From lb
>a windmill could spin until it falls apart and never generate as much energy as was invested in building it.
EnergyAnon here.
One thing to think about is the concept of energy shifting.
The idea is that if I have a bunch of cheap energy RIGHT NOW (like lots of water behind a damn, excess nuclear energy at night, etc) then I can build a windmill which will produce energy at a more constant rate for the next 20 years.
tldr - its not always about how much energy, but the timing of that energy.