Hydroelectric power stations generate nearly 6.7% of the world's electricity.

The world's largest hydroelectric dam - the Three Gorges Dam on the Yangtze River in China - generates up to 22,500 megawatts of electricity.

This means that the dam can generate enough electricity to power more than 18 million homes (based on the average energy consumption rate in the United States).

How do these large hydroelectric dams work? Let's explore the basic components of a hydroelectric dam and the process of creating sustainable, productive electricity.

Step 1: Utilizing potential energy

Gravity causes water to flow through a specific path, and dams prevent the release of this kinetic energy and effectively store the river's potential energy in a lake-like reservoir.

Hydroelectric dams work by "reserving" the water and potential energy of the river. The depth of the water and the velocity of the water as it flows through the dam's pressure tubes generate water pressure that rotates the turbines of the hydroelectric power plant.

Step 2: Turning the hydraulic turbine

Mechanical fan blades come in different shapes and sizes. In general, the larger the fan blade, the more difficult it is to turn. Large turbines require more energy to accelerate their movement.

The hydrostatic pressure from the potential energy of the dam creates this water pressure, which increases as the velocity of the fluid increases. As the turbine rotates, the water pressure is converted to kinetic energy.

This conversion effectively removes the flow velocity and hydrostatic pressure from the water, allowing it to flow slowly out of the bottom of the dam.

Step 3: Hydraulic Turbine Generator

The rotary motion of the turbine generates electrical energy. The turbine is connected to a generator, either directly or through a gearbox or transmission, which rotates the generator's armature.

Large generators, such as those operating in hydroelectric dams, generate a large amount of magnetic resistance, unfavorable to the resistance of mechanical rotation, which can only be overcome by the large torque forces generated by the rotation of the turbine.

Step 4: Capture and transmission of hydroelectric power

The generated electricity is quickly converted into grid voltage and then transmitted by the local power company via power lines.

Step-up transformers in hydroelectric dams utilize the relatively low generator output voltage to produce utility-grade voltage. Hydroelectric power plants output high voltages but low currents, making them more efficient and ideal for long-distance transmission.

For example, Glen Canyon Dam in Page, Arizona, which provides power to homes nearly 900 miles away in northern Nebraska, likely utilizes 500 kV transmission as part of the power journey.