Scientists develop dirt-powered fuel cell that could replace batteries

 Researchers led by Northwestern University have developed a fuel cell that generates electricity using microbes naturally found in soil. The device, roughly the size of a paperback book, produces small amounts of power by capturing energy released as these microorganisms break down organic material in dirt.

This soil-powered system is designed to run underground sensors used in precision agriculture and environmental monitoring. It offers a potential alternative to traditional batteries, which contain toxic and flammable materials, rely on complex global supply chains, and contribute to growing electronic waste.Powering Sensors Without Batteries

To demonstrate its capabilities, the team used the fuel cell to operate sensors that measure soil moisture and detect touch. This touch-sensing ability could help monitor wildlife movement, such as animals passing through a field. The system also includes a small antenna that sends data wirelessly by reflecting existing radio frequency signals, which keeps energy use extremely low.

The device proved reliable across a wide range of conditions. It functioned in both dry soil and flooded environments, and it produced more sustained power than similar systems, lasting about 120% longer.

The study was published in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies. The researchers also released their designs, tutorials and simulation tools publicly so others can build on the work.

Why Soil Microbes Matter for the Internet of Things

"The number of devices in the Internet of Things (IoT) is constantly growing," said Northwestern alumnus Bill Yen, who led the work. "If we imagine a future with trillions of these devices, we cannot build every one of them out of lithium, heavy metals and toxins that are dangerous to the environment. We need to find alternatives that can provide low amounts of energy to power a decentralized network of devices. In a search for solutions, we looked to soil microbial fuel cells, which use special microbes to break down soil and use that low amount of energy to power sensors. As long as there is organic carbon in the soil for the microbes to break down, the fuel cell can potentially last forever."

Microbial fuel cells, often called MFCs, work somewhat like a battery. They include an anode, cathode and electrolyte, but instead of chemical reactions, they rely on bacteria that naturally release electrons. When these electrons move through the system, they create an electric current.

"These microbes are ubiquitous; they already live in soil everywhere," said Northwestern's George Wells, a senior author on the study. "We can use very simple engineered systems to capture their electricity. We're not going to power entire cities with this energy. But we can capture minute amounts of energy to fuel practical, low-power applications."

Source: ScienceDaily