Efficiency Puzzle: Wood-Powered Tree-Farm?

[Hans Lemurson]

You want to grow poplar, not cecropia. Although if poplar isn't native to the  biome, teak can be better for the blight resistance

Yeah, Cecropia only gives like 70% as much wood.  Poplars all the way!  (I'm in a tundra biome with a basically nonexistent growing season, and the native trees are Pine and Birch.)

I upped the difficulty to Rough and saw that the wood yield was down to 32 (or 16 per half-grown tree).  Where I once contemplated building my base expansions out of wood, I am now occasionally running out of fuel.  Fortunately there have always been enough 40+% trees to restart the system, but I'm not sure how I'm going to build up a surplus to expand the system.  You have to burn a lot of wood before you get your first harvest.

30 1x1s would work if all I were doing was tree farming, but my colony has been living off of crops that I plant down before the crop of trees goes in.  You can't sow crops next to trees, but if you plant the trees after the crops, they'll both grow to maturity.  You have to clear the trees and halt their replanting in order to sow the food crops.

[BranStarksLegs]

Day 1, Hour 6 - Turned Sun Lamp on. Power in Battery was 694.
Day 1, Hour 19 - Turned Sun Lamp off. Power in Battery was 366.
Day 2, Hour 6, Turned Sun Lamp on. Power in Battery was 587.

Concerning the energy loss to batteries which is 50% I believe, wouldn't it make the system more efficient to minimise the reliance on batteries as much as possible. I suggest multiple sunlamp farms with trees at different stages in growth in each, turn the lights off when a farm enters its resting phase, at this point, rather than diverting the excess power into a battery (losing 50% of that energy), divert it into a farm that is just coming out of the resting phase.

This might boost the efficiency slightl

I'll test this later.

[Calahan]

I suggest multiple sunlamp farms with trees at different stages in growth in each, turn the lights off when a farm enters its resting phase, at this point, rather than diverting the excess power into a battery (losing 50% of that energy), divert it into a farm that is just coming out of the resting phase.

A plant's resting phase is determined by the time of day, and not by... ? (I'm afraid I do not know what you think it is determined by, and I won't guess). So all the trees will be resting at the exact same time. That being from roughly 19h to 6h the following day. So any sun lamp that is powered during this time is going to be wasted regardless of which sun lamp (farm) is getting the power.

Unless I'm badly misunderstanding what your idea is.

[Hans Lemurson]

If I wanted to be perfectly optimal about it, I'd have my colonists flick the off switch on all of the Fueled Generators every night at 20:00, and on again every morning at 6:00 after they get up.  However, that sounds like a giant pain in the ass.  Turning the sun-lamps off every night at the right time was itself annoying enough that I had to download a mod to schedule those switch-flicks for me.

As it stands, the batteries are only charging for 10 hours, and at 50% efficiency this comes out to a loss of 5 Kilowatt-Hours out of a total 24kWH produced each day, which is still ~80% efficient overall.

...Granted, that is a major loss when considering the slim profit margins that a self-fueling tree farm operates on, but I'm not going to turn Rimworld into a "reflex clicking game" just for the sake of 4 wood/day.

...
In my current farm setup, I have 5 generators powering 4 Sun lamps with a couple batteries for stabilization and just enough extra power to run 3 heaters.  It consumes an easy to calculate 100 wood/day, and I harvest 4*28=112 poplar trees every ~12 days which on Rough difficulty give ~15 wood each at 40% growth.  Every 12 day cycle earns me ~1700 wood and costs 1200 wood in fuel.  My net profit is ~ 500 wood, which comes out to just over +40 wood/day, or enough to power Two extra generators!!!!  Yeah, I'm living the high life here.

The math of figuring out how much energy you actually have in a battery/sunlamp system is a little complicated but it all roughly simplifies to the following: Your night-time surplus must be 3x as large as your day-time deficit.  (Charging happens for only 2/3 as much time and at 1/2 efficiency)

Each Sun-Lamp therefore requires 1200W power (battery buffered) to maintain, which comes out to 24 wood/day.

[Hans Lemurson]

Here is a picture of my glorious fuel-farm and its double-cropping exploits.  It is recovering from a fuel shortage caused by my failed attempt to expand the operation.

Here we can see Poplars growing happily among Potatoes and Devil-Strand.  The trees in the potato-patch were planted randomly by the pawns, and the ones in the Devil-Strand were planted under my firm and direct guidance.  The random-pattern has 24 trees in a plot, but the carefully-ordered patterns in other plots have 30 trees.

[Thyme]

fueled generator: <fuelConsumptionRate>22.0</fuelConsumptionRate>
corrections:

[...]
In my current farm setup, I have 5 generators powering 4 Sun lamps with a couple batteries for stabilization and just enough extra power to run 3 heaters.  It consumes an easy to calculate 110 wood/day, and I harvest 4*28=112 poplar trees every ~12 days which on Rough difficulty give ~15 wood each at 40% growth.  Every 12 day cycle earns me ~1700 wood and costs 1320 wood in fuel.  My net profit is ~ 380 wood, which comes out to just over +30 wood/day, or enough to power One extra generators!!!!  Yeah, I'm living the high life here.

Note how this small adjustedment pretty much ruined your profit. (btw, i mentioned the fuel consumption rate before)

The math of your sunlamp depends a lot on your growing time. I run my sunlamps for 13 hours, because between 1900 and 2000 it's no full hour. Didn't redo your math here.

PS: The efficiency of your farm would be 16%, as you have 6 generators running, 5 of which are needed to operate the farm. Not counting potatoes.

[Hans Lemurson]

22 wood per day? 
Oh, I see, I misread "3 days, 9 hours" as 3.75 days.  I really liked that number too, since it made everything clean multiples.

This does explain why my wood surplus has been rather smaller than I had predicted.  Turns out I can't actually run both extra generators indefinitely at the same time.  Not without more tree plots.  I am going to need to get my new farms operational, but that requires that I invest ~700 wood in its generators before I can harvest the crop.  Actually since it's on fertile soil, maybe it will only cost ~500 wood.

[Thyme]

Have you tried using one fueled generator for the heating and sunlamps on an independent circuit to power the sunlamps? You won't lose much growing time and get big savings on wood investment. Material cost is also less.

PS: Tree (all kinds) have a soil fertility sensitivity of 50%

[Hans Lemurson]

Have you tried using one fueled generator for the heating and sunlamps on an independent circuit to power the sunlamps? You won't lose much growing time and get big savings on wood investment. Material cost is also less.

PS: Tree (all kinds) have a soil fertility sensitivity of 50%

Keeping the heaters on a separate grid isn't necessary.  Constant loads just means that the batteries are never involved and therefore cause no efficiency problems.

...Or do you mean have the Sun-Lamps on a grid where I can just manually shut down all the generators at night?

In any case, I got my fertile-soil tree farm up and running and found to my dismay (as you just pointed out) that my Poplars were only getting a +20% growth bonus, not +40%.  Profit margins just got a little thinner, but they will still be better than my normal-soil farm even though I'm using 3 generators for 2 Sunlamps instead of 5 for 4.
...No, wait, they will be identical.  :/

[Thyme]

Oh, forgot to insert the "independent circuit powered by solar". You wouldn't even have to use a switch (1 solar = 1700W).

[Hans Lemurson]

Powering my tree-farms with something other than their own wood?!!!    HERESY.

[Limdood]

just a thought.  It kind of flies in the CONCEPT of the challenge, but might deliver a better result.

Due to the way heat and unroofed mechanics work, it would be possible to set up an outdoor tree farm even with no "growing season."

build a 12x11 room (optionally, add an extra recessed 2x2 area in it for the generator, since they give heat).  set up 25 individual 1x1 growing zones for trees.  Set those 25 squares ONLY to be unroofed.  Build your fueled generator and however many heaters you need in order to keep the room warmed enough for growing.  Since there are only 25 unroofed squares out of 132 (or 136) there will be heat loss, but it won't be locked to the outdoor temp.  You can now save 1600 power on a sunlamp, since you get natural light.  Optionally, make the room as long as necessary to optimize the heat....1 generator can power 5 heaters AND gives off heat on it's own.

[Hans Lemurson]

just a thought.  It kind of flies in the CONCEPT of the challenge, but might deliver a better result.

Due to the way heat and unroofed mechanics work, it would be possible to set up an outdoor tree farm even with no "growing season."

build a 12x11 room (optionally, add an extra recessed 2x2 area in it for the generator, since they give heat).  set up 25 individual 1x1 growing zones for trees.  Set those 25 squares ONLY to be unroofed.  Build your fueled generator and however many heaters you need in order to keep the room warmed enough for growing.  Since there are only 25 unroofed squares out of 132 (or 136) there will be heat loss, but it won't be locked to the outdoor temp.  You can now save 1600 power on a sunlamp, since you get natural light.  Optionally, make the room as long as necessary to optimize the heat....1 generator can power 5 heaters AND gives off heat on it's own.

Hmm...I had heard that small holes in the roof didn't lock you to outside temp, and had considered experimenting with this.  I wasn't sure about the massive heating bill it would entail, but given that you can power 6-7 Heaters continuously for the same Power cost as a "battery-buffered off-at-night Sun lamp", it may just be comparable.

It's a different sort of challenge than generating energy from a closed-loop system, but it presents its own unique puzzles and opportunities.  It also makes me wonder about putting hydroponic tables beneath open sky-lights for farming in all sort of hostile environments.  Depending on the temperatures being dealt with, it could be more energy efficient than sun-lamps, but I wonder whether it could work for gravel-farms on polar ice-sheets or if the heating costs would simply be too extreme.

It would be quite the achievement to create an all wood-powered base in the frozen north, even if it's not self-illuminating.  I wonder how much wood would be required to boot-strap your operation.  I will also need to study the wood efficiency of other heat sources like torches and campfires.  I don't think it will be as powerful as a Fueled Generator + 5-6 Heaters, but this can certainly be tested.

[TheMeInTeam]

I can confirm you can grow potatoes using both campfires and steam vents for heat on ice sheet.

Based on experimentation with tribal ice sheet starts on extreme difficulty, it's not realistic to do so sustainably.  However they plants WILL grow using the partial roof trick.  The problem is less heating cost, and more actually covering so much space for growing such a paltry amount of product.  Still, it's your only real farming option until you get hydroponics + probably geothermal (which can sustain 23 basins + sunlamp + 2 heaters or if that isn't necessary 1 heater and all 24 basins you can get in sunlamp range).

Hydroponic should work similarly, except you will need ~100 tile room to open enough space to use 6 hydroponics basins.  It saves on power but in terms of building materials and space it isn't trivial.

[Hans Lemurson]

Potatoes are good, but can you grow trees fast enough to refuel the fires?

Given that gravel only appears in thin strips around the rocky outcrops, walling them in involves the construction of quite the perimeter.  Expensive in both materials, time, and heat-loss.  Do you know how much heat you lose from exposed rock walls?