Tutorial:Chunk loader
A chunk loader is a contraption that keeps a given chunk or area of chunks loaded, regardless of where the player's location in the world or their dimension.
How to load a chunk
If you want a chunk to be loaded, you can either load it yourself (by keeping it inside your rendered area), or build a chunk loader.
Nether portal chunk loading
The usual way to load chunks is to use nether portals. Every time any entity goes through the portal, it fully loads the chunk on the other side for 15 seconds, as well as 8 chunks around that chunk. If entities continue to go through a portal every 15 seconds, you can ensure that both sides of the nether portal are loaded indefinitely. The usual way to do this is to loop an item back and forth every 15 seconds or less. Note that this loads the both sides of the portal, both the nether and overworld side. This video, made by xisumavoid, showcases a simple chunk loader based on this idea, which uses item entities as the dummy entity to load chunks.
The contraption uses following items and blocks:
- 10 pieces of
redstone dust, - 6
redstone comparators, - 2
redstone repeaters, - 6
droppers, - 2
redstone torches, - 2
hoppers, - 20 pieces of
obsidian, - 10 pieces of
glass, - 22 general building blocks, like wool or cobblestone,
- a button,
- 18 stacks of any item to fill up the self-fixing mechanism.
An alternative nether portal chunk loader is shown in this video, made and designed by _darkvictor_. This chunk loader uses minecarts as the dummy entity instead, which makes for a much simpler design.
Since update 1.21.2, entities have a lower cooldown for going through nether portals, down from 15 seconds to 0.5 seconds. This means the dummy minecart used as an entity in the chunk loader no longer has to be dismantled (converted to an item) in order to go back through the portal quickly enough. (This was in the past, and in the design by _darkvictor_ explained above, used to replace the minecart with a different entity, effectively removing the cooldown) We no longer have to do this in chunk loader designs, and instead all that is needed for a chunk loader in recent versions of the game is to loop a minecart back and forth on a rail.
In Minecraft versions before update 1.21.5, nether portal chunk loaders tend to stop loading their chunks when the world is exited, and have to be restarted. That was changed in update 1.21.5, and nether portal chunk loaders do not have to be restarted anymore, since chunks loaded by nether portal chunk loaders will not be re-loaded when the world is reopened.
Ender pearl chunk loaders
Ender pearls can also be used to load chunks. Because ender pearls interact with bubble columns, a simple contraption known as stasis chamber can prevent the pearl from landing indefinitely. Any ender pearl, or one that is in a stasis chamber, fully loads the chunk it is currently in, and lazy loads the 8 chunks around it, which is a smaller area than nether portals which fully load a 3x3 area centered on the portal and lazy load the 16 chunks around that area. This can be easily used to load chunks in Overworld and End. In the Nether, where bubble columns using water can't exist, different methods of holding an ender pearl in stasis have to be used.
It should also be noted that pearl-based chunk loaders behave differently than portal-based, because all ender pearls are tied to the player that threw them, and they vanish from the world when the player logs out, stopping all chunk loading. However, when the player logs back in, all pearls reappear and self-load themselves, restarting the chunk loading. Another thing to keep in mind is the fact that all ender pearls tied to a player vanish when that player dies (default behavior, can be changed with /gamerule enderPearlsVanishOnDeath).
Alternative methods
The end portal loads chunks in the same way as nether portals, although because the loaded area consists only of 9 chunks around the obsidian platform in the End, this method can't be used to chunkload any areas in outer End islands. To chunkload in the outer End islands, instead use ender pearl chunk loading or End gateway loading.
End gateways can be used to load chunks in the outer End islands. When an item goes through an End gateway, it will fully load the 3x3 chunk area on the other side of the gateway for 15 seconds, as nether portal chunk loaders do. Although, this is limited to the area around an End gateway. Use ender pearl chunk loading for more flexibility.
For worlds with cheats enabled, the /forceload command can be used to keep any given chunk loaded.
What does this accomplish
Some events can happen in chunks loaded by these contraptions, allowing some farms to work, even when you're far away or in a different dimension. These farms are mostly based on mob AI: iron farms, chicken farms, wither-powered blast chambers, and more.
Other events that happen in these chunks:
- furnaces will smelt items,
- villagers will restock trades,
- piglins will barter gold,
- any redstone clock will keep ticking, etc.
However, farms based on random ticks will not work even with a chunk loader, as they require a player to be nearby. These include: gold farms, plant farms (e.g. sugar cane farms), lava farms, and more.
Another type of farms that require players to be nearby are farms spawning hostile mobs. Chunkloading them doesn't do anything either.
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