How to Build a Kelp Farm for Furnace Fuel
Dried kelp blocks are among the best renewable fuels in the game, and kelp farms are fully automatic. Here is the build.
Kelp is one of the quiet workhorses of Minecraft. Smelted and compressed it becomes dried kelp blocks, an excellent furnace fuel that is completely renewable, and the farm to produce it is one of the simplest automatic builds available.
Why dried kelp blocks
Raw kelp is not fuel. The chain is:
- 1.Smelt kelp to get dried kelp.
- 2.Craft 9 dried kelp into a dried kelp block.
Dried kelp blocks burn for a long time — comfortably enough to make them a serious alternative to coal, and unlike coal they never run out. Pair a kelp farm with a furnace array and smelting becomes free forever.
There is a pleasing efficiency here: a kelp farm can produce enough fuel to smelt its own output and still leave a large surplus.
How kelp grows
- Kelp grows upward in water, one block at a time, on random ticks.
- It grows from the top, extending toward the surface.
- Breaking a kelp block destroys everything above it, but the part below survives and keeps growing.
That last property is the whole basis of the farm: break the plant at a fixed height, and the lower section regrows.
The build
- 1.Make a water column. A single column of water source blocks in a 1x1 shaft is enough to start, though wider farms scale better.
- 2.Plant kelp at the bottom.
- 3.Place an observer facing the water column at the height you want to harvest — a few blocks up.
- 4.Put a piston beside it so that firing breaks the kelp at that point.
- 5.Collect the drops. Kelp floats and flows, so a water stream at the top carrying items to a hopper works well.
- 6.Hoppers into a chest.
When kelp grows into the observed block, the observer fires, the piston breaks it, and everything above breaks with it and floats to collection. The stub below regrows.
Scaling it up
Kelp farms tile well. Build a wall of adjacent water columns, each with its own observer and piston, sharing a single collection stream along the top. Because the columns are 1x1, a large farm fits in a surprisingly small footprint.
The main practical limit is item throughput. Kelp produces a lot of drops at once when a tall plant is cut, so make sure your collection stream and hopper line can keep up — otherwise items despawn before reaching the chest.
Automating the smelting
The natural pairing is a furnace array:
- Kelp from the farm feeds the top of the furnaces.
- Bamboo blocks or dried kelp blocks feed the fuel slot. Our bamboo farm guide covers producing bamboo fuel at high volume.
- Output hoppers carry the dried kelp to a chest, or straight into a crafter for blocks.
Set up once, and the system converts kelp into fuel with no further attention.
Other uses for kelp
- Dried kelp is edible. It is not great food — our food guide covers better options — but it eats very quickly, which has its uses.
- Kelp blocks are decorative and work well in underwater builds.
- Kelp placed in water is a useful water elevator marker in some designs, since it fills a column with source blocks.
That last point is genuinely handy: placing kelp down a shaft and then breaking it leaves the column full of water source blocks, which is a quick way to build a water elevator without hauling buckets.
Where to build
Anywhere with water and light. An ocean, a river, or an artificial pool inside a base all work. Kelp needs light to grow, so an enclosed room needs lighting.
Unlike a guardian farm there is no structure requirement and no hostile mobs involved, which makes this one of the safest farms to build early. If you are working through the farms on this site in order of difficulty, kelp and bamboo are the two to start with.