WoodGas for heat and power

What I would like to do is use wood gas heat my house and make Electricity to sell back to the grid.

So, here is my where I am now:

  • I heat with wood using a Heatmor 400 DCSS outdoor boiler (up to 200,000btu) and 15-20 coords of mostly hard wood to heat a large old farm house and a shop for part of the winter. I have found that the larger the pieces of wood are the longer they last in the boiler as the air flow from the 2x150cfm blowers seem to send a lot of heat out the chimney. Now we will run out of large trees to cut for firewood at some point and be cutting regrowth and softwood to burn.

And here are some of the resources we have:

  • a large old 130hp Allis tractor and a small 23hp tractor, a newer tracked Cat 90+hp skid loader and a small 24hp wheel skid loader, a big 4 yard Volvo pay loader and a few 3/4-1ton farm trucks that can pull our 27’ gooseneck trailer.

  • Minnesota has a full retail power buyback net metering per Kwh up to 40Kw. I know that to grid tie there are inspections and Insurance of $300,000 and a engineer if its over 20kw. 8.15 per Kwh is the rate right now for us.

  • a 1.6l Chevette motor that is 60-70hp i think, was used for pumping water at one time.

What we don’t have is a Chipper or Chunker to make the wood smaller for a wood gas setup. I have looked at the chunker that Wayne Keith made from a old truck axle and other like it. It looks like a chunker would be slower to process the wood then a chipper but cost less to buy/build. The other thing with the chunker seems to be that larger wood 6"+ would require a VERY strong and much heavier built setup.

As for a pto chipper, I guess it seems to start at the Chinese ones for $2-3k and go up from there.

So any thoughts and ideas about size, cost and feasibility would be appreciated.


Forest hello
Wood gas for grid tie — YES — Bigger is better in my view go with a V-8. Liquid cooler for the wood gas. Wood gas coolant and motor coolant used for heat, if you need more heat turn on electric heaters. I also live in MN I use about 1000 gals of # 2 heating oil per winter. I don’t think burning the wood gas just for heat is worth while but taking the heat from a genset is.

Your goals are about the same as mine, except I’m not all that interested in the transportation part.
I still have a long ways to go. We live in western Wisconsin and our net metering deal sounds about the same a yours. I assume you are on a single phase power line since you mention the 40 kw limit.

Regarding the wood supply:
I think it was Jim Mason (or maybe Tom Miles?) who said something like this:
“—What starts out to be a gasifier design problem usually ends up being a fuel management problem.”
Boy is he ever right!!!
Anyway, the design of the gasifier will determine the fuel size and shape you need. I don’t think you get to just put any size of wood you want into any gasifier, so chunker vs chips is dependent, to a large degree on machine design, it appears to me.
—Although the GEK seems to be about as fuel tolerant as anything out there----

Wood chippers:
Again, I ain’t no expert, but:
There seem to be two basic styles of wood chipper available to ordinary human beings- drum and disk. In my short experience, the drum chippers make pretty small chips and the disk chippers can make bigger chips. I’d go with a disk chipper if I needed chips.
Having talked to several people who chip wood for a living as part of their tree service business, I was surprised to learn that the all say that the size of the wood chips is not adjustable, per se. They take what they get, focusing on productivity.
In general, and again, this from a non expert, the higher the horsepower of the chipper, the bigger the chips, the greener the wood the bigger the chips, the bigger the wood the fewer the twigs. The best (thickest) chips I ever got were from a 400 HP chipper doing whole trees.

Pete Stanaitis