his averages out to a shocking 215 kilowatt-hours (KWh) of juice used by miners for each Bitcoin transaction (there are currently about 300,000 transactions per day). Since the average American household consumes 901 KWh per month, each Bitcoin transfer represents enough energy to run a comfortable house, and everything in it, for nearly a week. On a larger scale, De Vries' index shows that bitcoin miners worldwide could be using enough electricity to at any given time to power about 2.26 million American homes.
Expressing Bitcoin's energy use on a per-transaction basis is a useful abstraction. Bitcoin uses x energy in total, and this energy verifies/secures roughly 300k transactions per day. So this measure shows the value we get for all that electricity, since the verified transaction (and our confidence in it) is ultimately the end product.