The microhydro plant in Rangkhani cost about 2.6 million Nepalese rupees, or $29,000, to plan and build, and generates 26 kilowatts of electricity for more than 1,000 people. A “run-of-the-river” plant powered by water channeled directly from the fast-flowing stream, without any containment dam, it flooded no land and creates no greenhouse gas emissions. After spinning the generator’s turbine, the water feeds back into the river downstream.

Microhydro power plants are defined by the government’s Alternative Energy Promotion Center, the umbrella organization for the renewable energy program, as those generating less than 100 kilowatts of electricity. By way of comparison, a small conventional hydro plant generates about 10 megawatts, or 100 times as much electricity as the largest microhydro plant. A big hydro plant like the Three Gorges Dam in China generates 22,500 megawatts.

For Rangkhani’s microhydro plant, part of the flow of the Kalung Khola was diverted via a series of concrete and stone channels built over the lush, hilly terrain, then funneled down to the powerhouse through a pipe called a penstock. Strategically channeling the river gets the most out of the water’s speed and flow, creating the most efficient conditions for driving the turbine blades that convert gravitational energy from the falling water into electricity.

Transmission cables from the powerhouse carry electricity to buildings in the neighborhood.

In contrast with the dams, flooding and dislocation of communities associated with large hydro power projects, well-planned run-of-the-river microhydro plants do minimal damage to surroundings, energy experts say.

Microhydro plants “do not have major environmental impact compared to large hydro and storage hydro,” said Rabin Shrestha, senior energy specialist with the World Bank in Nepal.

Although the landscape is altered, the channels are similar to the canals that from time immemorial have carried water for crop irrigation for great distances across the countryside, and a government regulation requires that at least 15 percent of the river water be left to flow along the natural riverbed.

Drinking supplies are also not affected, since mountain villages like Rangkhani typically rely on springs rather than rivers for their drinking water.