Green Gyms Powered by Members' Workouts

Your gym workouts might do more than just work up a sweat -- they also can help power the lights in your club. It's the latest development in the green revolution: Gyms that convert the kinetic energy produced by their members' workouts into electricity.

The technology that converts kinetic energy into electricity is relatively simple. Electromagnets in a generator turn mechanical motion into electrical currents. It's easy to apply to all kinds of activities. Dance clubs have started harnessing the motion of their dance floors to power audio systems. Kinetic backpacks from Nixon use energy generated by hikers to power their Apple(AAPL) iPods. Tremont Electrical Supply has created a device called the PEG (personal energy generator), which transfers the kinetic energy generated by a person walking or running into electricity that can power any handheld USB-powered device.

The River Gym in New York City, which is in its planning stages, would include a series of floating, enclosed gyms navigating routes along the East and Hudson rivers.

Only a few energy-producing gyms are up and running now, but one might be opening near you soon -- so keep an eye out for clubs like these:

Ridgefield Fitness Center in Ridgefield, Connecticut, is the beta-testing center for Green Revolution, which plans to install kinetic-to-electric energy converters in more than 200 gyms across the country by the end of 2009. Michael Curnyn, head of marketing for Green Revolution, estimates that over the course of a month, a gym with 20 energy-producing cycling machines could generate up to 300 kilowatts of electricity, preventing the emission of 420 pounds of greenhouse gasses.

California Fitness in Hong Kong was the first gym to convert the kinetic energy produced by its members' workouts into electricity, which it uses to power lights and televisions. The gym's 88 cycling, elliptical and Nautilus(NLS) Stairmaster machines are hooked up to generators. According to company President Steve Clinefelter, spending one hour a day on one of the gym's exercise machines could easily generate up to 18.2 kilowatts of electricity, preventing 4,380 liters of carbon dioxide from being released each year. California Fitness plans to equip the rest of its gyms in Asia and the U.S. with this technology in the near future. Fees (converted into U.S. dollars) are $30 a month with an enrollment and processing fee of $36.