If you remember that light-up-a-potato trick from science class, you might be wondering why potatoes can’t be used as a cheap type of battery in developing countries. The answer is simple: in many parts of the world, potatoes don’t come cheaply. However, scientists in Sri Lanka are taking the basic chemistry and applying it to plantain batteries, with pretty good result.
Why a Plantain Battery?
Although the researchers are finding that plantain is not quite as efficient as potato for producing electricity, plantain does have a number of advantages.
As reported by PRI (Public Radio International), plantain battery research in Sri Lanka has been motivated partly by the ease with which plantain trees are grown in individual yards in that country, making plantain cheap and accessible even in remote areas.
The team, based at the University of Kelaniya, also focused on using a non-food source of raw materials for the battery.
Competition between food and energy is already a critical issue for biofuels, so if plant-based batteries are to be adopted on a wide scale, the use of a non-food source is essential.
By that measure the banana-like plantain fruit is a nonstarter, but the trunks of plantain trees are normally left to rot after the fruit is picked, and that is where the research team found their potato substitute.
DIY Plantain Batteries
Apparently, anyone with a plantain tree in their backyard can make their own plantain battery.
It looks a bit cumbersome, but do-able. All you have to do is harvest pith from the inside of a plantain tree trunk, boil it, chop it, mash it, and sandwich it between two electrodes, one of copper and one of zinc.
Tie it all together with duct tape and there’s your battery.
Phosphoric acid in the pith provides the juice to react with the two electrodes, producing a small current.
According to PRI, the battery has an output of less than one volt, but when the Sri Lanka team linked four of the devices together, they got enough current to prove useful.
As reported by SciDev.net earlier this year, so far, the team has been able to power two LEDs for about 500 hours on plantain batteries.
Green Chemistry for a Green World
Plantain batteries are just one small part of a broader trend in which low-cost, biodegradable materials are subbing in for pricey, sometimes toxic substances, especially petroleum products and petrochemicals.
Plantain batteries might sound exotic in some parts of the U.S., but they’re downright normal compared to some other avenues of exploration, including biofuel made from beer broth, bioplastics made of cow bones, and water treatment systems based on banana peels.
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Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.