In an ideal world, we could convert our physical activity (walking, running, exercising, etc.) into stored energy. Gym equipment would have energy storage cells. Also, wind energy passing through (electric) cars and transportation vehicles would be captured and converted.
Healthier active people. Clean(er) renewable energy.Updates:
According to Evoke Agent Indrek Rünkaru
, Dr. William Bird had the idea to convert indoor bicycles into electricity generators in 1990. There are over 75 green gyms in Great Britain.