"According to my calculation, a single Bitcoin transaction uses roughly enough electricity to power 1.57 American households for a day."
http://motherboard.vice.com/read/bitcoin-is-unsustainable
I find this interesting thinking about Bitcoin as a currency. The first cryptographic currency example that I had read, from a cryptography book, didn't involve active power. I'm really surprised that Bitcoin has been able to gain this much popularity with its design. Does this explain how you might be able to lose a household-sized amount of money in a transaction on this network? I don't know, but I think that the blockchain idea might not be the ideal for digital currencies.