Long story short, a bunch of people terraformed a planet and then were immediately technologically and societally forced back to the Stone Age thanks to interference/extermination/general-not-goodness on the part of some other people who could nonetheless not be half-assed to finish the job. They've been building their way back up for a few millennia; assume that technology-wise, they're identical to Earth in all ways except for those related to fossil fuels.

However, this planet was terraformed from what was essentially a barren rock, meaning it never had millions of years for the remains of dead life-forms to decay into fossil fuels - the people in question arrived, terraformed (took about 500 years), got obliterated as a society (took about 1), and have been evolving back into a modern society since (took about 15,000). It takes fossil fuels significantly more than 15,501 years to form.

The principal origin of fossil fuels is the anaerobic decomposition of buried dead organisms, containing organic molecules created in ancient photosynthesis. The transitions from these source materials to high-carbon fossil fuels typically requires a geological process of millions of years, sometimes more than 650 million years.

This means that, once technology hits a level where steam-powered ships would have otherwise come into the scene, things instead go differently, since steam-powered ships run off of coal or oil, both of which are fossil fuels, and do not exist on this planet. Moreover, naval air power would be significantly different, since there's no jet fuel. Later on, your WW1-through-WW2-level battleships will be different, since there's no oil for them to burn.

For the purposes of this question, this planet is functionally identical to Earth other than the fact that it does not have any fossil fuels.

The question: How would modern naval warfare be altered by a complete lack of fossil fuels?

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    $\begingroup$ You’re not going to have anything that approaches modern naval warfare if your population doesn’t have fossil fuels. Fossil fuels are absolutely necessary to create the massive quantities of steel and aluminum that modern warships need. You will need fossil fuels to even build the infrastructure for nuclear power generation $\endgroup$ Jan 23 at 7:40
  • $\begingroup$ You also have to assume all past technical knowledge was completely obliterated which would actually extremely difficult to to do. $\endgroup$
    – Mon
    Jan 23 at 9:50
  • $\begingroup$ "WW1-through-WW2-level battleships": What battleships? What airpower? This world is stuck in the Early Modern period. Unless they come up with some technological breakthrough in the equivalent of the 17th century; but in that case, why would you think that they will repeat our battleship-building moment of madness? The point being that there will be no battleships ever in that world. (In real history, battleships used up a tremendous amount of steel and money and effort, and were never useful in any war.) $\endgroup$
    – AlexP
    Jan 23 at 11:02
  • $\begingroup$ @drachinifel I believe this is in your wheelhouse :-P $\endgroup$
    – Criggie
    Jan 23 at 18:32
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    $\begingroup$ "steam-powered ships run off of coal or oil", only when coal or oil is less expensive than wood. In your world that's not the case (non-existent thing is infinitely expensive). $\endgroup$
    – hyde
    Jan 23 at 22:14

7 Answers 7


'Fossil' fuels are still produced

Not all fossil fuels come from fossils. Things like sunflower oil habe great potential. You can already use it to mix with diesel, though highly illegal in most countries for doging all the taxes on fuel.

My knowledge of the incredibly complex thousand stages and (by) products of oil is limited. But using such oils can be a starting point for a great many things. Most likely you can get similar or identical products like plastics, lube or medicine from plant oils. This is important, as many products to create and maintain machines are made from oil.

But we might not have any problems. The use of oil has stagnated research in other areas. Because why bother coming up with new methods for lube or oil if there is already an abundant and cheap (by) product available? If you remove oil we might still have all these important products from different sources, as necessity sparks research and creativity. They might be better and cheaper, they might be more expensive and worse, but we would have alternatives.

To come back to naval battles, it is fully unsure how such a societies technology would evolve. They might have tons of plant oil used for it's engines. They might have focused on electricity much more and use batteries or other forms like hydrogen to store electricity. Ultimately most big boats are electrical, as even oil is just used to drive generators. That means they are inefficient and electrical boats are a big step in efficiency if done well. In addition they might still use sails to reduce energy usage, though leading to much less predictable boat speeds and arrival times.

  • $\begingroup$ Diesel engines can have their injectors modified to make the engine run using nothing but SVO (straight vegetable oil) for fuel. In cold climates, you'll need to warm the oil up before starting the engine. Ethanol can be used in a typical gasoline fueled engine. Based on this, I think Trioxidane's answer is quite reasonable. $\endgroup$ Jan 23 at 8:49
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    $\begingroup$ Presumably the terraforming deliberately included plants that could be refined into substitutes for fossil "fuels", including substituting for coal in manufacture of steel (as noted in o.m.'s answer). The big difference between Earth today and this world is that with no ancient energy "savings" to use up, much greater areas of arable land must be devoted to growing "fuel". Therefore less land to grow food, therefore lower supportable population than Earth today. $\endgroup$ Jan 23 at 10:12
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    $\begingroup$ "Electrical boats are a big step in efficiency": if you don't mind that your ships are biggg, with very low carying capacity and very very slow. Efficient, maybe, in a very narrow sense. Useful, no. $\endgroup$
    – AlexP
    Jan 23 at 10:58
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    $\begingroup$ @AlexP your mindset is still firmly in our time. In an age where there's no fossil fuels and all oil is agricultural it can make sense. In addition, all research and development has gone to making electrical boats better instead of relying on oul products. That is the whole premise of the answer. They might have a great hydrogen solution thanks to the oil restriction. $\endgroup$
    – Trioxidane
    Jan 23 at 15:00
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    $\begingroup$ @Trioxidane There's a distinction to be drawn between using electricity as the transmission (quite efficient) and using electricity as the power source (not efficient, because batteries are heavy and delicate). There's some improvement to be made in batteries but they have a long, long hill to climb before they can challenge liquid fuels for energy density. $\endgroup$
    – Cadence
    Jan 23 at 23:11

The Age of Sail

There were naval battles long before the mass exploitation of fossil fuels. Your colonists could build multi decked sailing ships with pre industrial techniques and could use charcoal foundries to cast gun bronze and make very serviceable cannons

  • $\begingroup$ Wouldnt they go for steam engines rather than sails? $\endgroup$
    – Demigan
    Jan 23 at 9:44
  • $\begingroup$ Coal is a fossil fuel. $\endgroup$ Jan 23 at 9:59
  • $\begingroup$ Agree with the sail, not with the bronze, let alone bronze cannons ! Cannons are post-medieval, they are big and require lots of energy to mold. Your colonists only did 500 years of terraformation,, fuel will be scarce, trees are needed to make oxygen. And how would they produce charcoal ? That involves energy use: you need to heat wood, to produce charcoal. Ca 75% of the weight is lost, before the charcoal can be used en.wikipedia.org/wiki/Charcoal $\endgroup$
    – Goodies
    Jan 23 at 13:30
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    $\begingroup$ @NixonCranium pre-made fossil fuels are absent. Fossil fuels that are produced by the populace are still available. $\endgroup$
    – Demigan
    Jan 23 at 15:27
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    $\begingroup$ @Goodies cannons are not post medieval. Cannons were being produced in significant quantities Europe by the 14th century. Furthermore, charcoal was used for literally millennia to smelt bronze. It is a solved problem $\endgroup$ Jan 24 at 1:12

Without fossil fuels your people would never advance beyond medieval technology levels.

Fossil fuels are, in essence, portable energy source. They are still today because even today we do not have designed anything that can compare to energy density and easy to use of a simple litre of oil. Even though we need oil for virtually any technology and if oil run out our entire civilization may collapse, we still cant stop burning oil! Remember that medieval wind or water power generation methods were much less efficient than what we have today.

To advance from medieval technology towards industrialized society you need a lot of energy. This energy has to come from somewhere. Water, wind power and charcoal can power medieval society just fine, but if you want to concentrate manufacturing capacity to the point where civilization enter industrial age you need more efficient energy source. I have no idea what can replace coal and later oil as such low tech yet relatively efficient energy source.

Charcoal is not an answer. Roman pottery production in the 1 century BC and further approached industrial concentration levels by the use of slave manpower and charcoal. Those "factories" developed in Italy, but as the time progressed, were relocated further and further north. That was because they quite literally were burning entire forests for charcoal. At some point they simply run out of forest to burn and production of terra sigilata pottery stopped, but long term deforestation ill effects still influenced Roman world. Industrial scale production of steel and other early industries (like textile production) required much more energy. I'd say more than earth-like planet can generate in form of trees to be used for charcoal, as before you reach industrial age your civilization will collapse due to ill effects of deforestation.

In fact, world without fossil fuels is the easiest method to force perpetual medieval age so typical to classic fantasy worlds.


A civilization capable of terraforming a planet should be well aware of electricity, conductivity in metals, magnetism, etc, even if they've been bombed back to the stone age.

It does not require fossil fuels to discover electrical power, and how to store energy generated by wind power and solar power. Look into green power.

We don't need solar cells, thermal solar power is the concentration of sunlight by simple magnifying glasses or parabolas; both of which can be produced without fossil fuels. Focus a few square yards of sunlight and you can boil water to operate a small steam engine that can turn an alternator and make electricity. You can even melt copper and iron directly with just a few square yards of focused solar power.

The same thing goes for windmills, I've seen a homemade windmill, built entirely by one man (a mechanical engineer), that turns a large generator and powers a modern electrical house. The same thing goes for waterwheels, most modern dams produce electricity by gravity-fed waterwheels turning electric generators.

And of course electricity is like a fluid in the sense that we can combine a lot of small sources to make a much larger current.

You can store electricity in batteries, lead-acid, molten salts, etc.

With sufficient electricity, you can create modern forges with electric cauldrons to melt metal and refine whatever metals you want, and create any alloys you want.

I think it is important to note that the first known electrical device was invented in 1835, 187 years ago at this writing, and the entire planet has been revolutionized into an electrical society in less than two centuries. I believe in another century, fossil fuels and "combustion" in general will be considered a disgusting, polluting and unhealthy remnant of the past.

Given electricity you could easily advance, in 150 years or so, to nuclear powered naval ships that are completely electric; constructed entirely with parts electrically produced.

And I think it is fair to say that our own legacy of fossil-fuel powered engines are entirely unnecessary, or if energy density is truly a problem, we can with electrical equipment synthesize high energy liquid fuels that are not nearly as polluting as fossil fuels.

All you need is solar power, and you skip over the fossil fuels entirely. We clearly don't need them for explosives and missiles, either. Naval warfare would progress along the same lines, first wind-powered, but quickly electrically powered instead of fossil fuel powered, and entirely recognizable.

  • $\begingroup$ Theoretically... But it takes some really advanced tech that we haven't discovered yet. Take solar for example. When the sun is shining you get an average of 2.5 horsepower per square foot, plus or minus based on your latitude and the season. Multiply by the 15% efficiency of our current solar tech and you get about 1/3HP per sq.ft. A WWII battleship runs on 32,000HP. You'll need 85,334 square feet of solar collector to move your large naval ship... when the sun is shining. With charge/discharge efficiency for batteries, you'll need at least 256,000 sqft to run at night. Fear the clouds. $\endgroup$
    – Perkins
    Jan 24 at 17:52
  • $\begingroup$ @Perkins I am talking about thermal solar, not photovoltaic. Thermal can be 31.25% efficient: en.wikipedia.org/wiki/… And I presume a battleship can be dang large with battery storage. Typically I'd expect them to have huge batteries with forklifts, have the recharge stations on land, and just dock and trade out expended batteries for fully charged ones. Battleships had to stop for fuel. So really half your area requirement, 128K sf, and that is only a 3 acre collection area. 50 acres per refuel station, to average out collection. $\endgroup$
    – Amadeus
    Jan 24 at 18:20
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    $\begingroup$ Battleships are huge, yes. But they're packed to the gills with weapons and equipment. You're not going to use batteries. You're just not. Diesel fuel packs about 45MJ/kg. The most powerful batteries we've got -- lithium-air -- clock in at a whopping 6. The most powerful rechargeable ones are 2.5. The USS Wisconsin carried 7million kg of diesel fuel. You'd need 126 million kg of rechargeable batteries to get the same amount of power. The whole boat only displaces 45 million kg. Batteries are good for small, short-range vehicles, or when you have no other option. $\endgroup$
    – Perkins
    Jan 24 at 20:02
  • $\begingroup$ @Perkins Then perhaps they don't have battleships, and think of something better. Battle swarms. As for "You're just not", I disagree. This isn't a choice between diesel and batteries, the question rules out all fossil fuels. Diesel is refined from petroleum, thus it is a fossil fuel. Thus, in this scenario, it is batteries or nothing, and that means batteries. Perhaps there is some armored "mother ship" that recharges smaller attack ships. Keep in mind, there is not alternative but electric vehicles. $\endgroup$
    – Amadeus
    Jan 24 at 20:58
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    $\begingroup$ No, the question rules out naturally-occurring deposits of mineralized hydrocarbons. It's very much not "batteries or nothing." "Diesel" is nothing more than a specific weight range of long-chain hydrocarbons. If there's no underground crude oil for you to refine it out of, then it's about the same as peanut oil (would take a bit over 3000 acres of peanuts to fill the tanks) or just a bit heavier than whale oil (which may or may not be available) or several plant oils. Wood gets you 16MJ/kg. Charcoal gets you 30. I compared with diesel only because that's what the Wisconsin used. $\endgroup$
    – Perkins
    Jan 24 at 21:38

The industrial revolution, as we know it, depended on iron and coal. Substituting charcoal would:

  • Increase the land requirement for forestry.
  • Probably increase the manpower requirement for lumberjacks and charburners.
  • Complicate some processes which rely on high-grade fuels.

So you might start with a society where iron and power are more scarce than in the real world. Do they ever get enough for railways, power grids, microchip fabricators? These people would be in a bad position to produce biofuel in industrial quantities. At a wild guess:

  • More reliance on sail for propulsion, with engines for auxiliary power only.
  • Less reliance on steel hulls. Perhaps wooden hulls with iron/steel frame reinforcements?
  • I might have said that aviation lags behind, but historically there was no aviation in the age of ships like these (1830 to 1880), so lags might not be quite the right term.

Bio fuels

Experimentation with fermentation and the production of methane etc via bio-reactors could lead to the industrial production of carbon based fuels. But it would take time!

However as knowledge of microbiology, photosynthesis, biochemistry and genetics etc was rediscovered the ability to produce carbon based fuels on an industrial scale would become a possibility.

  • $\begingroup$ Biofuels are far too expensive. They would need the production and efficiency increases that industrialization provides to attempt to bring it above economic unity. It is so close to energy unity that is is not worth it from an energy standpoint. Additional bio fuels are in direct competition with food production. $\endgroup$ Jan 24 at 21:15
  • $\begingroup$ Depends how its done. You don't have to use crops. Algal based bio fuel can be grown in salt water, so it doesn't even necessarily require land, well at least fertile land anyway. Deserts can also be used. For for that matter so can bioreactors (Vats) on a huge industrial scale. That and genetic engineering to develop strains of algae/bacteria with the desired yields. At the moment the oil yields from some strains range from aprox 30-70% (dry weight) so you breed/engineer for the highest yields possible. $\endgroup$
    – Mon
    Jan 24 at 21:55

So this is going to depend quite a bit on just what they started with for a planet, what the terraforming process was, and how much of their knowledge was lost (as opposed to just infrastructure destruction.)

It's possible that they have a fair-sized cache of immature fossil fuels that would still work reasonably well.

Look at it this way. Fossil fuels are the remains of ancient plants (and animals, but mostly plants) that died in such a way that no bacteria or fungus ate them. Then they sat around for a while and all the water and such evaporated leaving big, long chains of carbon. (A bit oversimplified, but sufficient for our purposes.)

To terraform a world like, say, Mars where all the oxygen is locked up in various oxides (and especially CO2) You're going to need to free that oxygen somehow. There are lots of ways you can do this, but when you release the oxygen into the atmosphere for people to breathe, you're going to be left with a big pile of whatever the oxygen was bound to just sitting there.

Pull your oxygen out of the iron oxide, you'll have a whole bunch of cheap iron. Pull it out of SiO2 and you'll have lots of material to make computer chips from.

Pull it out of CO2 and you'll have a massive pile of carbon left sitting there. Big chunks of pure (or nearly so) carbon are commonly called "coal".

So the question is what did they get the oxygen out of for what byproduct they have sitting around, and how did they do it for how accessible is that byproduct.

If the world had water, but no life, and they just seeded algae into the oceans to free up some oxygen (even here on Earth most of our oxygen generation comes from the oceans) then they'll have a whole pile of dead algae corpses on the bottom of the ocean slowly turning into coal and oil. The natural refining process takes quite a long time, but speeding it up really only takes a pressure cooker. (This is how "synthetic" oil products and charcoal are made.)

If there's not much for water and they used land-based plants then they don't even have to scrape the muck off the ocean floor, they're just making charcoal and/or biodiesel. Hydrocarbons are about the most efficient energy storage we have by weight and by volume, so it will definitely still make sense to use them, especially at the lower technology levels.

Even once they have photovoltaics or solar-thermal generators the fact that plants are, by comparison, super cheap per square foot to sow and harvest (and they stash away energy in nice, convenient, portable, long-term hydrocarbon storage) is going to mean they continue to be an attractive option. Especially where, by then, they probably will have developed specialized varieties to maximize output and purity of the rendered oil and charcoal.

So basically the answer is that, without a large reserve storage of energy that was banked up millions of years ago, they're going to be devoting a lot more of the surface of the planet to agriculture, specifically to grow things that produce a lot of combustibles in a small volume. Precisely what this will be will depend on the actual climate of the planet. Peanuts, sunflowers, various kinds of tree, possibly massive algae farms -- the efficiency of chlorophyll is about the same regardless, so it's just a matter of finding a species that thrives and stores its energy in an easily-extractable manner.

Anything else probably takes some kind of "magic" since we don't really know of a non-hydrocarbon based path between the stone age and modern technology.


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