A hydroelectric power plant is one in which the potential energy of the water stored in a reservoir is transformed into the kinetic energy necessary to move the rotor of a generator, and subsequently transformed into electrical energy.
Hydroelectric plants are built in riverbeds, creating a reservoir to retain water. For this, a thick wall of stone, concrete or other materials is built, generally supported by some mountain.
The dammed water mass is conducted through a pipe to the blades of a turbine that is usually at the foot of the dam, which is connected to the generator. Thus, water transforms its potential energy into kinetic energy, which makes the turbine blades move.
A power plant does not store energy, but its production follows the demand requested by users. As this demand is variable throughout the day, and with the time of the year, power plants can operate with a variable production.
However, efficiency increases if production is constant; For this, there is a way to store the energy produced during times of low consumption, and use it in times of strong demand, through the hydraulic pumping plants.
These plants have two reservoirs located at different levels. The water stored in the upper reservoir produces electricity when it falls on the turbine, as indicated above, covering the hours of strong demand.
The water subsequently reaches the lower reservoir, at which point it is used to pump the water from the lower to the upper reservoir.