A gym in Central is aiming to use energy normally wasted during workouts to power lights and electrical equipment.

Lucien Gambarota, a French inventor, has connected cycling, stepping and elliptical skiing machines at California Fitness to light bulbs and batteries and, using gym members as guinea pigs, is attempting to prove that energy normally wasted during workouts can create power.

"A normal gym machine will transform all the energy generated by the user into heat. You need air conditioning to offset that heat and the gym also needs lighting," he said. "With this system, the lights only work if someone is using the machine, and instead of heat, the machine is producing electricity, so you don't need as much air-conditioning."

An average person can power and sustain a 30-watt light bulb during an hour's workout and contribute to cutting down on a significant amount of carbon dioxide, according to Mr Gambarota's calculations.

"For every one kilowatt of energy produced by CLP or Hongkong Electric, 500 grams of CO2 is released into the atmosphere. According to my calculations, if we use 20 machines at one gym for 10 hours a day, 365 days a year, we can save about 9 tonnes of C02."

If 100 machines in each of California Fitness's eight gyms in Hong Kong were modified to convert energy, this could prevent 35 tonnes of CO2 a year being released.

California Fitness hopes to equip most of the machines with the technology by Lunar New Year. The technology only works on machines not powered by electricity, so cannot work on treadmills.

The inventor teamed up with the gym's regional fitness development director, Rob Devereux, to test his theory that gyms could effectively power themselves.

"Anyone using electricity is releasing carbon dioxide into the air. What we're trying to do here is reduce the amount of carbon dioxide we produce. People come to the gym to be healthy and then they go outside and breathe in the pollution," Mr Devereux said.

The pair hope the experiment will spur the government to take sustainable energy more seriously. Mr Gambarota said: "From a pollution point of view, this government is incompetent. They talk about blue skies and run their TV campaigns, but there are no blue skies in Hong Kong and there's no such thing as clean coal."

If the trial is successful, it will be rolled out at the company's other gyms in Hong Kong and possibly at its 400 gyms worldwide.

Josie Close of the University of Hong Kong's Centre of Renewable Energy said it would encourage people to contribute to a cleaner environment.