It's not that power intensive to do a BTC transaction (although the requirement for every full node to duplicate the work kinda limits its relative efficiency).

It's not that power intensive to do a BTC transaction (although the requirement for every full node to duplicate the work kinda limits its relative efficiency). What drives up the power usage is the way miners compete for new bitcoins. 25 new bitcoins are minted every ~10 minutes, and 1 BTC is worth 56,378.78 USD right now, so the miners can collectively spend up $1.4 million (in electricity, hardware depreciation, etc) every ten minutes and still break even.