Mother Earth News (MEN) Gasifier
Jeff Davis, May 2006
I clocked about 2400 miles of driving with this gasifier. That was an estimate and no subtraction for gasoline assist for up hills and starting out. So I'm sure it is somewhat less than 2400 miles. It was built out of discarded hot water tanks, exhaust pipe, black pipe, fittings and some stainless steel parts. Wood cubes were used for the fuel. At the time of use, I didn't have a good supply of dry fuel (wood). The mileage was about 2 lbs. of wood to the mile, at best.
It was the Mother Earth design that was some what popular in the early 80's. MEN is short for Mother Earth News. It would not be my choice today. I would personally never use a water filter/scrubber, like this design did. A spray type would be OK. Mother Earth claimed that it was easy to clean, just drain the water and replace with fresh water! Well for me it was prone to plugging up, which made for a real challenge to remove about ten gallons of tarry, soupy, stinky slop. Also, water likes to freeze in the winter. I also feel that it helped increase the total pressure drop of the gasifier and the lower the pressure drop the better. A lower pressure drop means the the engine/prime mover will have an easier time drawing the producer gas through the system. This means more power or in my case not much power!
I remember the globs of tarry goo that it would leave in the parking lot at work. I thought for sure someone was going to say something! I also remember the day my grand father came over to check it out. Dad and I had it running when he pulled into the driveway. For some reason, dad opened the lid to look inside (maybe it quit or something) and I was on the back of the truck also. Well, that was my first experience of a mild explosion, as they call it! Dad hung on, I jumped out of the bed of the truck and grand dad got into his truck and drove away. I can still remember the sound it made.
Although I never weighted the gasifier it was on the heavy side. Just too many ideas that could have been eliminated to help reduce weight and pressure drop. All kinds of pipes inside to help pre-heat the incoming air (this also would increase the pressure drop), water filter/scrubber, small tank on the outside that collected condensation and tar (that just plugged up and stayed plugged up). But the gasifier did work and a lot of the problems came from me trying to burn wood that was just too wet. In other words, I was the biggest problem. Gasifiers are systems and people do not like to think of themselves as being part of the system but they are! Also the fuel supply is part of this system.
At the time I was about 20 years old and this project is where I started to learn things like welding, cutting, brazing and general fabrication. But at the time it was the greatest feeling to finally roll this damn thing off the back of my truck and now 20 years later I'm starting all over again! Go figure. On the other side of the coin I felt the most alive building it and making those first trips down the road.
I had no true understanding of the fuel problem that was ahead of me! My distorted understanding was that one could chop up any old chunk of wood along the way. Well mean old Mr. Reality settled in fast and he never went away. For starters lets say that we have a good supply of DRY wood. Dry meaning 20% or LESS moisture content. Lets also say the we could get a pound to the mile and we drove 40 miles a day five days a week. That would be 200 lbs a week or 800 lbs a month or 9600 lbs a year. It would also need to be cut up into small pieces. But I needed 2 lbs per mile which adds up to 19200 lbs per year. Furthermore I drive more miles per year than that. One also needs a dry place to store your fuel. Before I constructed a gasifier, I should have built a solar kiln.
Below is information that can be found in a few publications from MEN:
Experimental Vehicle Newsletter #9: Shows the updated gasifier with updated WET filter. Quote from #9: In issue 3 of the Experimental Vehicle Newsletter and issue 71 of MEN an updated version of our original wood-gas generator was introduced. The plans that were subsequently published were based on the version shown in those issues. Even though that unit proved to be reliable and easy to operate, intensive research was continued to perfect a high- performance generator for the competition in the Future Fuels Challenge Rally. Even in the hours before starting time for the cross-country run from California to New York, major modifications were being made on our vehicle (see MEN NO. 72, page 192) As predicted, the three-thousand-plus mile trip was completed with out a hitch....but the refinements on our design didn't stop there. MOM's researchers continued to fine tune the gasifier and the carburetion systems in an effort to reduce maintenance and to simplify their construction without sacrificing performance. The following details are based on information gathered during research over the past 18 months. These discoveries probably represent the final chapter in Mother's investigation into the wood-fired operation of internal combustion engines. End of quote:
Experimental Vehicle Newsletter #10: Explains the woodgas carburetors. I liked the carburetion setup. It was a QuadraJet carb (4 barrel) with the primary barrels on gasoline. The secondary barrels was modified for woodgas. The woodgas throttle was controlled by a motorcycle twist grip mounted on my gearshift lever.
My plans are stock number 84030 called "WOOD GASIFICATION PLANS". Ordered on 11/04/81. It shows a dry filter but I used the wet filter in Experimental Vehicle Newsletter #9. I like the looks of the dry filter that's on the plans. Looking at the plans today, in 2006, I must say that they look pretty good. Not sure about the knife nozzles though. I do like the dry filter.
If you can not get a copy of these plans do not feel bad. Below are some links to Mother Earth News that shows most of the gasifier. I also believe that they got most of their information from the book "GenGas: the Swedish Experience from 1939 to 1945". You should be able to buy a copy at www.woodgas.com.
Make sure that you click on the link "ILLUSTRATIONS" at the top of the page.