The University of North Texas is turning a workout facility into what it says is the largest human power plant in the nation.
Thirty-six elliptical machines at UNT's recreation center have been fitted with a device that captures the kinetic energy they produce and coverts it into electricity.
"The energy that they produce is usually heat that escapes into the building. It's then turned into electricity that is used right here in the rec center to power the lights, power everything," UNT spokesman Stuart Birdseye said.
As students rev up the machines, a monitor shows how much clean, carbon- free electricity is being produced. Birdseye said more resistance means more energy.
"When you talk about energy, you think about windmills and water -- other things producing energy, not yourself, working out," student Denise Romo said.
Developers say a typical, 30-minute workout creates enough energy to power a laptop for an hour or charge a cellphone six times.
"I wonder how much money we are saving the school," student Daniel Hold said. "It's kind of neat to think of it that way."
Birdseye said the university hasn't had the system long enough to see an impact on cost.
UNT spent nearly $20,000 to outfit the machines.