During WWII when gasoline and diesel were rationed or otherwise unavailable, over one million vehicles in Europe ran on customised gasifiers that used fuel made from burning wood and charcoal? It was the first affectual widespread alternative fuel conversion in History.
A biomass gasifier is a chemical reactor that converts wood, or other biomass into combustible fuels that can be burned for heating, cooking, or for running an internal combustion engine. This is achieved by partially burning the biomass in the reactor, and using the heat generated to thermally break down the rest of the material into volatile gasses. By passing them over a bed of hot charcoal an efficient reactor will also convert combustion by-products like CO2 and water vapor intoflammable CO and H2.
A typical wood gas generator converts timber or charcoal into wood gas, a synthesised gas consisting of atmospheric nitrogen, carbon monoxide, hydrogen, traces of methane, and other gases, which – after cooling and filtering – can then be used for generating power around the home or power an internal combustion engine. The gasifier converts wood-mass or pulp into flammable gasses with little ash and charcoal residue.
Wood gasification is one of the best solutions to power a home because it can provide both electricity and gas for heating, all from renewable wood.
Wood and other biomass is made of complex macro-molecules like Cellulose and Lignin that break down into hundreds or thousands of different smaller molecules via the reaction process. There are thousands of different complex chemical reactions going on inside the reactor. The air pipe enters the can tangentially and causes a cyclone effect in the top of the can which mixes the air and wood gas thoroughly. The result is the woodgas burns with a powerful roaring flame like a propane torch
Construction of these wood gasifiers vary according to its usage. Designs begin from simple charcoal & wood burners for heating water, middle of the range units for powering Car & Home, and large industrial units for Residential & Mass Production. One design features a 5 gallon batch fuel hopper that holds enough wood chips for over one hour operating time. A fan provides combustion air through five nozzles to produce a rich gas mixture sufficient for starting and powering a 3 to 12 horsepower engine. The hopper is loaded with wood chips and brought up to optimum temperature before the engine can start. The reactor vessel for this design is fairly easy to construct because it is made mostly from 4-inch pipe fittings that have been screwed together with a few simple welds.
Another design features a 12 volt DC alternator for charging solar batteries. A 2,000 watt inverter for intermittent 120 volt applications like powering drills, lights & other accessories can be added to this unit. For cooking and heating, the gasifier can be run by fan pressure which can produce 200-300 cubic feet of producer grade wood gas per hour. Propane burners can also be customised to run on wood gas, however it is advised that they be tested & tagged by an authorised technician.
A down-draft gasifier design generally produces the best quality gas as compared to petrol burners. Wood gas generators have a number of advantages over use of petroleum fuels:
- They can be used to run internal-combustion engines using wood, in the absence of petroleum or natural gas during a fuel shortage.
- They have a closed carbon cycle, contribute less to global warming, wood being both a natural & renewable resource.
- They can be easily & quickly be knocked together in a crisis using readily available materials.
- They are far cleaner burning than a wood fire or even a gasoline-powered engine producing little if any soot.
- When used as a fixed or static unit as in a household, they meet necessary small combined heat and power requirements with heat recovery from the wood gas producer, and the engine/generator to heat water for hydronic heating, provided that a sufficient supply of wood is available.
- Larger-scale installations can reap even better efficiencies, and are useful for district heating.
Except in the use of a gas holder water-displacement apparatus, long-term storage of wood-gas, is not a viable option, due to the volatile elements present in the gas, which, if allowed to build up could explode. Under no circumstances should wood-gas ever be compressed to more than 15 pounds per square inch (1.0 bar) above ambient, as this may induce condensation of volatiles, as well as lead to the likelihood of severe injury or death due to carbon monoxide or combustion if the vessel leaks or fails.