Wartime Fuel of Shortage Times: Wood Gas-Powered Trucks
During World War II, fuel was rationed by both the Allies and the Axis powers. The military’s needs had absolute priority, but civilian transport couldn’t come to a standstill because without it, the war-torn economies would grind to a halt. Someone had to deliver raw materials to factories and later transport goods from factories to stores. Workers needed transportation as well. Faced with very limited access to gasoline and diesel, temporary alternatives were sought, one of which was wood gas.
Wood Gas: How Does It Work?
Wood gas is produced through a process known as wood pyrolysis. This involves heating wood biomass in a special container with limited oxygen access. During this process (in the part of the installation called the gas generator), gas is released, consisting of carbon monoxide, hydrogen, and methane. The gas is then filtered to remove solid particle impurities, cooled down, and passed through a secondary filter before finally reaching the engine, which has been adapted to run on this type of gas. Although an engine running on wood gas operates similarly to a gasoline or diesel engine, it is less efficient. This means more wood needs to be gasified to cover the same distance compared to using liquid fuel.
Wood Gas Trucks
Today, wood gas-powered trucks can mainly be seen in technical museums across Europe. However, this doesn’t mean they’re no longer in use anywhere in the world. In countries with underdeveloped economies, where access to conventional fuels remains a challenge, wood gas trucks can still be found on the roads. You can see them in Cuba, some African countries, and especially in North Korea. Occasionally, photos from this most isolated country reach the West, showing old Chinese or Soviet trucks equipped with characteristic cylindrical tanks, which are part of the gas generator installation. Interestingly, even military trucks are equipped with this source of propulsion.
In Europe, trucks (as well as buses and passenger cars) running on wood gas were most popular during World War II when fuel was rationed. Although no manufacturer offered mass-produced models with such propulsion (since all production efforts were focused on the war), it was possible to buy ready-made gas generator installations to retrofit existing vehicles to run on wood biomass gas. After the war, when fuel became readily available again, wood gas trucks became obsolete. This was a typical temporary solution during times of shortage, whose drawbacks outweighed its benefits. We’ve already mentioned that a wood gas-powered engine was less efficient. Additionally, this power source limited the vehicle’s cargo space (as extra wood had to be transported, sometimes on roof racks in passenger cars), and the weight of the gas generator installation further reduced the vehicle’s performance. Aesthetics were also affected, though this was the least of concerns at the time.
Wood Gas Today
As mentioned earlier, after World War II, wood gas as a fuel for trucks lost its significance (aside from isolated cases worldwide), and it’s unlikely to make a comeback today, even as we strive for zero-emission road transport. Although wood is a renewable resource, relying on it does not necessarily make a fuel source sustainable. While burning wood gas is significantly less harmful to the atmosphere compared to gasoline or diesel, the lower efficiency means much higher wood consumption. To meet the energy needs of an entire fleet of trucks, enormous amounts of wood would be required, potentially leading to excessive deforestation and forest management problems. Not to mention the reduced payload capacity of trucks, as some of the space would have to be allocated for transporting biomass for “refueling.”
This means that the only reliable path to zero-emission truck transport remains in BEV trucks and hydrogen fuel cells, along with transitional solutions like HVO biodiesel and BioLNG gas. Wood gas will likely continue to be used in heating buildings, rather than powering trucks.