It is too small to clear objects that are in its orbital path.
It has a rocky surface but no rings.
Since, it is very small, it has no ring and it has rocky surface it must be either be a Moon or the dwarf planet PLUTO. Although mars and mercury are also small and planets and have rocky surfaces but they can clear objects in there orbital path.
The mechanical energy in the falling water is used to spin the generator, and gets transformed into electrical energy. That's the first choice on the list.
