> If you brought Bitcoin's transaction volume up to Visa's it would be using as much electricity as the rest of the world put together.
Nope; that's not how it works. Bitcoin's energy use scales not with the block size but with the value of the block reward. If bitcoin prices rise, more hash power will be applied to compete for it. And when the reward halves, many mining outfits become unprofitable and will be turned off.
Bitcoins transaction volume is capped, because of the block size limit. So rising the transaction volume isn't even possible. At least not without Miners aggreeing to a fork.
This is also why the prices are so high. Miners have an incentive to not change block size because they earn much more money if their product (transaction spots in the block) is scarce.
It still stands that the transactions themselves aren't what are costing energy. I do think the miners incentive to keep fees high is a perverse side effect of the system. In this respect it's healthy that hard forks and altcoins are present to put competitive pressure on BTC core to evolve. Lightning network, if implemented, should do much to improve the situation.
