New to Gasification - Where to start?

Hi everybody, I’m new to wood gas and feel like I’m spinning in circles. I’m hoping someone can point me in the right direction. Wow, what a great forum. So much information. I think I’m in the right place.

I’d like to build a wood gasifier to power 10 hp to 18 hp generators. The basic solution is to use this to charge a solar battery bank on grey days throughout the year. A successful system would produce reliable clean gas and this would save a lot of propane per year. I thinking a chunk wood system apposed to a charcoal system because I have a huge supply of soft woods (Balsam fir, spruce, red pine, etc). If it made sense, I can buy large quantities of hard woods (Birch, maple, etc).

For a bit I was considering building the FEMA system. then soon understood that these systems create a lot of tar. I was wondering if the tar production was just because the FEMA may not have a good filtering system and maybe that could be remedied. I also looked at purchasing some other books like the WG Builders Bible and Steve’s plans on offgrid48. If its the best way to go I’m interested in purchasing plans. I just dont want to have to purchase them all to figure out which is best for my needs.

I’m just confused on which system to pursue that would be best for my needs. Your suggestions are greatly appreciated. Thanks in advance, Joe


Welcome to the forum!

How many CCs is the 18hp engine?

The Builder’s Bible is a really good book to have, and many have built that design to great success. It’s best running minimum engine size is a 500cc, but people have made it work for the 420cc Honda clone engines.

I’d steer away from Offgrid48’s design, it is a flat out cheap imitation of Ben Peterson’s design with poor modifications like silicone hose in places that can get hotter than 300°F.

It’s good that you’ve done a little initial research, the FEMA would have given you a lot of heartache.


Before you shoot down charcoal, you should actually try making it first. Making both fuels first. Keep in mind your wood fuel must be as dry as possible with small engine gasifcation. How do you plan to chunk the fuel do you have a chunking machine or plan to make one?

Another thing is you will not get the stability you get with a charcoal system. A wood gasifeir is not a free flowing reactor versus a chacoal reactor is. Tar can not be filtered you can not filter a gas out of a gas unless done at a high level and this is not practical for engine fueling. It would be too restrictive. Some tar grades will not even drop under vacuum, tar is not filtered it is condensed out.

I would recommend starting with charcoal simply because they are incredibly easy to make and there are easy methods to produce it. Start here and then if you want to try wood fuel then build it. Ive done both and I find charcoal is more viable and easier. The small engines under `1000 cc it gets more dificult to woodgas and 500cc is really the limit. That is the limit and just because you can does not mean you should. With all the dificulties involved keeping a wood gasifier running its just not worth all that fiddling around.


Here is my new DIY charocal retort solution. However this is just one method of many others that you can persue.


Hey Joe , Welcome , i am doing and have been doing exactly what your wanting to do since 2012 , at this moment in time i only run charcoal for making power and topping up my batteries on cloudy over cast days , no need to over complicate a system if its just for stationary power its a start and forget system ,( well for 4 hours at a time approx ).
Have a pop along to YouTube and Look for Gary Gilmores "Simple fire " and then go have a look at Matts systems you wont go far wrong and they are quick and affordable to make .


Thanks Cody. I have 3 gennies. The larges is 457 cc, smallest is 120 cc. I’d like to run all of them. But its not a deal killer. Thanks for you advice. It really helps. Joe


Sounds like good advice Matt. I don’t have my mind made up to any set process yet, so glad to hear your advice. If I was to start off with a charcoal device, what plans or guidelines would you suggest.

I do have a rudimentary chainsaw chunking system. Long term would require a better system.

Oh and I do like your retort system.
Thanks, Joe


I’d lean towards a charcoal gasifier for those engines. Once you have a fuel processing system down either direction is simple. Plus with charcoal you only have a risk of tar if you didn’t convert the wood all the way.


Thanks Dave, I’m heading to YT now.


Start with the Simple Fire unless Krisjan, Cody, Bob and a few others can chime in and aid you with a downdraft version.

My version is not DIY friendly, however I do have the Ammo box tutorials. But I do not recomend to build that as is from video. Use the concepts I show but for a real usable system it will need to be bigger and built more robust. That ammo can build is for SHTF emergencies and longevity will be limited.


I 2 nd a Simple fire , with a flute nozzle and a large enough container to run for 4 hours at a time .


I cast a vote in favor of the SimpleFire motion.


YEA. Thanks Cody, Matt, Dave, Steve. I viewed Gary’s Youtube. Yea I was making things more complicated than needed. I tend to do that a bit.

I need to get my mind around all this and then I’ll keep you all posted when I get started. I’m sure I’ll have a lot of Qs.
Thx, Joe


Perfect!! You belong here!

Here is the playlist for my unit.


Hey Joe , if you go to the magnifying glass at the top of the page and copy paste this in (Nozzles for Charcoal gasifiers, part 2 ) you will see not only new methods of making nozzle’s for the simple fire but also a few other builds as well below the link .


Yes there is also the updated version of the nozzle you will need for the SHTF Ammo Box build I posted there as well. That can work on any charcoal gasifier as well.


Thanks guys. I’m gonna check all this out.

How do I get to Gary’s “files”? He mentions it is under the “Forum” tab. Can’t seem to find it.

Thanks again and kind regards, Joe


Hi Joeb
Welcome to the DOW.
For the engine sizes you have said you currently do have in Response #5 and say you are currently fueling with propane in your first post . . .
Then do gasify these on charcoal. Take these guys experienced advices.

Here is the rub about wood charcoal . . . they mean pre-made wood charcoal. You can only pre-make wood charcoal that can be handled, sorted size graded, and then stored out of true hardwoods. Only true hardwoods will make the wood chars that can take this kind of handling roughness.
Conifer woods as in your balsam fir, spruce, red pine make soft will crumble to black char dust chars. Of course excepting conifer large hard knots, 100 year tight-rings limb sections, stump roots and such. Who has sustainable quanitiles of these, eh.

Now I figure you are probably pretty adept at wood stoving heating with your conifer woods.
These “Eastern” boys often have the luxury of picking and their fuel woods speices. Living in mixed species areas
Almost all of the daily woodgas vehicle drivers will quit on pines, spruces and go to their own local hardwoods. Soots up (actually char-dusts) thier particle separators, cooling tubes and filters much less.

You want make electricity with your conifer woods then DO Use the Ben Peterson Book system. Built by the book. BenP was born and raised out here far west in Douglas Fir land.
His system proofed on these woods. His exprences over 12 years developing for conifer woods is where the DO USE at least a 500cc engine generator advice originates. Better yet 700-1000cc engine systems. These are 20-30 hp rated on gasoline. ~15-20% less on propane. ~30-50 less on raw wood or charcoal.
Those taking this advices have had raw woods using success for generating electricity.

Open up Dean Lasko’s topic here on the DOW titled Newbie from Canada to see this.
Go to the newest engine advices on the topic Engines to Woodgas Run from post #130 for the latest use, and advices on using the larger IC engine driven inverter-generators.
As Dave in Australia uses these (on charcoal) then it cuts the ties from having to build design for rigid engine RPM or even engine power.

Just like your woodstoveing energy release output on a raw wood gasifier will vary quite a bit cold starting up through a hopper load to the ending. Ha! Just like daily PV solar.

Ignore offgrids48’s system and information. He has yet gotten the hard experiences actually long term using an IC electric generator on his tweeked systems. Even after years now encouraging him to do the full developing. He cannot meaningful help on this 1/3 the systems for using wood to make electricity. 1/3rd being the fuel prepping.making - where is his information on methods for that? 1/3rd being the actual IC engine generators

And my expeernces says larger air cooled electrical generator systems output heats along with the gassers down stream shed heat can dry as-cut conifir woods down fit to use. Conifer woods dry much faster than hardwoods.

Steve unruh


Thanks Steve, More to think about. I’m really liking the simplicity of the charcoal systems. I do have access to hardwoods. Birch, maple, alder. I may even be able to get oak. I may wanna try this first. I appreciate the comparison and advice.
Regards, Joe