If you currently use a heater for 1 hour/day at home, and then you turn it up to 2 hours/day, you do need about twice as much energy to power that heater as before.
However, if I make 100 additional requests today, Google doesn't need a new server. If everyone in the world makes 1% more requests, Google doesn't need a new server. So to try to calculate the cost of me doing one additional search is perhaps slightly misleading.
I'm not saying there is no cost. I'm just saying that the cost is incurred in chunks, and not "per request".
