Several meters (yards) of difference in level
A certain amount of canal water
that is allowed to run down to the lower level
With this it produces (without any extra energy):
Pressurized air and
"Suction" (Low pressure, partial vacuum)
much time? No!
Hydraulic Fluid ? No ! (e.g. 50000 Liters)
? No !
Uranium ? No !
Plutonium ? No !
Crude Oil ? No !
Data Processing ? No !
Coal ? No !
Force ? No !