It's not a fundamental thing it's just that looking at the per-transaction energy cost really puts things in perspective. And 500kWh is hard to comprehend so I like to put it in perspective by comparing it to locomotives. An F40PH, which is a very common American passenger locomotive as seen on Caltrain, Amtrak, Metra and the MBTA puts out about 2.4MW at full blast. So, just under 5 transactions per hour, per locomotive. It's staggering.