North Korea has had to deal with a horrific fuel shortage over the last decade. Sanctions and a mismanaged economy have left the country unable to buy enough petroleum based fuels for vehicles. North Korea coped by falling back on an old but cheap and reliable solution, wood gas. When you burn wood or coal in a low oxygen environment you produce carbon monoxide and hydrogen gas that can be sent directly to a diesel or gasoline engine and produce enough horsepower to move a truck, boat, or any other engine. This is not as efficient as diesel or gasoline/petrol type fuel. A liter (quart) of gasoline produces as much engine energy as 2.75 kg (six pounds) of wood. That means you need three times as much fuel (by weight) when using wood and coal. The process (which usually takes place in a container the size of a 55 gallon barrel) produces a lot of air pollution and requires more regular attention than a diesel or gasoline engine. But it works, and during World War II, when many nations were cut off from regular supplies of petroleum based fuels, wood gas was the solution for running vehicle, boat, and factory engines. Germany, for example, had over half a million vehicles running on wood gas by the end of World War II.
It is unclear how many wood gas powered vehicles are operating in North Korea, but they are a common sight along the Pacific coast and anywhere far away from the capital (which gets the best of everything). There are probably thousands of these vehicles up there.
The wood gas technology is mature. The basics were developed in 1839, but the first practical wood gas fuel units did not appear until 1900, and just before World War I they were gaining widespread popularity. Wood gas became popular for vehicles in out-of-the-way places where you could get the vehicle in but regular supplies of fuel were more of a problem. By the time World War II rolled around the wood gas technology was widely known and quickly implemented when petroleum fuel became hard to get. Since World War II wood gas has still been useful in remote areas and with those seeking to get “off the grid” and not be dependent on petroleum.