Thrive Energy released their gasifier system as an open source project. Their design uses small (US typical) sized wood pellets and was originally designed and is used for small generators and engines 400-700cc. It has long run times, tar free operation and the grateless design avoids numerous issues common with gasifiers. The video was just posted on assembly of a no-weld kit that is for sale that contains all the hard to make (if you don't have a metal shop), parts.
I have followed wood gas for years, and this is a pretty neat simple system especially for off-grid and you don't want to mess around with wood prep. I am looking at getting one for a ceramic kiln, and a foundry as well as backup generation.
I wasn't sure =which= topic to post it under. I thought I saw other wood gasifiers in this topic. FM please move if it is the wrong area!
It definitely fits a niche where you don't have the time or equipment to do the wood prep, and/or want long unattended run times. You could do a pellet mill as well, but you don't have to get started. You can run it in your backyard in town without drawing much attention.
It does not seem to have nozzles so its a fema type design but I could be wrong. No radiator or filtering either so you would have to build those for engine use. Fema types are prone to tar making unless run at continuous output like say a fan for heating purposes. If your main purpose is a kiln then fine but I would want to see some longer run times before id hook it up to a generator. Smaller wood units are tricky. Using a processed fuel like pellets does save a lot of the headaches though. I found charcoal gasifiers to be more suitable for small engine use. I consider gasifiers to be biogas since they use biomass break it down with heat and release a flammable gas.
I want a system where I can feed it 15" diameter logs once a day, not a system where I would have to chip or pelletize the wood before use, or have to feed it frequently. To me it looks like the systems with the least labor use either thermoelectric generators (Devilwatt makes 100 watt ones) or home-built stirling engines cranking a generator. If I have to turn wood into chunks, pellets, or chips, then it is too labor intensive to be worth it. Convenience is more valuable to me than efficiency.