Starting off, these domesticated herbivores, much like cows, exist on a terrestrial world 15-20% larger than Earth. With a higher gravity of 11.2 G, Earth-like atmosphere, and if it existed in our solar system, would be positioned behind Earth like Mars but 1.5 AU from the Sun rather than Mars 2.0 AU. Lastly, 38% of the surface is landmass. I figure I provide this extra information if it helps at all.

These "dairy cattle" in my idea, partially for "economic balance" reasons relative to nothing in particular, produce 4 liters of oil in a 1-2 week timespan versus our cattle that produce 4 liters in a single day.

In one major part of this world, these oil-cattle are native and incredibly valuable specimens for the early industrialization of this mountainous continent. They're often the casus belli between large tribal kingdoms and city-states inhabiting these regions and the rising bourgeoisie are as much as oil-cattle barons as they're the new nobility.

My problem is, how do you prevent the ignition of their oil product? Human raiding since time immemorial would probably make them extinct if torches, farmstead fires, forest fires, black powder firearms would render them crispy.

Knowing nothing about oil even after reading numerous things, I came up with several possibilities, I hope?

  • Petroleum Pasteurization? Farmsteads have minor refineries that render the oil usable for consumption perhaps. Even though these oil-cattle would need to nurse their calf, I guess their stomachs process oil just fine too.

  • Instead of oil byproduct, these oil-cattle resemble Rimworlds Boomalopes, with large blubber sacs around their body, that can be fleeced like sheep wool periodically and then processed like Whaling in pots. I really like this idea, but regenerating blubber seems so hard to explain naturally even though this is science fiction.

  • Their oil contains the nominal amount of hydrocarbons, but also large percentages of protein and fat that render the oil much harder to ignite between being in its body mass ready for lactation, and being pumped out.

Please help me, thanks.

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    $\begingroup$ Oil needs oxygen to burn. There's no oxygen inside a cow's udder. Ergo, the oil won't burn when it's inside the cow. $\endgroup$ Commented Jun 30, 2022 at 23:13
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    $\begingroup$ "With a higher gravity of 11.2..." - is that 11.2 G or 11.2 m/s^2? Or something else entirely? $\endgroup$ Commented Jun 30, 2022 at 23:30
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    $\begingroup$ I'm now imagining the patent bovine oil lamp .. a live cow suspended upside down from the ceiling by ropes tied to its legs with wicks inserted in its nipples 😁 $\endgroup$
    – Pelinore
    Commented Jun 30, 2022 at 23:34
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    $\begingroup$ Perhaps take a look at flash point and see how it related to the properties of your oil and the atmospheric temperature/composition. "G" would be the gravitational constant (or magnetic induction, or a number of other mathematical things depending on context), "g" would be the local version of gravity on a particular planet. $\endgroup$ Commented Jul 1, 2022 at 4:33
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    $\begingroup$ A quality dairy cow can produce 20-40 liters of milk per day, not just 4. Funnily enough, that contains roughly 4-10 liters of butter-fat per week. So your oil-cows almost exist, they just need some genetic tweaking to produce oil instead of fat. $\endgroup$
    – towr
    Commented Jul 1, 2022 at 8:25

6 Answers 6


Cow oil has a high flash point.

Ever tried burning vegetable oil? It burns steadily in a lamp with the right kind of wick, but put a match to a cup of oil and nothing happens. The oil is not volatile enough to provide enough vapour to burn without help.

All you need is to make sure your cow oil isn't very volatile at normal temperatures - make it more like sunflower oil than petroleum.

The oil will still be useful for burning: it will burn with a wick, or on an already-hot fire, or with an atomiser (such as a diesel fuel injector). Bandits might go to the trouble of setting fire to your oil store, but they are more likely to ignore it and torch the hay barn instead. If a wildfire gets a cow's udder hot enough to ignite the oil, she's already dead.


The Oil Must Be Refined

enter image description here

Olive oil, coconut oil, and whale oil are all flammable. But you cannot simply put a flame to an olive, a coconut or a whale, and expect it to burn.

Okay maybe you can set a dry coconut husk on fire, but that's not what I mean. I mean the flesh. This stuff:

enter image description here

Olives, coconuts and whales have to be processed before they work as fuel. Usually they are heated so the oil becomes liquid and separates from the other water based compounds and floats to the top. Then it is collected.

Your cow oil is not pure oil. It is an emulsion of oil in water. It does not burn the same way mayonnaise does not burn. But if you heat the mayonnaise in a vat the oil will rise to the surface.

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    $\begingroup$ Has anyone actually tried lighting up a dead whale on a beach? 😂 $\endgroup$ Commented Jul 1, 2022 at 12:42
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    $\begingroup$ Bacon might be good for initial tests, but if we want to get published in a really good journal, I think we need to carefully measure exactly what the minimum requirements are to get a self-sustaining whale fire going. $\endgroup$ Commented Jul 1, 2022 at 13:20
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    $\begingroup$ @EscapedLunatic Dead whales can actually be moderately combustible due to the gasses produced during decomposition, so lighting one on fire is probably not a good idea. $\endgroup$
    – DBS
    Commented Jul 1, 2022 at 13:23
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    $\begingroup$ @DBS - torching dead whales is a terrible idea, but we can't let that stand in the way of science. 😄 $\endgroup$ Commented Jul 1, 2022 at 13:32
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    $\begingroup$ I don't know about lighting a dead whale on fire, but Oregon once blew one up with dynamite. $\endgroup$
    – JS.
    Commented Jul 1, 2022 at 23:15

Natural milk already contain fats, that's how butter is made. As far as I know no mammals has catched fire because of lactation.

First of all it's an emulsion with water, and second but not less important, no nipple releases sparks or flames which can trigger the combustion: even plain butter, left to the air, will simply turn rancid and not catch fire. Meaning the oxydation will proceed at a slow enough rate to not release flame.

  • $\begingroup$ Yeah, in my mind "already contains" means the "oil" is in addition to the "milk". So you're simply separating milk for cereal from oil for car. $\endgroup$
    – WernerCD
    Commented Jul 1, 2022 at 13:58

You are worried about nothing.

cows are not inherently flammable and making a little more oil will not change that. Mammals are already covered in oils, skin and hair are soaked in oils, but cows are not known for catching on fire not even when humans press red hot iron against their oil soaked skin and fur. The few animals that are flammable have long fur which drastically increases surface area. its the same principle as wood, a try starting a log on fire vs a pile of wood shavings. Or to think of it another way cows are already filled with methane, which can actually cause barns to explode but we don't worry about cows catching fire unless the building they are in is on fire. Skin just is not that flammable, even when you remove the water, there is a reason by blacksmithing apron is made of leather.

Barrels of stored oil might be a fire hazard but the cows are fine.

enter image description here


The Cows

First and foremost, unless your oil cows only have sloth-like mobility, they will likely have survived fires (natural and synthetic) by simply running away.

To further jump on the "probably not as big a deal as you think" train, fuel-oils (like gasoline and diesel) are atomized, mixed with an oxidizer, compressed, and then ignited. The liquid itself isn't very combustible; it's when the fuel is vaporized (which greatly increases the surface area of fuel exposed to the oxidizer) that it becomes dangerous. You don't have to compress the fuel before burning it, but the energy released from burning a compressed fuel is more easily harnessed to do useful work (just some additional background). Gasoline's flashpoint (essentially the temperature at which it vaporizes) is >-23C, which is why it burns readily when ignited pretty much anywhere on Earth's surface. Diesel doesn't burn nearly as easily; it's flashpoint is >55C, which means it has to be heated up before it will ignite.

Even if a cow was full to bursting with oil (4L), that's actually not very much fuel, and wouldn't burn for very long. According to this, refined fuel oil (which is similar to diesel in consistency but has a higher flashpoint of >90C) has a density of a little less than 1 kg/l, and if spread out over a 10 m diameter circle, the entire 4L would burn up in about 1 second (in your atmosphere, this would be even faster; see Other Thoughts below). Spreading all the cow's oil over a 10 m diameter circle and lighting it up is a little ridiculous, so let's more reasonably assume a 0.5 m diameter circle (someone slashes a cow's udder and the oil spills out on the ground underneath it, then they light it on fire). Even after correcting for the reduced surface area of the burn (the burn rate is proportional to the surface area of the fuel burning), the fire will still only last about 7 minutes (on Earth) without additional fuel. If you've ever lit a camp fire with dry twigs and brush, then tried to throw a log on it, you'll know it doesn't go well--the twigs burn hot and fast, but the log doesn't catch. Without amassing quite the pool of fuel and other combustibles, you'll end up with the same thing from your oil cows. Plus, they probably won't take kindly to having their udders slashed.

It is also important to remember that in order for the oil to burn, it has to be exposed to the oxidizing agent (which is typically oxygen in the atmosphere). Unless your cows absorb oxygen into their oil glands at a prodigious rate, even if the temperature of the cow rises to the oil's flash point, it won't combust. An oil cow caught in a fire would have the water in it's body boil (at 100C) before the oil caught fire. This is essentially the same reason the propane or LP in the rubber hose that goes to the grill doesn't all ignite and cause the tank to explode--since there's no oxygen to react with except at the burner (where the gas meets the atmosphere), it doesn't burn (yes, the positive pressure of the tank compared to the atmosphere is also a part of that equation; it's not a perfect metaphor).

From a logistical standpoint, your oil cows aren't any different from any other livestock throughout the centuries. Sounds like they're a valuable resource, and since they're domesticated, there's vested interest in ensuring that at least a breeding pair survive, which means oil cow farmers will do what they need to in order to protect their herd. Plus, a dead oil cow is only worth the meat (assuming it's edible), byproducts (bone, ivory, etc.), and whatever tiny fraction of that 4L of oil you can squeeze out of its glands. Presumably, they are significantly more valuable alive, and unless the cultures of your planet have a prevailing "scorched earth" policy in all their conflicts, they'll probably see an oil cow herd as part of the spoils of war. Plus, if you're a bandit or raider, why kill what you can conquer and use? Raiding cultures were not generally motivated by a strong desire to kill the people they were raiding; they wanted to take their stuff, wait for the oppressed people to make new stuff, and then come back and take more stuff.

From a completely different perspective, even if your cows produce oil which requires no refining, they themselves do not have to be particularly combustible. If you're really concerned about it, your oil cows might have evolved a particularly flame-resistant skin. Maybe they sweat profusely as a defense mechanism, which makes it really hard for them to be set alight without devoting a lot of time to holding the flame against them. From personal experience, it's no easy task keeping a half-ton bovine immobilized--even when you're not causing them pain and they aren't panicking. An entire panicked herd can pretty easily demolish most fences, and it would take a particularly dedicated attacker to chase down the herd just to kill them.

Oil Storage

Every time mankind has developed a particularly dangerous material (in a contemporary context), they have also developed some way in which to store it reasonably securely (reasonable also being in a contemporary context). In times past, combustibles were stored in clay pots--not particularly safe, but better than out in the open (think Greek fire). This same idea can be applied to the oil from your oil cows.

I'm assuming since you mention a mountainous region, the warring states you mention aren't nomadic. It wouldn't be much of a stretch to assume, then, that the oil from the cows is stored in caverns in clay, wood, or stone vessels. An "oil cave" would be a dangerous place to light a fire, but by necessity, the locations would not be advertised to foreigners or competitors, and if a fire did break out, it would be contained to that cave. Frankly, outside the advances in the material used to create the vessels, this is still basically what we do today with combustibles--stick it in the ground somewhere out of sight and out of reach.

Other Thoughts

At 11.2G, if your atmosphere is the same thickness as Earth's (i.e., the column of gases from sea level to space is the same height), your atmosphere is significantly denser at sea level (or whatever baseline your planet has that is equivalent to sea level) than Earth's atmosphere. If the atmospheric gas ratio is approximately the same (78% N2, 21% O2, ~1% Ar), that would mean the density of O2 molecules would be much higher than here on Earth (proportionally higher, but not directly proportional due to gases being compressible fluids [I think]). This would probably mean that oils burn significantly faster in your atmosphere, since the number of oxygen atoms available within the area of combustion is significantly higher than on Earth--basically, free compression.

Since your oil burns significantly faster, the fire may not be able to spread as far. This might explain why your naturally flammable cows aren't extinct--when one catches fire, it burns so hot and fast that the fire consumes all the fuel too fast to spread. No fuel, no fire.

A thinner atmosphere would produce a more similar gas density to Earth's, but would also have other side effects unrelated to your oil question. Meteorites could be far more common (assuming space junk is as prevalent in your universe as it is here). The sky wouldn't be the same blue. Ionizing radiation may interact differently, though a different magnetosphere could easily balance that.

Do with that what you will!


Knowing nothing about oil you should read about cracking.

Note in The Road Warrior (for it's level of realism), there's an oil derrick, a tanker truck, and a giant tower thing (cracking tower). At varying levels of the tower, different types of hydrocarbons come out. At the bottom (or the top, IDK) you get fuel oil in which you can extinguish matches. At the top (or w/e) you get gasoline, the vapors of which can spontaneously combust. Somewhere in between you get diesel which will also extinguish matches.

So if you want it to go straight into an engine but have low flammability, make them excrete diesel.

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    $\begingroup$ and be sure to use a cattle-itic converter. $\endgroup$ Commented Jul 3, 2022 at 2:31
  • $\begingroup$ Boo! I mean Moo! $\endgroup$ Commented Jul 3, 2022 at 17:14
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    $\begingroup$ Incidentally, you can extinguish matches in gasoline too, as long as the day isn't hot enough to evaporate too much of the gas. Same with even more flammable things like isopropyl alcohol, which I used to put cigarettes out in to the horror of my workmates. They were all convinced I'd blow up the workshop smoking around the IPA I was using to clean electronics. Ah, the good old days. $\endgroup$
    – Corey
    Commented Jul 4, 2022 at 2:02
  • $\begingroup$ Thanks for your answer. Do you think usable oil from cows like this would contain enough hydrocarbons to be useful? $\endgroup$
    – NagaPrince
    Commented Jul 4, 2022 at 17:53

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