Newswise — Walk into a gym and you'll see exercise machines that plug into a wall outlet and run off electrical power. They have displays with flashing lights and use electricity to power internal systems that provide resistance, so you can vary the difficulty of your workout. But today, dozens of gyms are adopting a new kind of exercise machine. The equipment may look much the same, but they're actually different in a major way. Rather than consuming power, they're generating electricity as people sweat, feeding it to the electrical grid and offsetting some of the gym's energy use.
By adopting power-producing exercise machines in this way, gyms can promote themselves as environmentally friendly and also reduce their electric bills. At least three start-ups in the United States are now selling equipment to retrofit aerobic machines--stationary bicycles, elliptical trainers, and steppers--into electricity-generating gear. These companies have already converted several hundred machines at U.S. health clubs and university gyms.
But does the technology make sense? Each machine generates a small amount of electricity, and the costs of converting the equipment are steep. In the July issue's "Turning Sweat into Watts," IEEE Spectrum discusses the benefits and challenges of electricity-producing exercise equipment, dissecting the economics behind the technology and, as a thought exercise, estimating how many gym-goers it would take to power a home or the entire United States.