Wood gasification
The project
- Goal
- Preparation
- Construction
- Results
- Word of thanks


The project: a modern gasifier on a Volvo 


My aim was to equip a car with a modern stainless steel gasifier. An American pickup truck was the first option, because of the practical loading platform, where the generator can find a spot. Also the low engine speed of oversized V-8’s suits woodgas very well.
A neat truck would however cost a considerable amount of money. Both the purchase and the vehicle holder's tax are high. Old-timers are even more expensive and often require a major overhauling. And a large car consumes more fuel, which has to be produced.
Therefore the only alternative was a strong sedan. Putting the installation on a trailer was no option. It should be a practical car, for which a parking lot could be found easy, even in the city.
I am Volvo-minded and a “brick” was still on the list “ever to possess cars”. Gradually and certainly after completion, the 240 has proven to be a right choice.

According to initiates, it has been the first serious attempt to build a mobile wood gasifier since the second world war in the Netherlands. The interest of biomass companies and the media forced me to build a neat construction. Thereby it would be necessary to engage professionals.


First I phoned the Dutch Road Association questioning if there are requirements with respect to driving on woodgas. There are none. Also, there are no tax issues; although later it appeared to be a huge problem…. But fortunately it could be solved.
The road association insisted on neat building and prevention of sharp parts, which could hurt pedestrians. This gave me the courage to start.

Next: study of necessary literature and become member of two woodgas forums for the necessary theoretical background. I recommend everyone who wants to build a serious gasifier to read at least one book concerning wood gasification. Without realizing what happens in the generator and without correct calculation of the oxidation and reduction zone, it is impossible a build a successful unit. Most of the initiatives fail because of a surplus of enthusiasm and a lack of ready knowledge. And lack of patience, a lot of patience….
In English there are several documents available, such as the FAO 72 paper: “Woodgas as Engine Fuel” and the “Handbook of Biomass Downdraft Gasifier Engine Systems”. Both books are outdated, but very useful for the basic knowledge and sufficient to build a successful gas generator. And they can be downloaded from the internet.

A tricky item was the weight at the back of the car. Every kilo on the platform is one and a half kilos on the rear axle. A light construction was necessary in order not overload the axle. Therefore a third part of the installation is mounted in the front of the car, for better weight distribution.

A targeted search on the forums taught me how to carry out the calculations. Calculations (for which the car must be either known or present) led to construction drawings, which have been changed numerous times. Meanwhile family members put my pencil drawings into Autocad. Kepser Prometaal was contacted to cut, bend and roll the parts. Will, neighbor and professional TIG welder, was asked to weld the critical parts. Innumerable problems emerged, but were solved one by one. That consumed a lot of time, but was very satisfying and enlightening . Although building a house is way simpler.....


Even before all the drawings were definitively ready and put into Autocad, I started building the details around the major components. The ECU’s of ignition and injection had to be disconnected during driving on woodgas and an extra ignition distributor from an older model had to be added. The gas/air mixer with four gas valves was a time consuming part to build, as well as the connecting bowden cables and levers. A new filter box with a separate compartment for the woodgas could only find its spot before the radiator, which had to be moved back towards engine. All in all I have spent more time under the hood and the dashboard than on the rear of the car.

Collecting the components does cost a lot of time. Without an open budget, the creative part of the brain conflicts with the rational part. But an enrichment for both!

The gas cooler has been built before the front axle, to take away weight from behind. I did not want the cooler being visible, because a cooler with sufficient capacity needs much space and does not look very elegant. It is also a sharp part that can wound pedestrians or cyclists at a collision. That is why it is under the car. A disadvantage is a smaller ground clearance. Still, it is a spectacular component. People gladly get on their knees to have a look.

Also the reheater is moved to the front. It reheats the wet gas from the cooler to get it dry into the final filter and engine. The reheater substitutes for the grill. There are few stainless steel grills. And none that weigh 25 kilo…
For a layman, the front therefore seems unchanged at first sight.

Every larger part is provided with puff lids or valves, to relieve a cough.

Being bored at a certain point, I called the Tax and Customs Administration with the question if wood or woodgas is taxed. A call I regretted later… The first answer I got was that every engine fuel is taxed. They would inform me how. After two weeks I received an extensive e-mail with bad news. Wood and woodgas are indeed tax-free, but because it concerns an engine fuel, the Tax and Customs Administration took a known fuel which is near woodgas, being methane, with nil tax. Well, good news, I thought…
Now, all taxed fuels have to be made on a place called AGP, where the customs authorities can check if a producer sticks to the law. In my case the car is the AGP. But an AGP is not allowed to be mobile. Conclusion and recommendation to the commission of wise men of the customs administration: “Gasification for mobile applications is prohibited”…
Boy, did I regret my telephone call! Fortunately a senior official of the ministry blew the whistle to his subordinates and wished me much success with the project! Thus my call brought something good, although the road to it was not very pleasant.


Doomsday was by the end of July 2008. After almost a year of preparation and construction that day would be put to the test. Really exiting!
We filled the hearth with charcoal and chopped wood on top. The electric lighting by means of a diesel glow plug was a wild guess of mine and I had no idea if it would work. So I turned the blower on, powered the glow plug and peered to the chimney for smoke: nothing. Tried again: nothing. Frustrated, I pulled the plug from the hearth and hot char flew out! And a minute later: flammable gas!

Thus we flared for an hour, in order to have the hearth settled. Meanwhile I had to adjust the ignition with a stroboscope light, whereas Diny, my wife, ran the starter motor. And believe it or not: the engine started! Just like that…. Woodgas lights that simple.
Anyone who has seen the woodgas videos on Youtube notices the face of a woodgasser, ready for the maiden trip, at the same time cheerful and anxious. For me that was no different.
I drove away carefully, but it ran so smooth, that after a couple of kilometers a speed of 100 km/h was reached! More than I dared to dream of. After thirty kilometers the party was over, because the high vacuum between intake manifold and mixer drew a hole in the hose.

Weeks went by and many of the bugs were removed and modifications added. Much of the theory can be found on the internet or in the literature, but actual driving on woodgas and solving problems are an attack on the self-educated mind. Or to put it bluntly, learn by damage and disgrace.

After 2000 kilometers on woodgas everything worked properly. Top speed is 120 km/h. Cruising speed 100-110 km/h. Fuel consumption approximately 30 kilos of wood for one hundred kilometers, which is also one effective filling of the fuel bin. The back seat loaded with sacks of wood make the total range approximately 400 kilometers.

The most beautiful compliments were given by the experienced Finnish woodgassers. According to them, the Volvo is the first car which is entirely built according to the current state or the art. The crown on the job is a reference with photographs in Vesa Mikkonens well known book: “Woodgas for mobile applications”.

Word of thanks

I want to pay my regards to the people who have cooperated in the project: 

“Maxgasman” for his enormous knowledge of mobile gasification. Without him I would have failed. Moreover he could temper my over-enthusiasm to a lower, but more stable level.

Vesa Mikkonen for his fantastic book (I it should have purchased it way earlier) and our frequent contact.

The members of the WoodGasforum and Woodgasbuildersforum

Chris, Bart and Stephan of Kepser Prometaal in Cuijk for providing the stainless parts

Will for its excellent TIG welding; you do not know how many compliments I have had to take for you!

Henry and Jacko for the Autocad drawings

Brother-in-law Toon for the use of the lathe

Car-electrics Van Dommelen, Wanroy and car company Wim Rische, Cuijk for selecting and repairing the ignition. How can one have so much work put into such a seemingly simple part? for donating the inverter

Devobo, Deventer, for the supply of the carwood

TJ Houston for proofreading this manuscript and Birgit for proofreading the German version

Mark Hendriks for building the website


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