Hi Tom,
For preppers the type i build might be of interest.
The offgrid pro and the Troy Martz gasifier are based on this concept.
All these gasifiers work, but it is nearly impossible to make a living with a gasifier as product to sell.
The level of charcoal, maintained at a minimum height, serves the purpose of cooling the hot gas.
In my case simple pvc can do the job.
Have a look at it, its easy to build, easy to understand and a lot of cheap fun with it.
To be complete; it is based on the work from Gary Gillmore and became very workable with the valued input of the members on DOW.
I live and work in Thailand, teaching and helping with this concept to help others