Courtesy of technology created by ReRev™, fitness equipment supplier Precor's elliptical machines can now deliver human-generated energy back to the electrical grid.

The kinetic motion of aerobic exercise is efficiently captured in a cost-effective way to convert otherwise wasted energy into productive renewable energy that feeds back into a building's electrical system.

Working exclusively with Precor's retrofitted elliptical machines, the typical amount of energy captured via ReRev's technology during a 30-minute workout will produce 50 watt hours of clean, carbon-free electricity.

Over the course of 10 hours in a typical gym, 15 ellipticals can generate energy equivalent to 16 central air conditioners running for one hour.