Gasification and wood gas


Feb 28, 2017
Peoria il
Being the nerd that i am I've been looking into woodgas and gasification for years, and as promised here's some of the stuff I've found.

Disclaimer: I'm sure i don't need to explain the hazards of attempting this stuff to people who run chainsaws while hanging on a rope everyday, but this can definitely kill you. A gasifier is basically a carbon monoxide and hydrogen generator, and the gas is very hot and will contain oxygen as well. So all 3 components of fire are present, and with hydrogens explosive range of 4 to 75 percent it can and has spontaneously exploded if stuff isn't right. Most engine conversions utilize the vacuum of the engine to suck the fuel through the gasifer and other components, so not only will leaks be undetectable they will be introducing even more oxygen into the gas stream, making an explosion far more likely. Unlike propane or natural gas it contains no odorant to warn you of leaks, so it's a poisonous fuel gas that you cannot detect with your senses. If you feel unqualified to attempt something like this with natural gas or propane you aren't ready to try this either. There's a ton of people on YouTube and stuff showing some of this stuff, and a large portion of which know just enough to kill themselves. People filling bladders with it, building compressors with parts salvaged from refrigerators, etc. so don't do dumb stuff like that.

Up first is the fema gasifier, literally the govs contingency plan if oil stops.

Next is a really good site on the matter, geared towards converting existing vehicles to woodgas. Most of the information out there being used by people doing this as a hobby currently can be found on his site, and it's a great starting resource.

As is predictable adapting an internal combustion engine to run on a tar containing gas is not without its problems, and can definitely lead to engine failure. The incoming gas is hot, has fines entrained that can sandblast parts and ruin bearings when it contaminates the oil, so you will likely be working on whatever you try this on, and may destroy it. You will be needing to add and likely fabricate components such as coolers and filters to get the gas suitable for running in an engine, so there's a bit of a skill level you'll need before attempting this. As i learned more i wanted to run internal combustion engines less and less, and started looking into other external combustion heat engines more and more, like Stirling engines, steam engines, and turbines, which is the longer lasting alternative from what I've read, and what's commonly used in practice.

If you are looking for using it for heat tho it's a far easier endeavor, and stuff like the tars won't matter. At the beginning of the industrial revolution before electricity all sorts of gas appliances were in vogue, and was powered with producer gas, natural gas was flared off at the wells because it was considered too costly to pipe all the way to the end consumer, obviously that changed dramatically as time went on. So when you're reading about gas lights and stuff, this is exactly what it was burning.

Producer gas and wood gas are the same thing btw, it's basically using heat to break down the longer hydrocarbons into hydrogen, carbon monoxide, and co2. Depending on the type of gasifer it's often hot enough to even crack the tars, and will even separate water into its elements. The feedstock can be anything carbon based that will burn, but in practice the fuel needs be be able to be fed evenly, some are prone to clumping and bridging, which can create hazardous situations and poor gas quality. I have several engineering books like this one that I'll post later when i have a bit more time to go through them a bit again, this one goes into depth on designing furnaces to run on producer gas for different industrial processes.

Kyle, this is insufficient. I require more wall of text. In specific, the Stirling engine. I really think it's underutilized technology. Gimmie what you've got. I.E. how would you like to see it expanded on, where do you think they'd be best implemented?
Yeah, I am unqualified enough to not even read it!! I am on vacation and had some time to look at some threads that I might have missed but now I know why I might have skipped this one 😳 Kyle, you are a smart cookie!
  • Thread Starter Thread Starter
  • #6
Thx, but I'm not, just trained in a different trade.

Forgive me, i kinda forgot about this thread with everything going on in my day to day lately, and figured pretty much no one cared to go much further lol. It's obtainable for everyone by running internal combustion engines or for heating, but as you get deeper into it you start getting into boilermaking and pipefitting, so i figured no one here would want to persue that. A little backstory on my interests in this stuff is likely helpful as well, I've been interested in this to develop it to profit me personally, and the expected return needs to justify my efforts for me to start actually trying to build something. As a fitter I've worked on a ton of different equipment, sometimes in research facilities, and so I'm intimately familiar with how some random stuff works. Since anything i would build would be experimental and would normally require a large start up cost, i figured i need to be able to cobble it together myself cheaply at home, so I've slowly been building up my capabilities to achieve that, simply welding stuff wouldn't be enough, i would need pretty substantial machining, forging, and foundry capabilities, which after 20 years or so of picking away at little projects and hoarding junk is finally becoming within my grasp.

At first it was for producing fishmeal, in illinois we're overrun with asian carp, ironically the number 1 farmed fish in the world. They are filter feeders, grow to a very large size, produce the best fish oil out there because of almost no mercury or other accumulations (filter feeders), and are dirt cheap here. The amount of waste that comes from processing them is the huge hurdle, but it's often turned into fishmeal, a globally traded product that goes for about a dollar a pound, the fish are sold at roughly 10 to 15 cents a pound. Everyone selling it uses natural gas or other expensive fuels to cook and dry it, so i figured if i could use wood waste i could make it wayyyyy cheaper than anyone else could, and with the sheer amount of them here i could grow it into a very lucrative business. I was planning on building a ferrocement barge type boat to process them on to avoid needing industrial zoning requirements and to maximize efficiency (fish get caught, procesed, and debulked in 1 step), but with equipment like that on board i would need a captain with a 100 ton captain license, which a buddy of mine was pursuing at the time. He didnt end up getting one, so i stopped pursuing that for the time being, the fish are up to 30 pounds or so which requires equipment of a certain size to be able process them, so a small setup really wouldn't be feasible, and even trying it would be big enough to attract attention and regulatory bodies.

Stirlings are super cool, kinda went down a rabbit hole learning about them awhile ago. A bunch of problems with gasification is because it's easy to make a gas that'll burn, but to clean it of tars and fines and cool it to run in an internal combustion engine (ice) is hard. But with an external combustion engine like the stirling its easy, because all of that is simply against a heat exchanger, so tar and stuff simply becomes more heat and you don't have engine contamination problems. David gingery has a book on them you can get pretty cheap on kindle, i love pretty much everything he's written. I've mentioned him before here i think, he has an entire book series of building a machine shop (foundry, lathe, shaper, mill, drill press, and accessories) from scratch, an amazing read and it's really cool how he solved the problems as they arose. Not really practical anymore since the introduction of cheap imported hobby machines, but worth the read because of the process it takes to bootstrap it together. He covers how to design and build stirlings in his stirling engines book, but even he doesn't build one to power all his stuff explicitly, he just gives you sample project plan and design considerations to build your own.

There's likely to be more utilization of stirlings as we shift to renewables, and they've been developed to harness solar in the southwest part of the country where you're at using a parabolic mirrors to focus the sun to a single point. Stirlings suffer from a being larger and heavier than an ice for the same power, and the working gas ideally is really lightweight and doesn't contain oxygen so it won't cause problems with the engine lubrication (ie explode). But the big problem with them is their material requirements because of the heat and pressures involved, and if gasification is being used you'll easily hit temperatures that will require much more expensive materials to work, especially in the sizes I'm interested in. I've read up on other variations of heat engines, and was even considering trying to build a fluidyne engine which uses a liquid to work as a piston, they are usually pumps but that can be used to power stuff too, but the same problems arise. I have questioned why they arent used as a bottoming cycle with small steam systems, and would think that combining the 2 would be very good in smaller installations.

Stirlings were developed to replace steam engines to eliminate the dangerous boiler and high pressure piping, which used to kill people with alarming regularity. But since stirling engines still have the same problems as other external combustion engines with high pressures and temperatures they aren't utilized much, frankly there's easier and cheaper alternatives. In my research everyone says they're great, but if you'll notice no one is really using them at a useful size, small yes but i want something bigger so i decided a stirling wasn't the best way foward for anything i wanted to try, the materials and working gas problems were frankly too high to justify it. I'm also a steamfitter, and have done plenty of pressure vessel work, so much so that i personally used to do the R stamp for the company i was working for every year and did the majority of their code work, so the desire to avoid steam and it's associated problems isn't there for me lol. Boiler inspection requirements are tho, so I've been looking into ways around that or profitable enough to justify it, as i would likely have to start a company and get an R stamp (even though i literally do this for a living working for companies who had the stamp because of me), a goal of mine but not currently feasible, and would have to wait until the final stages of starting a profitable enterprise.

With that in mind I've since shifted my reading to steam engines. Reciprocating engines are very achievable, and plans to build them are even found in some old machining books I've downloaded, since they're all from the early 1900s. I wanted to learn how to use my lathe before i tried to use it since it's so big (18" swing, 48" between centers) and i want to learn the old school skills of metalworking too so i could utilize it to it's capabilities, I've found for me reading greatly decreases the learning curve of stuff and that thing is big enough to tear me in half without even bogging down. Reciprocating steam engines are ideal for many applications, but turbines eventually were chosen for most applications, so that's where my reading is currently at now, and they're actually simpler than reciprocating engines, they just require tighter tolerances.

Turbines are often chosen because they are the highest power per weight of any engine and efficiency available currently, nothing else even comes close. Modern turbines are usually axial ones, and utilize the most modern and expensive components available for longevity. But turbines aren't new, and were once utilized for all sorts of stuff where sheer horsepower and reliability were the primary concerns. Radial turbines are much simpler than their axial relatives (the tesla turbine a notable exception), and are actually more efficient than axial turbines at smaller sizes (under 5 mw is considered small in that world lol, that's the efficiency crossover). In the early 1900s efficiencies of radial turbines hitting 85 percent were common running on plain babbit bearings, and had very long working lifespans, and modern diesels still haven't achieved numbers better to date, but they do better on running at different load requirements. Most large ships were powered by turbines until diesel took over (fuel economy, turbines really like to be wide open) in the 50s and 60s, so it's a proven technology. There's a reason why engineers chose steam turbines over everything else, and I've come to the conclusion they were right.

If we're looking to utilize gasification of a cheap renewable fuel like wood waste we don't care as much about fuel economy, we want the most power we can get with the easiest and cheapest way to do it given the other limitations of what we can build. The first way would be to use an existing ice engine so we only have to do the fuel conversion, and that's a definite way to go about it, and is probably the best way for most stuff that most people want to try. By using only charcoal we remove the tar problems from our efforts, its wasting energy from the fuel but it's the simplest way to get around the tar problem of engine contamination, and it allows us to choose a simpler and cheaper gasifier and downstream components. If i was looking to utilize wood gas today to try to power stuff i would go that route myself, all that's left is removing the fines and cooling the gas, a cyclone filter, heat exchanger, and other well developed and easy to understand stuff is all we need.

I was planning on doing exactly that, and then set it up to power my house. I figured i could then sell electricity back to the power company here by applying for a green setup, as solar panel installations were doing at the time for full retail price, so i could have a base income that didn't rely on me working, and could be expanded upon as time went on, even have an 88 f350 with a 460 engine to do it with. But since i started looking and planning this they've changed the requirements to be compensated monetarily, you now need to be over 1000 kwh capacity to qualify, anything less is simply rolled over as a credit to your future electricity use. This would save money of course, but not enough to really matter for me personally. So now I'm looking into what i need to get over that threshold, so that's why I'm looking into turbines because at that much power it's about the only way. I would then need to get ferc certified as a qualifying facility, and I'm not sure if i can do that at a residential setup, and would likely need to upgrade the lines coming in to my place, so i would likely need an industrial zoned property with a large enough hookup to do it, so to the backburner it goes lol.

Its far enough out that I have plenty of stuff to do first, but is a long term goal. I figure if i could design and build small package boiler and turbine gensets using old technology and materials which are designed to run on renewable sources i could be very profitable, and by going simpler it's basically the complete opposite direction of the current industry because fuel costs are so much less. I would then go signatory and set up the fabrication myself, and then would be removed from needing to bid work because i would have a product that I'm making for myself, absolutely no middlemen. I've even started looking into energy crops to fuel it since wood waste wouldn't be enough if i pulled it off, and have currently decided to look into using duckweed grown vertically on transparent shelves in a self contained unit, since it basically doubles in size daily and is the fastest growing plant on earth. It's currently being used to power a plant in new jersey, I'm not sure if they're using wet gasification tho (uses supercritical water to gasify the feedstock, removes the drying process but needs much more demanding materials because of pressure and corrosion).

I understand high pressure steam boilers with superheat, turbines, and the like aren't obtainable to most here including myself at the moment (not all i might add), so i doubt anyone wants books on stuff like that. Just this weekend i worked in a 50 mw cogen plant welding turbine piping, the turbines I'm hoping to build were in common use over 100 years ago, and i have the tooling and most of the materials here at the house already. So as crazy as this all sounds it's within my grasp, i have 21 years left in my working career yet, if i get it going by then I'm set. My tree service and running pipeline and other high pay travel work were supposed to give me enough income and flexibility to work on this in between jobs, but cancer had other plans so my priorities have shifted for awhile and I've been working 40 hours plus since i finished treatment, makes it hard to work on projects like this, and my kids are too small to work on it with me yet (aka be around while I'm welding and stuff) so I'm just enjoying that time together and nibbling away at getting set up.

You wanted a wall of text so i hope i delivered, and you now know why I've bothered to look into this in the first place and where my focus was. Gasification is a cool technology and can be used to replace traditional wood burning if one was motivated enough, and I've researched that extensively when planning the fishmeal plant, and it can be used to power engines of varying complexities. I'm more than willing to help anyone by providing resources I've found and technical insight where i can, but my focus has taken for granted my skills and capabilities as a fitter to fabricate the components needed from scratch. Honestly beyond powering existing ice engines or heating water for a woodburning replacement its likely beyond the capabilities of all but a handful of people here, and there's other much simpler, safer, and likely cheaper alternatives for powering engines such as making biodiesel from waste cooking oil. Even for heating purposes it's far more involved and critical than building a traditional wood burner, and necessitates an outside installation with the accompanying piping and heat exchanger complexities. Gasification basically makes hydrogen and carbon monoxide in large quantities at high heat, so it's not exactly the safest hobby to have, but it be used for heat and can power an engine so there's that. I've thought about setting up a truck to run on it, but i drive 10 min to work and back so it's never been a need, it requires a warm up time that's not really practical for urban driving. Feel free to share what you are wanting to build and we can go from there, or if anyone wants me to elaborate on anything mentioned i could do that too.
Last edited: