A team at Northwestern University has created a paperback-sized device that can rest within the soil and draw energy from it. The dirt-powered fuel cell is quite unique and can draw almost limitless energy from the soil it is placed within.
The device is what scientists call a microbial fuel cell. These nifty inventions have been around for more than 100 years, and they work very similar to a battery. However, instead of relying on the chemicals a battery does, they instead work with the bacteria found in the soil around them.
While they have been around for a while, scientists have had issues keeping them supplied with water and oxygen when they are buried. The team at Northwestern University hoped to overcome this issue by creating new designs that give the dirt-powered fuel cells continual access to oxygen and water.
The design they settled on is large enough to sit deep enough to access moisture from the deep soil, while the top of the device sits flush with the surface of the soil. This creates a fresh air gap that can run down the entire length of the device’s electrode. Further, the device is set up to protect the cathode from oxygen and water exposure to help it keep running even during less-than-ideal environmental scenarios.
The team reports that this particular design performed consistently across various moisture levels. On average, the device generated 68 times more power than was required to operate the onboard moisture and touch detection systems, the team says. The dirt-powered fuel cell could also transmit data via a tiny antenna to a base station nearby.
Of course, the power generated here by this device isn’t enough to power a full-fledged car or smartphone just yet. However, it could power smaller sensors long-term without requiring battery changes as often. Sure, that isn’t the most significant improvement ever, but considering the device pulls energy from the soil around it, that’s not a bad deal at all.
This and other advancements, like the car that runs off salt water, continue to improve our power generation options. The team published their findings in Proceedings of ACM on Interaction, Mobile, Wearable and Ubiquitous Technologies.