健身器材可以用来发电?

It's a workout with two goals, mean green students are doing their bodies and the environment a favor when they hop on these machines.

"When you talk about energy, you think about like the windmill and there the water and other things producing energy, not yourself, working out."

These 36 elliptical machines have been fitted with a device that captures the kinetic energy they produced and converts it into electricity.

"That energy that they produce is usually just heat that escapes into the building, it is then turned into electricity, that's used right here in the Rec (Recreational) Center, to power the lights, to power everything."

As students rev up, this monitor shows how much clean carbon free electricity is being produced. Stuart Birdseye works at the Rec Center and says more resistance means more energy.

"The students center using the equipment don't have to do anything different."

"And the developers claim that a typical 30 minute workout create enough electricity to power a laptop for an hour, or charge a cellphone up to 6 times."

"On how much money we are saving the school basically, it's gonna need to think about that way."

"We haven't had a long enough to see the impact on cost."

UNT (University of North Texas ) spent nearly 20,000 dollars to outfit these ellipticals, the cost these machines may never pay back. But the school said it's more than the dollars they save, as students give just a little back, one workout at a time.