Given that ASIC mining runs more like 10 W / GigaHash [1] (not 650W as stated on blockchain.info/stats), we are actually looking at more like ~$150K per day, or $56M per year to run.
At the moment, the value of bitcoin is $7.2B [2], so we can assume that if it scales up to $2T (about the same as M1 of the dollar[3]), then if cost scales linearly, it will cost about $15B per year to run the bitcoin network. That is probably less than it costs to pay the mint, federal reserve, and secret service.
Do we know how prevalent the ASIC rigs are? I'd be really interested to see a rigorous study of Bitcoin's energy costs. Even so, it seems like the estimates on Blockchain.info are off by an order of magnitude. I've amended my comment to include the power consumption on which my estimates are based.