By fuel I mean every form of energy at your disposal - propane, natural gas, electric, gasoline, wood, sterno, muscle power and the corpses of the dead.
The problem is fuel is bulky to store. Some of it - gasoline especially - is dangerous to store and "goes off" over time as the more volatile components evaporate, no matter how much conditioner you put in it. Batteries leak their charge, if not their innards, over time. Hand cranked gennies need fuel too - if you are not eating enough that thing may as well be a doorstop because you are not going to be able to use it.
A cord of wood is 128 cubic feet (4 foot high, 4 foot wide and 8 foot long) and, in a cold area, you will need between 4 and 6 of those per winter simply to keep the house slightly above freezing. Don't forget that wood needs to sit for a year or so to season enough to be usable too, unless you cut dead timber.
Heck, even candles, the simplest form of night lighting that exists, are one shots. Use one, it is gone for good.
It is another of the prepper's balancing acts.
In a true TSHTF scenario, your energy use is going to be drastically cut down. Down to levels the global warming crowd would first applaud you for then call BS on as they throw cans of deodorant in your general direction because you haven't bathed since the outside temperature dropped below 60 F.
Even in a short term outage - the couple of weeks thing that most people prep for - you are going to go through fuel like grass through a goose.
Time to make an energy plan for your family.
Each family is different - one with a sick child or an elderly member needs to devote substantially more energy to heating than a family who are disgustingly young and healthy - but there are a few basic rules.
1/ The psychological benefit of a hot meal outweighs the fuel cost.
I spent a lot of time in Equatorial Africa. It is, to put it mildly, rather warm there. Yet a hot meal at the end of the day is standard, for the same reason a hot tea is the beverage of choice. It counter intuitively cools you down, you can digest it more easily and it is something you look forward to rather than force down.
2/ If it can be replaced by muscle power, it should be.
5 gallons of gas takes up a space roughly 1 foot by 1 foot by 8 inches. (measurments may be off, I am used to metric) and will run your gennie or your chainsaw for a couple hours. The same space in high energy food will run you for nearly a week. The trade off is obvious. A gallon of gas to run your chainsaw for a couple of hours, or a gallon's worth of food to run you with a hand saw and axe for a week.
3/ Layers matter.
Remember what your Mom said? "If you are cold, put on a sweater." Or two. Or 6. Or go to bed fully dressed in a bed containing as many people that can physically fit in it. As long as you are fed enough, you are warm, that is what homeothermic means. You get hot, not because you are actually hot but because you are not cooling down fast enough.
4/ Maximise natural resources.
There is no book so riveting that you can't put it down until daylight. For most of history, staying up after nightfall unless you were the night watch was not an option. Ya might want to get used to that again. Sure, there are candles, hurricane lanterns, hand cranked lights - all of which need some of your precious fuel or food to work.
A Methane digester
is not a bad option for topping off your stocks - it will take almost anything and turn it into a nice, burnable and storable gas and fertilizer. But they take time to ferment.
Just some thoughts - opinions?