Monday, June 13, 2011

Permaculture Projects: Make your own Charcoal!

Hardwood Charcoal

I recently purchased a new smoker/BBQ, and I have been barbecuing quite a bit as I season the smoker and just practice with it.  This means I have been going through a decent amount of charcoal.  I am hoping to be able to make all of my own charcoal in the future, so I thought I would explain how you can make charcoal at home.  This is a relatively easy project.  If you have access to wood from your own land or from neighbors (e.g. a tree knocked over in a storm) or even access to agricultural waste (as you will see in one of the videos below), then you have the ability to make your own charcoal.

First, some definitions:
Charcoal: This is the dark grey/black carbon-containing remains (usually of trees, but also bone or other organic matter) after all the water has been removed through pyrolysis.
Pyrolysis: Thermochemical decomposition of organic matter at high temperatures in the absence of oxygen.
Lump Charcoal: Charcoal made directly from hardwood.
Briquettes: Charcoal made from sawdust and other wood by-products with a binder (usually starch).

Basic Steps for Making Charcoal:
  • Fill a clean and dry metal can with material that will become your charcoal.
  • Limit the amount of oxygen that can get into the can.
  • Build a fire around that can.
  • Wait 10 minutes to 3 or 4 hours (depends on the material) then let the fire die.
  • Allow the can to cool and the ashes to become cold (usually the next day).
  • Open the can.
  • Charcoal!

It really is basically that simple, but the devil is in the details as they say.  I have seen many ways that this is accomplished.

I'll take each step, one at a time, and show the options available.

Metal Can - This can be any size.  1 gallon paint can to 55 gallon drum or even larger.  Just make sure it is clean and dry.
Wood - Any wood can be used as long as it is not treated with chemicals, stains, or paint.  Make sure it is "seasoned" (i.e. not recently cut wood with a high moisture content.).  You can use unseasoned wood, but it will take a lot longer and use more fire to burn all the extra moisture out of it.
Limiting the Oxygen - This is a crucial step.  One thing to keep in mind is that as charcoal is being made, lots of gasses are being released.  This can quickly build up pressure.  In industrial charcoal production, you can create a safe, completely sealed environment.  For the average person, this means you need to allow the gas to escape without allowing too much oxygen inside.  I have seen many ways to solve this problem: seal the can with the lid and then punch holes in it, put holes in the lower sides of the can, place the can upside down on flat ground, weld a small exhaust pipe to the can, etc.  Just remember that if the hole is too small, the can may explode (or more likely pop the top off).
Build a Fire - Fairly straight forward.  Typically build around the can or under the can.  I have a link below to a pretty ingenious method where the fire is built on top of the can.

That is basically it.

Chicken Satay grilled over a bed of charcoal... mmmm!

Here is the link I mentioned above on making charcoal by Gary Gilmore.

Here are a couple of videos showing a variety of ways to do this.

Fantastic video!  Done by Amy Smith from MIT (yeah... that MIT).
She highlights how to make briquettes using a method she created for developing countries.  Brilliant!

Vey informative.  Sorry about the weird marketing text about halfway through.

Another innovative method by the Eco Redneck.


3 comments:

  1. Here's a great use for your homemade charcoal

    http://www.waldeneffect.org/blog/DIY_blacksmithing_and_knife-making/

    ReplyDelete
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    Pyrolysis Plants

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