Here we are looking at the same argument using the energy input in absolute terms.
The second separation step, however does typically require energy input.
It is the global cost, the total energy input.
Ten years from now, wind and solar will still represent less than 1 percent of the world's energy input.
If the room is big enough, all the water will evaporate with no additional energy input.
Only the rate of energy input and the heat capacity determine the change in temperature.
This refers to how complete of a picture is drawn for energy inputs.
If there is not much energy input to the system, it will tend to become stratified.
"We don't even know where this energy input is going to come from."
We should reward those which are minimising their energy input.