Get a generator for future power outages if practical for you. If not, there are some battery backup units that will work for a short time. The first time this happened to me it was around Christmas and I had lots of bubblewrap around. I wrapped the tank (only had 1 tank at the time. This approach would be useless for me now) in multiple layers of newspaper, then multiple layers of bubblewrap then heavy comforters. Every 30 minutes, one of us would reach in through one corner and stir the water or use a turkey baster to send current where it needed to be. It worked that time for us, but we have since gotten a generator. Good luck!