Clean Energy From Humans? No Sweat

Sweating to cool things down: OSU's retrofitted elliptical machines feed electricity back into the grid. (Oregon State University)
A light switch can be powered by sun, wind or water, but what about by the sweat of one’s brow? Oregon State University is one of the first universities to do just that, by harnessing kinetic energy from students’ workouts.

On February 16, OSU unveiled 22 elliptical machines that capture energy and feed it back to the school’s power grid.

The school partnered with St. Petersburg-based company ReRev to retrofit their machines in the Dixon Recreation Center. Hudson Harr, a recent University of Florida graduate and CEO of ReRev, thought of the business idea while working out.

ReRev technology converts counter-productive heat energy from exercise machines and sends voltage directly back into the utility grid (instead of a battery). Each elliptical machine has the ability to produce 1 kilowatt of electricity every 10 hours, enough to charge the battery for a 2004 Toyota Prius. A real-time display system shows gym goers their power production.

“A battery-free system like this, tied to the grid, is quite rare,” said Brandon Trelstad the university’s sustainability coordinator.

Trelstad added that OSU’s effort will produce an estimated 3,500 kilowatt hours of electricity in a year – enough to power a small house. What’s more, OSU will save money on cooling costs since latent heat produced from the machines will be captured.

The retrofitting costs about $300 per machine and was supported by the Energy Trust of Oregon as well as an $8.50 fee students pay every term earmarked for renewable energy. Since the fee was imposed in 2007, about three-quarters of the university’s electricity has come from renewable production.

OSU chose the Dixon Recreation Center as a location because of its high volume of users. “The center’s workout volume, combined with the large amount of equipment, could eventually produce the same amount of electricity as a small solar photovoltaic system, placing students directly in the renewable energy production chain,” said Matthew Pennington, chief of staff for the Associated Students of Oregon State University.

The school plans to retrofit up to 40 ellipticals in the future.

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Published: March 31, 2009