In early January, amid the bleak winter landscape in the suburbs of Boston, Aviva Aiden shows up at a hospital for an interview.
She has a stethoscope around her neck, both hands in the pockets of her white doctor's smock, and a smile on her face. This American woman is enrolled in the doctorate program at Harvard Medical School, and is hoping to become a clinician.
Around two years ago, Aiden was featured in the mass media for a reason totally unrelated to her aspirations in medicine.
She had set up a project aimed at generating electricity from microbes living in the soil, and charging a cellphone with it. This was highly praised as a revolutionary idea, and received $100,000 (9.2 million yen) in funding from a foundation run by Microsoft founder Bill Gates and his wife, Melinda.
To date, 15 people have been involved in the project's development, including engineering students from Harvard University and the Massachusetts Institute of Technology (MIT). Five hundred batteries were taken to Uganda in East Africa, and are being used by people in rural villages with poor electrical infrastructure as part of operational tests.
“There aren't always proper roads,” says Aiden. “We stuck cheap chemicals or materials on the back of a donkey or a horse.”
HOW CAN ELECTRICITY BE GENERATED FROM SOIL?
“A spoonful of soil contains billions of microbes, and they emit electrons when breaking down organic material,” explains Peter Girguis, an associate professor at Harvard University who has provided guidance to Aiden. “Those electrons can be attracted by electrodes to produce electricity.”
This mechanism has been known for more than a century, but the electricity produced by bacteria is so faint that there have been no practical applications for it. The technology has been lacking to attract electrons efficiently.
However, technological progress has opened new ways forward. According to Girguis, one of these is LEDs.
“A small LED light uses less than a 1,000th of the electricity needed to power a standard incandescent light bulb. The power generated by microbes isn't enough to turn on a television, but it can turn on an LED light.”