Soil-Powered Fuel Cell Harnesses Earth’s Energy

A groundbreaking innovation from Northwestern University showcases a compact device capable of producing electricity by harnessing the power generated as microbes decompose soil, as long as there is carbon present.

This device, about the size of a paperback book, operates on microbial fuel cell technology, which has existed for over a century. Unlike conventional batteries, it utilizes bacteria to transfer electrons to conductors while they consume soil, mimicking the function of an anode, cathode, and electrolyte in a battery but deriving power from natural microbial processes rather than chemical sources.

Providing Consistent Water and Oxygen Supply to Microbial Fuel Cells (MFCs)

Until now, the challenge has been ensuring a consistent supply of water and oxygen to microbial fuel cells (MFCs) while they are buried in soil. Bill Yen, a former student at UNW and the leader of the project, remarked, “Despite being a concept for over a century, the inconsistent performance and limited power output of MFCs have hindered efforts to apply them practically, particularly in environments with low moisture levels.”

Therefore, the team embarked on developing multiple fresh designs aimed at ensuring constant access to oxygen and water for the cells. They achieved success with a design resembling a cartridge positioned vertically on a horizontal disk. Within this design, a disc-shaped carbon felt anode lies horizontally at the device’s base, deeply embedded in the soil to capture electrons during microbial soil decomposition.

Optimizing Cathode Design for Efficient Oxygen Supply

Meanwhile, the conductive metal cathode is positioned vertically above the anode. The lower portion is sufficiently deep to access moisture from the soil’s depths, while the upper part is level with the surface. An air gap extends along the entire length of the electrode, and a protective cap on the top prevents soil and debris from obstructing the cathode’s oxygen supply. Moreover, a portion of the cathode receives a coating of waterproof material, guaranteeing that in flooded conditions, a hydrophobic segment persists in contact with oxygen, thereby maintaining the fuel cell’s operation.

During testing, this design consistently performed well across various soil moisture levels, ranging from being completely submerged to “somewhat dry,” with soil moisture at just 41% by volume. On average, it produced power exceeding the requirements for operating its built-in moisture and touch detection systems, as well as transmitting data wirelessly to a nearby base station via a small antenna, by a factor of 68.

The electricity produced by this technology, similar to other enduring sources like betavoltaic diamond batteries, isn’t enough for running devices like dirt-fueled cars or smartphones. Instead, its main purpose is to consistently power small sensors without needing frequent battery replacements.

Harnessing Soil Microbial Fuel Cells for Long-Term Energy Solutions

Yen emphasizes the importance of seeking alternatives to environmentally harmful materials such as lithium and heavy metals for future tech advancements. Soil microbial fuel cells offer a promising solution by tapping into the energy released from soil decomposition by microbes. With organic carbon present, these fuel cells could potentially operate indefinitely.

Thus, sensors driven by this technology could greatly assist farmers in monitoring various soil conditions like moisture levels, nutrient content, and contaminants, enabling precision agriculture. Installing multiple sensors across a property could ensure continuous data collection for many years, possibly even decades.

Highlighting the impressive aspect, the research team underscores that all components of this design are readily available for purchase from a hardware store. Therefore, there are no supply chain or material obstacles preventing the widespread commercialization of this research.

Read the original article on: New Atlas

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