Woodchips for Gasifier Fuel
Last Revised: April 17, 2020
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Wood Chips for Gasification
As many of you know, I only intend to burn woodchips in my gasifier. So I am continuing to learn all I can about
this fuel source.
A wood chip, to me, is of a rectangular solid shape, having dimensions L(length), H(height and W(Width or Thickness).
My concern is in being able to produce wood chips that are as thick as possible, compared to their LH dimension and
containing as few fines and longs as possible.
Now Let's talk about Measuring wood chips!!!
Putting some science to calibrating wood chips:
Up till now, when I talked about wood chips, I had to say that they were big or small or fat or round. Just recently I
this great article written by the American Pulpwood Association that talks about the importance of wood chip qualtity in
pulpwood industry. They, of course, want THIN chips and we want THICK chips, but they don't want long pieces or "fines",
as us gasification folks.
Note: The American Pulpwood Association changed its name in the year 2000 to "Forest Resources Association, Inc."
Here's the "Chip Quality and What Does it Mean to Your Customer" Document from the Pulp Industry
Just for reference, here's another detailed Guide with lots of specs and details:
Wood Chip Heating Guide
The Wood Chip Quality Gauge
Here's a picture of the gauge in use:
In the manual there is a straight-on picture of this wood chip quality gauge. I captured the picture and then resized it
so it would print out at exactly full size. Then I glued a copy to a piece of writing tablet cardboard and cut out the
rectangular shapes and the large circles with an exacto knife. I cut out some of the small round holes with a
I cleaned up the picture of that gauge since I built this webpage. If you want a gauge of your own, you can click on this
picture and print one for yourself:
Wood Chip Meausuring Gauge
Just make sure you check its printed size and resize it if needed. There are both inch and mm rulers on the gauge itself for reference.
So far, I am most interested in the rectangular scale, since it gives me the ability to analyze the chips by thickness.
Here's a picture of about 20 minutes of work to test a recently discovered batch of chips:
Background on These Larger Wood Chips:
Up till now, I have been getting my woodchips from roadside utility right-of-way and highway roadside cleanup operations.
The goal of these folks is
to simply get the trees and brush out of the way. They don't worry about fines, longs or pins.
In my previous articles on the subject, I have talked about the complexity of cleaning and classifying (sorting) that kind of
Just recently, I passed a woodlot about a mile from my home where a crew was clearing about 10 acres of timber and brush
to make tillable land. They had a huge (400 hp)wood chipper at work and it was eating everything from brush to whole trees up to
at least 12 inches in diameter.
It was the spring of the year and the ground was very soft, so they had built themselves an elevated driveway for the semi
trailers that were hauling loads of chips away to be used in a (steam I think) power plant about 60 miles away.
Anyway, the elevated driveway was made of woodchips. I stopped to look because these chips were a lot bigger and (apparently)
a lot cleaner than what I had been getting. I stopped by and asked the landowner if I could have a sample of those chips to
test and he replied that I could have all I wanted.
I came back the next day (after a big rainstorm, unfortunately) and loaded 10 five gallon pails with the chips on the surface
of the driveway. Even though they had dried for 12 hours, they were still very wet just an inch down into the pile.
I brought them home and spread them out about 2" to 3" thick on my garage floor, opened the garage door a foot or so and
aimed a box fan at them.
The average gross weight of the pails was 18 pounds. After 24 hours, the average dropped to about 14 pounds
so I am getting rid of the excess moisture pretty quickly, I think.
Comparison of these larger Wood Chips to Smaller Wood Chips from Roadside Chippings
Here's a size comparison between these recently discovered Wood Chips and those I got from roadside chipping a couple of years
First, Here is a close up of the larger Chips:
Here's a close up of the smaller Chips:
I spent about the same amount of time sorting wood chips of the "smaller" batch with my new Wood Chip Quality Gauge
and here's what I got:
(The piles in the area below the 48 inch ruler are just about a mirror image of those above it, except that I have combined the
"Longs" and Fines" together in the lower pile)
You can see that the distrbuiton of Wood Chip Thickness is different between the two samples. But you can also see that
the L and H vary a lot, too. I think I'd rather have the larger chips, but time will tell.
Which wood chips work best for you?