The gravel pad the tank sits on provided enough distance from the flames to keep the tank temperatures low enough that it did not vent/explode. That said, and I have no way of proving it other than looking at what burned and how, if the winds had been high and carrying a lot of sparks or flaming material, perhaps enough could have accumulated around the tank to cause it to vent/explode. No way of telling for sure without running some tests, and doing that would involve too much risk. Besides, if there is that much flaming material in the air, I'm not sure my home, even though it has a concrete tile roof, boxed in eves, stucco walls, and screened vent openings, would survive. The videos I've seen of the firestorm in Paradise reminded me of a snow blizzard at night, with the snow replaced with glowing orange and red embers. People were walking around in it, so the air temperature wasn't enough to catch things on fire, so it was the embers themselves, landing on flammable material, that spread the fire so quickly. My strategy here has been to remove the flammable material where I don't want fire. I assume the embers will go everywhere, but if there's nothing to burn, they'll go out by themselves. I don't think the embers carry a lot of heat, not enough to heat a propane tank to the point of venting/exploding, unless there's a steady supply of them over a fair amount of time, and I think there's enough distance between my tank and the fuels heavy enough to provide such a heat supply. At least I hope so, because I can't mitigate the brush hazard on the other side of the state park boundary.
If you're headed down the propane trail, are you aware that there are aftermarket kits to convert your Honda generator to use propane? I looked into it for my 6500 Honda, and it seemed like once converted, the generator could be run on either fuel without much fuss.
As far as transporting Diesel/gasoline, my bulldozer neighbor has two 100 gallon tanks that fit in the bed of his pickup truck, and uses them to fuel his various tractors and heavy equipment. That avoids needing a large storage tank and meeting the stringent building code requirements and the vagaries of fuel delivery service. I think he's pretty much dedicated an old pickup truck to carry the tanks; I wouldn't want to do that to my F250 as I prefer to keep the cap on the bed and be able to use it to haul other things. Perhaps some arrangement of the tanks on pallets would make removal/replacement easier, and that thought is worth exploring.
When I asked him about Diesel fuel "spoiling", he says he's never had a problem, likely due to him using enough of it to keep his supply moisture free. He also uses a fuel additive that very likely incorporates an algaecide. From what I understand, it's water in the fuel that promotes algae growth, and using tanks small enough that they get resupplied frequently keeps the moisture at bay.
I'm pretty sure a single 100 gallon tank of Diesel wouldn't be enough to last through the three and a half week evacuation period I just endured, and that would be the goal of any system, generator or solar based, I come up with. Both propane and Diesel have the same issue with maintaining a large enough supply of fuel to last that long. Solar, on the other hand, seems to meet the duration criteria by being self refilling, and capacity is just a matter of building a big enough array of panels to meet a typical 24 hour power cycle in the summer (my peak energy use time due to A/C) and installing a large enough battery bank to get through the night and periods of low solar influx. And perhaps maintaining a small generator for times of high demand. You know that game very well, so I'm curious as to why you seem to be maintaining such a large generator capability. Is it just too expensive to maintain sufficient capacity in a solar/battery system to supply your needs?
