Sure, as long as there are no tradeoffs involved. But there are. Opportunity cost for one. Your saved energy calculation is the absolute upper bound possible,

Sure, as long as there are no tradeoffs involved. But there are. Opportunity cost for one. Your saved energy calculation is the absolute upper bound possible, the real value is likely close to 0 or even negative (crypto). Even the upper bound you've calculated is an infinitely small amount of energy compared with everything else we use energy for at the global scale. It's irrelevant. If you want to save the world, do something that has a clear positive relationship towards it. Ditch your car, plant a tree, vote for the right politician.