I travel with my dogs, to dog shows, trials and such so I use a lot of fan power in the summer without the benefit AC or a generator. I rewired the battery connections of my O2 cool fans to run off a cigarette lighter plug so I don't need to buy expensive batteries. Both have fairly long cords I picked up at Radio Shack to reach from the floor between the seats of my van all the way to the back windows if need be. I always travel with a portable power pack (sears) that I can plug them into and run fans for the dogs. The power pack will power two fans about 20 hours without a single burp. Hope this setup gives you an idea or two to help find a solution that works for you.
Carolyn