Run-of-river and small hydro
Hydropower with little or no reservoir, from river plants to village micro-hydro.
Capture · Water and ocean · No. 30
- Capture
- Output: Electricity or motion
A hydraulic ram lifts water uphill with no fuel or electricity, using the river's own push and just two valves.
Chart: Illustration: Run-of-river and small hydro
Where it comes from
Chart: Map of where it comes from
A low weir diverts part of a river into a channel or pipe that runs along a gentler slope, then drops the water to a powerhouse and hands it back.
Three things to know
- Size classes are tidy: small means 1-20 MW, mini 100 kW to 1 MW, micro 5-100 kW and pico anything up to 5 kW.
- An in-stream turbine in Igiugig, Alaska cut the village's diesel use by a third while running, and cameras saw no injured fish.
- Many small weirs on one river can fragment it as badly as a single big dam, blocking fish on their way upstream.
The journey
- 1 RiverWater flows with little or no storage
- 2 Weir or intakeDiverts part of the flow
- 3 Channel or pipeRuns gently downhill to build head
- 4 Turbine or wheelPelton, crossflow, Kaplan, wheel or screw
- 5 Local useMini-grids, mills and village water pumps