# Wood Gasifier talk



## a_dahl (Jan 29, 2014)

I am looking to get a discussion going on wood gasifiers. I am currently in the planning stages to build my own. I will probably build the stratified downdraft gasifier first for simplicity and eventually I want to build a imbert style gasifier that will eventually be used to run a generator for my off grid power station. I haven't really came across to many forums on the internet or any discussions here on HT. I want to see how many of you out there have experience with wood gasifiers and if you could share that experience. I also wish to gain the attention of others out there who are not familiar with wood gasification and get them interested. I feel the more people we can get discussing and designing these gasifiers the more efficient and economical we can make them for people who are living off grid.


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## Nimrod (Jun 8, 2010)

I am interested in wood gas too. It seems to be the best way to be self sufficient so I have been reading up on it. 

Wood gas does not have the energy in it that gasoline vapor or natural gas or propane has. An engine running on wood gas won't have as much power as it would on one of the other fuels. With a truck, you can settle for less power or get a truck with a bigger engine for more power although the bigger engine won't have as much power as it would on gasoline. 

I think generators have to run at a certain RPM to put out stable AC electricity with the right voltage and frequency. If you buy a gasoline fired genny and hook it up to wood gas, the engine won't run fast enough and it won't put out the right electricity. I think you can get around this by running an inverter generator like the Honda EU2000i off wood gas. It generates DC and inverts it to AC. 

Is this correct?


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## oldasrocks (Oct 27, 2006)

Why don't someone build a genny fired by a steam engine?


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## Harry Chickpea (Dec 19, 2008)

Yahoo groups has an active and informed wood gas group. Seriously, go there. Read, read, read.


In answer to oldasrocks, the efficiency of steam is horrible, the requirements (legal and practical) are too stout for most, and a catastrophic failure is too horrible to consider. I'm a buff of history and the old railroads and the track record of steam is nauseating.


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## a_dahl (Jan 29, 2014)

You are correct that wood gas puts out less power than say gasoline or propane etc. but it has the ability to power car and truck engines and generators effectively. From my readings of people who use it for there vehicles say that you do notice the decrease in power and you can't expect to make a race car with this kind of fuel. You have to be careful how hard you hit the gas and always know that you will be that guy who no one likes getting stuck behind on mountain roads. Even though there are numerous examples of people successfully powering there vehicles full time. Plus they say always keep a way to switch between wood gas and gasoline so that you can compensate for those obstacles if you need to. 

As far as using wood gas to power a generator it is also totally possible. You can you tube countless examples of people who do it. As far as taking a big increase in load and being able to handle that increase is why you can use a system of batteries that you draw your load from and use the wood gas powered generator to charge that system of batteries. Also similar to the vehicle example above if your drawing power from the generator directly you can just manage how much you load at once so you don't possibly stall the generator. 

I hope that helped you get a better understanding also once you start using a gasifier and tinkering with it you are going to learn its limits and possibly even ways to improve those limits. That is why I created this thread so we can discuss all of this. If we can get people tinkering and going through all the trial and error we can eventually come up with some solid working designs that can help others who don't have that kind of time.


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## a_dahl (Jan 29, 2014)

Oldasrocks just like the other person posted steam is very inefficient and requires constant temperature and very dangerous. From a industrial standpoint steam can work. From a small off grid standpoint it is not economical, efficient, safe, etc. I looked into it as well and that is how I ended up learning about wood gasification.


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## a_dahl (Jan 29, 2014)

Thank you Harry chickpea I will check it out.


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## oldasrocks (Oct 27, 2006)

Thanks for the bad news on a steam boiler. I figured since it was used for so long safetly checks could be built in to make it safer. Guess I figured wrong.


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## biggkidd (Aug 16, 2012)

I look forward to seeing where this thread goes.

Larry


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## Dixie Bee Acres (Jul 22, 2013)

biggkidd said:


> I look forward to seeing where this thread goes.
> 
> Larry


Me too, my 13 yo son is very interested in gassification and we have talked about some possibilities of it.


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## a_dahl (Jan 29, 2014)

View attachment 22453


This is just a simple schematic of wood gasifier operation. Thought I would post this for those who are not familiar with it. This is the FEMA version which you can easily get plans for off the internet. FEMA published the plans for people to use in time of crisis or fuel shortages. This stratified downdraft gasifier is a spinoff of the imbert gasifier used during WW2. It is suppose to be easy to make with readily available materials. The down fall to this FEMA version is that it doesn't have a dedicated oxidation zone which means it can't maintain the high temps needed to produce clean wood gas. So you would need a really good filter set-up or risk clogging your engine up with tar and soot. This is a good starting point IMO for getting into wood gasification I plan on building one like this once I get some more material together. I will use it to run a old lawn mower for testing purposes. From there I plan on converting it into a imbert set- up.


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## a_dahl (Jan 29, 2014)

Does anyone have any information on how to figure out the dimensions for the air nozzles and throat diameter for a imbert style gasifier? And some info on the hearth design? I keep reading that those dimensions can be critical to producing good clean gas but haven't found any info on how to figure out what the dimensions should be. Is there a formula to use or what?


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## a_dahl (Jan 29, 2014)

a_dahl said:


> Does anyone have any information on how to figure out the dimensions for the air nozzles and throat diameter for a imbert style gasifier? And some info on the hearth design? I keep reading that those dimensions can be critical to producing good clean gas but haven't found any info on how to figure out what the dimensions should be. Is there a formula to use or what?



I answered my question. Wood gas as engine fuel FAO 72. This is a publication from the 80's with really good info on gasifier design. I highly recommend everyone google FAO 72 and download a copy of this publication from the food and agriculture organization of the United Nations. Enjoy!


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## a_dahl (Jan 29, 2014)

Currently sketching out my stratified downdraft gasifier design. Will post pics once done with details on materials and dimensions.


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## biggkidd (Aug 16, 2012)

Thank you for keeping us up with your plans and ideas. I am trying to check back everyday. I can't wait to see how you make out with this. I would like to build one myself, just to many projects at the moment.

Keep up the good work.

Larry


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## fishhead (Jul 19, 2006)

What does that blower on the drawing do? Depending on which way it blows it would either suck the gas out of the system or push it back into the wood chamber.

I've been told there are plans for producing wood gas on the DOD site too.


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## Esprit (Dec 17, 2011)

There was an article in Mother Earth News a couple of years back about a fellow who powered his Dodge pickup trucks this way. The only downer was they didnt publish any detailed plans.


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## a_dahl (Jan 29, 2014)

fishhead said:


> What does that blower on the drawing do? Depending on which way it blows it would either suck the gas out of the system or push it back into the wood chamber.
> 
> I've been told there are plans for producing wood gas on the DOD site too.


 
The blower is used to draw air through the system for start up then once you are getting gas you can start your engine and that will draw a vacuum on the gasifier.


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## fishhead (Jul 19, 2006)

That makes sense.


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## oldhermit (Apr 28, 2013)

I had a relative die in a steam engine accident. The way I understand it steam shot out of a fitting and scalded him to death. Not a good way to go.


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## just_sawing (Jan 15, 2006)

The other part of the gasifier question is a problem for the government. A gasifier by their own standards are CO2 neutral so they has no real way of trying to stop you from being independent. 
Every Homestead should have a working model to supplement and reduce the grid cost.


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## bloogrssgrl (Jan 20, 2008)

My husband is planning on building one to heat our home, but I don't think he intends to use the gas to power anything with the one he is designing at the moment - just recirculating the gas to a secondary burn chamber, kind of like a super efficient wood boiler. However... that could possibly change either with the one he's designing now or one he plans to build in the future.
At the moment, we are still in the stockpiling of materials phase. Fortunately, he works for a power plant and gets to take home the extra goodies after the maintenance outages. Pallets and pallets of refractory... 
Would love to see how your project progresses!


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## neverfear (Sep 26, 2006)

This is the one that I just installed at my new house and it's currently running as we speak. This bad boy boiler is the cats meow, hands down, bar-none, it's a beautiful thing Indeed!

http://www.woodboiler.us/index.php/gasification-model-epa/


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## watcher (Sep 4, 2006)

Any hard numbers on the volume/weight of wood needed per unit of gas produce?


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