I haven’t posted since May 2018, breaking my plan for a post every month. Let’s catch up, I’m now 7 posts behind. So this is the post for June 2018, about when I started playing Factorio.
So let’s talk Factorio. Specifically, let’s talk the math of turning crude oil into material goods. The usual goods I care about are lubricant, solid fuel/rocket fuel, batteries, processing units, raw sulfuric acid (for uranium mining), and plastic.
My usual method is to place pumpjacks on oil fields, then use a train to ship the crude oil to a refinery at some central location (i.e. the starting location), where I then turn it into each of the things I care about. Similarly, all of the accessory materials (coal/iron/copper) also get shipped by train to the central location, where I make all of my things.
This works okay, but in some cases clearly involves an excessive number of trains coming to my main base. To take solid fuel as a quick example: To make a cargo wagon full of solid fuel (2,000 units. From light oil, of course), you need 20,000 light oil, for which you need 44,444 units of crude oil, or about 1.8 fluid wagons full (with advanced oil processing). It gets worse if you want rocket fuel - a wagonful of rocket fuel (400 units) requires 4,000 solid fuel, which requires just over 3.5 wagons of crude oil.
Notice that I’m ignoring the heavy oil and the petroleum gas from the advanced oil processing step, as those products would presumably be used to make other things.
Also notice that I’m counting everything in wagonfuls, not itemfuls. I posit that the fundamental unit of efficiency in a large base is the wagon - a mega base (or distributed base) would presumably receive 1 wagon of rocket fuel rather than 3.5 wagons of crude oil along with having to hold all the equipment to do the conversions (space is unlimited, except when it occupies space where you want to put other things like assemblers).
I’m assuming that it’s simpler to ship oil to a processing yard for processing before shipping the results to the main factory. There is an extra step, in that you’re splitting what would’ve been one rail line (“move crude oil to factory”) into two (“move crude oil to processing” and the more complicated “move end products to factory”), but the flow into the factory is lower and thus simpler.
But, TL;DR is that here we’re optimizing for the somewhat vague target of “fewest wagon targets into your main factory.”
Moving on. For making a wagonful of lubricant, you need a wagonful of heavy oil, so no real gain there. But, a wagonful of heavy oil requires 10 wagonfuls of crude oil! (let’s say water is easy to access wherever your processing plant is, otherwise everything gets really complicated)
Let’s do something a little more complicated: plastic. A wagonful of plastic (4,000 units) requires 40,000 petroleum gas, which in turn requires 72,727 crude oil - or 2.9 wagons. But! It also requires 2,000 coal, or 1 wagonful. So if you move coal from your factory to your processing plant, you’re only saving 0.9 wagon-movements per wagon of plastic. But, if your processing plant is distant from the factory (as we’re assuming), then you can ship the coal directly to the processing plant, changing what would’ve been 2.9 crude oil wagons + 1 coal wagon into your factory into a mere 1 wagon of plastic to your factory, almost a 4x improvement.
Okay, let’s do sulfuric acid next. 1 wagon (2,000 units) of sulfer requires 30,000 units of petroleum gas, or 54,545 units of crude oil (2.18 wagons). A wagonful of sulfuric acid consumes 2,500 sulfer (1.25 wagons) and 500 iron plates (0.125 wagons), or 2.725 wagons of crude oil and 0.125 wagons of iron.
That’s not too much of a savings, unless you’re willing to also ship copper in. A wagon of batteries (8,000) consumes 160,000 sulfuric acid (6.4 wagons), 8,000 iron plates (2 wagons), and 8,000 copper plates (2 wagons). Those 6.4 wagons of sulfuric acid would’ve required 17.44 wagons of crude oil. By producing batteries at an outpost, you’ve reduced over 21 wagons going into a central outpost to a mere 1 wagon, with ~5 wagons going to your processing outpost.
Processing units are a little more complex - a wagonful (4,000) requires nearly 20 wagons of green circuits, so it’s more efficient for you to move the sulfuric acid to the processing unit factory (only 0.8 wagons of sulfuric acid) instead of vice-versa.
A wagonful of explosives requires half a wagon of sulfer and half a wagon of coal. No particular gain in building explosives at your remote outpost vs. shipping in sulfer. Half a wagon of sulfer adds up to only 1.09 wagons of crude, so there’s a minor advantage over shipping in crude oil.
However, if you plan on building explosive cannon shells, a wagonful (8,000 units) consumes 16,000 explosives (8 wagons) and 4 wagons of plastic, along with 4 wagons of steel, so manufacturing a wagon of explosive cannon shells saves 16 wagons of goods coming to your central factory.
The math can go on. And of course, there’s the added complication of arranging your rails to go every which way. But, if you want the elegance of not having to deal with chemicals at your main base, distributed oil may be the way to go.