Grid-Fitting Fully-Automatic Sleet Wheat Farm

This is my guide on how to make a fully-automatic Sleet Wheat farm that's designed to fit within your typical 18x4 grid. For better or worse, I really like the designs I use to fit the grid as much as possible. That combined with a need for Berry Sludge and a relatively small number of guides available online led me to create my own design which I've decided to catalog here.

That being said, here were my goals when building this design:

• The design must be fully automatic. Everything must be accomplished without any Duplicant labor at any part of the process.
  
• It must be able to fit completely within a number of vertical 18x4 grid floors. Minimize wasted space.
  
• It must be able to accept hot input materials. For this reason I tested all of my designs with 100° C water and dirt.

And here's what I came up with:

To build this farm, you'll need the following resources:

• 6320kg Copper/Gold
  
• 1200kg Steel
  
• Plenty of Igneous Rock for Insulated Tile
  
• Other raw materials

And these are the costs to run it:

• 140kg/cycle (233.3g/s) of Dirt (equivalent to 7 Pips)
  
• 560kg/cycle (933.3g/s) of Water
  
• An average of 450W of power
  
  • Note: This value comes from an Aquatuner uptime of 70% and a constant 390W production by the Steam Turbine. While these are the values that I found from my testing, they will vary substantially based on the input temperature of the materials. Because higher temperatures mean higher power draw, expect this value to be significantly lower in most real-world use.

For those input materials, this farm will output an average of 22.9 Grains/cycle. If converted directly into Frost Buns, that's an average output of 9160kcal/cycle (though of course there are other useful foods with Grains as an ingredient).

This section is compromised entirely of me talking for far too long about heat math and related concepts. There's nothing here you need to know to effectively use this design; feel free to skip it entirely.

Because I knew from the start that I wanted the design to be resilient to high-temperature inputs, over the course of the design I did some heat calculations to determine the constraints of the design. This section exists solely to talk about that math and make myself feel like I didn't completely waste my time.

Note: A lot of the information used here has been taken from the ONI Wiki[oxygennotincluded.wiki.gg]. It's a very useful resource, thank you to all who have worked on it!

The biggest thing to know about Thermodynamics is that energy and temperature are actually two separate but correlated measures. Energy is a measure that is universal between materials: it can be directly compared no matter what material you're working with. Temperature is different; the amount of energy required to warm an object by a number of degrees depends on the material. That amount of energy is known as the Specific Heat Capacity (SHC) of the material; in ONI it can be found in the Properties panel. It represents how much energy, in DTUs (equivalent to the real-life BTU), is required to warm one gram of a material by 1° C. I wanted to try to stick to a single-Aquatuner design, which has the effect of placing a hard limit on the number of DTUs we can remove per second. Math time! The Thermo Aquatuner cools a 10kg packet of liquid by 14° C. Using Polluted Water (SHC: 4.179) as our coolant, that comes out to the following equation:

Removed Energy = 4.179 * 10,000g * 14° C = 585 060 DTUs
(If you're new to ONI Thermodynamics and interested in learning, I'd highly recommend you run these calculations yourself and then compare our results. It's a good way to learn - I'm happy to help if you get stuck or confused along the way.)

That means we have a firm limit of adding 585.06 kDTUs to the farm areas per second. If we try to add more, the system is guaranteed to eventually overheat.

(Note: This math changes depending on what material you use. Try it yourself! Just change the "4.179" in the equation to the SHC of whatever liquid you try. You'll notice that some materials work significantly better as a coolant than others, which brings up one other super option - Super Coolant! As you might imagine, using Super Coolant within the Aquatuner has the potential to drastically change this design. I chose not to because I wanted to avoid Space Age materials, but I'll discuss how you could do that a little further on.)

Now that we know our limit, we need to determine how much energy we're adding to the system. I'm going to talk about this in terms of Modules - one Module is a chunk which houses seven plants and the required automation equipment.

Each Module contains 7 plants, in sum requiring 58.33g of Dirt per second and 233.33g of Water per second. Let's assume that our inputs are 100° C, and that over their lifetime in the Module they will be cooled 105° to -5° C. In reality this isn't a perfectly accurate assumption, but it's always best to guess high and overcompensate rather than guess low and be met with an unexpected catastrophic failure.

Now we can calculate how many DTUs are being added to the system per second, per module:

Added Energy = (4.179 * 233.33g * 105° C) + (1.480 [SHC of Dirt] * 58.33g * 105° C) = 111 450.5 DTUs

From our calculation we can see that every second, we are adding approximately 111.45 kDTUs to a Module.

From here, we can easily calculate the number of modules that a single, Polluted Water coolant Aquatuner can support.

# of Modules = 585.06 kDTUs / 111.45 kDTUs = 5.25 Modules

Well, we can't exactly build a quarter of a module, so we'll round that off to a nice 5 Modules - the perfect number for our design!

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Wait, why does it only have 4? There's a fundamental flaw with our calculations so far: where does the heat go? If you've played any amount of ONI before, the answer is probably obvious: a steam chamber with a Steam Turbine, of course!

Well, that adds its own problems. The Steam Turbine isn't 100% efficient. Steam Turbines work by taking in Steam and then outputting 95° C Water, effectively removing the energy difference between the Steam input and the Water output. But it doesn't do so perfectly - 1/10th of the energy removed from the Steam, plus 4 kDTUs, is added to the Turbine itself each second. We have to accommodate for this heat in our design, or our Turbine will rapidly overheat and stop cooling entirely.

Fortunately, accounting for this isn't too challenging. Because the maximum amount of energy entering the steam chamber is a constant, we can simply lower our maximum heat allowance to take into account the amount of energy entering back into our coolant from the Steam Turbine. This still adds up to the same value, but it changes where the heat comes from to include Turbine inefficiency.

Truly Removed Energy = 585.06 kDTUs - ((585.06 kDTUs / 10) + 4) = 522 554 DTUs

So, once all is taken into account, we can safely pump 522.56 kDTUs of energy into the farm per second. Going back to our Modules calculation, how many does that supoort?

True # of Modules = 522.56 kDTUs / 111.45 kDTUs = 4.69 Modules

Once again, we can't have a fraction of a Module, so round that off to a clean 4 Modules. And with a good chunk of leeway, too! With that in mind, we can calculate the average number of Sleet Wheat Grain we're outputting per cycle. We produce 18 Grains every 22 Cycles (+4 cycles because we wait instead of having Duplicants harvest) and we have 28 plants total, so:

(18 / 22) * 28 = 22.91 Grains/Cycle.

When cooked into Frost Buns, that's 9160kcal/Cycle. Not bad!

If you know the mutations, you might be tempted to use the Juicyfruit mutation. For those who are unaware, the Juicyfruit mutation causes plants to immediately drop their produce on the ground once grown, rather than waiting 4 cycles. However, it also increases material requirements by 25%. Because the 25% material increase is more significant than the materials we are saving by not fertilizing for 4 cycles, we are effectively trading materials for growth speed.

Personally, my belief is that those extra Grains aren't worth the hassle of getting enough of them to fill a farm. On top of that, the extra resource cost is significant enough that it makes more sense to spend the extra resources you would be inputting on another plant entirely. For the amount you're gaining by using Juicyfruit on 4 plants, you could spend those same resources on 1 standard plant and get more output. For that reason I do not recommend it ever, except for maybe the rare circumstance that you can't make another farm.

If you choose to use Super Coolant, things change drastically. Super Coolant has an SHC of 8.440, so let's plug that into our Aquatuner calculation from earlier.

Removed Energy = 8.440 * 10,000g * 14° C = 1 181 600 DTUs

That's.. a lot of energy. So much that it wouldn't take long to destroy our Steel Aquatuner, so if you're inclined to do this you should definitely make it out of Thermium (and probably change the Steam Turbine setup, too). But if you did it, how many modules could you support?

Truly Removed Energy = 1181.6 kDTUs - ((1181.6 kDTUs / 10) + 4) = 1059.44 kDTUs
True # of Modules = 1059.44 kDTUs / 111.45 kDTUs = 9.51 Modules

A total of 9 Modules, for a combined 51.55 Grain per cycle. That's a lot, and I'm not sure why you would want that, but you could!

Right up front, here are all the overlays:
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If that's all you need to build it, great! You're good to go. If you want a step-by-step walkthrough, though, I've got one for you: From your three vertical grids, fill in your Insulated Tile perimeter. Igneous Rock is best. Don't close anything off yet.

Build out all of the Piping you're going to need. The Insulated Pipes are Igneous Rock; the Radiant Pipes are Copper.
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Note about the Thermal Aquatuner: The design here can be mildly confusing if you've never seen it before. The goal is to allow the Polluted Water to pass through the system and continue flowing freely if it is too cold; so we set up the pipes in a way that if they do not go through the Aquatuner, they will instead flow through the Liquid Bridge and back onto the path.
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There are two separate Conveyor Rails here. The first is the Dirt supply; it links every Conveyor Receptacle together. The other is the Grain export; it links every Conveyor Loader together and brings the produce to wherever you want it to be. It's important that these two rails remain completely separate.

This is what the Wiring looks like:

The metal tiles should be built out of Copper. The other materials don't matter too much, but if Aluminum Ore, Wolframite, or Copper Ore is easily available I recommend that for the Hydroponic Farms. Set the Conveyor Loaders to only accept Sleet Wheat Grain, do not allow them to receive Dirt.

Plant your Sleet Wheat, and seal up the farms completely. Ideally try to maintain as much Oxygen inside as possible, but it isn't too important.

Create a Water Lock into the Steam Chamber and begin vacuuming out the room. For this part I recommend building a separate Water Lock for the Steam Turbine room, but combining them for the purpose of allowing them to be vacuumed out. You should also include the two upper tiles to the right of the Steam Turbine room in the vacuum; this is where we will place our wire conduit. Set it up like shown beforehand.
Note: The image shows Heavi-Watt Conductive Wire instead of regular. This is not a necessity; I just prefer to do this to future-proof the design. Take this opportunity to construct your Thermal Aquatuner from Steel, and to add in the Liquid Pipe Thermo Sensor automation. Set the Liquid Pipe Thermo Sensor to "Above -5° C".

With both chambers vacuumed out, add ~1000kg Water to the bottom of the Steam Chamber. Construct two Tempshift Plates from Copper and seal it in.

Begin by sealing in the wire conduit. Ensure there is wire inside and then place a Joint Plate to seal the vacuum in. Then, add Hydrogen to the Steam Turbine room. Around 1kg per tile will work just fine. Doing this isn't required, but it does help. Remove the vent, place the Turbine, and then seal the room.

Add the two Power Transformers to supply power to the Conductive Wire. This design is not self-powered; be sure to connect it to your power grid.

Add Polluted Water to the Coolant Loop until it is full. Use a bridge onto the line so that it does not overflow or get confused.

Connect your Water and Dirt supply lines. The farm has been designed to handle up-to 100° C inputs. Higher temperatures may function, but have not been tested.

Lastly, hook up your Output Sleet Wheat Grain line. This can go directly to your kitchen, deep freezer, or wherever you need it.

And that's the design! I hope you found it to be useful. If you need help or have feedback/suggestions, feel free to comment! I'll do my best to get back to you quickly.

Thank you for reading :)