Harvesting Energy From Humans

The next big thing in alternative energy: your body. Wasted energy from your movements may not be enough to power your house, but it will be charging your cellphone and more within the next decade

Knee Generator: Energy output: 7 watts
The Bionic Energy Harvester can produce enough power from a one-minute walk to juice a cell phone for 30 minutes. The generator [red] sits on your knee and gathers energy toward the end of your step, when your leg begins to brake.
Greg Ehlers/SFU [inset: Claus Lunau]

The human body contains enormous quantities of energy. In fact, the average adult has as much energy stored in fat as a one-ton battery. That energy fuels our everyday activities, but what if those actions could in turn run the electronic devices we rely on? Today, innovators around the world are banking on our potential to do just that.

Movement produces kinetic energy, which can be converted into power. In the past, devices that turned human kinetic energy into electricity, such as hand-cranked radios, computers and flashlights, involved a person’s full participation. But a growing field is tapping into our energy without our even noticing it.

Consider, for example, a health club. With every step you take on a treadmill and with every bicep curl, you turn surplus calories into motion that could drive a generator and produce electricity. The energy from one person’s workout may not be much, but 100 people could contribute significantly to a facility’s power needs.

That’s the idea behind the Green Microgym in Portland, Oregon, where machines like stationary bikes harvest energy during workouts. Pedaling turns a generator, producing electricity that helps to power the building. For now, body energy supplies only a small fraction of the gym’s needs, but the amount should increase as more machines are adapted. “By being extremely energy-efficient and combining human power, solar and someday wind, I believe we’ll be able to be net-zero for electricity sometime this year,” says the gym’s owner, Adam Boesel. His bikes, by the way, aren’t the first to put pedal power to work. In some parts of the world, cyclists have been powering safety lights for years with devices called bicycle dynamos, which use a generator to create alternating current with every turn of the wheels.

Dance clubs are also getting in on the action. In the Netherlands, Rotterdam’s new Club WATT has a floor that harnesses the energy created by the dancers’ steps. Designed by a Dutch company called the Sustainable Dance Club, the floor is based on the piezoelectric effect, in which certain materials produce an electric current when compressed or bent. (The most common example is a cigarette lighter, in which a hammer causes a spark to be emitted when it strikes a piezoelectric crystal.) As clubgoers dance, the floor is compressed by less than half an inch. It makes contact with the piezoelectric material under it and generates anywhere from two to 20 watts of electricity, depending on the impact of the patrons’ feet. For now, it’s just enough to power LED lights in the floor, but in the future, more output is expected from newer technology. In London, Surya, another new eco-nightclub, uses the same principle for its dance floor, which the owners hope will one day generate 60 percent of the club’s electricity.

Page 1 of 3 123next ›last »