First Gasifier - Stationary Generator Power

I’m new to the forum here and I’m getting ready to start on my first gasifier. This project will (hopefully) turn out as both functional and educational, so that I can progress toward building a woodgas powered vehicle. I’ve got the basic plan for what I want for a vehicle already thought up, though I can guarantee it’s not one anybody else has done, and it may not end up being viable, though that is a bridge I’ll get around to burning later. For now I’m setting my sights on a gasifier to power a small engine to turn a generator. I’ve been reading, watching, and learning as much as I could over the last few years in an on and off approach. It’s been so long since I first learned about the principle of a gasifier that I can’t even remember where I first found out about it.

My reason for starting with a small engine gasifier is that I’ve got a large portion of the necessary materials (scrap) already on hand, so it is a great way to cut my teeth without having to invest a lot more than time. As I said above, I’ve been researching them for a while now, but most of the information i have found has been one directional, meaning that I have been able to see what people are putting out there, but I’m unable to dig in and ask questions and get answers about the specifics. This has been the first forum I have found pertaining to gasifiers that has had more than one or two posts over a two year time span.

I come from a background of designing things built from steel, and breaking that design down so that every piece is pre-engineered and designed prior to fabrication. because of this it is hard for me to just jump in and start cutting and welding, because i’ve already got a ton of questions before I’m really started. I’ve been searching for a place where I can post my thoughts and get feedback and maybe a little guidance from the members. I’ve read the information about the site here, and I understand the concept that much of the knowledge here has been learned at the cost of the owner and is not open source. Since I am currently an unpaid member I hope that my questions don’t infringe on policies here, and if they do, I’ll refrain until a time when I am a legitimate supporter. I understand and expect that my build will require adjustments and tweaking as I go, though I have hopes that I can avoid some pitfalls through communication with others. For now, onward with my plans:

I had planned on a build that loosely resembled the FEMA gasifier, though with some additions and changes: It seems that many builds now employ a cyclone style filter followed by a replaceable filter media filter (wood shavings?). I was also thinking that a radiator / fuel cooler would be beneficial, and not difficult to add. i have a lot of questions, such as: location and requirements for an electric blower, intake manifold / carburetor modifications, and a lot more that are escaping me at the moment, but i’m planning on working through my build one stage at a time and handling my issues as they arise. As far as broad strokes go, this is where I am:

Available Fuel: Various species of hardwood: ash, beech, maple, oak; processed by a Wallenstein BX42 chipper.
Engine: Wisconsin-Robin EY21 618cc flat twin (16HP @ 1800RPM) I believe the engine actually may turn 3600RPM, but has a 2:1 gear reduction final drive
Target generator: To be purchased after gasifier and engine completion. ideally the harbor freight 7200w belt driven generator head for $300, but if it turns out to be too aggressive of a choice I will source a smaller unit.
Materials: Various salvaged compressor tanks, hydraulic tank, forced hot air furnace heat exchanger, various new, used, and surplus steel plate, pipe, and structural shapes.
Equipment: MIG, TIG, stick welders, plasma cutter, oxy acetylene torch, mill/drill, lathe, sandblaster, assorted air and hand tools.

I hope to have a rough start on a drawing for the gasifier / reactor unit soon, though my “soon” could be days or weeks, based on what else comes up. Until then I welcome any comments or advice.

welcome to the site… don’t build a FEMA

Welcome to the site. Here’s some initial feedback… FEMA is not the best choice, as it’s a tar maker. Others will chime in on that. [EDIT: Looks like Arvid beat me to it!] If you’re looking for quick and easy gasifier experience, go with Gary Gilmore’s simple fire. You’ll have to make some charcoal to run it, but you won’t tar the engine up, and your material/labor investment will be next to none. It will do quite well for the small engine you’re looking at.

Once you’ve had your fun and are ready to get serious, there’s several good designs out there to copy. Or if you’re doing your own design, there are hearth dimensions to follow. But I’d highly recommend building something that works first, and then using your operator experience to feed back into what you’d like to improve.

Some good designs can be found on this page:

Hello Mark B. My second build was a FEMA type. These are very simple and fast to build but also they are very tricky to run clean. Any oxygen that gets below the grate, through the burn tube or from air leaks in the main drum, will turn the unit red hot. If they are over worked they will make heat if they are under worked they
will make tar. They have a narrow working band. I would not use one the run a I.C. engine but they do make
a nice flare and are easy to build.

Since you are interested in going with a belt drive, may I recommend using a DC alternator or multiple alternators. You can easily achieve 5 kW with the high out put alternators available today. If you need more you can then achieve this via your battery bank with the proper inverter. This will have some advantages over an AC system. One is, AC systems need consistent RPM’s as opposed to a DC system that does not require this. This allows for any inconsistencies in your gas volume and volatility. Also you can get away with getting more out of your selected engines HP because you will not be limited to the HP range at a fixed RPM. So you will basically be able to run at higher rpms to yield more power out of your engine. Another advantage is, if you have a decent battery bank some of the power loading will get absorbed through the batteries. To add to this if you select a pure sign inverter you can then plug whatever you want into them. This is not the case for an AC generator as they can make your more delicate electronics let some smoke out.

Also because you are running the belt you will be already set up to use a golf cart starter for your engine. You are going to want this in your design.

Yeah build any thing but a FEMA to run an engine.

Welcome to the Small Engine Users Corner of the DOW MarkB.
This is an open to all area.
Do not be afraid to ask/talk about any design here. Those with proprietary works will just be silent about that but still remain helpful on yours.
The actual WK design has yet to be Minified, built and proven engine ran yet. Those wanting to go that direction will be told to buy into Mr Waynes vehicle system book Premium membership and their WK-mini projects discussions will be moved over onto the Premuim side Projects sections for feed back from the real actual using experienced KW system users.

Very good detailed intro post.
You want to whole wood chipped fuel run.
So . . . . I went thorough all of the small system builder/users here using this kind if fuel and had difficulty anymore narrowing down to direct you to just 2-3 builder/designers projects. Ha! This very good.
I’ll give you this challenge.
Read through all of the gasifier project posts questions, answers and explainations here in the Small Egine Users Corner and Gary Gillmores Charcoal Gasifiers sub-forum here also.
I’ll bet you cannot come up with a single queastion that has not been answered and explained that I can direct link you too.
Hmmm. What to bet though? A more detailed explanation from SteveU ?? Ha! Pretty cheap bet man. Secret detailed photos of my own system? In my photo album here. $20 bucks? US? CND? Monopoly money?

A few things to help you get started:
Read this specifically about small gasifers for chipped fuel woods - the MicroGasifier download. Read once. Read twice. Then read again. Now Dutch John clearly says here on the DOW that small gasifier systems are HARDER to small engine operate versus larger vehicle sized gasifer systems.
I’ll say YES to that also!
You will not believe this until you have experienced it first hand.
Gasifier systems do not scale well. Have to experience this to know this too.
Same with FEMA’s. Only once you experience just how narrow range tweeky they are most simplt refuse to believe.
So anymore I’m saying: FEMA? go for it. Anything, anymore to get a fellow off of park to DOing. Heated woodchips in a paint can even anymore.
But . . . with these road markers.
Screw right past flare/staring time wasting and go directly into loaded engine running. Only an IC engine will tell you what an IC engine wants.
Just use cheap thrown away push lawn mowers for this.
Then develop ALL systems simaltanousely. Hearth. Particulate removal. Gas cooling. Filtering. Engine mixing. Expect to destroy one or two cheap lawn mowers just getting to know what IS important to know and then focus concentrate on. This will save much time and effort.
I learned well by destroying two old Tecumseh’s myself. This will have you up and running for real that good Wisconsin-Robin in less than three months of root-hog, gitter’done. Slower go would be 6 months tops. This is the proven pace of the real DOers.

Or, if you want to hobby/idealize this project into years to get up to loaded engine runnig . . . you will still be welcome here also.
Just have a different set of respondents for your project.

Steve Unruh

Thanks for the fast replies everyone. This is what I’ve been looking for - so far I’ve only been able to digest what people want me to see, unable to get any questions answered.

Chris: Thanks for the advice on lower tar producing alternatives. I think for now I’m going to skip the charcoal fired gasifier. If possible, my plan is to build unit(s) that will run off the byproduct of my equipment (wood chips). Though if I have the urge to get a functioning gasifier quick, I may explore that avenue. I had come across the GEK site previously and looked into their open source plans. At the time I sort of dismissed the design, only because the components were more complex in structure and I already had a lot of “surplus” that would work for a less complex unit. i may take a closer look now to see if some what I have can be used or easily modified to build this design. I assume the GEK design would be suitable for my plan?

Matt: Prior to joining I read a bunch of information on this site and had come across your alternator based information. I confess that it is not anything I have looked at, so I would have to do a lot of research to just get up to speed. i assume that you are generating 12V power by default, and must have a battery or batteries along with an inverter to generate household current. What I have seen about inverters is that the quality tends to match the price, and for anything I build I think i would want 5kw as a minimum with single phase 240V output. A high end 240v inverter and (multiple?) batteries is a lot of upkeep for something that isn’t used daily I’m not at all scared of an ac generator - in fact, they are a way of life where I live. I can probably figure a week a year is spent using one of them for whole house power, and I’ve never had any failures in my appliances. My first experience with it was the ice storm of '98 when I was without power for 2 weeks. That was by far the worst single stretch of power outage I have seen, but every year we have a couple storms that knock the power out for a couple days or more. As far as your comment on a golf cart starter, I’m a little lost. I know they are often starter/generators, so is that needed, or were you thinking I needed a starter for my engine? That Wisconsin-Robin is an older industrial behemoth - only 16HP, but it weighs a solid 180lb and has electric start already.

Steve: Thanks for the clarifications. I didn’t want to start on the wrong foot by asking stuff I shouldn’t. I’ll be doing a bunch more reading, and I already understand the scalability issue from stuff I read in the past. I have a feeling that I may in fact have to build a FEMA unit just so I can see everything for myself. Whether I try a FEMA build for my current engine (on a trial basis only) or whether I get some disposable 5HP ones is up in the air. Scaling down for a 5HP would likely be even more difficult that a 16HP, so I worry that I may not really learn too much useful.

Thanks for all the information so far everyone.

Ok I see on the starter I was thinking small engines. You would be lucky to a get an hr or two out of the small engine starters before you burned one up. Been there done that many times already. But it sounds like your machine is heavy duty so you may not have issues. Yes the golf cart starters are the motor generator type and you can crank one of those over for good lengthy times when needed.

We build DC to AC for many many reasons and one is for the consistency issues in the smaller gasifiers. If you want to run continuous power then if you run an AC system you will need to run it continuously. You will need to monitor the machine the entire time. You also need to size an AC system to account for spikes to start motors and things like this. With a DC set up you don’t need this you can pull your stored power for motor spikes. Even though there are inefficiencies with converting DC to AC you make up for this by having the ability of storing this power and not needing to run it full blast. You make what you need and shut it off. This allows you to make what you need vs running an AC gen head 24/7. If you plan to use the grid as your battery, you still need to get a grid tie inverter capable of sinking to the grid frequency.

Inverters are getting cheaper but you are right you get what you pay for. We so far are using “the inverter store” as our vendor and have had very good luck with there products. As far as pluging things into anything less than a pure sign inverter you can run most any thing with a motor, but solid state electronics can be an issue. Ive already burned up my modem, and a coffee pot.

Batteries are an investment but it can be done on the cheap side. Used batteries can be acquired very cheap. For voltage you can run what ever you want, we don’t run just any alternators. Ours are specially built for us but you have more than enough options on E bay. I would suggest the heavy duty 24 v truck alternators with 100 amp out put. This will get you in the 2400 watt range.

In any case your 16 hp engine will most likely yield 2 kW possibly 3 kW max output running on wood fuel.

Mark this is a block diagram of one of my old units.

the first pic is what i started from, after building a fema

the second pic has all the numbers in it and yes it will work with chips. designed by Stephen Abaddess and posted with his permission.

Welcome on the best platform…
My advice to you for starters would be the same as Chris and Matt.
Start with a simple charcoal unit and work your way up in understanding.
(First crawl, then walk,… )
Matts way of avoiding bottle necks is my favorit.
It works at my house as an backup system as well.
Starting with charcoal and after that making a smooth transition…
It is as stated already, difficult to run small systems on woodgas, but not difficult to run on charcoal.
Feel free for any question…
Here on the site are many pictures and diagrams available,.
Proven old ones and reliable new ones.
Enjoy your project.

Matt wrote, “If you plan to use the grid as your battery, you still need to get a grid tie inverter capable of sinking to the grid frequency.” Do you know of a method of using the 220 vac output of a generator that could be converted to dc (rectified) and fed to a Grid Tie Inverter? The MPPT (maximum power point tracking) would need to be disabled, wouldn’t it. Can you recommend a GTI? If purchasing one that is not a high voltage string inverter, I assume you would look for a 12 volt or 24 volt wind generator GTI? Do you know of a reliable one that doesn’t cost an arm and a leg? I have a 600 watt Chinese unit ($131) on my solar panels, but it is making only twenty-one cents/day of electricity cost reduction when powering the grid. (Long payback…more than 2 years, just to recover the cost of the GTI.)

This is about as cheap as it gets.

Just my two cents, induction / asynchronous generator with grid tie. Could be used off grid using a battery and small inverter for the exciter.

Hello Mark Billing.
I have read all the posts in this thread. A couple of times you have mentioned asking questions, but not getting answers.
You have pretty much told us what you do and don’t want to do, so why not ask all of those so-far-unanswered questions here and now?

Pete Stanaitis


What I said was that until finding this site, all of the information I have found was one directional, so I was unable to ask any questions. There are TONS of youtube videos of home built gasifiers, there are many more sites where people have posted information about their gasifiers, and they have even started to make their way into fringe reality television. But for every one completely detailed bit of information, there are several hundred that only show you the result and not the path to get there. I’m a nuts and bolts person. When I see something, I don’t see the end result, but instead i see every little internal piece that makes it tick. For understanding gasifiers, this is something that i haven’t had access to until now.

As far as my questions go, It sounds like my direction may have to do a 180 degree change before I even start, so I am going to have to reassess everything before asking anything. all my previous questions are now null and void. You’re at a different perspective that I am - people here are already either partially or completely educated on the subject. From my point of view a HUGE portion of the gasifiers you can find on the internet are based on the FEMA design, and much of the information would lead the reader to believe that they are capable and can be built to produce decent results. Everyone here disagrees and says that both tar and difficulty of use are huge issues.

I’ve now got to decide what direction I go t start with. If i am to go with the charcoal route I have to first learn how to make charcoal - not sure if I am ready to do that at this time of year. I’m also trying to assess the materials I have and see what it would take to go in the route of an imbert style. I’m also still tossing the idea of a FEMA around, just because of the simplicity of build with what I have on hand. The questions are still there, but now I don’t even know what they are.

Everyone that i see using a FEMA design are doing two things 1st, they limit how much feedstock that is in the burn tube, thus controlling the burn level and 2nd they are using a very specific feed stock… mostly pellets… if you want to sit by your gasifier putting a handful of pellets as it needs them then I do believe you can make gas, and even run an engine on it… that’s just my observations on it anyway.

Hello all and welcome aboard Mr Billing ,

It is my policy not to criticize anyone’s gasifier design and that includes the FEMA. I think the FEMA does what it is designed to do and that is to be built and operated in an emergency situation. We have the FEMA plans right here on the DOW site along with others . In all the literature it talks about operating in emergency situations and even the name FEMA has the word emergency in it .

I think if the operator is skilled enough he could use the FEMA and drive from point A to point B. If so I think the FEMA may have done it’s job and what it was designed for .

Here in the US the FEMA and FEMA hybrids may be the most common gasifier built. If there is anyone out there that has operated a FEMA over a hundred hours without bending a push rod please raise your hand . Sorry I can’t raise my hand, and it will always be the intake valves and usually the hardest to reach .


Ha! Ha! Well put MarkB.
Let me help you a little bit with these daunting trees in the DOW forest you are now overwhelmed with.
Member Tomas McDaniels did take a heavy duty made Chinese made gasifer stove system and modify it for motor fuel gas making and power his place through a 9 day power outage. Pictured here: “JKQX10 Gasifer Mod”

These as made are actually “stratified” meaning the really do not have zone fixing side air jets. or a focusing restriction in them. He modified his to have these. He used wood chips. After 9 days continuous running he burnt out damaged his restiction plate modification.
As his picture shows he used a larger single cylinder engine overdriving an AC motor for synchronous AC generated output.
After this experience he is now onto building up a WK-mini system. Icannot link you to his pictures and posts to that.
Premium members can pull up a members profile page and look back specifically at all of a members posted up comments and pictures.

David Blooms excellant process steps block diagram show the post reactor train sequence all woodgas systems will want to have to be effective. See these steps out of place and you’ll know a fellow needs to do much less broadcasting out and do a lot more actual running and wood fuel consuming instead. Particle removal FIRST -> Cooling and condensate removal SECOND -> Filtering LAST. Alternative to DavidB’s block diagram is to have TWO suction blowers. One before this “downstream” (post reactor/hearth) train so still too cool, still warming up tars, soots and condensates are flare burnt off so’s NOT to crud load/clog your downstream componets. A second blower to then later pull NOW warmed up produced true woodgas only then through the downstream filter train.

Do not be confused by us using a variety of not so primary air heated hearth systems versus those using very eleberate hardcore primary air pre-heat systems. These approches both have been, and can be made to work.
Same with the direct AC synchronous generation versus direct DC genration. Both approches have been, and can be made to work.
You will even see a divide on internal cone dependent and coneless, all tube and tank shaped designs. Again these both have, and can be made to work.

Really depends, depends, depends on you man.
Good skilled metals fabricators love to make cones. I hate it.
Good skilled welders love to weld, and welds, and weld. I do it as just a gitter done necessity - then on to the real job on hand.
Comfortable electronics people love to design and build control systems. Just a tool to me. How much to purchase? How much to learn and maintain it. And if the hardware will not last and live through working conditions and give at least a 5-10 year service life I am pissed greatly. This valuable time and $'s lost distracts me from the things I really want, and enjoy doing.

Not that I am indifferent at all to these approches. I’ve tried them all. To pounding carbon monixide headaches. And nerve wracking hour after hour of screaming-meemie 3600 RPM ax murdering mood setting spells.

Then put my permanet investment into what will serve me and mine.
And I have sold myself professionally “fabricating”, “welding” and “electrons chasing”.

Moderate air preheating; moderate in-system fuel wood drying/conditioning; mondo heat conservation and insulating; “dry” hot settlement particulate removal; three different ways to cool and condense depending on the time of the year, heat needs and wood drying conditioning needs; and last now Hay filter! Hay Filter! Hay filter!

I put my initial electronics dependencies now out in a named branded warranted Miller/Kohler welder generator with it’s own electronic gasoline fuel injection and electronic stabilty control. One with a damn good HD electric starter. You WILL need that for the variable BATCH woodgas quality direct extended cranking starting ups. Have multiple American made cast iron Electrodyne DC truck alternators to belt drive add to it in place of a factory aircompressor package.
My other electronic dependencies are in the best made of good Canadian iron and copper 100+ pounds heavy DC to AC TRACE brand inverter. And backing up that are three 1500 watt and two 500 watt commercial grade American made REDI-LINE heavy permanet magnet, steel and copper DC to AC motor-generators. These can be manually flip switch by-pass operated. Individual consumer circut installed.
I will have my 5 kW electrical one way or the other with My trees suppling the wood fuel. Period. No, If’s. No, And’s. No, Butts!

Consider all else as a distraction that will not get you to this point also.

My actual only woodgas forte is that I can now make anything work. Only differences to me now really are; how well; how long anymore. And How hard it will make me have to work it to get the results?? Only results that counts is that engine out shaft power to make the electricity.

A GEK III direct over gravity hopper feed system would be a nice simple start for chipped fuel. ~60 FEET of welding in one of these. GEK IV offset auger feeding in hopper system will double your welding and fab peices and will get you seriously distracted by the electronics and all of the motors . . . imho.
A Minified WK will prove to have no less welding lines to do than a GEK III. Maybe even 2X more. Be far Less pieces to cut, form and fab though. And only one, not an actual cone, guiding-in/condensate heat isolation/recirculation slit slope in it.

ArvidO’s/Stephen Abbeddesa’s has NO cones. And fewer weld lines than a weld together FEMA. All easy tube shapes. ArvidO proven on softwood fuel chips. Eastern hardwood chip proven by StephenA. Maybe Arvid can link to some of Stephens chipping/blower system vidios?

I am now a dedicated chunk wood fueler so my best ready on-hand links are to the best gitter’done systems for chunk fuel wood like Stigg-Erik Verner’s coneless tank body and top slopes units, Phil Coveys propane tanks built unit, Danny Cox’s SS beauty, and Steven Amptramps three different systems now.

Since you probably cannot access my photo album here to see . . .
a few pictures to put the walk into the talk.

I actually have more time, effort and expence involed into fuel wood drying as any other single aspect of my “system”. PNW rainforest. Much wood. All wet for up to 10 1/2 months of the year.
NO system can handle my wet wood except one - Mine.

MarkB. this is why you’ll also have develope your own hybrid system for you; your specific conditions; and needs.

Steve Unruh

Stephen’s chipper