U.S. Department of Energy - Energy Efficiency and Renewable Energy

Energy Savers

How a Microhydropower System Works

Hydropower systems use the energy in flowing water to produce electricity or mechanical energy. Although there are several ways to harness the moving water to produce energy, run-of-the-river systems, which do not require large storage reservoirs, are often used for microhydropower systems.

This illustration shows a green hilly area with a few pine trees here and there. A river flows through and down from the hills. The river first flows through an intake, which is indicated as two white walls on each side of the river. The intake diverts water to a canal. From the canal, the water travels to a forebay, which looks like a white, rectangular, aboveground pool. A pipeline, called a penstock, extends from the forebay to a building, called the powerhouse. You can see inside the powerhouse, which contains a turbine and other electric generation equipment. The water flows in and out of the powerhouse, returning to the river. Power lines also extend from the powerhouse, along and through two transmission towers, to a house that sits near the river's edge.

For run-of-the-river microhydropower systems, a portion of a river's water is diverted to a water conveyance—channel, pipeline, or pressurized pipeline (penstock)—that delivers it to a turbine or waterwheel. The moving water rotates the wheel or turbine, which spins a shaft. The motion of the shaft can be used for mechanical processes, such as pumping water, or it can be used to power an alternator or generator to generate electricity.

A microhydropower system can be connected to an electric distribution system (grid-connected), or it can stand alone (off-grid).

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Related Links

Reading List

  • Micro-Hydroelectric Generation. Volunteers in Technical Assistance (VITA) Understanding Technology Series. Available from VITA.
  • Mini-Hydroelectric Generation. Volunteers in Technical Assistance (VITA) Understanding Technology Series. Available from VITA.