Topic summary
Run-of-the-river
Extracted from the Wikipedia article Run-of-the-river hydroelectricity.
"Unfirm" power
Run-of-the-river power is considered an "unfirm" source of power: a run-of-the-river project has little or no capacity for energy storage and so cannot co-ordinate the output of electricity generation to match consumer demand. It thus generates much more power when seasonal river flows are high (spring freshet), and depending on location, much less during drier summer months or frozen winter months.