The water system is a near closed system that just needs to be filled-up occasionally and then mostly the same water is used over and over.

The water pumps are simple mechanical devices on each exercise machine.

The water pumped to the roof just has one generator to turn when it flows down.

Basically, I would use the exercise system to charge DC batteries and have a DC lighting system. Then a single solar panel could also charge the batteries. Also, small wind turbines are available.