They Run Their Truck on Wood!
(Page 2 of 3)
January/February 1981
By the Mother Earth News Editors
WHERE THERE'S SMOKE . . .
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The producer gas is formed under conditions of high heat and controlled "respiration". As air enters the generator, the solid fuel within the hearth burns, releasing carbon dioxide and water vapor ... and at the same time "manufacturing" a hotbed of charcoal in the base of the generator. The gases are then drawn by engine vacuum through the glowing carbon coals, where a destructive distillation process breaks down the CO 2 and water into carbon monoxide and hydrogen ... a mixture which—along with nitrogen, a small amount of methane, some unconverted carbon dioxide, ash, soot, and water vapor—forms the final "gengas" fuel. Of this chemical potpourri, only about 45 to 50% is combustible . . . and some components (notably ash, soot particles, and water vapor) must be filtered out to prevent poor performance and possible engine damage.
After the gaseous fuel is "scrubbed", it's mixed in a roughly one-to-one ratio with fresh air and used directly in the engine. The Nunnikhovens opted to set up a dual-fuel (gasoline/producer-gas) arrangement for convenience. To do so, they simply installed a solenoid-operated shut-off valve in their truck's petrol line, and rigged it so that the switch stops the flow of gasoline to the carburetor whenever the air mixer valve is moved from the full-open position (which, of course, is always the case when the vehicle operates in the "gengas" mode).
YOU GET WHAT YOU PAY FOR
Th e Hawkeye Staters' earliest experiments confirmed their expectations that the wood-fueled vehicle wouldn't have quite the get-up-and-go that it did in its gasoline mode. (As near as they can figure, between 35 and 50% of their original power has "gone up in smoke".) On the other hand, they couldn't be happier with their fuel bill (which is pretty close to zero, since the pair can cut or scrounge much of the wood).
But even if their fuel were purchased at the market price of $100 a cord, or roughly 3¢ a pound, Steve calculates that the timber equivalent of one gallon of gasoline (20 pounds, or a five-gallon bucketful of scraps) would cost only about 60¢! The economical nature of the fuel—coupled with the fact that an entire woodburning propulsion system can be put together for about $100 in scrounged parts—certainly makes the idea of "poplar power" look mighty attractive.
