Run of the river hydro power relies on the natural flow of a waterway. If the water flow in a stream is reduced, so is the available power output of a hydro turbine placed in the stream.

[You will need the Free Adobe Reader to access some of the documents on this page.]

Run of the river hydropower involves placing small, mini, or micro hydro turbines into waterways without large dams. There are a number of ways to do this as shown in this European Union Hydropower Document . (This is a big file, over 11 MB, so it takes a bit to open.)

Another good resource is this Small Hydro Project Analysis Manual from the Canadian Ministry of Natural Resources in collaboration with the U.S. National Aeronautics and Space Administration.

Run of the river hydro projects can involve small dams, but they are done in a way that doesn’t flood massive amounts of land or interfere greatly with marine life. Other hydro turbines operate without dams.

Some projects involve running a pipe down the stream. This pipe becomes a Penstock that creates a head pressure, which allows a hydro turbine to run efficiently.

And some methods simply place a water turbine in a strong current area of a river in a manner that involves no visible structure at all. They lay quietly under the surface of the river, out of sight, with minimal environmental impact, and generate power from the natural flow of the river.

Run of the river hydropower turbines are much smaller than those found on large, dammed reservoir projects. While there is no defined standard for size, several terms are in general use.

Small hydro power plants range in size from about 1 MW (Megawatt or one million Watts) to 50 MW.

Hydropower turbines in the 100 KW (Kilowatt or thousands of Watts) to 1 MW size range are referred to as mini hydro plants.

Micro hydro turbines refer to anything less than 100 KW in size. _________________________________________________________________


Run of the river methods are inherently more environmentally friendly than big dams. These methods do not flood land or obstruct rivers in ways that adversely restrict marine life movement.

Since no new land is flooded, existing forests are left in place to continue the process of absorbing greenhouse gasses.

New hydro turbine designs and conservation minded construction eliminate fish kills and many of these ideas are in the process of being retrofitted to larger dams. _________________________________________________________________


Generating costs depend on the amount of flow, the degree of drop across a short distance, and the technology used. Hundreds of these projects are being installed annually and most operate on a competitive basis with fossil fuel powered generating plants. It’s only a matter of placing the generators at suitable locations in a flowing stream. _________________________________________________________________


Because run of the river systems take advantage of much smaller water flow volumes, they are far more widely available than power dams.

Some of these systems are so small that they can be economically used in a small creek to reliably generate electricity for just one home.

Run of the river hydropower can be extraordinarily reliable and offer continuous power around the clock, 365 days a year.

But because stream flows do vary from month to month. The big key to high reliability levels is a combination of good site selection and hydro turbine sizing that is compatible with the stream in which it is placed.


If you live by a stream of any size, these Department of Energy sites can help determine if your site is suitable for this type of hydro electric power, and what kind of equipment will best serve your needs:

NREL Run of the River Hydro
DOE Hydropower Prospector _________________________________________________________________


All run of the river hydropower systems are restricted to existing river areas and some are entirely underwater. Many of the surface structures will exist in areas that are already industrialized.

These small hydropower systems should never pose aesthetics problems like wind turbines that noisily dot the countryside, or stack gas emissions coming from fossil fuel fired power plants. There won’t even be a vapor flume from a cooling tower.

Any way you look at this form of hydropower, it comes up a winner.



Return To Energy Resources

Leave Run of the River Hydro and Return Home _________________________________________________________________


Discounts and Free Offers From Our Sponsors


Free Price Quotes at
Executive Openings!
Free: Executive Career Search. $60,000+

Click Here For The Wall Street Journal Online
Special Free Week offer to either the Print or Online editions of The Wall Street Journal!

Search It!

Site Build It Information