Hydro Energy and Water Power

Hydropower is the generation of electricity from the energy of moving water. It is one of the oldest and most widely used renewable energy sources, relying on the natural water cycle in which solar heating evaporates water that later falls as rain and flows downhill. As water moves from a higher to a lower level, its potential energy is converted into kinetic energy, which a turbine captures and a generator turns into electrical power.

The most common form is the hydroelectric power plant, where a dam holds back a reservoir and releases water through turbines at a controlled rate. The height of the water, called the head, and the volume of flow together determine how much power can be produced. Because reservoirs can store water, hydroelectric plants can adjust their output quickly to match demand, and pumped-storage schemes can even move water back uphill to store energy for later use.

Other forms of water power harness the motion of the sea. Tidal power uses the predictable rise and fall of tides driven by the gravitational pull of the Moon and Sun, while wave power captures energy from the up-and-down and back-and-forth motion of surface waves driven by wind. These marine technologies are less mature than river-based hydroelectricity but offer additional renewable potential. Together, hydro, tidal and wave systems convert the energy of water into usable electricity without burning fuel.

Frequently asked questions

How does a hydroelectric dam make electricity?

Water stored behind the dam flows down through turbines, spinning them. The turbines drive generators that convert the motion into electricity.

What is the difference between tidal and wave power?

Tidal power uses the regular rise and fall of sea level caused by gravity, while wave power captures energy from wind-driven surface waves.

Why is hydropower called renewable?

It draws on the natural water cycle, which is continuously replenished by solar energy, rather than consuming a finite fuel.