> A more fundamental worry is that digital-currency mining, like other sorts of mining, has environmental costs: all that number-crunching uses a lot of electricity, and not all of it comes from renewable sources, as it does in Boden. The rapid development of the ASICs chips has made the machines more efficient, but even if all mining worldwide were carried out in modern facilities like Boden’s, the combined electricity consumption would be 1.46 terawatt-hours per year—the consumption of about 135,000 average American homes.
http://www.economist.com/news/business/21638124-minting-digi...
The whole consensus network of Bitcoin is based around burning so much energy/space/infrastructure on hashing that a single actor wouldn't be able to invest a bunch of money and take a controlling majority.
I can't speak to how much energy we burn with ACH systems, paper money, etc., but those are much bigger than Bitcoin in terms of usage. If you add up the total energy consumed by every bank and mint in the world, you might get a higher absolute number. In terms of energy used per amount of value transferred, the traditional currencies almost certainly win.