverages the Earth's teeming microbial life to transfer energy, according to a report published by Euronews on Friday.
"The possible scale of that impact is really exciting," lead researcher Dr. Michael Harbottle of Cardiff University told Euronews Green. "To see something that's really quite novel, possibly having a big impact, is what's driving us."
Harbottle first had the thought after reading about a chemically-powered concrete battery, and he questioned whether a biological method would not have more to offer.
Researchers at Cardiff University are already using a plentiful natural resource, similar to sand and water batteries, to help solve the problem of renewable energy storage.
How would storing underground energy work?
The subject matter of Harbottle's research is still conceptual. But he wasn't the first to recognize soil's potential in this way.
There are numerous instances of people successfully conducting experiments by simply adding soil to a jar, adding a few electrodes, and connecting them, the scientist claims.
The idea is to stimulate particular microorganisms in the soil by using buried electrodes to receive electricity from solar panels.
"If you make energy available to microorganisms, they'll use it in some way to survive," explained Harbottle.
"Just like providing food, if you provide electrical energy, there are organisms who can use that to perform electrosynthesis, where they synthesize [combine] carbon-based molecules from carbon dioxide."
These bugs that feed on them expel electrons that go across the circuit and produce electricity as needed—just another peculiar phase of sunlight's 150 million-kilometer trek to Earth.
Acetate as a chemical energy reserve
It is similar to photosynthesis, which occurs when plants take up CO2 and change it in their cells below the ground. Electricity, carbon dioxide, action: The "bugs," as Harbottle refers to them, start using the energy to decrease the carbon dioxide and create a more complicated chemical called acetate.
He claims that this acetate functions as a chemical energy reserve and is the same type of molecule as one could find in vinegar but without the acid. When necessary, a separate circuit (known as a microbial fuel cell) is activated, causing a different group of bacteria to become active and begin breaking down the acetate.
Although acetate is not harmful, may an excessive amount of the substance harm other life forms in this diverse ecosystem? Harbottle admits that it could. Though the deeper, wetter soil underneath the busiest top layers is where the experts focus their attention, the impact needs further investigation.
According to Harbottle, "One advantage of the idea is it doesn't require resource-limited or hazardous chemicals like lithium that are used in other battery technologies."
"It creates organic molecules that are often present in the soil anyway, that are produced naturally by microorganisms in smaller quantities."
'High risk' but 'transformative impact'
According to the project, the prototype will function every day, storing solar energy for use at night, unlike some long-term energy systems.
These batteries might eventually be positioned below solar panel fields. However, because microbial fuel cells can currently only produce modest voltages, its application in relatively low-power projects seems more immediate.
The researchers, a cross-disciplinary group of electrical and geoenvironmental engineers, eventually hope to scale up by connecting hundreds of cells to create a much higher voltage.
A non-departmental public body of the government called U.K. Research and Innovation, which oversees funding for research and innovation, has invested £15 million (€16.9 million) in the emerging technology along with 67 other projects that it acknowledges are "high risk" but could have a "transformative impact."
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