BITCOIN has been alarming people for years because of the amount of electricity needed to mint new virtual coinage. Alex de Vries, a bitcoin specialist at PwC, estimates that the current global power consumption for the servers that run bitcoins software is a minimum of 2.55 gigawatts (GW), which amounts to energy consumption of 22 terawatt-hours (TWh) per yearalmost the same as Ireland. Google, by comparison, used 5.7 TWh worldwide in 2015.