Charging cell phones with dirt power

Phone battery running low? Well get lower, down to the ground. Harvard University researchers have created a microbial fuel cell for off-grid, Sub-Saharan Africans to charge their mobile phones via mud.

Talk is dirt cheap. At least that’s the hope of engineers who have developed a charger to power cell phones via dirt—specifically, the bacteria living within mud and other mundane matter.

Harvard University researchers are testing a microbial fuel cell (MFC) that harnesses free electrons produced by the metabolic processes of bacteria. The MFC's conductive surface sends the electrons through a anode-cathode-resistor circuit to generate electricity and just maybe, charge a phone. The Navy, too, has been dipping its toes into MFC power. Instead of soil, they're looking to marine detritus to power unmanned vehicles and environmental sensors operating below the water's surface.

Back on land, the MFC a la mud can charge a phone within 24 hours, according to its developers. That's an eternity for most cell-phone junkies. But in locales where the electrical grid is spotty or non-existent, the charger could be a lifesaver. Take Sub-Saharan Africa. About a fifth of the homes there have cell phones, but charging them seldom entails just plugging them in a wall outlet.

Research Aviva Presser Aiden, says in a statement:

For households lacking power in Sub-Saharan Africa, recharging a cell phone battery often means a long, possibly multi-hour walk to a charging station, where recharges cost between 50 cents and a dollar. Because the per-capita income is several hundred dollars per year, this is a significant cost. Existing solutions for charging cell phones in off-grid areas are inadequate. For instance, a solar-panel based charger costs around $20, and is difficult to even bring to market because of poor access and inability to repair them if they break.

And for times when telecommunication is crucial—calling a doctor during an emergency or receiving what should be routine medical care and information—a little dirt could prove invaluable. Aiden's team envisions the chargers being made cheaply with readily available components, such as soda cans and window screens.

The Bill and Melinda Gates Foundation recently granted the project $100,000 to test how the MFC performs in the field and determine how people in remote corners of the the world might best adopt the technology. So far in the lab, the device has worked continuously for more than a year and been able to generate enough power to light LEDs.

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Image: Bill & Melinda Gates Foundation and Flickr/Slightlynorth

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