A cousin just installed a 16kW generator to power the whole house. It goes on and off automatically, triggered by power failure and restoration, and runs on natural gas. See video here.
It costs about $4K plus installation. Various models on www.generac.com. He says, “I was going to use a smaller, less costly unit, but the trade-off is to then have a more labor-intensive installation of selecting only critical circuits to power. Also, I did not find portable units that run on natural gas, which this does. I don’t have to store any fuel. As to neighbors hooking up, I planned for that, as the power is adequate. Next-door neighbors on both sides can plug in. BYOC (Bring Your Own extension Cord). Some goodwill to offset the 60 dB noise, about as loud as an air conditioner (I am told).”
UPDATE: As a postscript, yesterday, four days after the installation completed, we lost utility power at 9:30 AM and it is still not restored. Expected soon. Very heavy winds caused havoc with downed trees over a widespread area. As to the generator, it started automatically and functioned flawlessly all day. I manually stopped it at night to eliminate noise and save fuel cost, then turned it on this morning. When power restores it will shut off automatically. I hope your electric power source is more reliable!