Bitcoin energy consumption - unsustainable?

[kimochidesh]

AntMiner S9 is more energy efficient as compared to old mining devices. It consumes about 0.1 W/Gh...way less than .27 W/Gh in the article. So its better to replace a old miner to a new one as it consumes less electricity and hence more profits.

[cryptohorsee]

The energy consumption is very large. I heard that the single bitcoin transaction takes a lot of energy. I hope that the lightning network will be integrated soon.