So total network power consumption is at least (1.42E-9 J/hash)*(262E12 hash/s)=372040 J/s = 372 kW. Like I said, this is the most efficient scenario, with little room to improve with new mining hardware in the future. A year ago it was far, far worse.
One way only, but try this with Visa and dollars
The only inefficiency that matters is (average transaction fee / average transaction volume).