Hydropower

Power, head and flow rate

Online Hydropower Calculator

The calculator below can be used to calculate available hydroelectricity.

Density (kg/m³)

Efficiency

Volume flow (m³/s)

Head (m)

The theoretically power available from falling water can be expressed as

P_th = ρ q g h (1)

where

P_th = power theoretically available (W)

 ρ = density (kg/m³) (~ 1000 kg/m³ for water)

q = water flow (m³/s)

g = acceleration of gravity = 9.81 m/s²

h = falling height, head (m)

Due to energy loss the practically available power will be less than the theoretically power. Practically available power can be expressed as

P = 1000 μ q g h (2)

where

P = power available (W)

μ = efficiency (in general ranging from 0.75 to 0.95)

Equation (2) can be simplified to express practically available hydropower in kW to

 P ~ 10 μ q h (kW)

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