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Woodgas Pickup Truck
For the first "Power Exchange" workshop in March 07, our project was to convert a 1975 GMC pickup truck to woodgas operation. And do as such in one weekend. We didn't quite make the "one weekend" goal, but at some point the following week we did find ourselves with a working gasifier unit, driving around West Oakland and Berkeley, on nothing but wood pellets and grins.
The weekend workshop started Friday night with a not-so-short lecture, by me, on the technology, history and future opportunities of gasification. I smoked cigarettes (a readymade gasifier), heated steel pipes full of coffee grounds to make pyrolysis gas, and ran my little demo Quadrafier into a typical Home Depot 5kw generator. Saturday and Sunday was building, noon to nine each day, with about 15 people total. The names of all participants are at the bottom of this page.
I purposely did not preacquire any materials for the workshop, or even really settle on any particular design or sizing before the weekend. I was interested in what we could do starting with nothing. Well, nothing on top of full fab and machine shop with lots of junk lying around, and a year plus of reading about eveything "gasifier". So not really "nothing", but nothing purchased directly in preparation to do this. We tried to use only things readily available in most junkyards.
The finished rig is admitedly a bit of a carnival of gasification. No attempt was made to have it small, tight and discrete. On the contrary, the goal was to have all the systems exposed and exploded for easy teaching and demostration. It is likely a beauty that only a gasification geek can appreciate. And maybe John Rinaldi too (aka: Chicken), the truck's current owner..
Pictures of the "finished" truck are below.
Pictures of the construction process are at the following links.
Jessica Hobbs pictures
(first firing attempt)
Participants in Workshop and Fabrication
Jim Mason, Jessica Hobbs, Chicken John, Phil Glau, Alec Plauche, Les
Young, Bruce Arneson, Steve Nelson, Roger Carr, Eric L. Forsman, Kiko
Almund, Dov Jelen, Caroline Miller, Chris Schardt, Patrick Buckley, Dann
Davis, Darrel Licks,
Notes on Construction
We decided to start with the most simple type of downdraft gasfier: the
stratified downdraft, based on the Reed/LaFontaine design in the FEMA,
Building a Simplified Downdraft Gasifier book.
Our main variation on standard construction was to make the firetube easily replaceable. In fact, in the end our "gasifier" tank is really only a gas cowling and ash catcher. Firetubes or any other gasifier hearth center design can eaily slide into the center and bolt down. This easy change out of the critical hearth/firetube section makes experimentation much easier, as well as adjustment of the gasifier size to match gas flow needs. Running all the "tubes within tubes" at the same time, down to the desired smallest one for fire, also creates excellent insulation of the operating firetube. We can restart the gasifier without a match after a full night of rest. The heat retention is exceptionally good with essentially a three or four wall tank.
Here's what we used in construction.
- a 25 gal propane tank, 14" in diameter, is the starting fire tube,
with a 50 gal vehicular propane tank making the external gas cowling.
- inside this cowling, we can insert 12, 10, and 8 inch firetubes at the
moment. more variations to come soon.
- the cyclone is made from a 8" diameter welding bottle with hvac
reducers press fit inside to establish the needed taper.
- the radiator is 4" square tubing for tanks, with 3/4" emt
conduit as the tubes, with the galvanizing removed in acid before welding.
- the dry filter is a shop vac filter in a 5 gal bucket
- the carburetor is a pipe T at the stock air cleaner inlet, with a butterfly
valve on the air side. the buterfly in the stock carburetor is the throttle,
as usual. gas is shut off to the carburetor to change over to woodgas.
both woodgas and air pass through the stock air filter.
- plumbing is shop vac hose after the radiator. before the radiator is
all steel drain piping, hard welded.
more details coming soon.