Making Charcoal at Home
Charcoal making at home.
Charcoal has many uses from medicinal, water filtration, soil enrichment, and even powering an engine. Here are instructions to make charcoal with a double barrel retort. Once the principles of a charcoal retort are understood charcoal can be made from soup cans to 55 gallon drums or even larger.
- 2 steel 55 gallon drums- It is easiest if one of them has an open top with lid.
- Woody biomass- old pallets, tree trimmings, dirty firewood
- 2 pieces of angle iron or steel rod
- Hammer and chisel or saws-all
- Drill with drill bit between 3/8” or 3/4”
- 3 Bricks for the base
- Heavy object to hold the top down
Drill holes in the bottom of the bottom barrel. Drill about sixty holes that are 3/8” to half inch in diameter (3/4” would work also) into the bottom of the barrel evenly spaced.
More holes are better but just make sure the integrity will not be compromised after a few burns and corrosion takes place. Use the most solid barrel for the bottom to increase the life of the system.
Cut the bottom out of the top barrel. The barrel should be a tube without ends when done.
Go around the bottom edge of the bottom with the saws-all. The sharp end of the chisel and a hammer will also work.
Take the gasket out of one lid using a screwdriver. This lid will be used to seal the bottom barrel when the burn is done.
Place the bottom barrel where the burn will take place. Put three bricks or other rocks to support the bottom barrel off the ground. Make sure there is clearance for air to get into the bottom holes during the burn and make sure the bottom barrel is level and stable.
Fill the bottom barrel to the top with biomass. Make sure to throw the blocks in there loosely. If they are stacked neatly it will stop the air from getting around each block. Using small tree branches and brush also works. If using branches make sure the barrel is tightly packed and use tree shears to lop the branches to length.
I have not tried a barrel of pure wood chips but I do not think it would work well due to the tight packing of the chips. I have heard of people using wood chips by putting them on top of a barrel of larger pieces and letting them filter into the barrel.
Make sure that the biomass is uniform in size. If using 2×4 boards try to fill the barrel with them. If using 4×4 blocks try to fill the barrel with them. Some size disparity is fine but if using mostly 1X4 boards and then one 4×4 board, there may not be complete conversion of the 4×4.
Start a fire at the top of the bottom barrel. Make sure the fire is going well and is self-sustaining.
I will typically use a hatchet to split one of the blocks into slivers and then rip some pages from an old phone book to start the fire.
Put the angle iron or barrel support on the top of the bottom barrel. Place the top barrel on the angle iron so it is level.
Wadded up paper may be dropped down the top barrel to fuel the fire and to increase the draft.
Note the time and grab a beer. The burn takes about an hour to hour and a half for the complete burn. I typically mow the back yard as I am making a batch of charcoal. Sometime the exhaust may get a little smokey. If this happens and does not correct itself move the top barrel a little to the side to allow more air into the top barrel. Scrap wood or other yard debris can be thrown in the top barrel to create more charcoal fines. Use the glowing on the outside of the barrel to tell how far the burn is progressing or look inside to gauge the progress.
Once the burn has progressed to the bottom remove the top barrel. Use a long sturdy stick or some thick insulated grilling gloves to remove the top barrel. The bottom barrel should be anywhere from 1/4 to a 1/3 full.
I typically leave the top barrel off for 5 minutes or so and stir the bottom barrel. If the flames coming off are a clear to blue color I slide the bricks out of the bottom and let the barrel rest on the ground. I pile a little dirt around the edge to make sure it is sealed. I then place the lid on the top of the barrel and place a couple cinder blocks on top to hold it down. The goal is to have enough weight to flatten out the lid to form a better seal. Place a barrel lid clamp on the barrel if one is available but it is not necessary. Some have used a 1/4″ plate of steal with weight to seal the barrel. Some smoke will come out but it should stop after a while due to the barrel cooling and the condensate/charcoal fine mixture sealing the holes. If there is smoke coming out of the bottom pack the dirt around the area. I typically wait 24 to 48 hours and feel the outside of the barrel before opening. Hot charcoal can still be on the inside due to the highly insulative properties of charcoal. The longer the charcoal can sit before opening the better.
There are many ways to process the charcoal and it depends on the use of the charcoal. My main use of the charcoal is to run an engine through a process known as gasification. For my purpose the charcoal should be between 1/4” and 2” diameter. I use wire mesh to screen and remove the fines. The fines are collected on a tarp below the wire mesh. The larger pieces are checked for brown spots or hard spots which indicate not fully converted wood. The partially converted pieces I save and use to start the next batch. If you cannot easily break a piece of charcoal with your bare hands it is probably not fully converted. Once the charcoal is screened I run it through a home-made grinder and add it to the gasifier or to my storage barrels.
The fines are collected and added into the compost pile or spread directly on the garden. Dry charcoal can ignite very easily so be careful where it is stored. If the charcoal will not be used for a gasifier, feel free to douse it with water before processing. This will greatly reduce the amount of dust and fines during processing. Ensure the wind is at your back and it is preferred if you wear some sort of respirator or mask. If the charcoal is for a soil additive or compost pile, dump it on a tarp and stomp on it until it is the appropriate size. If pallet wood or junk construction wood is used there will be nails in the charcoal. This is not a large concern for me but I will typically use a large magnet to get most of the nails out of the charcoal. I do not have an issue with a few nails in my compost.
Clean up the area and put the barrels away. Put the bottom barrel back onto the bricks to prevent rusting. I put the top barrel on top of cinder blocks next to the bottom barrel so it does not collect water. Filling the bottom barrel with biomass can save time later. Just make sure to put the lid over it to prevent rain from getting in. I store the charcoal in a mix of 55 gallon steel and plastic open top drums. I also use garbage cans similar to the “Brute” or “Rubbermaid” variety and they have held up well for the last 2 years.
If you would like more information on this process you can look up more information on TLUD (Top Lit UpDraft), double barrel retort, or http://youtu.be/XiFHXg9o2wo to watch the first video in a series of a friend who makes charcoal with a similar method. I have changed from the air holes on the side to air holes on the bottom and it is much easier to seal the barrel.
I have not mentioned many safety concerns and dangerous aspects of this because there is no way I can keep everyone safe from every possible scenario. Personal Protection Equipment is highly encouraged and thinking through each step before doing it will help immensely.s