Woodchips for Gasifier Fuel

Last Revised: May 3, 2016


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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.
Wood Chip Quality Gage

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 found this great article written by the American Pulpwood Association that talks about the importance of wood chip qualtity in the pulpwood industry. They, of course, want THIN chips and we want THICK chips, but they don't want long pieces or "fines", same as us gasification folks.
Note: The American Pulpwood Association changed its name in the year 2000 to "Forest Resources Association, Inc."

To see the whole manual about woodchip quality for the pulp industry, Google the following:

quality wood chips make a difference

The first hit is: "Quality Chips Make a Difference".
Click on that link and download the pdf file to read or to save.
It is an interesting "manual" all by itself, but it does contain a picture of the "Chip Quality Gage" that is the subject of this page.

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:
Wood Chip Testing Gauge
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 leather punch.

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:
Wood Chips Sorted by Thickness

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 woodchip.
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.
Drying 10 Pails of Larger Wood Chips
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 ago.
First, Here is a close up of the larger Chips:
Large Wood Chips with Ruler
Here's a close up of the smaller Chips:
Small Wood Chips with Ruler

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)
Both Sets of Wood Chips Sorted

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?