Published on May 14th, 2008 | by Clayton
A Truck That Runs on Coffee Grounds (and How Wood-Gas Powers Cars With Garbage)
Photo Credits: deborah sherman photography
The Cafe Racer Truck Runs on 100% Recycled Coffee Grounds
A commenter on Ben’s wood-powered truck post pointed us to a similar car hack. The truck above is also powered by a wood gas generator, except this one runs on coffee grounds. The Cafe Racer is a 1975 GMC pickup that essentially burns up used coffee to create a combustible gas. The gas is filtered on its way to the engine and, Viola, a caffeine-powered truck.
It’s interesting to note that this and the last vehicle mentioned are promoting a specific fuel (wood and coffee grounds), since the onboard wood gas generators can gasify almost any type of combustible material.
Gasification is a non-selective method using heat and a controlled amount of oxygen to convert biomass into a flammable vapor. In addition to Coffee Grounds, the Cafe Racer could use wood chips, old tires, and municipal trash, almost anything—which, by the way, is the same technology Coskata is using to make cellulosic ethanol out of garbage.
As Wikipedia puts it, gasification “was an important and familiar 19th century technology” that was commonly used until petroleum took over around the close of WWII. Although popular at that time, wood gas conversions are a bit of a throw back, but you never know what could gain popularity as gas prices continue to rise. Additionally, wood gas generators aren’t restricted to vehicles, and have found use in heating, cooking, and electricity production.
So how can a wood gas generator power a truck?
The reason a wood gas generator can power cars and trucks is that the internal combustion engine is actually powered by vapor, not liquid. In a gasoline-powered engine, gasoline is vaporized before entering the combustion chamber. Diesel is a little different; it’s sprayed into the combustion chamber as fine droplets which burn as they vaporize. Either way, if you can put a clean combustible vapor into the engine, you’ve got power*.
(*Just to mention where this information is coming from, I thought I’d point out this interesting factoid: back in 1989, FEMA sponsored a series of “emergency technology assessments” that included a book on gasification conversions. The title of the book is “Construction of a Simplified Wood Gas Generator for Fueling Internal Combustion Engines in a Petroleum emergency.”)
Gasifying a solid material partially burns it, which preserves some of the energy that would normally be wasted in the gas (otherwise there wouldn’t be anything left for the engine to burn). The gas contains a mixture of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), nitrogen (N), and a small amount of methane (CH4).
The big question for wood gas use is (as usual), how do these systems compare to other petroleum alternatives in terms of environmental impact? The group behind Cafe Racer claims that it’s a carbon-negative demonstration vehicle, but they don’t substantiate that on their website. I wasn’t able to find much on the issue, except the risk of death from carbon monoxide poisoning in poorly designed systems, but my gut instinct tells me this isn’t the cleanest way to get around. If you know of a resource on the emissions of wood gas generators, please send it my way.
The important point here isn’t so much that you can run a truck on wood gas produced from waste materials (even though that’s pretty cool), but that this technology could play a major role in producing petroleum alternatives in the near future (more on that later).
If you enjoyed reading about this, check out these links, and see more pictures of the Cafe Racer below:
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