Below are links to some very important woodgas files.
Even though I do not suggest building a FEMA style gasifier the information is very relevant to woodgas. the document is well illustrated and is pretty easy understand. I shy away from building a FEMA unit because it is overly simplified and while it does make woodgas, it has a propensity to produce tarry woodgas, much more than a imbert style.
FEMA Woodgas Generator
The United Nations Food and Agriculture Department produced the FOA 72 document. It is considered one of the better sources of woodgas information. I have used some of the information in this document in the basic design of my system. The diagram and corresponding information table (3.2 and 3.3) found in this document is for woodchips. Also take note that the measurement line for the dimension dt in figure 3.2 only measure the size of the restriction opening it is not a pipe extending half way to hnt. I made this mistake twice, no three times before I figured it out.
The World Bank commissioned the writing of the technical paper 296. It has a lot of information on woodgas.
World Bank Technical Paper 296
The Dasifier is a woodgas design that uses woodgas as the fuel source. It is an updraft / down draft hybrid. It can be used to smelter aluminum, copper, silver and gold. The file is in Microsoft word format (.doc) but opens well in other word processors like open office.
This is a very simple generator, for a 12v system. While in this example the motor is running on gasoline, we have been successful in running small engines on woodgas. Nothing like being able to charge the batteries on a solar or pv system