For a more accurate (although still large) value for the amount of power used to secure the blockchain, see here: http://blog.zorinaq.com/bitcoin-electricity-c

For a more accurate (although still large) value for the amount of power used to secure the blockchain, see here: http://blog.zorinaq.com/bitcoin-electricity-consumption/ http://blog.zorinaq.com/bitcoin-electricity-consumption/ Tl;dr: "the electricity consumption of the network at 3250 PH/s adds up to 470-540 MW".