Wood-fueled pickup trucks
A wood-fueled pickup truck, owned by Wayne Keith of Springville, Alabama.
A few weeks ago I gave a talk at the West Virginia Small Farms conference on “Farming with Less Fossil Fuel” (See slides, 4 Mb pdf). The speaker after me was Wayne Keith, from Springville Alabama, who talked about the wood-powered pickup truck that he drove to the conference. Was I ever up-staged!
Mr. Keith runs several of his trucks on wood and other biomass. Each truck has a gasifier in the back, which converts carbon-rich material — wood, switchgrass, junk mail, dead cats etc. — to a volatile mixture of carbon monoxide and hydrogen, called syngas. Syngas can replace gasoline as fuel for internal combustion engines. Mr. Keith’s old Ford F-250 gets about a mile per pound of sawmill waste.
1941 Adler Diplomat 3 with gas generator (Wikimedia)
The idea isn’t new. People started using gasifiers in the 1800s, and quickly realized that syngas could be used to run automobiles. When Europeans faced gasoline shortages during World War II some added gasifiers to their vehicles. Both the UN-FAO and FEMA offer online publications on replacing gasoline with syngas in internal combustion engines.
One of the nice things about the technology is that existing vehicles can be modified to run on syngas. Part of the reason given for the push for bioethanol production in the U.S. is that it is compatible with existing internal combustion engines. In contrast to the transition to electric or hydrogen-powered vehicles, existing machines could be modified, rather than replaced.
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- UN-FAO publication
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- FEMA publication
Let’s say that we want to run a vehicle on wood. There are at least three ways to do it:
- Use an on-board gasifier to make syngas for an internal combustion engine.
- Generate electricity for electric engines in a wood-fired power plant.
- Convert the wood to ethanol to burn in an internal combustion engine.
Which is the most efficient?
I’ll trust that Mr. Keith’s ‘mile-per-pound’ estimate is accurate for the first option. As a rule-of-thumb, wood-fired power plants consume 1.5 tons of wood per megawatt-hour (wet weight) and electric vehicles get about 3 miles per kilowatt-hour. That works out to exactly a mile per pound, wet weight (do the math), making Mr. Kieth’s pickup truck roughly as efficient as an electric vehicle. The pickup truck requires no batteries, and uses its original internal combustion engine. The biggest disadvantage of the gasifier is its bulk.
Theoretically, an ethanol plant can make about 50 gallons of ethanol per ton of wood (wet weight). A pickup truck that gets 20 miles per gallon of ethanol would get about 0.5 miles per pound of wood (do the math) — half the efficiency of the other options. The efficiency of wood ethanol is further compromised by the fact the processing demands acids or expensive enzymes to hydrolyze cellulose into sugar, and considerable energy for fermentation and distillation of sugars into ethanol. People did it during World War II, and they’ll probably try it again, thanks to US ethanol mandates, but I don’t think it makes much sense.
Hmmm… Electric tractors might be a neat idea, but maybe we should be trying to run more farm machinery on syngas.
Energy Farms 
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Hi its oct 2012 how can i get up to date with this idea an build one?
Thanks
I have a correction for Mike:
“I’ll trust that Mr. Keith’s ‘mile-per-pound’ estimate is accurate for the first option. As a rule-of-thumb, wood-fired power plants consume 1.5 tons of wood per megawatt-hour (wet weight) and electric vehicles get about 3 miles per kilowatt-hour. That works out to exactly a mile per pound, wet weight (do the math), making Mr. Kieth’s pickup truck roughly as efficient as an electric vehicle.”
You missed something important – Wayne’s truck on gasoline got 16mpg or so. The electric vehicle you refer to, (Nissan Leaf) on gasoline would have gotten anywhere from 40 to 50mpg on gasoline (similar to Geo Metros). So the electric car is about half to one third as efficient as Wayne’s truck. If you could squeeze a gasifier into a Geo Metro, you’d go almost three miles on a pound.
Good point, Chris.
I wasn’t referring to a Nissan Leaf specifically, so much as a ‘typical’ electric vehicle. Here are some numbers I’ve played with, based on production-model EVs and their nearest conventional equivalents, using EPA highway efficiency ratings where available:
Your point is well taken, though. Pickup trucks get worse than average mileage, so it isn’t fair to compare a pickup to an ‘average’ vehicle.
Hi,
Forgive my possible ignorance on the subject but why is necessary to take your gasifier around with you? Whats to stop you leaving that at home and just putting the syngas in your tank? Seems like alot of unnecessary weight to me….
Syngas is a volatile mixture of methane, hydrogen, and carbon monoxide. These are all gasses, not liquids, at the typical temperatures encountered while driving. This means they take up a lot more space than liquid fuels like diesel or gasoline. About 8 cubic feet of methane is needed to produce as much energy as a cup of crude oil. Compressing or liquefying these gasses is possible, but requires energy. For a simple, low-input system like Wayne Keith’s it makes sense to haul the wood, which is a relatively dense form of energy, and turn it into syngas as he drives. The bulky syngas doesn’t need to be stored.
but do the gases need to remian hot to produce the energy?
No, the gas does not have to remain hot. In fact, Wayne Keith feeds the gas through the pipes that form a ‘fence’ around the back of his pickup truck bed to cool the gas before it goes to the engine. The energy to drive the engine comes from burning the gas.
Rob Frost, who blogs at One Straw, has found that syngas really needs to be about 70-75F or cooler to be dense enough to run engines well.
But surely wouldn’t a car need to undergo huge modifications to run efficiently on biomass? one mile per pound of sawdust doesnt sound that efficient to me, obviously the technology could benefit from some serious indusrty investment but not every car has room for a huge tank of biomass at the back.
Perhaps I’m reiterating the post content, but I see three options currently available for running vehicles on biomass:
A mile per pound of wood waste may not sound very efficient, but it’s twice as efficient as the first option, and at least as efficient as the second. I agree that further R&D could advance the technology: Wayne Keith has converted six pickup trucks, with each one better than the last. I saw his latest vehicle in November, and he was claiming 2 miles per pound.
Not every car has room to carry biomass and gasifiers, which is probably why Wayne Keith has focused on conversion of pickup trucks. The gasifier-driven cars I’ve seen look kind of odd, with gasifiers protruding awkwardly from their trunks. It’s worth noting, though, that batteries for electric vehicles are also heavy and bulky. The move from lead acid to lithium batteries has helped reduce weight and bulk a lot, but has also driven up electric vehicle costs. Gasification technology is relatively cheap and low-tech.
A group of us up here in Wisconsin are very excited about biomass gasification and are working on a stationary gasifier to be placed as a heat unit (hot water) in a large Hoop House this year with the hopes of developing Co-Gen once we can iron out some filtering issues to prevent the fouling of modern gas engines (converted to syngas) generators. We have 4 built and are hoping to put hundreds more hours of burn time on them in the coming year to prove the technology more viable. Fuels are to be grown on site with willow coppice and farm waste, bio-char to be reapplied in test garden plots and other experiments.
-Rob
this is a great idea, I like anyone who is trying to at least go left or right off the oil/gas methods of transportation.
21st Century MotorWorks is doing the same thing, but claims up to 2 miles per pound — twice as efficient as Wayne Keith.
Thanks,
I’ll follow this up.
Regards
David
Wow… Where can I get one of these?
Your will see from our website that we have abundant wood for fuelling this.
Any chance of somehow contacting Mr Keith?
Regards
David Thorp
MD
Treenergy Woodfuels Ltd
Click on the last picture in the blog post to view one of Mr. Keith’s PowerPoint presentations. His email address is on the title slide.
I’m not aware of anybody offering vehicles that have already been converted for sale, but you can purchase a gasifier experimenter’s kit at http://www.gekgasifier.com/.