so i just learned that people make charcoal by putting wood in some container with little oxygen and build a fire around it. but why not just burn the wood directly, and take the leftovers?
im guessing some of the wood burns away if you aren’t using a container, so it’s less efficient, but if you’re in a forest with limitless wood it doesn’t really seem to be worth the effort when you can easily just create a bigger fire. another reason i can guess is that the charcoal you get from using a container is higher quality. if that is the case, why does it produce higher quality charcoal, and what does it mean for charcoal to be higher quality?
In: Chemistry
When you heat wood to very high temperatures without allowing it to burn, it becomes very dry.
Fire needs an oxidiser to happen, so by depriving the wood of oxygen, you don’t allow it to burn whilst still getting it to hundreds of degrees.
When wood burns, as well as drying out, the organic hydrocarbons such as celluose react with the oxygen in the air to form water and carbon dioxide, releasing lots of energy to continue the process.
To try and burn already burnt wood would be useless, as all the compounds in the wood that burn have been burnt.
How much charcoal do you need? Collecting wood is a chore, so collecting ten times as much wood is ten times as much of a chore. In addition, charcoal left after a fire is kind of hard to come by – it will naturally burn away almost all decent coals unless you extinguish it manually. Doing this to try and maximize your charcoal yield will probably produce a lot of incomplete product – partially charred wood.
The purpose of the low oxygen environment is to prevent the flames from really burning well. The main goal is to dry out the wood and burn off certain types of chemicals, not to actually burn it entirely. A slow, weak fire does that pretty well, and is easy to build.
Things only burn once. Leftover, remains of burnt wood is mostly burned, so it might ignite again but won’t last long. The weak flame will do a poor job burning, but a decent job drying out and all that.
The main component of wood that burns actually needs to get pretty hot. Think about the amount of kindling, etc required to get wood burning properly. Charcoal is the good stuff, left behind when the annoying stuff is cleaned out.
When you’re in the wood, you’re not really looking to make a lot of charcoal for the purpose of storage. Because, like you said, you can add more wood to the fire.
However, for the purpose of commercialization, charcoal in a kiln yields more high quality charcoal while retaining a lot of the mass.
Charcoal is energy dense, and can burn for longer than a piece of wood of the same size. But if you’re burning wood to make a smaller piece of charcoal, there’s no point.
However, if you’re turning wood into charcoal while retaining most of its weight, you have a better material for burning.
The process of making charcoal with little oxygen is called carbonization.
Once you have burned wood, you cannot “reburn” it. It is ash, and there is nothing combustible left to relight.
Charcoal is wood that has been heated beyond the burning point in a low oxygen environment so that it “carbonizes”. It leaves you with something that still contains all the combustible stuff, but none of the stuff that makes that combustion less efficient.
As for “higher quality”, that has to do with the manner in which it is created. You will sometimes find bits of the charcoal you buy is not fully carbonized. The less of that in the bag you buy, the better it is. Also, bigger chunks are deemed by some to be “better”.
Wood has a lot of volatiles inside of it. Charcoal is the process of superheating the wood to get volatile gases to burn off and moisture to leave without burning the carbon. In the case of the coal left from a normal fire, there will be lots of leftover junk still in the wood that didn’t cook off so the fire from made with those coals will be dirtier. When charcoal burns it is much cleaner as the only thing burning is the leftover carbon of the wood and non of the “other stuff” that was in the original wood
charcoal burns very little smoke, so it is useful for indoor applications
charcoal also burns hotter than wood, especially with a bellows or other airflow, which gets your fire hot enough to smelt ores, and melt metals and glass
If you just burn wood, you’re mostly making hot air and ash.
Charcoal is what’s left over after incomplete combustion.
So if you want to deliberately make a lot of charcoal, you have to get hot enough to burn without actually burning most of it (i.e. without oxygen)
It’s the same stuff. The big difference is burning it in a retort style container will let you finish with a known amount of charcoal with very little ash in it.
Also cause fires would usually just burn through the charcoal as it’s making it so you’d get very little after in that method.
But if you light a big fire, wait for it to go mostly to coals then throw it in an airtight container it’ll snuff out and you’ll be left with all the charcoal still. Some people use this method cause you need no new equipment like a retort.
You’re basically taking wood and kickstarting the combustion process. You’re also taking little scraps of wood that would otherwise be useless and condensing them into usable fuel.
Charcoal making was a common thing for otherwise unemployed peasants to do in medieval Europe. You gather up a bunch of sticks from the forest and turn it into something that people can use.
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