source I've found):
In there a range there of 9120 BTU/lb for Redwood to 8440 BTU/lb for
Yellow-poplar. Thats an 8% difference. Not huge but significant.
There is another document at:
That has a much more comprehensive list. This shows a range of ~7300 to
~12200 BTU/lb. The highest is more than 60% above the lowest. Now
there are different studies all in that table, but even comparing like
studies gives almost as big of a range of values.
The softwoods are generally higher because of their resin content. (that
pitch is just like oil)
Hope that helps.
That we knew, Dan. I've mentioned it a few times already, as have others.
Plus or minus extractives, is the phrase I've used. The greater the amount
of extractives, the greater the energy density, which, as you note, can vary
from a resinous high of 12K to a miserable low of 8K 33% (50 if you're
trying to make your argument) is a big swing, but the majority clusters
within 10%. Your low is for bark.
Then there's the footnote - "clusters at 8500" and the disclaimer of a post
hoc study that the methods used to determine the data were not consistent.
Comparing cellulose to cellulose is pretty dull, but try resinous
larch vs birch or willow. Even though the pound per pound difference
is much less than the volumetric difference, it's still significant.
Read a book. Read several. We're talking about per pound
not volume. Dried wood of any type is composed mostly of
cellulose and lignin. Slight differences in aromatics. You
may be thinking about density, that's why we are comparing
BTU's on the base of weight.
According to these guys, it is 8600 per pound.
When considering the use of wood for heat, University of Illinois Extension
foresters offer the following information and advice: All species of wood
has the same Btu (British Thermal Units) per pound of wood; roughly 8600 Btu
per pound @ 15% moisture content. As the moisture content goes up in the
firewood, the heating value goes down (less Btu's) because more energy
(heat) is needed to drive off the moisture in the wood before it will burn.
This is why firewood needs to be seasoned at least 6 to 9 months before it
is burned. Freshly cut wood is not very efficient for heating use.
These guys are using 20% moisture for 7,000 Btu
Comparison to Other Fuels
How does wood compare to other fuels? In most
cases wood will be used as supplemental heating to
your conventional system of natural gas, L.P. gas, or
electricity. Table 4 gives Btu values of common fuels.
TABLE 4. BTU VALUES
OF COMMON FUELS
WOOD (per pound, high heat value,
20% moisture) 7,000
NATURAL GAS (per cubic foot) 1,000
L.P. GAS (per gallon) 92,000
ELECTRICITY (per kilowatt hour) 3,412
FUEL OIL (per gallon) 140,000
Dunno. But I do know this - it takes a bigger piece of pine to make a pound
of wood than it does maple, and that pine is going to generate a lot more
creosote than that piece of maple unless it's really dry - which makes it
even lighter. Net/net - pine (and poplar) suck for firewood in the
northeast. I burn some pine but more to get rid of it than for any real
Unless it's red gum. Cut it, whack on it 50,000 times with all manner of
splitterly devices, then saw the damn stuff up with a chainsaw after
failing utterly to split any of it. Then burn it.
Or better yet, turn on the gas logs when you're in the mood for a fire.
Every time I start to get romantic about how much different it used to be
having a real fire in the fireplace, I just look at my old mangled maul
standing in the corner and smile. :)
(I was a lot more lithe and lean and stuff in those days though, boy.
Especially swinging that damn 16# sledge that used to belong to my great
Michael McIntyre ---- Silvan < email@example.com>
Linux fanatic, and certified Geek; registered Linux user #243621
Maybe that was part of the problem. My neighbors next farm south had been
doing wood forever. One used a maul (go-devil for NE folks), the other an
axe, to split elm. Sixty seven and seventy three were their ages, with the
73 swinging the axe....
I retired my sledge this year. No more kids in residence to help the old
man with 4' lengths. Susan and I went to 20", and a splitter.
On Wed, 09 Feb 2005 23:35:44 -0600, Patriarch wrote:
Note the google.CA rather than google.COM domain. I like the old interface
better, which is still being used by "nationa" googles. I wonder if you
Merkins get redirected to google.com when you type in google.ca.
Replace "nonet" with "yukonomics" for real email
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