What does the Hotopp lock take ?
It takes:

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)
 
 
 
 
 

Does it take ...


much time? No!

Hydraulic Fluid ? No ! (e.g. 50000 Liters)
 

Electricity ? No !
Uranium ? No !
Plutonium ? No !
 
  

Crude Oil ? No !

Data Processing ? No !

Coal ? No !

Muscle Force ? No !