Proof of work systems (such as bitcoin and ethereum as of now) inherently cannot be made more efficient - their security requires that approving transactions must take so much computing power that an attacker can't afford to burn as much resources as they'd need. It'd be trivial to make the processing 100 or 10000 times more efficient, but that would defeat the whole purpose - instead, the computational (and thus energy) requirements must grow as the currencies become more valuable and processors more affordable; that's why we have the scalable difficulty factor in bitcoin etc - so that the mining gets less efficient with time.