Micro hydro

There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel.

Micro hydro is frequently accomplished with a pelton wheel for high head, low flow water supply.

[3] Usually, microhydro installations do not have a dam and reservoir, like large hydroelectric plants have, relying on a minimal flow of water to be available year-round.

[5] "Flow" is the actual quantity of water falling from a site and is usually measured in gallons per minute, cubic feet per second, or liters per second.

The available power, in kilowatts, from such a system can be calculated by the equation P=Q*H/k, where Q is the flow rate in gallons per minute, H is the static head, and k is a constant of 5,310 gal*ft/min*kW.

[7] For instance, for a system with a flow of 500 gallons per minute and a static head of 60 feet, the theoretical maximum power output is 5.65 kW.

[8] Typically, an automatic controller operates the turbine inlet valve to maintain constant speed (and frequency) when the load changes on the generator.

Very small installations (pico hydro), a few kilowatts or smaller, may generate direct current and charge batteries for peak use times.

Very low head installations of only a few meters may use propeller-type turbines in a pit, or water wheels and Archimedes screws.

Small micro hydro installations may successfully use industrial centrifugal pumps, run in reverse as prime movers; while the efficiency may not be as high as a purpose-built runner, the relatively low cost makes the projects economically feasible.

These systems can be designed to minimize community and environmental impact regularly caused by large dams or other mass hydroelectric generation sites.

With only a small stream needed, remote areas can access lighting and communications for homes, medical clinics, schools, and other facilities.

[16] One seemingly unexpected use of such systems in some areas is to keep young community members from moving into more urban regions in order to spur economic growth.

The cost of a micro hydro plant can be between 1,000 and 5000 U.S. dollars per kW installed [citation needed] Microhydro power is generated through a process that utilizes the natural flow of water.

With no direct emissions resulting from this conversion process, there are little to no harmful effects on the environment, if planned well, thus supplying power from a renewable source and in a sustainable manner.

Microhydro is considered a "run-of-river" system meaning that water diverted from the stream or river is redirected back into the same watercourse.