Its all a matter of your perspective. So what if you ran your chipper with a gasifier? How much fuel do you think it will take for it to fuel itself? In this scenarios you are burning wood to make fuel. When you make charcoal, you are burning wood to make fuel.
Burning wood to run a chipper is way more complex then burning wood in a kiln.
If you use 30 lbs of fuel to produce 80 lbs of fuel do you really get that 80lbs of fuel? Nope, you need to set aside 30 lbs of it for the next time you process fuel. That ratio is pretty realistic after you discard your waste.
Chipping is not straight forward, you generally have process time into prepping the fuel for the chipper. Same goes for charcoal, you have pre process to prepare it for the kiln.
When you are charcoaling think of that heat energy to process to charcoal the same as the fuel it takes to run any processing equipment. When you process for a kiln you generally will process the fuel in much larger chunks and you are really unlimited to what you can process. For instance ever try to chip up a use pallet? It wont fit and it will have nails in the wood. If you cant process waste materials like this than it is really is a waste.
To process for a kiln you do not need big equipment. An electric chain saw, skill saw, chop saw, table saw, and a small splitter is all that is needed. All of this can be ran off of electric from the very power generator you are operating. Even the splitter and all are low power consumption devices. Incorporate your kiln process into a heating application and you have a viable CHP system that produces fuel for itself.
Add in the reliability factor; charcoal systems run very stable and with out tar production. With a direct gasifier you are guaranteed to make tar I promise you this! Its only a matter of when you do. A direct raw fuel stationary gasifier must be automated, there is absolutely no way to overcome grate clogging, hopper bridging, and gas energy density fluctuations 100% with varying fuel inputs without it.
Oh then everyone seems to forget about the water drip system. This is putting energy back for basically free and is a very simple feature to add. With this system, this can boost gas energy density beyond wood gas. We really need to break that myth that wood gas is more powerful than char gas. This is not true at all, a good charcoal unit with a high volume water drip will outperform direct wood gas any day.
Rather than focus on a complex wood gasifier, focus on better charcoal production methods. I have achieved a 50% fuel production ratio with my kiln process and we do use our system for heat. There is no better way IMHO