An article in the LA Times highlights Portland, Oregon’s Green Microgym, where clients exercise on spin bikes attached to electrical generators.

The Green Microgym claims to be the only fitness center in the world that generates some of its own power. To do so, it relies on a combination of solar power and human power. Riders on four spin bikes connected to a single generator can contribute approximately 350 watts to the gym’s electrical needs. The gym is working toward harnessing energy from elliptical trainers as well.