There&#x27;s a pretty good writeup about this issue in the Stanford&#x2F;Princeton Cryptocurrency Class:<p><a href="https:&#x2F;&#x2F;drive.google.com&#x2F;uc?id=0B4-bDFu_72Beelkxd3VlbXoyd0E&amp;export=download" rel="nofollow">https:&#x2F;&#x2F;drive.google.com&#x2F;uc?id=0B4-bDFu_72Beelkxd3VlbXoyd0E&amp;...</a><p>Excerpt:
According to our estimates then, the whole Bitcoin network is consuming maybe 10% of a large power plant’s worth of electricity. Although this is not an insignificant amount of power, it&#x27;s not yet a large amount of electricity compared to all the other things that people are using electricity for on the planet.<p>Any payment system requires energy and electricity. With traditional currency, lots of energy is consumed guarding and moving gold bullions around, running ATM machines, coin sorting machines, cash registers, and payment processing services, and transporting money in armored cars.<p>Some people say Bitcoin wastes energy because the energy expended computing SHA-256 hashes doesn’t serve any apparent purpose. But you could make this same argument for traditional currency as well — there’s a lot of energy being wasted and it doesn&#x27;t serve any purpose besides maintaining the currency system. So, if we value Bitcoin as a useful currency system, then the energy required to support it is not really being wasted.<p>That said, we can ask if there’s a way to do better ...