Newbie with a question

Hi I am new here and interested in learning all I can. All I can do for now is surf the net. In my research I came across this guy Larry Dobson. The following is a link to his site. The guy seems to have a lot of experience with gasifiers and the link has some pretty interesting concepts and files. Does anyone have any knowledge or background they can share here?


Welcome to the site Allen. I don’t know too much about Larry Dobson’s design, but I do know that the Open Source Ecology folks are teaming up with him to build gasifiers for their system. Check out

We have Larry Dobson’s design here in the resources area if you need it:

The Dobson gasifier is designed for heat applications only and uses ceramics in the build to handle the high temps. I asked the designer about using sheet metal in place of castable refractory and he felt sheet metal would not be able to hold up to the intense heat. I agree with him. Wayne;s gasifier is designed to use the heat for more efficiently and a better quality of wood gas that is higher in hydrogen concentration according to tests done by the University of Auburn is produced. You will not find anything close to his design in any of the books. Fifty bucks would have saved me years worth of my time.

Chris and Woody,
Thanks for the advise. I have requested the info on how to pre-buy Wayne’s book. I am sure it is and will be money well spent. I am afraid this is going to be one of those “I just can’t get enough of it things” as the research continues. Any rabbit trails I can avoid will be helpful.
Thanks again,

hi Allen, I’m a newbe also I live in brandon area not to far from mcdill afb. would like to get aquanited with you if you are ever in the area. Baybe we can get together and do some buildplanding. contact me at mjedens at yahoo dot com

Hi All
Larry Dobson is a “close” in state neighbor. I have visited with him and on hands touched some of his stuff. He is for sure real. Do read his material and especially tab up read all of his pervious work, look at his systems pictures of put into the real world 90% efficient furnaces. Especially read his published Department of Energy papers. His back ground and experience is in fueling with up to 60% moisture wet chip and sawdust for heat. In the combustion triad of Temperature, Time and Turbulence he clearly has stated his systems strongly promote HIGHest Temperature, LONGest residence Time, at the LOWest turbulence possible. Closed top, side jets with restricted opening hearths are a High Turbulence, moderate residence Time (both related to Superficial Velocity) at a controlled lowest effective Temperature possible. LarryD knows from engineer training and experience that HE must use ceramic in the core to survive with his method. Some of his pictures show his silicon carbide castings glowing orange. Experience has taught him that just falling relatively “cold” fuel dumps can thremal shock crack ceramic casings. We know that in “Imberts” gotta get the temperatures UP and generate enough heat to carry through the reactions, yet control them to in a relatively narrow range to keep from heat/erosion killing the system materials. Wayne does this using common carbon steels with controlled heat pull out and recycling. The later APL/GEK systems with temperature feed back electronic controls. A few other builders monitoring reduction zone temps and manually controlling now too. Pre-WWII, post-WWII European, current Victory Works and others get the temps up quickly and them let them float upward float and combat system destruction with high chromium/nickel refractory grade alloys.

AllenJ. with more time for now than ability to DO something also read a VTHR furnace link Robin Redmond put up here in the General Discussion Forum on a "single chamber stratified batch . . . " for another perspective. Close coupled gasification and not motor fuel capable.
Rabbit trails are OK. But soon as you can get with somebody actually DOing/Operating something to avoid the expensive down an Alice hole time and $$$ wasting. Once you need to feel/see some of these principals involved you can simulate ~80% in a good modern air tight/controlled air, closed bulk woodstove as long as it has a good drafting insulated chimney and a glass front viewing window to be able to see/smell and feed back human control.

I have a standing offer to LarryD to take up an 8.5 kW gen set to proof his system as motor grade fuel gas capable when he is ready. just three hours and a ferry day trip away. This latest he is postulating as an 80% heat/20% motor fuel system. Stationary only. Have to have use for all of that heat. If he sticks with cast ceramic cores I am skeptical about rough road service.
I believe he will be stationary IC motor fuel successful. Ha! Ha! I an still trying to wrangle him out of a 30 year old cast in former Yugoslavia no longer made excellent wood stove he has in his house. He won’t even take money and an offer for a new modern replacement. As I said; smart, smart man.

Steve Unruh

Thanks Steve,
Great comment and information. If I followed you, Dobson’s design is for a different purpose than Keith Wayne’s and may be better for a stationary system that can utilize the heat. If you wanted a system to just run a generator, is the Dobson design inefficient since heat is wasted? It also looks like a difficult build.

Glad to see your still at it…I always appreciated your input & knowledge …