Researchers at Northwestern University in the US have created a fuel cell that harvests energy from microbes living in soil so that it can potentially last forever (or as long as there are soil microbes).
Why?
As Bill Yen (who led the research) suggests, the value may lie in its ability to supply power to IoT devices and other devices in wild areas where solar panels may not work well and where having to replace batteries may be challenging.
For example, talking about the IoT (on the Northwestern University website) Mr Yen says of the growing number of devices: “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 decentralised network of devices.”
Mr Yen also highlights how, putting a sensor out in the wild (e.g. in a farm or in a wetland), can mean being “constrained to putting a battery in it or harvesting solar energy” and points out that “Solar panels don’t work well in dirty environments because they get covered with dirt, do not work when the sun isn’t out and take up a lot of space.”
Makes Sense To Use Energy From The Existing Environment
In tests, the revolutionary new fuel cell was used to power sensors measuring soil moisture and detecting touch, a capability that the researchers say could be valuable for situations like tracking passing animals.
To tackle the issues of the limitations of relying on normal batteries or solar panels in unsuitable areas, the researchers concluded that harvesting energy from the existing environment (e.g. energy from the soil that farmers are monitoring anyway) is a practical and sensible option.
How Does The Cell Work?
After two years of research and 4 different versions, the fuel cell is essentially an updated and improved version of a Microbial Fuel Cell (MFC), an idea that’s been around since 1911! In essence, an MFC generates electricity using bacteria in the soil in the following way:
– Bacteria in the soil break down organic matter, releasing electrons in the process.
– These electrons travel through a wire from the anode (where bacteria are) to the cathode (another chamber), generating electricity.
– In the cathode, a reaction uses these electrons (plus oxygen and protons) to form water, keeping electrons flowing as long as there’s “food” for bacteria.
The Combination of Ubiquitous Microbes and A Simply Engineered System
Northwestern’s George Wells, a senior author on the study, says the key drivers of the success of the fuel cell design are the fact that it uses microbes that are “ubiquitous; they already live in soil everywhere” and that it has a “very simple engineered systems to capture their electricity”.
Special Features
The features that make the MFC made by the researchers at Northwestern University so successful are:
– Its geometry. Rather than using a traditional design where the anode and cathode are parallel to one another, this version leverages a perpendicular design.
– The conductor that captures the microbes’ electrons is made of inexpensive and abundant carbon felt, and the anode (made of an inert, conductive metal) is horizontal to the ground’s surface, with the cathode sitting vertically atop the anode.
– Although the entire device is buried, the vertical design ensures that the top end is flush with the ground’s surface.
– A 3D-printed top prevents debris from falling inside.
– A hole on top and an empty air chamber running alongside the cathode allow consistent airflow.
– With the lower end of the cathode being deep beneath the surface, this ensures that it stays hydrated from the moist, surrounding soil (even if the surface soil is dried out in the sunlight).
– Part of the cathode is coated with waterproofing material to allow it to breathe during a flood and, after a potential flood, the vertical design helps the cathode to dry out gradually rather than all at once.
More Power
The Northwestern researchers claim that the power produced by their fuel cell can outlast similar technologies by 120 per cent.
What Does This Mean For Your Organisation?
This is an example not just of how an old technology has been re-vamped and supercharged, but also how a relatively simple solution fuelled by nature can be the answer to modern world challenges.
This simple, cheap device, that uses a potentially endless supply of free, natural energy as its power source could be of huge value in areas like precision agriculture to feed the world. For example, farmers wanting to improve crop yields can now have a long-lasting, no-maintenance, natural way to power the sensors/devices needed to measure things like levels of moisture, nutrients, and contaminants in soil. This cell will also free farmers from the task of having to travel around a 100+ acres farm cleaning solar panels or changing batteries. Another major advantage of the product’s design is the fact that some of it can be 3D printed and all the components could be purchased in a hardware shop.
All this means it has a wide potential geographic reach. The fact that there’s already a plan to make the next version from fully biodegradable materials, avoiding using any conflict minerals in its manufacture is also a big environmental plus. In short, this simple, cheap, and highly effective cell could offer opportunities and fuel results that are dramatically greater than the sum of its parts.
