I read about project Loon some years ago and I don't think the intention was ever to "base" the balloons over particular locations. Rather I think the idea, fanciful as it may seem, is to have large numbers of these things continually floating around at high altitude on the prevailing winds and each beaming broadband onto what would be a fairly large area of the earth from those altitudes. I guess they use solar power and get the broadband connections beamed up from terrestrial stations or perhaps even satellites. They are obviously also equipped with ADS-B since we can see at least some of them on internet flight trackers but I'd be interested to know if anyone, in deepest Africa for instance, is actually getting broadband from them. Who knows what other tricks might be up there?