[Low Tech] Crop Rotation Patterns

[scc]

Originally Posted by Anaraxes

The are also other, older processes than biodiesel that start with coal or biomass of any sort, not necessarily oilseed. During WW2, Germany got most of its high-quality avgas, as well as lubricating oils and rubber, from the Bergius process. There's also the Fischer-Tropsch process, which is especially good for making heavier hydrocarbons like diesel or waxes. It starts with any source of hydrogen and carbon monoxide (which is usually something like liquified/gasified coal or biomass, or methane / natural gas). So there are potential alternatives. Or perhaps you prefer the setting to have amber waves of canola.

The thing with those process you mentioned is that where do you get the hydrogen? IRL we get it from oil

[Flyndaran]

Originally Posted by scc

The thing with those process you mentioned is that where do you get the hydrogen? IRL we get it from oil

There are organisms that produce it and some can "easily" be made to make far more with genetic tinkering. So one could hypothesize an alternate history where such a bacteria was found in situ.

[Anaraxes]

Originally Posted by scc

The thing with those process you mentioned is that where do you get the hydrogen?

As I mentioned, such processes usually start with coal, biomass (plant material of some sort), or natural gas. Sometimes methanol, although that's also an intermediate step. Lots of organic molecules in addition to the hydrocarbons contain lots of hydrogen and carbon. We use petroleum because it's convenient and cheap (at the moment). Also closer to what we want to end up with, though that's one of those technological circles: you design engines to run the fuel you have, which means that's the sort of fuel you want to have, so you develop fuel industries focused on producing it, which makes it cheap and available and thus a good candidate to design engines to use.

[Anthony]

Originally Posted by scc

I'm actually asking the question for the Steampunk/Space idea that keeps popping into my head where petroleum is mostly reserved for spaceflight and so something else must be used for ground vehicles, and well recently I remembered that Diesel's original design was designed to burn vegetable oils.

Biodiesels have around 9% lower energy density than petrodiesels; outside of a few high performance applications (such as rocketry), that's not a big deal. The main reason we use petrodiesels rather than biodiesels is cost.

Originally Posted by scc

Note for those with AtE: Vegetable oils are definition liquid at room temperature, so unless there's snow on the ground you won't need to heat it

You might; the viscosity of vegetable oil varies substantially with temperature, so even if it's technically liquid it may not flow well enough to work properly in your engine if it's too cold.

[Flyndaran]

Petroleum isn't just an accident of history. It's simply the densest, most easily accessible, and mobile energy source on earth. Even dietary fat isn't "that" much better even if we ignore the biological complexity needed to metabolize it.

Oops, ninja-ed and slightly corrected.

[scc]

Originally Posted by Anthony

You might; the viscosity of vegetable oil varies substantially with temperature, so even if it's technically liquid it may not flow well enough to work properly in your engine if it's too cold.

The place I work at refines, bottles and otherwise packages vegetable oils. We sell spreads (margarine) in both drums and pallecons, and that's vegetable oils modified to have a lower melting point and we pump them, unmodified vegetables should still be pump-able at lower temperatures (And burnable)

[Anthony]

Originally Posted by Flyndaran

Petroleum isn't just an accident of history. It's simply the densest, most easily accessible, and mobile energy source on earth. Even dietary fat isn't "that" much better even if we ignore the biological complexity needed to metabolize it.

Densest energy source on earth, by quite a lot, is fission fuel, but it's not very accessible. Dietary fat is actually significantly worse than diesel (37 MJ/kg and 34 MJ/L vs 48/36). In general diesel has the best combination of energy per mass, energy per volume, and ease of use (storable liquid), though there are somewhat better materials if optimizing for any one of those things.

Originally Posted by scc

The place I work at refines, bottles and otherwise packages vegetable oils. We sell spreads (margarine) in both drums and pallecons, and that's vegetable oils modified to have a lower melting point and we pump them, unmodified vegetables should still be pump-able at lower temperatures (And burnable)

Depends on the width of the tubes being used.

[scc]

Originally Posted by Anthony

Depends on the width of the tubes being used.

No more then 2 inches across which is is a bit much, but remember this oil has been modified so that it's that way instead of liquid.

Also forgot to mention this before, but this setting is only TL7 in space flight, everywhere else they would be TL5-6

[dcarson]

When they started using gasoline in cars it also had the advantage of being a cheap byproduct of the much larger kerosene industry.

[scc]

Originally Posted by dcarson

When they started using gasoline in cars it also had the advantage of being a cheap byproduct of the much larger kerosene industry.

No kerosene industry likely in this timeline, or if there is it's relatively small.

I'm thinking these people achieved powered flight at around TL4