OK, I cannot estimate how much energy would be saved, or more would be wasted, unless we have this chain running.
However, even more energy were burned, now it is not for the chain security only, the computation is used for a honest proof of the user data storage.
I would like to comment on 2 subjects that you also mentioned here.
First of all, conceptually, when mining Bitcoin, the energy is not wasted. Nobody would say that a car factory wastes energy to run their machines either, right? You are minting new coins and expending energy for that; I don't understand why so many people believe this is wrong.
Secondly, also conceptually, adding a secondary use to your mining, such as using the heat or using an algorithm that performs 'useful' computations - since all of this has monetary value, you just extract more money out of the same energy, i.e. just increasing the efficiency of your gear. This means everyone will do it, the power consumption will not drop and the difficulty just goes up a little.