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.