Small-Scale Hydropower

Most small-scale hydropower projects are free of the environmental impacts associated with large-scale projects because they use a "run of river" design that does not require a large dam and storage reservoir. Instead, run of the river projects generate electricity by diverting only part of the stream. This produces relatively little change in the stream channel and flow, and minimizes impacts on fish migration, water quality, and wildlife habitat.

Strictly speaking, "microhydro" is a term that refers to hydroelectric power plants that generate up to 100 kW of electricity, and "small hydropower" refers to facilities with a generating capacity of 100 kW to 30 MW.

Photograph of rocky, mountainous terrain showing water flowing down a small section of river rapids. To the right of the rapids is a small concrete structure through which part of the river has been diverted. Above the concrete structure is a utility building.

An 800-kW run-of-river hydropower plant provides electricity to the 700 residents of King Cove, Alaska. (Photo: Duane Hippe)

The following links provide more information on small-scale hydropower systems:

  • Small Hydropower Systems — A good introduction to the basic issues you'll want to consider before purchasing a microhydro system, with information on different types of turbines and waterwheels.

  • Is a Microhydroelectric System Feasible for You? — This fact sheet goes into more detail than the one above, with information on determining head, flow, and power output; plus a long list of excellent references on small hydro systems that was updated in October 2003.

  • Layman's guidebook on how to develop a small hydro site (PDF 11.4 MB) Download Adobe Reader. — Written for the European market, this 260-page manual from the European Small Hydropower Association provides in-depth information on topics of interest to small hydro developers everywhere: site evaluation methodologies, fundamentals of hydraulic engineering, electromechanical equipment, economic analysis and financial mathematics, and mitigation of environmental impacts.

  • Home Power — This on-line magazine provides a wide range of information on small renewable energy systems, including hydropower:

  • — A European Web site with information on microhydro systems, including books, manuals, software, conferences, organizations, case studies, and a discussion forum.

  • Hydropower incentives — From the Database of State Incentives for Renewable Energy (DSIRE). Choose "hydroelectric" under "Select a Technology."

  • Microhydro system suppliers — This database provides contact information for companies that make, sell, install, consult on, or service hydropower systems smaller than 50 kW. You can search the database or browse by business type, by geographic location, or alphabetically. Separate databases of businesses specializing in microhydro energy system components and microhydro turbines are also available. This database is part of the Source for Renewable Energy database developed by Momentum Technologies LLC.

  • Workshops on designing a microhydro system — Hands-on workshops put on by Solar Energy International , a nonprofit organization seeking to provide education and technical assistance so that others will be empowered to use renewable energy technologies. Most workshops occur in Colorado, and include field exercises and tours of operational systems.