While You're at It,
Why Not Generate
A Little Electricity

Harvesting the Energy
Of Hong Kong Gym Rats;
Lighting Up Dance Floors
March 1, 2007; Page A1

HONG KONG -- A health club here is hoping that a car battery, some StairMasters and dozens of gym rats can help ease the world's energy problems.

Rita Wong is doing her part. One evening recently, the fit 27-year-old, dressed in black spandex, pedaled furiously on an elliptical machine at the California Fitness health club. As she worked up a sweat to a Madonna song blasting on the gym's sound system, the energy she created was transformed into electricity and stored in a battery that powers some of the gym's lights.

"It's very good motivation," Ms. Wong said, pointing at the fluorescent bulb above her head. "You can watch yourself burning fat to turn on that light."

[Rita Wong]

This virtuous cycle is just one of a wave of projects on the fringes of the renewable-energy movement that are trying, in small ways, to tap the power of the human body.

Experiments range from a dance floor that generates electricity from the vibrations of the dancers to energy-harvesting shoes that convert motion from walking into electricity. One shoe prototype can generate about six watts, more than enough to power a cellphone.

Like many of these projects, the California Fitness setup isn't going to light up the Hong Kong skyline or even power the club's own air conditioning. The gym chain has rigged up 13 machines at one of its clubs here. When all of them are in use, the power generated amounts to about 300 watts, roughly enough to run three 27-inch television sets, five 60-watt light bulbs or several hundred video iPods. If all the exercise machines were in use 10 hours a day for a year, the gym could generate roughly $183 worth of electricity. At that rate, it would take about 82 years to pay off the initial $15,000 investment.

Converting elbow grease into electricity has a long, odd history. The first telephones, in the 1800s, had hand cranks that generated an electrical signal to alert the operator when one wanted to make a call. Hand-crank flashlights have long been available. So have hand-crank portable radios.

But unlike these predecessors, many of the new projects focus on capturing energy that is a byproduct of casual human activities, such as walking or exercising. Scientists call such devices "parasitic" generators. Many of the most futuristic projects focus on harvesting the energy of crowds.

Enviu, a Dutch environmental group, is building a nightclub in Rotterdam that will have a dance floor that converts vibrations from all those feet into electricity. One potential design for the floor involves piezoelectric crystals, which generate a small electric current when compressed. But Enviu's 20-by-20-foot floor cost $260,000 and will generate only enough power to run some lights embedded in it.

A London design firm called Facility:Innovate has been developing flooring materials that could ultimately be used to collect energy from throngs of people walking into busy subway tunnels. In one design, each step on the floor would push fluid through a microturbine, generating electricity.

Human power may have more practical uses as an energy source in developing countries or in remote environments where electricity isn't available. The U.S. military has spent millions of dollars in recent years on research into so-called "heel strike generators" that can be placed in soldiers' boots and might help reduce the battery load they have to carry.

Larry Rome, a biology professor at the University of Pennsylvania, recently launched a company called Lightning Packs that aims to sell backpacks that generate electricity from the jiggling motion of walking. In a recent test, his prototype was able to produce about 15 watts of power from the up-and-down motion of the pack.

A California Fitness club in Hong Kong is drawing electric power from its clients.

His research on the backpacks was partly funded by the National Institutes of Health, which was interested in seeing whether the power-generating backpacks could be used to refrigerate vaccine supplies in outlying areas.

The human power project at California Fitness was set in motion by Doug Woodring, a 41-year-old extreme-sports fanatic and renewable-energy entrepreneur, who pitched the experiment to the gym's management last May. "I've trained my whole life, and many megawatts have been wasted," says Mr. Woodring, who has worked out at the Hong Kong gym for years. "I wanted to do something with all that sweat."

Mr. Woodring, a Wharton School graduate who is originally from San Francisco, introduced the management team to his business partner, Lucien Gambarota, a 49-year-old Italian inventor whose inventions include a light-up lollipop that makes your cheeks glow red. Mr. Woodring and Mr. Gambarota are partners in a Hong Kong alternative-energy start-up called Motorwave Ltd., which aims to generate power from the motion of ocean waves.

California Fitness, an Asian chain owned by San Ramon, Calif.,-based 24 Hour Fitness Worldwide, agreed to cover the cost of materials, which ultimately came to about $15,000, and added one condition. "We said, 'Please don't cause our exercise machines to catch fire,'" says president Steve Clinefelter.

In November, Mr. Gambarota set to work jury-rigging the gym's equipment with devices that included a broken washing machine. Mr. Gambarota concluded the elliptical machines and StairMaster exercisers were best equipped for power generation.

Those machines already contained small motion-powered generators used to light up their display screens. But the generators were producing significantly more electricity than was needed to power the screen, and the excess energy was being thrown off as heat.

Mr. Gambarota rewired the generators in 13 machines on the gym's main floor to capture the excess energy, running wires underneath the carpets to a car battery that could store the power. The battery was hooked up to an inverter taken from a mobile home. It converted the voltage from DC to AC and was connected to 13 fluorescent lights hanging above the exercise machines.

The company's U.S. parent is watching the Hong Kong experiment closely and says it would consider a global rollout if the Hong Kong project is successful. The company has three million members and close to 400 gyms in the U.S.

Some people have been capturing their own sweat for years, including children on bicycles whose pedaling generates electricity to operate their headlights. David Butcher, a 52-year-old manager at a Web company in Los Gatos, Calif., works out daily on a homemade exercise bike he has hitched up to a generator. So far, he has used the bike to power his TV and operate his Roomba robot vacuum cleaner. He once jump-started his car after 30 minutes of pedaling.

"I have an excess of physical energy," Mr. Butcher says. "I needed an outlet for it."