Cardboard as fuel or feedstock

Has anybody had any experience? We’ve got lots (and lots and lots) at work.

I think you could add some in with your regular wood. I wouldn’t try to run on just cardboard though. Because it’s basically paper, you’ll get a lot of ash and very little char.

In general, I like cardboard for firestarters, especially those wax produce boxes. It’s also good for insulating the chicken coop, and rapid prototyping with CAD (cardboard aided design).

Pulverized cardboard (run through a hammer mill) is an excellent feedstock for composting worm farms. I have a couple million head count each season.

I wonder if this pulverized or milled cardboard material when pelletized or pressed into briquettes would make for a good and useable gasifier fuel!? I know you can substitute wood pellets or even logs with this stuff. Anyone tried to use paper pellets or briquettes in a gasifier?

Best regards,


Interesting- just to expand on a short original post, we’re producing enough cardboard packaging waste to fill two 1100 litre bins a week. What enquiries about the suitability I’ve made, have revealed that it is restricted by the UK Waste Incineration Directive because of concerns about the heavy metals in the inks, and chemical residues from the processing, none of which seem to put Richard’s worms off- what sort of quantities can they process? I’d be very interested in learning more about your hammermill, and how effective it is at reducing the volume.

Greetings Brian,
The restriction may pertain to feedstocks used in food production intended for human consumption. My research has revealed that most modern inks are vegetable based and the glues used in cardboard box construction are derived from animal fats. It makes a great combination bedding and feedstock for composting worms. The worms love it.

My hammer mill is an early 20th century unit designed for general farm use. It was designed to operate on the old wide drive belt type side PTO tractors. I modified it to operate on my modern rear splined PTO tractor. It came with several screen sizes. Regarding “reducing the volume”, It kind of goes backwards with cardboard. Pulverized cardboard is very fluffy allowing a lot of airspace. It takes up about three times the original volume unless you compress it.

Under ideal conditions, these worms can process their weight in food each day, leaving behind one of the best natural fertilizers. 100 lbs of worms process up to 100 lbs feed per day.

I’m sure there is merit to using cardboard for pellitized fuel, however, the processing would be energy and labor intensive… It’s amazing how much energy it takes to pulverize. I can easily choke down my 40 HP tractor, while hand feeding the mill. I believe the pellitizing process would be similar.

Nice job Richard converting that hammer mill to pto drive. It even turns the right way with that friction drive. I am making a wild guess that it has about a 6 to 1 speed increase so with a 540 pto wide open it would make about 3200 rpm. I’m guessing that is quite a bit faster than the flat belt ever drove it. Are those bearings up to those speeds or do you run at part throttle?
Don M

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I’m impressed with the worms’ performance- it sounds like an interesting spin-off. The questions are: what sort of footprint would that 100 pounds of worms take up, and what maintenance schedule do they require, particularly during frosts?


There are many variables to consider when raising worms. Under “ideal” (temperatue, moisture, feedstock etc.) . conditions, populations can double in as little as 90 days. Maximum managable density is approximately 2 lbs per sq. ft. Beds are typically 6" to 12" deep. 800 to 1000 worms per lb. Ideal conditions are very rare and would require indoor, temperature controlled beds and constant monitoring and maintenance. I have recently scaled back my operation to 200 sq. ft. and apply about 800 lbs of food/bedding every two weeks. Last year I stopped using the cardboard and switched to a mixture of leaf mold and hot composted horse manure. Much less work. I’m lazy.

Thanks Don,
I was kind of proud of that project, because it actully worked out. There’s noone around here to appreciate my little successes. You are right on with your wild guess. The mill is rated for 2400 RPM. I run the tractor at about 1500 RPM. I think that puts it in about the right range. I sure don’t want to be around when things start coming apart in there. That’s a lot of iron flinging around in a small space.