So then, why would miners use less power? You state "In the first round, we run a similar Bitcoin PoW..." If the first round is similar to Bitcoin PoW, then it has the same economic incentives, in which the cost of mining is limited only by the value of the block reward, regardless of the complexity. It seems to me (I may be wrong) that you may be succumbing to a fallacy similar to the belief that more efficient miners (in terms of J/hash) in the future will cause the overall power consumption of mining to fall.