> and it takes more than 600kcal to create 600kcal plus transportation into your home

This is not a strong argument or at least a different area of discussion. Because you can say exactly the same for the electricity: you need more than the power. You need the coal+transportation, or power plant, or solar panels ...

I'm pretty sure humans are much more energy efficient ... for certain tasks ;)

Sure, do the math for both, considering also that the human will continue to run anyway and then see who should do the task to minimise worldsuck :P