The world is suffering from the creatures of fantasy and nightmares which can appear with just a few minutes of warning anywhere, regardless of it being the middle of the street or on top of your bed while you are asleep. It can be a single one, or millions that swarm the area. The world's infrastructure has been degrading, food and supplies are harder and harder to come by. While firearms work well against these creatures the bodies left behind attract and breed both insects and disease. It is not feasible to hold on to area's with low populations as a sudden appearance of many nightmares can wipe them out.

As fuel becomes harder to come by civilians turn to the only resource they have in abundance: dead nightmarish bodies. They have slowly but surely started an entire industry around the collection, transport and processing of all the bodies into as many useful things as they can.

The question: How can an abundance of dead bodies be used to create as many fuel types as possible.

The types of fuel that I am mainly looking into:

  • combustion fuels (cars, fuel-powered tools like chainsaws)
  • burning fuels (for cooking, heating, electricity and steam production)
  • lightsource fuels (torches, candles, "clean" bonfires to guide travelers at night like a lighthouse).
  • explosive fuels (propellant for bullets, grenades and other explosives).

Conditions that apply:

  • use of alternative materials is allowed, as long as 75% or more of the fuel substance is gained from the dead bodies.
  • anything of the creatures can be used. Their skin, bones, remaining fecal matter or small quantities of specialist materials if you see a use.
  • the size of the creatures goes from dog-sized to paraceratherium-sized (https://en.m.wikipedia.org/wiki/Paraceratherium).
  • while Cthulian sushi-monsters, giant spiders and more are part of the nightmare force, for ease of answering the important bulk of the bodies are of similar in consistency as pigs and cows and any other bodies are discounted (unless only tiny amounts of material needs to be gained from this group of bodies).
  • any magical properties, like the giant spiders not collapsing under their own weight, are instantly gone upon death of the creature.
  • the refinement process can take a maximum of 5 years.

3 Answers 3


Biodiesel, Dynamite, and Nitrocellulose

The first answer that springs to mind is biodiesel. The survivors would need to render off the fat from the bodies. That'd yield tallow, which could be used for things like lamps and candles, and possibly stoves. Then, using something alkaline like wood ash or lye, the fats in the tallow would be turned into soap and glycerin (the glycerin might have uses of its own). The soap, once separated and purified, could then be converted into fatty acids by acidifying it (stearic acid, for example). You then react the fatty acids with an alcohol like methanol or ethanol, in the presence of an acid catalyst, which gives you a fatty acid ester, which is the same sort of organic molecule found in commercial biodiesel.

As for explosives, if the survivors have access to a source of nitric acid (it could theoretically be made from nitrate salts derived from decomposition products, but my chemistry's a bit weak here), then they could convert the waste glycerin into nitroglycerin and then mix it with a suitable binder or stabilizer to make something like dynamite.

(As a commenter pointed out, getting sulfur and converting it to sulfuric acid (with which to make nitric acid and nitration solutions) isn't a trivial task, made worse by the fact that there isn't a massive amount of sulfur in dead things. There are other methods of making nitric acid from carcass-derived ammonia, but they require high pressures and temperatures and specialized catalysts. The Ostwald process can be used to make nitric acid from ammonia feedstock.)

As I said, my knowledge of chemistry is pretty basic, but if the survivors can make nitric acid from the decomposing bodies, and they've got a source of cellulose (grass, paper, wood, etc.), they could convert that into nitrocellulose, which is one of the major components of modern smokeless powder (gunpowder).

  • $\begingroup$ That sounds very promising. Digging around I found this answer, which would give me most if not all of what I want: worldbuilding.stackexchange.com/questions/115054/… $\endgroup$
    – Demigan
    Commented Aug 23, 2021 at 15:47
  • 1
    $\begingroup$ you still need a source of sulfur to make gunpowder or nitrocellulose. saltpeter can be made from organic ash, so burn your scraps for it, but you need a lot of it. you can make nitric acid from saltpeter but again you need sulfur or a platinum and rhodium catalyst. Stearic acid won't do it. $\endgroup$
    – John
    Commented Aug 24, 2021 at 17:25

Fat was largely used in the past as combustible for burning fuels and light generation, since it was relatively abundant. Think of tallow or spermaceti, among others.

It is straightforward then to use fatty tissues from the dead corpses as they are and then use the energy they provide to make further refinements to satisfy the need for combustion fuels.


What ever use that is fast and requires little to no effort.

In a survival situation, it needs to be fast and easy. If these things just appear and can appear anywhere, you can't have factories, laboratories and such as they could be smashed easily.

Anything you do would be quick and dirty.

Three uses spring to mind

Rend them down to tallow/oil which can be used for vehicles. If you switch to steam boiler based engines, you don't need to refine it to diesel. Boiler engines run on anything that can burn. You can also make crude flame throwers for weapons.

Next you can chuck them in a bioreactor for biogas for lighting, cooking, gas powered vehicles.

Finally you compost them for fertilizer

Ideally you'd do all three. Rend them down for the oil/tallow. Bio reactor for the gas and finally use the remains to fertilize your crops.

Gun powder you'd make like they use to. Sulfur you obtain from mines or volcanic areas. Nitrate from urine and carbon from anywhere. You wouldn't try and make it from bodies.

  • $\begingroup$ For some reason I completely missed this answer. I am currently trying to get an answer for building a flamethrower. Could you give a quick rundown on how to make the oil? So far my searches seem to indicate that the solid tallow is treated at an oil substance. $\endgroup$
    – Demigan
    Commented Aug 31, 2021 at 16:28

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