Could gyms across the World use their bikes, weight machines, & perhaps treadmills to output any electricity generated to a battery bank? And provide power to their own lights and maybe even to the grid - practical or impractical?
Much of the homeless have always been Green by recycling cans. Maybe homeless shelters could get fitness-bikes from Gyms acquiring new ones and have an option for the homeless to make some money by generating electricity? And adapters for normal bicycles for a battery attachment that can plug into your home and transfer its engery?