What does hydroelectricity do when it collects water?

Answer 1

'Collecting' water is not necessarily a major component of hydroelectricity.

If you want to generate hydroelectricity, then what you need to find is a place

where water is falling ... the more water, the more height, and the more constantly,

the better. When you find that, you have mass with a lot of gravitational potential

energy (the water when it's high up) converting a lot of that potential energy to

kinetic energy as it falls, and all you have to do to rob some of that kinetic energy

is to stick a pinwheel, a waterwheel, or a turbine into the falling water. The water

turns it for you, and you can spin an electric generator that way.

Hoover Dam 'collects' water behind it, in order to make the water deeper, and

let it build up more potential energy before it falls. Niagara Falls doesn't collect

water. It just uses the falling water that's always there.