After doing a few other projects, I decided to build a Peat Farm in Minecraft / Gregtech 5U. This is actually part of Forestry, not Gregtech, though much of what I do with the products is Gregtech.
I didn’t really need a peat farm. My tree farm supplies a fair amount of renewable energy in the form of charcoal and ethanol, and my oil rig supplies more than enough oil to handle power demand when it climbs above ~600 watts.
What bugged me was that the tree farm isn’t entirely hands-off. For a long time the main problem was excess mulch clogging the chest for saplings, which then backed everything else up. I solved that by doing what I should have done a long time ago - separated the mulch and sapling pipes. Now the carrot farm backs up, so my fruit juice production is very low now. That hurts ethanol production, but doesn’t stop it since I can make ethanol at reduced efficiency with water.
Still, the excess mulch nagged at me, and there was also a problem that the tree farm eats dirt and produces sand. I had to refill it with dirt periodically, and empty out the sand. I generally kept ahead of dirt consumption just through routine mining for ore, but I was slowly depleting my dirt stockpile. The excess sand I turned into sandstone and used for flooring.
Mulch has precious few uses - just fermentation for ethanol, and bog earth for a peat farm. A peat farm turns sand, water, and mulch into peat and dirt. The sand -> dirt conversion is 1:1, so if paired with the tree farm, it’s a closed cycle. The tree farm exhausts all the dirt it gets and turns it into sand eventually, and the peat farm then refreshes all of it back to dirt.
I decided to build the peat farm underground. It’s peat, not vegetables, it doesn’t need the sun. I built a new large boiler to handle the peat output, with an accompanying steam holding tank and set of steam turbines, because the tree farm was supplying more fuel than the existing boiler could use.
The results were… disappointing. The sand -> dirt -> sand cycle works, but the peat farm barely puts a dent in the mulch production. When going full speed, the peat farm could not supply enough fuel to keep the boiler running. Which is a sharp contrast to the tree farm, which is the same size and cost the same to build, yet very much oversupplies a single large boiler.
What’s more, once the initial cycle using my backlog of materials was done, it became clear the tree farm doesn’t really generate sand that quickly. It only produces about enough to keep 20%-25% of the peat farm operating. Since the peat farm’s operating at about 25% capacity, it severely undersupplies the boiler.
I ended up creating a second supply line from the tree farm to the second boiler. The primary boiler still gets as much charcoal as it can handle, but any excess gets routed to the peat farm’s boiler. I added some circuitry so this stops if the second boiler’s fuel chest gets to 50% full, so there’s always room for peat and charcoal won’t crowd it out.
I realized that despite my initial letdown, the primary purpose of the peat farm ends up being to dramatically reduce the maintenance I have to do on the tree farm. The sand -> dirt recycling is worthwhile in itself. That it produces some energy is a side effect, rather than being its primary purpose, which was my initial thought. The second boiler is worthwhile too, because the tree farm is producing more fuel than the first boiler can burn.
I think the new, combined renewable supply is around 1100 watts. I don’t know if that’s infinitely sustainable, or if things will fall off under sustained demand. I need to see how it behaves when I dump a big load of ore into the processing line while simultaneously running the blast furnaces.
Along that line, I’m not sure if the peat farm will pick up if I’m demanding more from the tree farm and maybe producing more sand. So I won’t repurpose the 75% that appears idle just yet.