I have recently been experimenting with some simple charcoal making in an oil drum. I did a couple of demonstrations a few weeks ago for first a Biodiversity day and second the Slow Food “Munch at the Manch” events at the Manch Forestry project, near Dunmanway.
Charcoal will potentially play an important role in the post-oil world, with many important uses including for use on a blacksmith’s forge-i it burns much hotter than wood; I have read that it can even reach welding temperatures.
The oil drum method is quite simple- in this case I am using an old honey barrel which has a clamp lid. Punture the bottom of the drum with a pick -axe, making a few holes so as to allow air to be drawn from the base upwards. Stand the drum on three blocks. Light a fire in the bottom of the drum and as it catches, begin filling the whole drum with logs- 8-10 inces long and 4-5 inches in diameter is ideal. Place them so they sit in fairly snuggly but no need to pack really tight. Once the drum is full allow the fire to burn for a while until it is hot enough for your spit to sizzle on the side of the drum. At this point, place the lid on loosely leaving a gap and pack earth and sods around the base of the drum leaving just a 4″ gap for air to pass. Burn for about 5 hours- expect lots of smoke! It is important to do the whole operation well away from people or places that might not want to disappear in clouds of smoke.
After ta few hours you can see the smoke lessen and turn a thin bluish colour- this means that the water vapor will have burned off. At this point, close off the last of the air gap at the base with earth and sods and seal the lid tightly- it is crucial to completely seal it so no smoke escapes else you may end up with just a load of ash. Leave to cool overnight or for a few hours. If successful, the drum should be about a third full of charcoal when you come to open it.
Once you have tasted food barbecued on home-made charcoal, you will never go back to imported stuff. There is also a business opportunity here for wood-owners, as the current price of charcoal is up to 10 times the price of the wood. This makes charcoal one of the most significant incomes potentially to make a woodland financially viable, using small-diameter timber.
Improvements of efficiency can be achieved using retort kilns
Other products such as creosote can be made sing similar processes. It is also possible to collect the resulting wood-gas and use it as a fuel for generators or vehicles as was common in the first half of the 20th Century