By my very rough-and-ready calculation, it’s consumed 45 kJ or 162 W h of energy during its lifetime, and consumes another 250 J or 900 mW h per year. That sounds like a lot, but a 78 A h car battery could deliver that much energy and still be 83% charged.,(reply>), (I assumed it rang four times per second, which seems about right but I’m not completely sure.)