How much longer could it run for it used some energy harvesting and/or only reported once every 6 hours? What if an open wi-fi network is not close? Seems it

How much longer could it run for it used some energy harvesting and/or only reported once every 6 hours? What if an open wi-fi network is not close? Seems it will only work around your house or maybe Maccas, really needs 3G to be useful.