An engine that runs on wood!

During world war 2 fuel was in short supply. Petrol, like most things, was rationed. So people turned to some ingenious inventions to keep their engines running and wheels turning. Gas was identified as a suitable alternative fuel and all manner of vehicles were quickly fitted with huge storage bags on their roofs.

Storing huge amounts of flammable gas on the roof of your vehicle was not thought to be a good idea though, especially in wartime! There was also the problem of re-filling the bag on a regular basis. And so the gas producer was invented.

A ‘producer gas trailer’ was attached to a vehicle and a pipe run to the air intake of the carburettor. This then mixed with the air entering the engine and allowed the engine to be run, even with an empty petrol tank!

The gas was produced in the trailer by effectively cooking a variety of fuels in an air-starved environment. In Britain the favoured fuel was coal, which was loaded into an almost air-tight chamber, with only a small air inlet and an outlet tube which went to the engine. When a fore was made underneath this chamber, the coal inside would start to cook and give off a mixture of gasses that powered the vehicle. After the gasses were cooked off, what was left inside the chamber was coke, which was then burned on the fire below to heat the next load of coal.

In other countries with little or no coal a similar system was used to cook small chunks of wood, which behaved in a similar manner. Cooking wood also produces useful gasses which can run an engine. However, like coal, it also produces quite a large amount of tar, which is not something you want. The solution is to pre-cook the wood in totally airless environment, which turns it into charcoal. By this stage most of the tar has been burned off from the fuel, leaving the much cleaner burning charcoal.

The videos below show Gary Gilmore experimenting with his ‘simplefire’ design of charcoal gasifier.

And then he installed in onto something that moved. In gary’s case a Gravely garden tractor.

This was all the encouragement I needed to attempt to build a similar gasifier to power one of my stationary engines. I used an old fire extinguisher for the main chamber of the gasifier and some 1 inch steel gas pipe for the pipework.

The gasifier is still under construction, so I’ll update this page as work continues.