Micro-Hydro

Humans have been using water as an energy source since the Greeks harnessed the resource over 2,000 years ago.  Running water can move a waterwheel, providing mechanical power, or turn a turbine to generate electricity.  Large hydropower installations, such as the Hoover Dam, generate more than 30 megawatts (MW) of electricity. Much smaller installations, known as micro-hydro systems, generate up to 100 kilowatts (kW) of electricity – enough power for a large home or small resort or farm.

Micro-Hydro Mechanics
Most micro-hydro installation are run-of-the river systems, which means only a fraction of a stream’s water is diverted for power generation.  As a result, a well designed micro-hydro system can coexist with the natural landscape as it causes minimal environmental disturbance.  When considering a site, the two most important features are flow and head.  Flow is the volume of water that could pass through your system and head is the vertical distance the top of the water source to the turbine.

During operation, water enters a forebay which functions as settling pond for large debris.  Water the passes through trashrack – or grill that removes additional debris – into the penstock which is a pipe or channel leading to a turbine or waterwheel.  After generating mechanical power or electricity at the powerhouse, the water is returned to the stream.



Illustration of a micro-hydro system.
Courtesy of DOE/EERE

Micro-Hydro Potential in North Carolina
A micro-hydro system is possible on any site with adequate flow and head.  However with higher elevation gradients, western North Carolina may contain the state’s greatest potential for micro-hydro.  In fact, a 1983 study – conducted by Appalachian State University – examined 24 western counties and found 1,592 potential micro-hydro sites between 5 and 20 kW.  Collectively, the sites had the potential to generate 30 MW of electrical power.

Additional Resources

Micro-Hydro Factsheet
Compiled by the Appalachian State University, this comprehensive factsheet discusses site assessment, types of micro-hydro systems, incentives, and regulations.  The factsheet contains additional resources and a list of western North Carolina micro hydro installers.

Department of Energy
The Energy Efficiency and Renewable Energy Division provides additional information on micro-hydro systems.