Bicycle generated power

[Skvez]

eletric pumps for power storage!... batteries have a finite lifespan [so] i'd set up a reservoir high up and then any excess power generated after a battery is full, will pump water up into that resevoir, then when you need the power from it, you slowly release it through a pipe with a generator inside

This is called "pumped storage" if you want to do a web search about it. Unfortunately typical efficiency of power out vs power in is only around 10%.