How does hydropower work?
Generating hydroelectricity starts with the annual hydrologic, or water cycle, providing seasonal rain and runoff from snow pack. The runoff from rain and snow collects in lakes, streams and rivers and flows to dams downstream. The water funnels through a dam, into a powerhouse and turns a large wheel called a turbine. The turbine turns a shaft that rotates a series of magnets past copper coils in a generator to create electricity. The water then returns to the river. From the powerhouse, transmission lines carry electricity to communities.
Electricity is always (except a PV cell) created by turning a coil of wire around a magnetic field. This generates a flow of electrons (aka electricity). So, you really just need to get something to turn. Usually, you burn some fuel to heat water to steam which expands and pushes through a fan-like thing called a turbine that is attached to the old coil of wires. With Hydropower, instead of heating water to make the turbines turn, gravity forces the water to push through the turbine and turn them. A damn allows the water to build up. You then control how much water to release through the turbine cylinders as it generates electricity.
