• Energy & Power

Small Hydropower Systems



If you’re considering building a small system on water flowing through your property, you have a long tradition from which to draw your inspiration. Two thousand years ago, the Greeks learned to harness the power of running water to turn the massive wheels that rotated the shafts of their wheat flour grinders. And in the heyday of the 18th century, thousands of towns and cities worldwide were located around small sites. 

Today, small hydropower projects offer emissions-free power solutions for many remote communities throughout the world—such as those in Nepal, India, China, and Peru—as well as for highly industrialized countries, like the United States. 

This fact sheet will help you determine whether a small hydropower system will work for your power needs and whether your location is right for hydropower technology. It will also explain the basic system components, the need for permits and water rights, and how you might be able to sell the excess you generate. 

Uses of Hydropower

In the United States today, hydropower projects provide 81 percent of the nation’s electricity generation and about 10 percent of the nation’s total electricity. That’s enough to power 37.8 million homes, according to the National Hydropower Association. 

A 10 kW system can provide enough power for a large home, a small resort, or a hobby farm. 

The vast majority of the hydropower produced in the United States comes from large-scale projects that generate more than 30 megawatts (MW)—enough electricity to power nearly 30,000 households. Small-scale hydropower systems are those that generate between .01 to 30 MW of electricity. Hydropower systems that generate up to 100 kilowatts (kW) of electricity are often called microhydro systems. Most of the systems used by home and small business owners would qualify as microhydro systems. In fact, a 10 kW system generally can provide enough power for a large home, a small resort, or a hobby farm. 

How Hydropower 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 microhydro, and sometimes for small-scale hydro, projects. For run-of-the-river hydro projects, a portion of a river’s water is diverted to a channel, pipeline, or pressurized pipeline (penstock) that delivers it to a waterwheel or turbine. 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 to generate electricity. This fact sheet will focus on how to develop a run-of-the-river project.  

In this microhydropower system, water is diverted into the penstock. Some generators can be placed directly into the stream.
In this microhydropower system, water is diverted into the penstock. Some generators can be placed directly into the stream.

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