Potential Energy - Hydropower

When a body of mass is elevated against the gravitational force - the increase in it's potential energy can be calculated as

E_p = F_g Δh

    =  m a_g Δh                                (1)

where

F_g = gravitational force (weight) acting on the body (N, lb_f)

E_p = potential energy (J, ft lb)

m = mass of body (kg, slugs)

a_g = acceleration of gravity on earth (9.81 m/s², 32.17405 ft/s²)

Δh = change in elevation (m, ft)

Example - Potential Energy of Elevated Body - in SI units

A body of 1000 kg is elevated 10 m. The change in potential energy can be calculated as

 E_p = (1000 kg) (9.81 m/s²) (10 m)

    = 98100 J

    = 98 kJ

    = 0.027 kWh

Example - Potential Energy of Elevated Body - in Imperial units

A body with weight (force) 500 lb_f is elevated 30 ft. The change in potential energy can be calculated as

 E_p = (500 lb_f) (30 m)

    = 15000 ft lb 

A body with mass 15 slugs is elevated 30 ft. The change in potential energy can be calculated as

 E_p = (15 slugs) (32.17405 ft/s²) (30 m)

    = 14478 ft lb

Potential Energy in a Tank or a Reservoir - Spreadsheet Calculator

You can estimate potential elevation energy (hydropower) in a tank or a reservoir by dividing the volume in horizontal slices and calculate the elevation energy for each slice - as it is done in the spreadsheet calculator below:

• Hydropower - estimate potential energy stored in tank or reservoir

You can copy the spreadsheet to your Google Drive or to your local drive if you want to use it as a template for your own calculations.

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm