The difference between charcoal and raw fuel direct gasification is with a charcoal system the pyrolysis zone / process is removed and is an external process. This is where TAR is produced and if the conditions are not right in a raw fuel direct system it will bypass the entire system including filters and condense at the engine. One drop of tar in an engine is one drop to many! This tar under vacuum will stay in gas suspension until it hits a positive pressure due point at near ambient temperature. In gas suspension it will bypass most filtration systems as filters can not be restrictive or you lose power. Combustion process in a direct fuel gasifier must sustain 2000* F and no less than 1600* F and do so for more than five minutes to get it on a YouTube video. Any gasifier can do this if dry enough fuel is used don't be deceived by this as the reality is you wont always have dry fuel when you need to run this equipment. "Oh just put good fuel in the machine and it will be fine" No! If it can happen it will and it only takes one instance to create a bad problem.
Here is the deception; in a direct fuel gasifier 30% of your fuel input is lost in process!! This is due to combating chemically bound and natural water in the fuel along with exothermic processing absorbing needed heat for the reduction process. A charcoal system is less than half this especially when water injection reformer technology is employed.