I've been reading about forge construction and the different fuels used to heat the metals they were created for. Charcoal seems like a good choice for a "solid" fuel as it will generate intense heat without any smoke (assuming the wood used to make the charcoal is fully carbonized.

The process for making charcoal seems simple enough... Heat wood inside a container vaporizing the organic material yet prevent a burn due to lack of oxygen. What kind of setup do you use? What I'm looking for is efficiency IE: most charcoal for the least cost.

I've seen pictures on the internet of a 55 gallon barrel loaded with scrap wood from construction but it "wastes" or rather uses 1/3 as much wood as what is in the barrel to get the temperature up high enough so that gases released from the wood can be used to finish the carbonization.