| || |
Potatoes are often the preferred vegetable of choice for teaching high school science students these principles. Yet to the surprise of Rabinowitch, no one had scientifically studied spuds as an energy source. So in 2010, he decided to give it a try, along with PhD student Alex Goldberg, and Boris Rubinsky of the University of California, Berkeley.
“We looked at 20 different types of potatoes,” explains Goldberg, “and we looked at their internal resistance, which allows us to understand how much energy was lost by heat.”
They found that by simply boiling the potatoes for eight minutes, it broke down the organic tissues inside the potatoes, reducing resistance and allowing for freer movement of electrons– thus producing more energy. They also increased the energy output by slicing the potato into four or five pieces, each sandwiched by a copper and zinc plate, to make a series. “We found we could improve the output 10 times, which made it interesting economically, because the cost of energy drops down,” says Goldberg.
“It’s low voltage energy,” says Rabinowitch, “but enough to construct a battery that could charge mobile phones or laptops in places where there is no grid, no power connection.”
Their cost analyses suggested that a single boiled potato battery with zinc and copper electrodes generates portable energy at an estimated $9 per kilowatt hour, which is 50-fold cheaper than a typical 1.5 volt AA alkaline cell or D cell battery, which can cost $49–84 per kilowatt hour. It’s also an estimated six times cheaper than standard kerosene lamps used in the developing world.