[n00b101]

I think a rough estimate of the cost of 500MWh/year is $500 million per year. That doesn't include cooling, hardware, real-estate, staff and other operating expenses. I guess the majority of this cost is ultimately paid for by speculators who buy Bitcoins off of the miners.

[hollerith]

$500 million per year is roughly what I get, too, but 500MWh/year is very different from 500MW, which is what I think you meant to write since the OP expresses its conclusion in MW.