On the other hand, the Internet's energy needs are expected to swell significantly in the coming years — even though computing keeps getting more energy-efficient. An interesting new study in Science by Diego Reforgiato Recupero finds that Internet traffic volume tends to double every three years. But network energy-efficiency isn't keeping pace. As a result, the world's IT infrastructure will consume 19 percent more energy in 2013 than in 2012.
Interestingly, as Alexis Madrigal explains here, most of the energy used by our computing infrastructure comes from wireless and cellular networks — by contrast, data centers themselves only use about 10 percent of the electricity involved. What's more, those wireless networks don't seem to be improving their energy efficiency all that quickly. That's why overall energy use could keep growing, particularly as cloud computing becomes more widespread.
Bottom line: On the vast scale of environmental disasters, Bitcoin barely registers. And, in the grand scheme of things, the Internet is still relatively green (that's particularly true if it cuts into other activities, like driving). But it's also true that our computing infrastructure is becoming an increasingly significant part of the world's energy demand.