Researchers at Northwestern University have created an innovative battery that generates electricity using naturally occurring bacteria in soil, offering a new way to power underground sensors.
Roughly the size of a paperback book, the device is designed to run low-energy systems such as agricultural monitoring sensors without relying on traditional batteries or solar panels. This makes it particularly useful in remote areas, where replacing batteries is difficult and solar panels can fail due to dirt buildup or lack of sunlight.
The system taps into microbes already present in the soil. These bacteria release electrons as they break down organic matter, and the fuel cell captures those electrons to produce electricity. While the concept of microbial fuel cells has existed for years, earlier versions often struggled with low efficiency and inconsistent output, especially in dry conditions.
To improve performance, the research team spent two years testing multiple designs before selecting a vertical structure. In this setup, the anode—made of carbon felt—is placed horizontally beneath the soil, while the cathode is positioned upright. Its top section is exposed to air for oxygen flow, while the lower part stays moist underground. A 3D-printed cover protects the system from dirt while allowing airflow, and parts of the cathode are waterproofed to ensure functionality during floods.
Field tests showed promising results, with the fuel cell continuing to operate in both dry and flooded conditions. It produced significantly more energy than required to power its sensors. These sensors can monitor soil moisture and even detect physical disturbances, such as movement from animals.
The system also includes a small antenna that wirelessly transmits data. Researchers say the technology is best suited for low-power applications, and they have made the design and instructions publicly available to encourage wider use and further development.
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