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Dev Corner | Thermodynamics

If you missed the previous Dev Corner, check it out here!


Briefing: Thermodynamics
Author:
@Zwirbaum


Hello everyone!

It has been eight days since the last dev corner, which means it is time for another one. Last time, I was talking about some of the new naval concepts and changes coming to the Hearts of Iron IV. Today I will be talking about the introduction of Coal and Energy into the game. As a casual reminder keep in mind that everything discussed here is in a relatively early stage, and as such is subject to change.I also want to add that not every dev corner will be a long one, and some may end up on a rather short side. But without further ado, let’s keep this lump of coal rolling.

For the first time since the launch of the game we will be adding a new resource to the game, as every other resource, Steel, Rubber, Tungsten, Chromium, Aluminium and Oil were since day 1 in-game (with Oil getting Facelift in Man the Guns to be used for Fuel production instead of equipment production). This resource is Coal - to put it very briefly it will be serving as a ‘fuel’ in the form of Energy for your industry to keep it running efficiently.

Core Concept
What are some of the goals when it comes to adding Coal & Energy, and what do we want to achieve with it?
  • We want to introduce a potential soft-limit on the current almost limitless industrial expansion.
  • Increase importance on expanding and securing a resource base for your needs.
  • Provide a bit more interesting choices when it comes to economic laws, give some incentive for a player to consider ‘demobilize’ at some point during the gameplay, and that War Economy / Total Mobilization is not always the one and the only one right choice.
  • We are not aiming at creating a super complicated or overly complex system for energy/economy model

What is all the fuse about?

dc_thermodynamics_001.png

Sardinia starts with 2 units of Coal at the beginning of the game. As usual, numbers are subject to change, so please do not despair yet.

Base Concept
So the system works like this: Coal is excavated just like every other resource in-game. Each unit of Coal that you have for your own use (so not traded away) will produce a set amount of Energy, which then in turn is used to power up your industry - your civilian, military factories and naval dockyards, which for the ease I’ll be later calling them in this dev corner as ‘factory’. Each Factory, regardless of the type, has the same base Energy demand, so what you are seeing in the top bar as your industry size should also give you a very rough estimate of the demand.


dc_thermodynamics_002.png

This totally mysterious country, that is totally unrelated to Sardinia from the previous screenshot starts with 56 factories, and now has a mysterious bar under the factory count.

Economy of the Scale
However the base Energy demand is not everything, as each Factory you own will also introduce a little extra scaling cost to the demand per factory, so a small, undeveloped minor country will be able to sustain their few factories with a rather small amount of coal, while historically accurate Luxembourg spanning across Eurasia will require much more energy in order to effectively satisfy the ever hungry maw of their Industry.

Lower Mobilization Law is your friend?
Most, if not all, economic laws will also have factory energy consumption modifiers, which will essentially either increase or decrease how much each factory (including the ‘scaled’ portion from ‘size’ of the industry) will demand energy. Higher mobilization laws will have higher energy demand, to represent longer working hours, more shifts etc.

dc_thermodynamics_003.png

Economy Law picker will also now proudly display the energy consumption modifier at the first glance, so that you do not need to scour through the tooltip to find the modifier. Before you start going crazy with guessing what is the second number, it is just the expected amount of consumer goods - the icon is currently placeholderish, as we haven’t adjusted the previous icon yet.

How does it work though?
I will start with a quick reminder how the Civilian, Naval and Military Industry operate in-game currently. Essentially each of the ‘factories’ have a specific base amount of output valued in points that they contribute daily to. (5, 2.5 and 4.5 respectively). And that was further modified by all the technologies, laws, ideas, ministers, national spirits with various ‘Construction Speed’ or ‘Dockyard/Factory outputs’ modifiers. I am not mentioning Production Efficiency, as that was unique to the Military Factories.

So how will that operate in the brave new world? We will now have a base output for each of the industry types - which means that regardless of the energy, you will always have at least this much output from your factories. And there will be ‘fully powered’ output values for the industry. Depending on the energy ratio you are providing, you will end up somewhere on that scale, e.g. If you have 50% energy - you will be getting output that is ‘50%’ way from the base output to the fully powered up. All the previously mentioned Construction Speed, Dockyard/Factory Output modifiers will also be scaled accordingly to the % of the energy you have.

dc_thermodynamics_004.png

This is the current debug display that allows us to see energy demand & consumption, and how much it impacts the industry. In this case we have 26.7% energy needs satisfied, and it means that each of our CICs provide 4.2 IC daily, MIC provides 3.7 IC daily and NIC provides 2.1 IC daily. Of course as usual, reminder that all values are subject to change.

Wrapping Up
And that is all from this dev corner. While this post is one the shorter side, impact from adding this ‘system’ could of course be quite big - however thanks to covering only this one matter, feedback, opinions, suggestions from you dear readers, should be laser-focused and allow us to get a much clearer picture of what you are thinking. Anyways, that is all from me for this week, and next week Thomas will be back with more things to say about the Factions.

Thanks for reading, and until next time, farewell!

/Zwirbaum
 
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It also may be worth rethinking the approach to resource availability through focuses and nation-exclusive decisions.

Currently, lots of new resource fields are hidden behind nation-exclusive options. Which is neat, it gives the nations flavor. But it's also not that logical. Either there are resources, or they aren't, regardless of who currently has their flag raised above that piece of land.

Let's take the Matzen Oil field of Austria for example. Only Austria can develop it via focus. Historically, the Soviets discovered and developed it in 1949. But when you as Soviets take Austria, you can't access it, because it's a focus choice for Austria only. Same for Anschluss, you peacefully integrate Austria, and now you lose access to something that physcially is there?

And I think China has similar problems. There are focuses in the Japanese tree to develop China, but when China takes over? Then nope, all those opportunities are suddenly gone.

Resource fields and extraction should get a unified framework I think. Focuses should help finding and developing those fields at low costs, but ultimately the fields should be accessible to the owner, whoever that might be at any given time.
Totally agree.
 
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ATM equal distribution
Please consider adding the ability to prioritize coal for certain factory types. If I am playing as Germany for example and have a deficit in coal, I do not want the same prioritization of coal going to my dockyard than my more essential military factories. Hoi4 only allows a player to destroy 1 factory every 30 days I believe, so as Germany I would essentially be stuck with my military factories producing below their potential because my dockyards that I can't get rid of are hoarding coal
 
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Any chance we can start moving away from the building slot limit system which honestly always felt forced rather than fluid unlike most of the other game's dynamics.
 
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Any chance we can start moving away from the building slot limit system which honestly always felt forced rather than fluid unlike most of the other game's dynamics.
What is there not to love about the US hitting max squalor and overcrowding after building 25 factories in Texas? Have you even seen Texas? It's so small, it barely could hold the entire UK three times in it!

Yes, on a more serious note, the building limits can at times get ridiculous. Now that we're turning the attention towards resources and civilian economies, that is one more thing that warrants a closer look.
 
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I... I don't know how to feel about this.
It's a very interesting idea, granted, but I don't think this will actually solve the problems you are hoping it will, I feel it is more likely to trade one issue for another or compound the original issue to begin with.

This also, I feel, negatively impacts minors that start with fewer civilian factories disproportionately. This wouldn't be much of a problem if the starting factory count globally was higher with output values adjusted to compensate and there were more starting resources on map.

This, however, would be a sizeable change I'm unsure the dev team would be willing to commit to. It would require pivoting the game more toward factory conversion rather than construction and require deep and extensive rebalances for factory outputs and industrial distribution.
 
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I would like to ask whether it would be possible to treat oil as a raw material to be refined in order to obtain diesel fuel, which will then power ships, trucks, tanks and so on. By building refineries, you process oil using electricity and get a certain amount of diesel that you can either store or sell on the arms market added by "Arms Against Tyranny." In addition, it would be good if, when designing a ship or train, one could choose whether to power it on coal or diesel according to one's energy availability.
One last thing I would like to ask (not related to the dev diary) is to increase the amount of war material that the IA puts on sale; it often happens that there are 50 artillery pieces on the market, put a minimum of 500 pieces that the IA can sell
I would also like to add that, in addition to what has already been said, it would be interesting if, a bit like the war material distribution hub, there were power plants that have a range to power the factories. This would therefore mean that building factories in areas without efficient power supply or power at all would prevent factories from operating completely. Otherwise, by borrowing a feature of Victoria 3 (nothing extreme) you might have a window where you choose the level of mechanization of industries. Italy, the United States or Abyssinia had different industrial capacities, production methods, etc. This would allow for minimal production even in inefficient factories
 
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Does this open up the possibility of CIVs using resources? I have long thought that a 'Commodities' resource representing all of the myriad materials that were used by industry prior to the arrival of plastics (which happens right in this period!) would be a good and useful addition to the game. It represents the needs for imports to keep industry going, allowing a functional U-boat campaign and opening up a good research/project topic to replace them with oil (via plastics and man-made fibres such as nylon) in the later game. General 'Supplies' should also require Commodities for production, making them clash with CIVs.
 
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Will unassigned factories contribute to energy requirements?

For instance, say that I have 10 factories, but enough energy to fully power just 5.

If I assign only 5 of those factories, will they function as fully powered, or 50% powered?

Scaling energy requirements for factories that are in use vs not in use is more complex, but might create a more dynamic system with interesting choices.
I really like this idea, especially if it plays into the whole concentrate vs dispersed debate.

Dispersed would lower the efficiency penalty for taking factories offline to reduce power consumption, and concentrated could provide some overall energy efficiency savings by the fact of concentrating industry can reduce transmission losses.

Difficult to balance but could really make the industry game interesting.
 
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Long-time lurker, first-time commenter, but as a self-professed expert on the coal industry I would offer the following:

My first impression seeing the subject was "oh, no...more complexity, another thing to worry about." But after reading the Dev explanation, I think this has the potential to elegantly deal with a number of issues, just don't let it get much more complicated. That being said....

It's difficult to understand the ramifications of adding coal as a resource without some idea of how it will be distributed, and in what quantities, on the map. I don't think you've addressed this...rather than something to be developed after the mechanics are better refined, I would think this would be the starting point for work on this project.

And at the risk of adding complexity, there are two interactions that you haven't addressed:

1) use of coal in synthetic refineries....after all, coal is the exclusive raw material for the refineries, their conversion efficiencies were not great, so they should consume a lot of coal; and

2) during this time, virtually all steel production was the integrated blast furnace technology...which requires coking coal for the iron ore reduction, and steam coal for energy needs. Without addressing the relative scarcity of good coking coal, you should perhaps consider giving steel production a bonus in coal-rich countries, or penalize it coal-deficient countries. Of course, having some coal being "special" would address this nicely (good coking coal can also be burned for steam), but that would complicate the feature, betraying my very first impression on the danger of feature bloat
 
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Does this open up the possibility of CIVs using resources? I have long thought that a 'Commodities' resource representing all of the myriad materials that were used by industry prior to the arrival of plastics (which happens right in this period!) would be a good and useful addition to the game. It represents the needs for imports to keep industry going, allowing a functional U-boat campaign and opening up a good research/project topic to replace them with oil (via plastics and man-made fibres such as nylon) in the later game. General 'Supplies' should also require Commodities for production, making them clash with CIVs.
Maybe the idea has been in the air and I'm not the only one modding this in, but I'm still amazed at how aligned we are here:

20250626204600_1re.jpg
 
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It's difficult to understand the ramifications of adding coal as a resource without some idea of how it will be distributed, and in what quantities, on the map. I don't think you've addressed this...

Eyup, the topic of logistics has been sidestepped, which is jarring considering we're talking about a new ressource that'd have a significant impact on industryial power as a whole. I know the main stated goal is for it to serve as a limiter to exponential industry growth, but really... There are consequences - and opportunities - to consider here.

Maybe as soon as a lump of coal is extracted, it vanishes instantly, and some electricity suddenly appears in a factory halfway across the world. I don't like how likely that sounds, honestly...
 
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Right now Dams and Civilian Nuclear Reactors provide a reduction in the energy factories from this state are using. (Local Energy Consumption Modifier), so let's say if the modifier would be -25%, then factories located in such state instead of consuming 100 energy would now consume 75 energy. (Random numbers are random)

It would be easier to understand for the player and to calculate for the game if it just contributed to the total energy of the country, I understand you want to simulate coal can be transported anywhere needed in the country while the electricity from nuclear plants and dams can't be transported far away.
That said the local energy production should be a flat number, not a % modifier. If it's a percentage then the nuclear plant should be more expensive to build the more factories or building slots in the province.