Choosing the right project

Small Engines
#1

Hi,

like many beginners, I’m looking for the right gasifier design for my needs.

To be clear, I would like to add that I would prefer to buy a ready-made solution, but due to the small number of commercial offers, I think I will have to build it myself. And if so, I would like to use a project that is well described, easily accessible, and should contain as many ready-made parts as possible or parts that can be made in a home workshop. I will add some more information that may be useful for your advice:

  • generated electrical power 5-30kW

  • fuel: hardwood and coniferous wood in pieces (mix), waste in the form of furniture boards, MDF boards.

Everything is well dried (humidity in the range of 10 - 20%)

  • power use: charging the energy storage (relatively constant load on the power generator)

  • it is good that the system is able to use waste heat. (I can then heat the house and the home workshop)

  • I am also interested in the system requiring as little adjustment as possible (I am talking about solutions such as Ben Peterson’s automatic air mixer)

  • and, of course, a solution that produces as little tar as possible

I’ve already done some preliminary research and I have a few of my own picks, but I’m curious what experienced designers will recommend.

If you need any more information, feel free to ask :wink:

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#2

I will also add that while reading the articles and your forum, I began to wonder whether I should abandon the concept of gasifying wood directly and instead make charcoal and gasify it.

Since my raw material will not be uniform (sometimes wood, sometimes waste), it seems to me that I would have to keep an eye on the gasifier from time to time. By turning all this into charcoal, I will obtain a more homogeneous fuel and the gasification process itself will be easier to control. What do you think, which path should I take?

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#3

Charcoal would be the easiest and best for a small engine like that. I’m sure most others here will agree with that. @Matt might have a complete unit left to sell you. He has made a living making them for years but I think he is starting a new business 3d printing stuff for the RC community.

Welcome to the forum!

GC

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#4

As a curiosity, I’ll just add what gpt chat says about it

My question:

Ok, let’s assume that I want to use waste as fuel. Which way do you think is better: Option 1: wood gas generator with advanced filtration system. Option 2: Pre-pyrolysis of waste instead of direct gasification. Then the charcoal obtained in this way is gasified.

GPT Answer:

Option 1: Direct Gasification of Waste with Advanced Filtration System

Advantages

  1. Single-stage process – no need for additional fuel conversion, saving time and energy.
  2. Space and equipment efficiency – a single gasifier and filtration system.
  3. Higher energy efficiency – less heat loss since fuel is gasified directly.

Disadvantages

  1. High tar and impurity content – even with advanced filtration, cleaning gas from waste materials is challenging and expensive.
  2. More complex filtration system – requires multiple stages, including cooling, cyclones, mechanical, and possibly chemical filters.
  3. Frequent maintenance – filters need regular cleaning, especially when processing resin-rich materials.

Option 2: Pyrolysis of Waste + Gasification of Charcoal

Advantages

  1. Cleaner gas – charcoal contains almost no tar, minimizing filtration requirements.
  2. Simpler gasifier design – the reactor is easier to build, and the filtration system is simpler.
  3. Better process control – pyrolysis removes harmful compounds (glues, resins) before gasification, reducing gas toxicity.

Disadvantages

  1. Two-stage process – requires a separate installation for pyrolysis, increasing complexity and fuel preparation time.
  2. Energy losses – the pyrolysis process consumes part of the fuel’s available energy.
  3. More space required – additional equipment is needed to produce charcoal.

Recommendation

If reliability and gas purity are your top priorities, Option 2 (pyrolysis and charcoal gasification) is a safer choice because it minimizes tar and toxic compound issues. Option 1 offers better energy efficiency but involves more complex filtration and maintenance, especially when using materials containing synthetic adhesives.

4o

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#5

Can you point to ready-made and community-tested studies with good and readable documentation?

I’m talking about something analogous to the book “Wood Gasifier Builder’s Bible” but for a charcoal gasifier

1 Like
#6

Charcoal is the only way. Start with charcoal first, low investment and this is the basics. Create a retort that you can use reclaimed process heat. Hot water and shop heat is easy to do with this. Use the pyrolysis gas from the charcoaling process for process heat. A retort can litterally produce nearly all its own process heat.

Start here if you feel the need to attempt a wood fuel system that you have learned the fundamentals here first that help you plan a system that will be more successful than a plan without this. But I think you will find its easier than most think taking it at face value.

Off the shelf power generators in the 400 to 500 cc engine displacement range are only good for around 2kW output on any syngas running continuouse. You will want to get a battery bank in and inverter system to make this viable. This will get old very fast its not free, solar is free wood gas is not its work!

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#7

For a charcoal gasifier design. Build a cross draft with the boiler nozzle design we have brainstormed here on the forum. Very efficient and it is very possible to exceed 30% energy density just from water cracking alone. Ive done better than that; Ive gotten up to 40%. But nothing in wood gasification is or will ever be linear. So this is going vary dependent on conditions and fuel.

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#8

I already have a PV installation with 15 kWh storage. The power of the panels is 10KW. I can expand the installation with additional energy storage units at low cost. I live in Poland. We have significant subsidies for energy storage here.

Cloudy days are a problem - if the sun doesn’t shine for more than 2 days. And of course, late autumn, winter and early spring.

Small wind farms in our country are effective only in the northern part of the country by the sea.

So in my area, if I want to be energy independent at low costs, gasification is the only option.

Out of curiosity, what is the price per kWh in your country?

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#9

When you can retort with zero smoke you have learned gasification.

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#10

Would you be so kind as to post a link from this topic?

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#11

So far, I have been using a wood gasification boiler for 3 years. Let’s say I covered some basics

IMG20210804214336
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#12

You can start here: This is the basic concept only. Build this bigger and make it more robust. The nozzle is outdated Ill have to find the thread for the updated version.

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#13

This first part in the video is how I make the nozzle.

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#14

Robert in the US of A Grid electrical power will vary significantly.
Mine is at the low end of the scale up here in the far NW in Big Hydro Electric power producing areas. Like in Norway. Western Canada.
Here is my actual mid-October to mid-November billing:

Photo on 1-13-25 at 2.47 PM
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In this time period I did not much use the wood stove heating. Using the two Mitsubishi mini-split heat pumps for 90% of the heating. As can be seen in June/July/August and even into September the mini-splits heat pumps are used for House AC cooling too.

Colder now the mini-splits heat pumps efficient drops and so I am heating much more with wood.

The actual working number I follow is the far lower right hand corner of for this time period of $6.28 USD a day.
Gasoline or diesel or propane for my generators would be 5-10X the cost per day at my highest of all 50 states carbons surcharge taxed to support the households normal electrical consumption.

We can; and have lived, on less that 1/4 of these power consumption levels. Could live comfortably actually.
The marine weather patterns like Norway, Ireland, Scotland, western Canada means up to 100 days in winter with virtually no PV solar able to keep up with what would be even our 1/4 minimal consumption. In my State due to restrictive $$$$$'s buy-in regulations investing to make PV for Grid feeding is a Green-Spin fantasy-trap I refuse to buy into.
Those trees; on our own owed, controlled property . . . they still grow and store solar energy in the ~100 days of winter low solar. Conifers. More trees fall down and rot than I ever could use. And these trees we are taxed, and restricted-use, the least of all of my available energy sources.
My fuel powered electrical generators are for Grid-Down backing up. And help feed my IC engine hobbyist addiction. I crave daily fixes of some kind of IC engine running; working; producing.
Chainsaws. Woodsplitter. Medium wheeled tractor and a tracked hauler. Wood carrying capable trucks. Seasonal lawn mowers; brush cutters/weed eaters.
Regards
Steve Unruh

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#15

Hi Robert, nice to see a fellow European. Welcome!

First, great job at demonstrating your situation and requirements. Makes advising easyer.
I agree with Matt.
In your case, and with all the instalation you alredy have, building a retort that reclaims the heat from a charcoal kiln shuld be easy. If you got enaugh heat acumulation capacity ofcorse.

The “advanced filtration sistem” routh you can forget about. Better to not make dirth in the first place. Tar cant realy be filtred out as its preety much in gaseous form (untill high turbolence whips it out-around valves and throtle body). And even if it is, what are you gonna do with the waste?

I have learnt in life its best to not look at everything as black and white. And your case is a perfect example. There is a third option you can take and l think its most apropriate for your situation. A charcoal wood hybrid. You can make charcoal out of big peaces of wood and save on the raw wood processing cost (chipping etc). The smaller bits of wood can be mixed with crushed charcoal up to about 50/50 by vplume to form what we call Rocket fuel. This fuel is wery forgiving for a beginner, as it doesent require a sofisticated and well sized gasifier. As long as its a downdraft it will work. The charcoal in the mix will keep temps high to burn the tars. It “lubricates” the wood bits so that the mix flows better, less bridgeing. It eliminates the need for condensation collection both before and after gasification. Charcoal will eliminate water.

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#16

Expand if you can. it is the least work and most likely the overall cheapest option like storage to get your through 2 days. overproducing isn’t a crime. Then you run the generator to refuel your battery bank. I don’t think your overall plan is bad. The larger issue is fuel prep time, and getting the generator to run consistently for a long period of time, and the cost of the generator depreciation itself. By charging a battery bank, you skip over some of the necessity for smooth electric output. Having a larger battery bank helps boost over surge current use.

electric rates vary across the us but the US and canada -on average- have some of the lowest rates in the world. However, I don’t know if that takes into account the line charges they add. Like we pay 8c/kwh, then another 7c/kwh in a line charge or delivery fee.

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#17

Hello and welcome Robert, my friend Kristjan gave you a good answer, so there is not much to add. Most of us who “meet” here intend to use wood as an energy source for driving engines and as an energy source for heating, we do not see wood as waste, but as the cleanest and most ecological fuel, as a gift from God. In fact, it is a perfect fuel and is a “battery” that the sun charges throughout the year.
My way is to use raw dry wood in a gasifier, which must be appropriately sized so that the wood has time and conditions for all conversions to clean gas. My opinion is that the stationary unit must have a large volume, where the wood is slowly “cooked” and converted into charcoal. The interior must be free of obstacles and constrictions, so that there is no jamming and bridging of the wood, except at the bottom, where the air nozzles are …

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#18

Thank you all for your detailed explanations.
I now know that in my case, I am 90% decided on a charcoal gasifier. While there is the additional step of producing charcoal itself, on the other hand, I can use various raw materials as fuel, and by converting them into charcoal, I obtain a more uniform fuel for the next process. I am also convinced by the argument of more stable generator operation when running on charcoal gas. Another advantage is that I won’t need to shred the wood into very small pieces for the retort. If I had only one type of wood and a chipper with a shredder, I might consider a wood gasifier.

As for the gas produced from pyrolyzing wood, I would likely use it to heat the process itself, as I think this is the most beneficial use.

Regarding electricity bills — you have an interesting situation in the USA. Electricity prices vary significantly by region — in extreme cases, I’ve seen videos on YouTube about cryptocurrency farms located right next to power plants, buying electricity for about 3 cents per kilowatt-hour…
As a curiosity, in Poland, electricity, including distribution, costs around 25 cents. Before Russia’s invasion of Ukraine, it was about 18 cents. And, essentially, prices are similar throughout the country. We have a law that mandates this to ensure uniform development across the country and to prevent privileged locations. I’m not sure how much of this is free-market economics and how much is socialism, but let’s not get into politics.

One more thing I’m curious about: Based on all the information I’ve gathered from you, it seems that for small installations and beginners, charcoal gasification is simpler and less frustrating. The chances of getting discouraged at the start are lower. So I don’t understand why there is so much more information online about wood gasifiers, while there are far fewer resources on charcoal gasification, and it seems less popular.

And a question for you: I also wrote about my concept of gasifying waste for engine gas (to Sergej Lahunov – you probably know who I mean). He claimed that it’s possible to get generator-grade gas from such materials and suggested direct gasification of the waste. Of course, I didn’t get more specific information because I would have to pay him $1,000 for detailed guidance. This makes me wonder, because from what I’ve learned from you, running a generator on wood gas is more challenging than on charcoal gas, and using waste-derived gas is even more extreme. I understand that Sergej seems to be respected, but what do you think about this? Does he really have some miraculous solutions?

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#19

I’m going to throw my 2 cents into the mix here Robert. First your wood boiler set up is a thing of beauty. If you desire a gasifier that is fairly easy to make then the examples that Matt posted would be hard to top. Most other styles of gasifiers other than Simple Fires ( Gary Gilmore updraft charcoal) require significant fabrication skills. Even a pinhole leak in any part of them will prevent them from producing usable gas. I would pay for a premium membership here because it allows you access to a wealth of information about the Wayne Keith designs but I believe that’s problematic because you are in the EU and it has some kind of wonky tax regulations. Someone else would have to explain. Anyway the rest of the site has maybe all there is to know about running on wood gas for no cost at all. Just takes a lot of time to uncover it. Rest assured that any question you have as a sincere wood gasser, someone will do their best to find an answer.

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#20

Another 2c, Robert.
Yes - building your setup is certainly easier if you go for charcoal. Wood gasification requires a good sorce of materials, some welding skills and a portion of determination.
BUT - once your setup is built, I don’t think running woodgas is more challenging. To be fair I haven’t tried running pure charcoal, but I find woodgas easy enough.
I think it all boils down to what kind of infrastructure you have to start with and personal preferences when it comes to fuel prep. If you’re able to supply your Atmos boiler with fuel and find it at least somewhat fun, you may consider adding to your equipment with a rebak/stepkovac. Since you’re in Poland you should have no problem with that.
I find the most challenging part of wood gasification is drying the fuel. It requires time, storing space and planning ahead.

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