Battery used Battery charging


Wood Gas Vehicles: Firewood in the Fuel Tank

During the Second World War, almost every motorised vehicle in continental Europe was converted to use firewood.


During the Second World War, almost every motorised vehicle in continental Europe was converted to use firewood. Wood gas cars (also known as producer gas cars) are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars. Rising fuel prices and global warming have caused renewed interest in this almost-forgotten technology: worldwide, dozens of handymen drive around in their home-made woodmobiles.

Wood gasification is a proces whereby organic material is converted into a combustible gas under the influence of heat - the process reaches a temperature of 1,400 °C (2,550 °F). The first use of wood gasification dates back to 1870s, when it was used as a forerunner of natural gas for street lighting and cooking.

In the 1920s, German engineer Georges Imbert developed a wood gas generator for mobile use. The gases were cleaned and dried and then fed into the vehicle’s combustion engine, which barely needs to be adapted. The Imbert generator was mass produced from 1931 on. At the end of the 1930s, about 9,000 wood gas vehicles were in use, almost exclusively in Europe.

Second World War

The technology became commonplace in many European countries during the Second World War, as a consequence of the rationing of fossil fuels. In Germany alone, around 500,000 producer gas vehicles were in operation by the end of the war.

A network of some 3,000 “petrol stations” was set up, where drivers could stock up on firewood. Not only private cars but also trucks, buses, tractors, motorcycles, ships and trains were equipped with a wood gasification unit. Some tanks were driven on wood gas, too, but for military use the Germans preferred the production of liquid synthetic fuels (made out of wood or coal).



In 1942 (when the technology had not yet reached the height of its popularity), there were about 73,000 producer gas vehicles in Sweden, 65,000 in France, 10,000 in Denmark, 9,000 in both Austria and Norway, and almost 8,000 in Switzerland. Finland had 43,000 “woodmobiles” in 1944, of which 30,000 were buses and trucks, 7,000 private vehicles, 4,000 tractors and 600 boats. (source).

Woodmobiles also appeared in the US, Asia and, particularly, Australia, which had 72,000 vehicles running on woodgas (source). Altogether, more than one million producer gas vehicles were used during World War Two.



After the war, with gasoline once again available, the technology fell into oblivion almost instantaneously. At the beginning of the 1950s, the then West-Germany only had some 20,000 woodmobiles left.

Research programme in Sweden

Rising fuel prices and global warming have resulted in renewed interest in firewood as a direct fuel. Dozens of amateur engineers around the world have converted standard production cars into producer gas vehicles, with most of these modern woodmobiles being built in Scandinavia.

In 1957, the Swedish government set up a research programme to prepare for a fast transition to wood gas cars in case of a sudden oil shortage. Sweden has no oil reserves, but it does have vast woodlands it can use for fuel. The goals of this research was to develop an improved, standardised installation that could be adapted for use in all kinds of vehicles.


This investigation, supported by car manufacturer Volvo, led to a great deal of theoretical knowledge and hands-on experience with several road vehicles (one seen above) and tractors over a total distance of more than 100,000 kilometres (62,000 miles). The results are summarized in a FAO document from 1986, which also discusses some experiments in other countries. Swedish (overview) and, particularly Finnish amateur engineers have used this data to further develop the technology (overview, below a vehicle of Juha Sipilä).


A wood gas generator - which looks like a large water heater - can be placed on a trailer (although this makes the vehicle difficult to park), in the boot (trunk) of a car (although this uses up nearly all the luggage space), or on a platform at the front or the back of the vehicle (the most popular option in Europe). In the case of an American pickup, the generator is placed in the truck bed. During WWII, some vehicles were equipped with a built-in generator, entirely hidden from view.


The fuel for a wood gas car consists of wood or wood chips (see picture below). Charcoal can also be used, but this leads to a 50 percent loss in the available energy contained in the original biomass. On the other hand, charcoal contains more energy, so that the range of the car can be extended. In principle, any organic material can be used. During the Second World War, coal and peat were also used, but wood was the main fuel.


One of the more successful wood gas cars was built last year by Dutch John. While many recent producer gas vehicles seem to come straight out of Mad Max, the Dutchman’s Volvo 240 is equipped with a very modern-looking system made of stainless steel (see the first picture and the two pictures below and then compare to this Volvo, this BMW, this Audi or this Yugo).

Producing wood gas is not that hard”, says John. “Producing clean wood gas is another thing. I have objections to some woodmobiles. Often, the produced gas is as clean as the appearance of the construction”.


Dutch John strongly believes in wood gas generators, mainly for stationary uses such as heating, electricity generation or even the production of plastics. The Volvo is meant to demonstrate the possibilities of the technology. “Park an Italian sports car next to a wood gas car and the crowd gathers around the woodmobile. Nevertheless, wood gas cars are only for idealists and for times of crisis.”


The Volvo reaches a maximum speed of 120 kilometres per hour (75 mph) and can maintain a cruising speed of 110 km/h (68 mph). The “fuel tank” can contain 30 kilograms (66 pounds) of wood, good for a range of 100 kilometres (62 miles), comparable to that of an electric car.

If the back seat is loaded with sacks of wood, the range is extended to 400 kilometres (250 miles). Again, this is comparable to the range of an electric car if the passenger space is sacrificed for a larger battery, as is the case with the Tesla Roadster or the electric Mini Cooper. The difference is, of course, that John has to stop regularly to grab a sack of wood from the back seat and refill the tank.

As is the case with other cars, the range of a wood gas car is also dependent on the vehicle itself. This is shown by the different cars that were converted by Vesa Mikkonen. The Fin places all his generators on a trailer. His most recently-converted car is a 1979 Lincoln Continental Mark V, a large, heavy American coupe. It consumes 50 kilograms (110 pounds) of wood every 100 kilometres (62 miles) and is thus considerably less efficient than John’s Volvo. Mikkonen has also converted a Toyota Camry, a much more efficient car. This vehicle only consumes 20 kilograms (44 pounds) of wood over the same distance. However, the trailer is almost as large as the car itself.


The range of electric cars can be considerably improved by making them smaller and lighter. However, this is not an option with their wood gas cousins because of the weight and the volume of the machinery. The smaller cars from World War Two only had a range of 20 to 50 kilometres (12 to 31 miles), in spite of their much lower speed and acceleration.


Enlarging the “fuel tank” is the only option to improve the range further (except for reducing one’s speed, of course, but that is another story). American Dave Nichols (the man who shows the wood on one of the pictures above) can load 180 kilograms (400 pounds) of wood into the back of his 1989 Ford pickup truck. This takes him 965 kilometres (600 miles) far, a range that is comparable to a fossil fuel powered car. The merit of this is discussable, of course, as to do this Nichols has to stop regularly to refill the tank: if he loaded the back of his pickup with gasoline, then he could drive even further.

According to Nichols, one pound of wood (half a kilogram) is sufficient to drive 1 mile (1.6 kilometres), which tallies with the Volvo’s 30 kilograms of wood per 100 kilometres. The American has set up a company (21st Century Motor Works) and plans to sell his technology on a larger scale. When he arrives home, he uses his truck to heat his house and generate electricity. His story has caught on in the US, and the reason can be summed up by his license plate: “Freedom”.


You can go around the world with a saw and an axe”, as John Dutch puts it. His compatriot, Joost Conijn, grabbed this opportunity to take a two-month trip throughout Europe, without worrying about the proximity of the closest of gas stations (which are not always easy to find in a country like Romania).


The locals gave him wood to continue his journey - with the supply stored on a trailer. Conijn not only used wood as a fuel, but also as a construction material for the car itself (picture above - video here). For another trip with a wood gas car, see “Around Sweden with wood in the tank“.

Does the woodmobile have a future?

During the 1990s, hydrogen was seen as the alternative fuel of the future. Then, biofuels and compressed air took over its mantle role, whilst today all the attention is focused on electric cars. If this technology fails, too (and we have expressed our doubts about it several times), can we go back to the wood gas car?

Despite its industrial appearance, a wood gas car scores rather well from an ecological viewpoint when compared to other alternative fuels. Wood gasification is slightly more effiicient than wood burning, as only 25 percent of the energy content of the fuel is lost. The energy consumption of a woodmobile is around 1.5 times higher than the energy consumption of a similar car powered by gasoline (including the energy lost during the pre-heating of the system and the extra weight of the machinery).

If the energy required to mine, transport and refine oil is also taken into account, however, then wood gas is at least as efficient as gasoline. And, of course, wood is a renewable fuel. Gasoline is not.

The greatest advantage of producer gas vehicles is that an accessible and renewable fuel can be used directly without any previous treatment. Converting biomass to a liquid fuel like ethanol or biodiesel can consume more energy (and CO2) than the fuel delivers. In the case of a wood gas car, no further energy is used in producing or refining the fuel, except for the felling and cutting of the wood. This means that a woodmobile is practically carbon neutral, especially when the felling and cutting is done by hand.


Moreover, a wood gas car does not require a chemical battery, and this is an important advantage over an electric car. All too often, the embodied energy of the latter’s enormous battery is forgotten. In fact, in the case of a producer gas vehicle, the wood behaves like a natural battery. There is no need for high-tech recycling: the ash that remains, can be used as a fertilizer.

A properly-operating wood gas generator also produces less air pollution than a gasoline or diesel powered car. Wood gasification is considerably cleaner than wood burning: emissions are comparable to those of burning natural gas. An electric car has the potential to do better, but then the energy it uses should be generated by renewable sources, which remains to be seen.

The drawbacks of wood gas cars

In spite of all these advantages, it takes just one look at a woodmobile to realize that it is anything but an ideal solution. The mobile gas factory takes up a lot of space and can easily weigh a few hundred kilograms - empty. The size of the equipment is due to the fact that wood gas has a low energy content. The energetic value of of wood gas is around 5.7 MJ per kg, compared to 44 MJ/kg for gasoline and 56 MJ/kg for natural gas (source).


Furthermore, the use of wood gas limits the output of the combustion engine, which means that the speed and acceleration of the converted car are cut. Wood gas consists roughly of 50 percent nitrogen, 20 percent carbon monoxide, 18 percent hydrogen, 8 percent carbon dioxide and 4 percent methane. Nitrogen does not contribute to the combustion, while coal monoxide is a slow burning gas. Because of this high nitrogen content, the engine receives less fuel, which leads to a 35 to 50 percent lower output. Because the gas burns slowly, a high number of revolutions is not possible. A producer gas vehicle is no sports car.


Even though some smaller cars have been equipped with wood gas generators (see for instance this Opel Kadett), the technology is better suited to a larger, heavier car with a powerful engine. If not, engine output and range might not be sufficient. Even though the installation can be made smaller for a smaller vehicle, its size and weight do not decrease proportionately with the decreasing size and weight of the car. Some have built wood gas-powered motorcycles, but their range is limited (a motorcycle with sidecar does better, though). Of course, the weight and size of the mobile gas factory is less an issue with buses, trucks, trains or ships.

Ease of use

Another problem of wood gas cars is that they are not particularly user-friendly, although this has improved compared to the technology used in the Second World War. See the second part of this pdf document (page 17 and further) for a description of what it was like to drive a wood gas car back then: “…experience at the Wurlitzer organ could be a distinct advantage”.

Still, in spite of the improvements, even a modern woodmobile requires up to 10 minutes to get up to working temperature, so you cannot jump in your car and drive away immediately. Furthermore, before every refill, the ashes of the last gasification process have to be shovelled out. The forming of tar in the installation is less problematic than it was 70 years ago, but the filters still have to be cleaned regularly. And then there is the limited range of the vehicle. All in all, it is a far cry from the familiar ease of use of a gasoline car.


The large amount of (deadly) carbon monoxide produced calls for some precautions, too, since a leak in the piping is not impossible. If the machinery is placed in the trunk, the instalment of a CO-detector in the passenger compartment is by no means a luxury. Moreover, a wood gas car must not be parked in an enclosed space unless the gas is flared first (picture above).

Mass-produced woodmobiles

Of course, all the vehicles described above are built by amateur engineers. If we built cars especially designed to be powered by wood, and produce them in factories, chances are that the drawbacks would become somewhat less significant and the advantages would become even greater. Such woodmobiles would also look more elegant.

The Volkswagen Beetles that rolled off the assembly line during World War Two had the whole wood gasification mechanism built in (sources: 1 / 2 / 3). From the outside, the wood gas generator and the rest of the installation was invisible. Refilling was done through a hole in the bonnet (hood).



The same is true for this Mercedes-Benz, in which the installation is completely hidden in the trunk (source).



Unfortunately, wood gas shares an important disadvantage with other biofuels. Mass producing woodmobiles would not solve this. Quite the contrary, in fact: if we were to convert every vehicle, or even just a significant number, to wood gas, all the trees in the world would be gone and we would die of hunger because all agricultural land would be sacrificed for energy crops. Indeed, the woodmobile caused severe deforestation in France during the Second World War (source). Just as with many other biofuels, the technology is not scalable.

Yet, while biofuel-powered car is as user-friendly as a gasoline rival, wood gas has to be the most user-unfriendly alternative fuel that exists. This can be an advantage: a switch to wood gas cars can only mean that we would drive less, and that would of course be a good thing from an environmental viewpoint. If you need to preheat your car for 10 minutes, chances are you will decide not to use it to drive a few miles to pick up some groceries. A bicycle would do the job faster. If you had to cut wood for three hours just to make a trip to the beach, you would probably decide to take the train.


In any case, the woodmobile demonstrates (again) that the modern car is a product of fossil fuels. Whatever alternative fuel you believe in, none of them comes even close to the convenience of gasoline or diesel. If, one day, the availability of (cheap) oil comes to an end, the omnipresence of the automobile will be history. But the individual vehicle will never die.

© Kris De Decker (Thank you, R.O.)


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This is a very interesting article, but i would offer the following obervations:

If you attach the wood gas generator to the car, thats two sets of mechanisms that have to be maintained, the engine and the generator. That will be difficult without parts, lubricants etc, provided by crude oil. Plus you have weight considerations, which will inhibit efficiency, and initial purchase and installation cost. Peronally, i wouldn’t bother.

Second, You discount Hemp oil as a resource for this type of propulsion system. Surely a more profitable and sustainable biomass resource is Hemp, which will provide a new yield every year as opposed to 25 years for trees to regrow. Surely Hemp oil would remove the need for a converter to turn the wood gas into combustible gas.

If you look at any civilisation in history, if they chop down their trees, they don’t last too long. Haiti is a good example of this, the damage from this earthquake would not have been as bad if trees where around to absorb the mud etc that landlides.



I’ve written my Diploma Thesis (environmental engineering) about wood gasification in Bio-to-liquid strategies.

One obervation about the use of wood as fuel: Wood gasification uses Biomass that’s rich in lignine, which doesn’t decompose anaerobically, which you can’t gasify or liquify easily. Wood gasification turns this biomass into something that can be handled by an internal combustion engine, and there are lots of those about. Diversification of biomass sources can (that’s not a purely technical question) help to gain energy in a more ecological way.

To the previous poster: The gasifier has hardly any moving parts, so lubricating isn’t so much of an issue there. Sides, how many kilograms of oil does your car (should you own one) use, compared to it’s consumption of fuel?


This brings whole new meaning to “fire up the engine”.

But I agree with James’ comment. We are already chopping down our trees at an alarming rate. We need energy with a more infinite supply than either oil or wood.


Couple of points:

  • There should be some mentioning of the possibility of carbon-negative transportation via biochar. This is fine-grained charcoal powder that is permanently sequestered from the atmosphere.

  • the syn-gas could be cleaned up and split into its various components. Some of the combustible gases can be compressed. (see: ). This would eliminate some drawbacks such as the long start-up time for a woodgas car. Applications for this also exist in agriculture (syngas-powered tractor). I have talked to farmers who are promoting this idea, so that they can use their farm residue as fuel.

  • the possibility of small-scale fermentation of woodgas exists. Again, this would be an application for non-mobile use. The syngas is fermented into ethanol (Coskata is commercializing this process)

  • the yield of syngas from biomass can be greatly improved by making use of an external heat source (such as solar thermal or nuclear). This way, none of the syngas would have to be diverted for thermal use in keeping the reaction going.

  • As will all automotive ideas, much lighter materials are possible, allowing for complete redesign of the automobile (see: Aptera)

  • of relevance:

Mike LaRosa

One of the better articles I’ve read on the subject. Thanks ! Only one “mistake” that I caught (“coal” monoxide). I’m glad to see Dave Nichols and Vesa in the article and of course, John. These folks have spent piles of time trying to get the word out and also present a clean and professional image with their units. I’m dissapointed that my trucks or cars or Wayne Keith’s trucks didn’t appear in it but then I’m not trying to market anything and my stuff is made from junk and Wayne does his bit in the southern US. I just enjoy being part of the scene and every mile I log on woodgas is a grin. I have many thousands behind me now. Regards and BBB, Mike LaRosa, Linden, Wisconsin, USA

Thornton Kay

Robin Hunt, Simon Chippendale and I built a producer gas unit using old second world war plans at Walcot Reclamation in Bath UK in the early 1970s. I was the boffin and they were the mechanics. After many hair-raising and eyebrow-singeing experiments we finally got it going, welded to chassis extensions looking very similar to your pics, I think to an old Singer or the like.

It had to be run on small blocks of wood, around 2ins or 3ins cubes, otherwise the pieces did not have a large enough surface area to generate enough gas. We tried it out on public roads, but its main disadvantage was that each time it went over a bump there was a large release of a massive bubble of gas which had nowhere to go, apart from out of an overhead relief valve which immediately lit every time it released the gas, rather like a jet engine.

The local traffic cops were bemused. They could not decide which laws we were breaking but they were certain we were. We gave up trying to work out the bumping gas release issue and the last I heard the mechanics took the car to a field, jammed the steering wheel over and the accelerator down, and shot at it until it stopped going. Who knows it might still be in a hedgrow somewhere outside Bath to this day.

Tim Auld

You might want to review your position on ethanol after digesting David Blume’s material on the sustainable cropping and production of the fuel. Corn is one of the worst performing crops, but there are many others yielding in the order of 2000 gallons per acre.

Because much of the crop is not fermented (the roots) and the nutrients can be returned to the soil, it can be both carbon negative and sustainable. Many crops can be grown on marginal or arid lands, on waste streams, and without cultivation, fertiliser, herbicides or pesticides. If the US stops wasting grain on feeding ruminants, and employs much more productive, ecology based production systems such as permaculture, there won’t be a shortage of arable land.

Ethanol burns cleaner, cooler, and can get better mileage than gasoline, requires only minor engine adjustment, and you don’t have the disadvantages of wood gas. Farm grown ethanol powered America’s auto fleet into early last century, before gasoline got the upper hand by crook. It even helped powered Nazi Germany. For a quick but comprehensive introduction to the topic I recommend the Alcohol Can Be A Gas DVD. He answers your concerns. It can be done poorly, and it can be done extremely well.

Alexander Healy

Wow! My only question is how to make it sustainable - how do you upkeep the supply of fuel?


The word “almost” in the first sentence has to be unwarranted. That cannot be true. The Russian, German, American, British Armies, etc., did NOT run their vehicles on wood gas.

Dutch John


We cannot. It is impossible to plant and harvest enough biomass to maintain the present milage per capita. For mobile applications, biomass remains a fuel for crisis times, despite it’s carbon negativity and low other emissions. Making your own fuel makes one humble. Making your own fuel reduces unnecessary trips to nil. Making your own fuel is hard on the muscles, but sweet for the mind. It both allows and forces you to think about how to contribute to a more sustainable world.

Kris De Decker

Roger (#9): it were civilian vehicles that were powered by wood gas, not army vehicles ( although some were, see this link for instance: )


I just received a link to Low Tech from my friend and I’m free to say: this is the best blog I visited. Ever! Please, improve your visibility in search engines, there are a lot of people worldwide who would enjoy your articles but no opportunity to find you.


So can you use wood pellets, like they use in pellet stoves? Could you feed them in a few pellets at a time (like a pellet stove)?

Pellets can be made from grasses, sawdust, scrap wood, seaweed, and other cheap renewable biomass. You can buy them in bags, or maybe at some refueling station of the future.

Would you really need such a large contraption if you fed your system with a measured amount of pellets?

Dutch John


There are a few small gasifiers powered by pellets. Auger feeding them is possible, but that’s too heavy and complicated for mobile applications. Besides the fact that pellets are too small for medium car gasifiers, you still need a large storage to get some milage. And the gas is still dusty and humid, so you also need that large cleaning train. Personally I prefer wood above pellets, because pellets require more fossile fuel for manufacturing and transportation and they make you dependant on suppliers. But you are right on the advantageous fact that pellets also can be made of other biomass.


Great Job John! The next evolution of the woodgas car is stationary refining of the syngas into liquid fuels for longer travels and better mileage without the extra weight. is a community focused on gasification with lot’s of videos and links for those of you that find this interesting.


Thanks Dutch! You can make your own pellets too. If you look on eBay there are pellet machines available. They are a relatively low tech device. Agreed about the added complexity of an auger or archimede screw pump for the pellets. Engineering challenges at the least, showstopper at the worst….

Johnny Payphone

They could not decide which laws we were breaking but they were certain we were.”

This is a very telling sentence. I first experienced this factor when trying to commute by bike. As a bicyclist is clearly a bum, punk, or escaped convict, I was often harassed by police who were completely uninformed about the law. (“You need a driver’s license to operate a bicycle” “You’re going slower than the law allows” “your bike trailer exceeds the width allowed for bicycles” etc etc) When it comes to vehicles, any hearse or art car owner knows that the police will ticket a noticeable vehicle 100 times more than the green saturn that they just don’t see.

Political activism and police relations are key to alternative fuel use! It’s that, or stealth. Community relations must be undertaken to educate the public and make them friendly to the technology, and antique laws must be changed to allow for new tech.


What would happen if you ran it on waste plastic?

Dutch John

Plastics contain a lot of nasty stuff, like chlorines. You do not want these poisonous pollutants blown into the environment.


What I’d like to see is a converted electric home generator that can run using this woodgas system. In case of a grid power failure one could just use the woodgas generator as backup. Imagine, no storage of diesel or gasoline which goes bad after several months time. If the grid failed then gas stations couldn’t pump fuel anyway. If this was small enough you could attached it to your RV and camp in way out places where there wasn’t any electricity.


A good technology for the fall of a civilization, but not for its permanence.


re Johnny Payphone

Could it be that in some quarters in the developed world some of the present day DIY low tech is seen as subversive and threatening, while other low tech is politically and commercially non-threatening?

Suggested low tech types and their acceptablity: 1. Low tech from the past = politically-correct and not threatening today’s commercial status quo 2. Low tech in the future, post apocalypse, mad max scenarios = nonpc and nonsafe 3. New sexy non-threatening low tech in developed world, eg strawbale building = pc and safe 4. Present day new age DIY low tech, eg producer gas cars = nonpc and nonsafe 5. University research low tech = pc and safe 6. Industrial and commercially developed low tech disaster relief technology for third world use = pc and safe 7. Third world development low tech = pc and safe 8. Developed world war time low tech = pc and safe 9. Undeveloped world low tech = pc and safe

From this you can see that anyone running a home made mobile producer gas car in peacetime Britain is seen as akin to Mad Max by the local magistrate.

Dutch John


How recognizable. I am allowed to drive on woodgas in the Netherlands, although customs already sees me as a threat. Once ten others also start to drive on wood, the party will be over.

Developing a small woodgasgenerator to power an electric genset for the third world is however encouraged…

Uncle B

Do a site on “Consumer Gas” from humanure and barnyard wastes - Consider that the Average American’s humanure is richer, by his diet, and larger by hid physical size than any pig manure found in Asia! Do we have a fuel source here? A free fuel source? Oslo, Norway runs city buses on sewage! Parts of Sweden also? India does this? San Antonio Texas is purported to take advantage of humanure also? Factory Farms produce copious amounts of Manure, why not bio-gas it into fuel and fertilizer? By law? This topic, low tech in nature but possibly highly rewarding for a full site!

Jim Mason

We’re running two 10 hour endurance tests on the GEK 10kw Power Pallet for the workshop weekend, this Saturday and Sunday. Peef set up a webcam so you can watch the proceedings online. See here:

The Power Pallet is running with full automation of fuel feed, woodgas/air mixture and grate shaking. All temp, pressure, and flow rate particulars are being datalogged for presentation after the run, as are the specifics of biomass in to electricity out. The fuel is regular wood chips. No exotically produced chunks. We’re running a variety of loads usually in the 3kw-6kw range.

Yesterday’s run went well. We ran somewhere between 10 and 11 hours without problem, no hands required to keep it going. We had one unplanned shut down to tighten a plumbing plug on the ash port that was leaking air. Air leaking by the grate mixes with hot gas and starts a bit of combustion. Always check your caps and plugs before you start. Doh!

Otherwise, everything worked happily. Not a single bridge or fuel blockage over the whole run. Filters looked good at the end too. It all seems annoyingly simple, given all the challenges to get to here.

Then again, bear isn’t annoyed. he’s just happy all his automation work is finally working so we don’t have to any more. Congratulations goes to bear for many rounds of deeply impressive mechatronic control work. And congratulations to jay for figuring out the bridging issues so the wood chips continue to flow without issue.

We’ll be posting more info in the forum as we go, so see here: Yesterday someone brought over a gas analysis machine and we finally got some real gas composition numbers. There is a picture of the read out in the forum at the link above.

We’re here until 11pm or so tonight. Come over and enjoy wood chip margaritas if you are in the area.

Cory Gohm

We throw away a lot of wood at the dump, and if we change our habits, such as and when we grow corn, we grind up the stock and throw that behind the combine which could also possibly be used as well. These are just two examples off the top of my head. Yes, it won’t be simple but it can be done.


Biomass gasification should only be used for stationary combined heat and power applications which increases overall system efficiency doubles (at least). There are vast areas where this technology is very practical - particularly in managed forests where the fuel is a byproduct of forest maintenance. Wood gas cars are an interesting novelty and a good demonstration of this old technology but of course they’re not a solution for sustainable transportation. I’ve read that when woodgas was a widespread alternative to unavailable petrol around the second world war various European governments had to ultimately legislate to ensure the countryside wasn’t stripped bare

Charles V. Greene

I would like to know how coal would work in this kind of burner? Would it produce a greater energy; Increase the overall speed and distance capability?.

Jonathan Spreadborough

In the United States there is a quite a few people who have completed successful woodgas projects. Woodgas is great stuff not just for automobile transportation but for electrical power generation. has some great info on woodgas, member pages with examples of their work, links to other useful woodgas sites and forums for discussing woodgas.


Bamboo has many advantages over timber. It can be harvested 3 years after cultivation. It will regrow without replanting.


We don’t haul petroleum refineries behind cars using fossil fuel, so why burden down a biofuel car with extra equipment?

If we leave the gas generator stationary at a gas station, we can make it bigger and more robust. This makes it more reliable (no rattling about to loosen the pipe fittings), and a larger burner means less heat loss, so greater efficiency.

Next, filter the gas to remove the tars, and pass it through a rubidium catalyst. Hydrogen leaks easily, and carbon monoxide is toxic; the catalyst will combine them to form methane and water.

Pass the gas through several filter beds (lime, zeolite) to remove the carbon dioxide and water. Regenerate the filter beds using waste heat from the burner.

Finally, compress the gas so you can separate out the methane from the remaining carbon dioxide and the nitrogen.

Store the gas in cylinders, and swap them for empties when cars come in to refuel.

Andres Mauricio

Making your own fuel makes one humble. Making your own fuel reduces unnecessary trips to nil. Making your own fuel is hard on the muscles, but sweet for the mind. It both allows and forces you to think about how to contribute to a more sustainable world.


I use a wood gas camping stove its a great piece of kit, these things are monsters in comparison.


I just wanted to inform you guys about logging in north America. I’m a logger, and we burn the top 30 feet of almost every tree, and any tree that is not straight enough for the mill. So if you guys could see the amount of wood that could be used for this, that is already being burned anyway, I believe many would be shocked. I hope that these cars become more common, I see a large surplus of this fuel being burned already, just to dispose of it.

Mark Garrabrant

I went to Germany in 1946 as one of the 1st military dependents and was fascinated by all the wood powered trucks. A lot or them used a dual chambered burner with a sealed gasification chamber and an open wood,charcoal or coal burner to heat the wood in the sealed chamber. The charred wood from the sealed chamber would be burned later to heat more green wood. A lot of the trucks were small 3 wheel pick-ups. I was 9 years old at the time. I went back at 14 years old and wood powered trucks were gone.

Ken Driessen

If you make the gas by destructive distillation in the absence of air like I do, compressed wood gas works great; it is basically natural gas. You don’t have to have psychotic hypocrite disorder (a PHD) or even a Masturbator degree to understand the Energy Bootlegger(tm), plain old common sense works fine. My invention, which is patent pending, as the Rural Residential Energy Harvester(tm). The Energy Bootlegger will change the world for the better as soon as the people demand the monetary manipulating, energy monopolizing, war profiteering spawn step aside. Yes I call them ZioNazis and certain Jews collaborated with Hitler while their less fortunate working class countrymen died so they could profit. See

DC Kerr

Whoa - gettin’ kinda deep…speaking of alternative feed stock for gasahol - check out melon-water. Very high in sugars & we dump millions of gallons each year. There are as many viable alternatives to fossil fuels as there are excuses for not using them. Ignorance shouldn’t be on the list. With co-generation…construction, demolition and other wood-waste shouldn’t be in our land-fills -dc

greenleaf rivers

does any body have an any ideas on producing a small amount of wood gas in the kitchen as a supervised experimental demonstration for my children?


This is a great article. Although running a car on woodgas is a cumbersome affair, it would be great to burn scrap wood and be somewhat free from big oil. I’m going to be converting a second truck I own to do just that, thanks to a high school kid with access to a cad based plasma cutter. To the posters above concerned about trees: I am a professional forester and we have more treed acres with more trees on those acres than there were here in 1492. Our problem isn’t cutting too much, our problem for the last 40 years has been cutting too little. Our forests are falling apart because of high densities of trees and species conversion due to lack of fire (and/or management). Contrary to popular belief, you can’t just let nature takes it’s course, unless you’re willing to watch things just fall apart and burn up. In my opinion, it’s better to log (create and maintain jobs) and use this wood for fuel, heat, or whatever than to let it fall apart and inevitably burn up.

Just my two cents. Bryan


Instead of wood, could you use bamboo instead? would it still have the same benefits?


Well, there is no way this would work on any scale in market-driven economy, not at least as far as any volume of fossil fuel is available… You’ll have to MAKE people use this (a common problem with all such thing, yeah).

May be the only area it could be usefull is - fuelling small / medium trucks in remote rural areas, where gas is not only quite expensive in comparison to the income of the locals, but also difficul to get. However, in practice that didn’t work, not even in Siberia where this technology has been tested from 1940s to 1950s.

Another possible application of this tech would be in a post-apocaliptic scenario, with anything else beyond reach.


Ridiculous! If you want to use wood for car fuel, make methanol from it.

Kris De Decker

Mike: making methanol introduces an energy penalty that would make a methanol driven car much less efficient than a woodgas powered car. You would need much more biomass to drive the same distance.

Richard Hiner

I am making a documentary video about a wood gas propelled truck and its builder. “Art” drove wood gas trucks 200,000 km on the Russian/Finnish border during WWII. The video will contrast the “Mad Max” post-apocalyptic world where people kill for fuel with my vision. I see of a bunch of new age multiracial “hippy” types sharing a wood gas powered truck pulling loads of local vegetables, fresh fish, kegs of beer and handicrafts to town for trade.

For now, this technology is only of interest to hobbyists, cranks like me, and, of course, you. That’s just fine. When the collapse arrives, let us share our knowledge to construct a more gentle and egalitarian society.

Daniel Girald

Regarding vegetable-based biofuels, I’m actually more into vegetable oils (either raw or waste cooking oil), biodiesel (which can eventually include waste fast from meat processing in the blend) and at a lower extent ethanol. But I can’t deny that I would like to perform some experiences with wood gas too.

Peter Lawrence

My back of the envelope analysis suggested that it could be worth while running farm equipment off gasified crop waste, particularly if the ash were recycled via settling ponds to grow green manure from nitrogen fixing pond weed.

With that, non-renewable farm inputs go way down, making it a lot more practical to grow other biofuels that are more convenient to use in other vehicles (it wouldn’t be anything like as practical to use the convenient biofuels to run the farm equipment as too much of the yield would have to be re-input, but that issue doesn’t come up with gasified crop waste).


Why not combine an Electric car with a trailer with a Wood gas driven Engine powering an Electric generator feeding the car att all times, even while driving, while burning gas fumes.

There would be no need to put out the fire while parking since the charging is Active as long as burning is Active. This would improve range of car an efficiency of Wood gas burner.

Erwin Lapschies

Looking for a reliable gasifier…. Please let me know where I can buy one…

paul mccombie

Erwin I am a newbe on woodgas but I joined drive on wood wayne keith has a unit that works rather well I took 4 monthes to build and add to a 97 gmc with good driving and love it.check it out .


The latest cutting edge gasifier I’ve heard about involves putting the dirty producer gas through molten metal, which cracks all the tar molecules to produce a very clean gas. This method allows for gasification of biomass other than just wood, since reduction zones are not necessary (molten metal cracks tar molecules) and the heat range of the material as it gasifies is also less stringent. Waste (trash) can be gasified, put through molten metal, and come out cleaner than the best wood-only gasifiers on the market today.

Wonder how this new gasification technique would rate on an environmental level if concentrated sunlight (parabolic dish or trough) were used as the heat source for both gasification and the heating of the metal to its liquid state. 2 birds with one stone; efficient trash processing sans landfills, with the byproduct of fuel gas.

But, of course, a solar powered refinery for waste gasification is a combination of two separate systems and hence, too complicated and creative for realistic consideration. Just ask the oil and coal companies and I’ll bet they’ll tell you all about how impossible this would be. ;)


If you are using charcoal as your feed stock you can increase the efficiency by using C02 instead oxygen to reduce the charcoal once you have it hot. The charcoal will strip one oxygen atom from the C02 making 2 carbon monoxide molecules instead of just one for each carbon atom burned from the charcoal.

jp vinkel

My father had a citroen running on charcoal but. had a handle that could switch if needed to the gasoline in the the tank


As a former forester I know there is a lot of “slash” leftover after logging operations. Especially in coastal ares where they harvest large trees like redwoods. They leave behind slash that is larger than the trees we harvest and use in the Boreal forest . The reason it is left in the bush is that it is not economic to haul it in to the mill. One of the ways to reduce this slash was moving chipper machines out to the cutover. Smaller logs and branches can be chipped, to use more of the tree. The chips are hauled to the mill in large tractor trailer units. But there is still a lot of unused wood in the form of rotten trees and unwanted species.

I don’t see gasification replacing petroleum fuels, but it could be an addition to the energy mix in the future: solar, hydro, wind, biogas, gasification, pedal power etc. There are lots of wood shipping pallets that are sent to the dump. And lots of construction waste could be recycled too. Using them for gas fuel would be a better alternative to simply dumping them.

Actually, I wonder if anyone has tried to use paper and cardboard as fuel in a gasifier. I imagine I could keep one running quite happily just by emptying recycling bins in my immediate neighbourhood.


Could you please indicate the source/reference for that sentence: At the beginning of the 1950s, the then West-Germany only had some 20,000 woodmobiles left.

stoytcho stoev

Have read the article years ago, but coming back to it with a new perspective of the problems.

As an interdiction I can say: If only the innovation energy of the individual ( and the companies ) was put in the right place, what a world would be all of us living in.

For starter, any fuel source, being supplied to ICE will provide you with no more then 25% ( 30% if extremely efficient engine ), motive power to the wheels, everything else is released as heat.

With meaning that using 100 liters ( or 100 kg wood ), max only 30 of them ICE is using for propulsion and the rest is up in the air as heat ( and extremely small percentage, less then 1%, for warming the car in the winter ).

The fundamental problem, is that the innovation is applied to the wrong base, in that case a motive machine with ICE, which is an extremely inefficient way for providing motive power.

An electrical engine, on the other side, provides easily 90%+ percent on the output as a motive power. An extremely efficient motive system, would be an efficient thermodynamic transformer from heat to motive power. A Tesla turbine (TT) is such a transformer, but for that one needs, small scale system, closed system boiler-TT-boiler to be engineered, and with efficient electrical generator, this is a win-win case for electric transportation, and efficiently using of the renewable wood-locked energy. It even can be made to be a co-existing system with exiting ICE, if ICE is engineered to channel its heat waste to boil water in a small boiler.

As to the electrical batteries in the car they can be considerably smaller ( it needed at all, of course ). For example 100kWh battery pack weights about 600 kilograms. a 20kg wood have theoretical energy density about 100kWh, same for about 8 kg petrol.

A main point here, is that we do not have a fuel problem, we have energy efficiency conversion problem, and the ingenuity of the most productive and innovative members of society needs to be directed appropriately, if we were to utilize wisely the limited resources this planet provides.


Can I ask what is the effect of wood gas to vehicles? Will it not harm the motor vehicles?


If the nitrogen were to somehow get separated from the gas itself, this would make the system much more attractive to those who demand perfrormance. The use of as much light alloy material as possible would greatly reduce weight.

Retaining the gasoline tank for driving during wood generator warm-up would add to convenience, as well as an oil bath gas cleansing system using periodic oil circulation depositing filtered-out soot into a filter. A warning light would inform the operator of the vehicle as to when the filter is to either be replaced or cleaned

[quote=James]…as opposed to 25 years for trees to regrow…[/quote]The earth is similar to a human head, in that hair falling out is replaced by fresh hair, in most cases. In modern forestry, wood is selectively culled, in order to make way for sprouting trees. It’s only primitive societies which recklessly deforest, in modern times


@ Sarah: In traditional applications, depending on the stove- and plumbing manufacturer, soot would collect in the cumbustion chambers which would require periodic engine disassembly. Theoretically, if the soot and tarry residue were to be fully separated from the gas, there would be no more damage in running a wood-burner than to run a modern propane-fueled vehicle, despite propane not burning as clean as natural gas. For vehicles motorized by 2-stroke engines, gas can only be used to fuel those using oil injection. For separating deposits from the gas itself, an idea of mine would be to use an oil bath air cleaner which is an older invention. But, still the most efficient, to date. There should be no reason as to why an oil bath air filtration system wouldn’t be able to remove all contaminants

BP Behrnes

I thoroughly enjoyed this article, if for no other reason than it brought back a lot of nostalgia for the time of my youth, the 1970s when the Fuel Crisis of 1973 brought about similar discussions of alternate sources of energy of all kinds, way back in the days of Mother Jones and Whole Earth Catalog and berkenstock sandals and Buckminster Fuller dome houses etc. I am not a mechanic and I am not a boffin but mostly just a dreamer and those were the dreams. Those were the days of peace love and granola and now it seems that we are in the age of peace love and granola and we’ll stomp your head in if you don’t agree with the BLM-Antifa-Wokers agenda. Tyrrany is not my thing. That’s why I evolved into who I am now from what I was, from a guy who voted for George McGovern in 1972 to the rock-solid Republican that I am now. My environmentalism now extends to little more than cutting up all the dead branches from my pine trees and raking up all the pine needles and using them for fuel for my wood stove. Its better to use ‘em for that rather than what most folks do where I live, which is to haul it all off to the dump, or the “sanitary landfill” — an oxymoron if there ever was. We also recycle. When we save up to enough bottles and cans to fill up my pickup truck and take it to the recycling center, the money we make is my wife’s mad money for the month, or enough for a fill-up of gasoline, which ever comes first. So with all that said, the green dreams of my youth are still dreams and I enjoyed reading your discussion of renewable automobile fuels. Keep up the good work.