THE SCALES aren’t the only things registering lower numbers at the recently opened Green Microgym on NE Alberta Street. Owner Adam Boesel’s electricity bills may soon be slimming down as well, thanks in large part to his lean, mean clientele. His gym is outfitted with bikes and elliptical trainers that can generate power from people’s workouts—which means that as his 72 members battle their bulges, they’re also producing the juice that runs the gym’s TVs, computers, and stereo. The gym is one of only a handful of self-powered fitness centers in the world, and Boesel expects the equipment to generate about five kilowatt hours per day—enough to wash about 15 loads of sweaty workout clothes. And the solar panels installed on the roof should shave off another $145 from his bill each year. Although he hasn’t seen the savings yet (the gym just opened at the end of August), Boesel is confident he’s launched the right idea in the right city. “People in Portland are very serious about alternative energy sources,” he says. “And when they find out they can exercise in a sustainable way, I think we’ll draw even more interest.” And more wattage. Here’s how the gym works.

PEDAL POWER
If Lance Armstrong were a trainer-in-residence at the Green Microgym, he could likely charge up the whole neighborhood by his lonesome on the Team Dynamo bikes, four connected cycles that have been modified to generate power. Even so, Mike Taggett, the owner of Texas-based company Henry Works, which makes the bikes, figures that if all four are in use by reasonably fit guests, they will produce about 1.5 kilowatt hours per day, enough to run a desktop computer for about five hours.

CHARGE ACCOUNT
Energy produced by the bikes and solar panels flows into a bank of batteries, where it can be stored for later use. Boesel estimates that he should need about 25 kilowatt hours a day to run his gym. At the moment he’s generating about 8 to 12 on-site—or enough to loop Rocky about 20 times on one of the gym’s TVs for inspiration.

HEAT WAVE
Steve McGrath at Sustainable Solutions, the Portland company that installed Boesel’s solar panels, estimates that, on a clear sunny day, the rooftop system will generate just under 8 kilowatt hours per day—enough to run a central air conditioner, typically the biggest energy sucker in any building, for about three hours. During the winter, however, energy production could plummet to a paltry 2.7 kilowatt hours. Fortunately, cold days don’t require AC.

MAKING THE ROUNDS Boesel has six elliptical machines on the premises—two SportsArt 8300 E Series trainers and four Life Fitness 9500 HR trainers—that each should generate about 75 to 100 watts per hour. Which is just enough juice to keep them running without sucking any power from the grid.