Not true. Since using more electricity costs more money, bitcoin miners have an incentive to use less electricity. Their incentives are to maximize hashes/s/watt.
This is true, but the reward is currently far larger than the electrical consumption, so mining is currently mostly a contest to bring more hardware online.
(kicking CPUs and GPUs out of the contest probably did a lot to lower power consumption, but I wonder if the growth of the network has overshadowed that)
Given that energy efficiency is mostly a function of the underlying silicon, miners don't have much control over it (especially once everyone has converged on 28 nm).
(kicking CPUs and GPUs out of the contest probably did a lot to lower power consumption, but I wonder if the growth of the network has overshadowed that)