Human Dynamo: Your Body as a Power Source
By Don Willmott
We humans move a lot, but all that kinetic energy tends to dissipate into the universe, which is a big waste in the eyes of researchers and entrepreneurs who are scrambling to find ways to capture it. Why not tap into body power to charge some of the increasingly small gadgets we’re strapping to ourselves on a daily basis?
Sweat it Out
Even the simple act of sweating can generate a charge. Researchers at the University of California, San Diego have designed a sensor in the form of a temporary tattoo that can make electricity out of perspiration. How? It detects and responds to lactate, a chemical the body produces during the process of glycolysis, which occurs during physical exertion. Checking lactate levels is nothing new—pro athletes do it all the time to measure their progress—but the new tattoo sensor also contains an enzyme that pulls electrons out of the lactate, and the result is a tiny bit of electricity captured in a biobattery under certain conditions.
In testing, the maximum amount of energy produced by a not-so-fit person was only about four microwatts due to the small size of the device, or less than half the energy needed to run, say, a watch. Still, it’s easy to imagine how bigger and more efficient patches or clothing-based biobatteries could charge your smartphone during your workout.
But maybe you’d rather just sit around and eat a sandwich. No problem. Engineers at Montreal’s École de Technologie Supérieure have built a peculiar chinstrap that converts energy from chewing into electricity. The goal: to power hearing aids or other small devices. The strap is crafted from a piezoelectric fiber composite (PFC) material that becomes electrically charged when it’s stretched due to something called the “piezoelectric effect.”
Using the researchers’ admittedly awkward prototype, 60 seconds of gum chewing generated 18 microwatts of power, about one-twentieth of the juice needed to run a hearing aid, but they say all they need to do is add more layers to the strap to make it more powerful. Their hope is that people who routinely wear helmets—cyclists, firefighters, mineworkers—could one day find a use for that extra jolt.
Along similar lines, researchers at Britain’s Cranfield University are using the same PFC materials to craft military gear that could turn soldiers into self-sufficient power plants with every bump of their backpacks.
Stamp Your Feet
In a Rio de Janeiro slum, a Shell-sponsored project run by Pavegen Systems has tapped into foot power, specifically the power of 22 pairs of feet running up and down a soccer field. The company has built 200 energy-collecting tiles into the pitch, with every footfall generating an electric charge. With the help of solar panels, the field can be lit for up to 10 hours on a full battery. When the field was opened in September, soccer legend Pelé, who was in attendance, was reportedly moved to tears.
If you’re thinking Pavegen’s technology could be used in other locations where there’s heavy foot traffic, the company is one step ahead of you: It’s tiles have already been installed in several schools, a subway station in France, a shopping center in Australia and in London’s Heathrow Airport to power LED lighting and phone charging ports.
Just imagine how well such tiles could work to power informaton screens in Tokyo’s subway stations or bilboards in New York’s Times Square.
Don Willmott is a New York-based journalist who writes about technology, travel, and the environment for a wide variety of publications and websites.