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15 bizarre green inventions

human-powered river gym

Photo: Mitchell Joachim & Douglas Joachim/Terreform ONE

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River gym

In 2005, New York Magazine held a contest for forward-thinking gym concepts, and Mitchell Joachim & Douglas Joachim submitted River Gym. This floating gym would harness the energy lost during New Yorkers' workouts and use it to move boats across the Hudson and East rivers. Not only does this innovative design use the energy created by people on cardio machines, the designers say it also “helps purify water, provides spectacular views and transports less-motivated citizens.”