BTU of different types of wood

Hi guys,

I saw this chart and thought it would be of interest to this group, it compares different types of wood and compares the BTU value.

Might be of use for those of us who are planting trees or managing a forest to know what types of wood is better for wood gas production.

Cheers,

Mart

http://www.thefireplacechannel.com/burningwood.html

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Hi Mart, This been a subject of discussion for many years. A major consideration is where the wood has grown. Generally the amount of BTUs is proportional to the density of the wood after drying. Gasifying wood is different than outright just burning it. I tried to get some of the guys in Finland and Sweden to supply us with densities of the woods they were using as they are near 60 degrees north latitude and have completely different growing seasons. I saved that chart you provided locally. Thanks for the link. Below is a link to measurements I took on some of the types of wood I run on here. I measured a 5 gallon pail full of chunks of several woods before and after drying. I think I just posted the dry densities. You will find if you do comparisons while driving on wood to it’s equivalent in gasoline that you get way more BTU’s than if you use the heating charts for straight combustion. Hard to explain but a fact when you figure in the hydrogen released and CO created by the process with the atmospheric and released water and then the compression and explosion in the engine.
http://www.intergate.com/~mlarosa/images/woodgas/local-wood-density-2-inch-chunks.jpg
Regards, Mike LaRosa

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Hi Mike,

I have been building Rocket Stoves, and TLUD stoves for a while, and I have watched others that build HHO generators to help burn gasoline more cleanly. It does make sense to me that at the temps you are reaching that the Hydrogen is helping the burn along. I have seen how when hydrogen is added to a car’s intake the emissions are far cleaner. I can also see the point of where the wood is grown, the mineral content of the wood would vary from location to location. I found this to be the case in biochar.

I recently grew some kenaf here in Florida, I was very happy to see Keith’s results of when he burnt it.

Cheers,

Mart

Well said Mike LaRosa.

MartH with your experiences you already know that on even on the IC engine side of things the mechanical dynamics of engine design say that simple BTU fuel comparisons do not work. Otherwise diesel fueled engines would Always kick bun-bun gasoline fueled engines ass. They do not. No diesel airplanes. No diesel chainaws. And the only diesel motorcycles are DYI’s.
Other: exotic dense rocket fuels/aviation fuels like the JP’s would be even better by BTU per wieght and volumn. Not better in IC piston engines.
Heck, powdered fossil coal dust would beat out by BTU all other IC engine fuels. Not very practical. Why this is never done if ANY type of liquid or gasious fuel is available.
The actual fuel energy RATE releases and the BYPRODUCTS of IC engine burning a fuel overide simplistic BTU’s comparisions.
Hydrogen fueled engines actually with specific IC engine design changes are able to match these other fuels with one of the lowest BTU of all fuels available.

Wood fuels the same. Especially in a gasifer.
Known best wood speices to gasifiy for IC motor fuels are already well known:
most pines, some spruces, some birches, some firs.
Other woods can be made to gasifier work, yes. With more operator working of the gasifier system required.
Your kenaf (paulina?) as an example. Wayne says he could get the same engine power but had to feed in 2X the volumn on this fast grow, low density speices. Tribute to the operator and his system to be able to do this.
I’ve personally gasified and IC engine ran with low density fast volitizing Western Red Cedar. Low, low BTU. Worked. Just took lots more wood by volumn and then wood sourcing/prepping to keep up versus much more common here, higher density Douglas Fir wood.
Western Red Alder the same power as long as I could keep the gasifer from flow choking down with alders 4X-6X higher mineral ash than super low ash cedar or doug fir.
Oregon White Oak same power as long as the wood was then 1/2 particle sized down to get the volitilty energy release rate up on this “slow” energy release wood to the same rate as “fast” energy release cedar and doug fir. Not fun having to do this extra wood size processing down on a tougher, harder wood AND then having to handle the 8X higher mineral ash in the oak wood. At least the oak ash does not gasifer internal temperature melt down and slag clog like alder ash does.

These are just some of the real world practical considerations in to be functional motor fuel suppling gasifer fuel wood.
Then wood sourced moistures, soots and others.
Some woods will dry MUCH faster.
Some woods MUCH easier to size process. Stingy, clingy cherry bark!
Some woods gasify MUCH sootier.

Few of these are considerations for “best” fireplace woods.
Few of these are considerations for “best” airtight stove buring wood fuels.

One of the North American achievements in gasification will prove to be the ablity to use non-ideal woods.
Just gitter’done. Use what you got.
Plant what will grow what is best in your area within your harvest time window patience.
We will figure out how to use it.
Ha! Even cottonwood.
Canadian Greg Manning sap down harvest and chips his “water sprout” poplar? wood in the dead of his artic dry winter and gasifies with it.

Regards
Steve Unruh

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There are diesel airplanes Steve. Cessna put a diesel in the skylane 182.
Every single jet engine burns diesel.

Thanks Charles Hill!
I learned something there with one model of Cessna 182 able to fuel with JetA fuel. Certainly an IC piston engine alright. I like learning new things everyday.

Now calling JetA a “diesel” is streaching the point a whole bunch. Many truck, auto, tractor compession ignition engines can run for a time on JetA and even other light JP series kerosenes until they sieze up or premature wear out their injectors and fuel pumps.
Big functional difference between stove fuel grade oil for gravity feed carburators and high pressure pumpable furnace oil fuels also. Viscosty and Lubricity.
Those with souces for the heavy end aviation fuels are carefull to bio-diesel supplement, or added fuel lubricant supplement with something in their stationary diesel IC piston engines. Like adding 2 cycle engine oil to the aviation fuel kerosene.

Question is: could this Cessna run on standard high sulfur Ag/farm or or the new pump island #2 auto diesels??
And do this at cold ceilings altitudes?

And in my example above I was only saying fuels, " . . better in PISTON IC engines."

Gas turbines a whole different animal completly. They have to be carefully tuned for different fuels also. These HATE particulelized fossil coal fuel ash residue and woodgas alkaline ash build up on thier turbine blades. They blade deposits unbalanced die very dramatically.
Why with fossil coal as the fuel they always use this to make steam and then go with clean steam terbines. Coal fired Centralia Power plant was just north of me for 30 years. I was a minor parts supplier.
Now IC piston engines can be designed/tuned to fuel with these “dirty” fuels as is obvious here on the DOW.
IC piston engine it is all about designing the engine to optimize the in cylinder burning fuel temperature/pressure curve and following that for the best to shaft power conversion.
Turbines yes are pure guts fueled by BTU’s . . . IF the sensitive turbines can handle the the burnt fuel byproducts.

Find the diesel fueled chainsaw yet? (Israeli used as I recall) 3x the bulk and weight of any gasoline fueled saw. Troops hated it. They “so sorry” broke them. “Seems” they had a lot of sand in fuel issues that they surprize, surprize they did not have with the lighter, more managable gasoline saws. Ha! Small wonder that.

Mike La Rosa is still correct that the fireplace suitability of a wood has little, or nothing to do with it’s suitability in a gasifer to make useable IC piston engine grade fuel gases. Only actual woodgas engine power running will prove this.

Regards
Steve Unruh

Steve,
Back in the mid 90’s I was in Vancouver BC at a trade show and I was surprised to see boats that had twin Yamaha diesel outboards. 200 hp. That was a first and havnt seen it since.

Wes

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Yes WesK anything can be done once, twice just to test the waters or for the O-o-o-R-a-a-H! of it. Like a ship in a bottle. A OoohRah V-8 powered chainsaw or crotch straddle motorcycle.
True proof of viabilty is a more general capable useage and acceptance of it.

Oldest diesel fueled chainsaw I’ve seen: Jonsereds XC USA. Really a two man saw. No two man saw was ever really liked.
The one man diesel fueled chain saw was a Swedish made Comet 1950-1953. Russian designer. A few thousand of these were made.
Ha! Where are they now? Why no updated manufacturers? Heavier Weights. Poorer power to weight ratios. Poorer manhour cutting productivity rates versus lighter faster gasoline saws.

Back on the Op’s topic of wood fuel BTU’s.
I’d put my Doug Fir drippy gooey pitch wood splits up against anything in the whole World by BTU/volumn.
Very bad energy Rate release contollabilty. Wants to overheat destroy equpment. Sooty as all get out even thinking of trying to energy relase rate control with air. Very little char produce versus all of those hot, hot volitals to then carry through temperature/heats/char for gasifier reactions.
All those BTU’s, and a very poor wood heating fuel. Terrible wood gasifier fuel.

Then my up to 4 inch/100mm thick Doug Fir bark. Again HIGH BTUs’ capable. Does Not want to burn. Remember this was mother natures fireproofing and bug proofing armor/skin of the tree. But get it hot glowing charcoal heated and buring; then a tremedous short HOT, HOT smoky volitals BTU relaase. And thwen after volitals burnt off it ALL wants to go into a super HOT glowing char glow at the same time. NO moderating this down except with severe measures. Very poor density and weight by volumn compared to trunk and limb wood so this energy burst release only lasts for mere minutes. Then a 11% to 18% choking ash left behind.
Very, very poor wood heating fuel. One of the worst of wood fractions to wood gasify with.

Ha! ~10% of my home heat this winter will be with no other use Doug Fir pitch wood split outs.
~15% will be with Doug Fir bark chunks. Tribute to my excellent 500 pound, heavy cat iron woodstove able to take these severe heat energy release bursts and live to do this year after year. Fifth year on this one.
Now using these “dirty” wood fuel fractions within the regional air emissions standards of only 20 minutes in any two hours period with visible smoke “re-fueling” legal however is All the Operator - me.

And I have tried wood gasifing with these. No-go past a vidio clip OohRah. Sustainability of operation is impossible.
Why I can positively say it ain’t about raw BTU numbers of the wood fuel for gasification.
Other factors are more important by far.

Regards
Steve Unruh

More diesel planes

There was recent discussion in a few places about energy density per hopper volume. Since I have both charcoal and also less than 3% moisture content hardwood chips; I thought I would weigh both fuels in identical weight 5 gallon buckets. So this gets us both weight and volume density for comparison.

Ill start with the chips, the common BTU value I have found with a google search seems to be 8000 btu per lb of dry wood. These chips are very dry and my meter will not register anything. But Im sure there is some moisture in some of it. They were just sun bathed for around the 3 days of good weather we had here. These chips were screened with 1/4" screen and filled even to the top the of the bucket.

Weight was exactly 10 lbs. per 5 gallon pale.
BTU Value = 80,000 btu.

Ok now the charcoal. This fuel was also made from hardwood. I also screened this fuel. Google tells me 9700 btu per lb of charcoal.

Weight was 6.45 lbs per 5 gallon pale.
BTU Value = 62,565 btu.

Ok so by volume near 0 MC wood chips are around 21.8% greater in energy density. Ok now when comparing charcoal verses wood fuel, you can not just stop here. We also must factor in differences technology efficiencies. General consensus is wood fuel gasification reaction process has a loss of 25 to 30%.

Charcoal, I dont know what the consensus is and I have not personally figured it out. I can only guess and if any one has some real numbers I will edit this. For now Im going to make an educated guess of a 10% loss and I think that more than actual.

Wood chips BTU net value after gasification 80,000 - 30% = 56,000 btu
Charcoal BTU net value after gasification 62,565 - 10% = 56,308 btu

Ok now start adding in the moisture and these figures will change again. Because you are typically not going to be running bone dry wood fuel. so that number is going to come down the more moisture that is the fuel. Now Charcoal it will be just the opposite with water injection as you adding more BTU’s

This is just some rough figures, different fuels, different gasifiers and many other factors will play into these numbers from one to the other.

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I wonder if one could come to a better understanding by filling a gasifier with the same weight of charcoal, the the same weight of wood chips, then measure how much energy the system put out, or how many miles traveled with each load… Interesting numbers.

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That would be an unfair dis advantage for wood gasification. By weight you will get even less energy density.

So for instance if we match the charcoal of 6.45 weight in chips you would end up with less volume. Just over 3 gallons of chips.

The BTU value then would be 51,600 BTU compared to charcoal of the same weight = 62,565 BTU.

Then factor process losses now the wood gasifier is down to just 36,120 btu energy density compared to the charcoal is still going to be 56,000 btu at this weight.

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