https://arstechnica.com/tech-policy/2017/12/bitcoins-insane-energy-consumption-explained/
This article suggests that the Bitcoin network uses about as much energy as Denmark, but is that really a long term issue? With so many renewables coming online to supply power, the energy that Bitcoin is using is getting greener and greener. While the energy is still an issue, at least the future for the usage is a little better.
The other big thing is that Bitcoin should become much more energy efficient per transaction as time goes on. The biggest expense for a Bitcoin miner is electricity. So anything they can do to lower that portion to increase profits will definitely happen. This means as more efficient mining hardware becomes available, it will be implemented, lowering total energy consumption per transaction.
There are also new technologies coming that will reduce transaction overhead, such as the lightning network. Bitcoin is still in its infancy, as is cryptocurrency is general. It is guaranteed that more and more effort will be put into lowering computing overhead per transaction.
Yes, Bitcoin uses a lot of energy, but the future is bright, and near.
