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


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.

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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.

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Wow This thread is 11 years old now
has anyone done any more recent work with cardboard pellets or brickettes?

I live in a small town that is ‘end of the line’ in many respects. There are no small manufacturing business here. but many retailers- so we have a sea of wet cardboard at the refuse tip.
My idea is to buy a 50hp tractor and use it with a flail mower over a steel box to mulch cardboard, mix it 50/50 with sawdust then use the same tractor to power a brickette press or pellet mill.
(assuming of course that cardboard brickettes would be a suitable feedstock)- what are your thoughts?


You would still want charcoal or wood to maintain a bed of charcoal. Also the ashes would plug up the char-bed a lot.

I don’t think the briquettes would make a good charcoal source either.

You could use cardboard as the heat source when making charcoal though. Burn up briquettes or just rolls of cardboard in a kiln filled with the good wood.


Hello Sutie

I think if you mixed your brickettes in at about 20
% would work OK .


You might want to check this out. He is mixing cardboard with sawdust for briquettes. But essentially it is a slurry wet enough to mix with a handrill, no chipper needed to test it out.

Part of the issue with a gasifier, is that it is made of pulp wood like cottonwood, pine, etc. that isn’t a hard wood to begin with. and a lot of times they incorporate recycled material in, which makes the fibers shorter.

The second issue is it can be fairly brittle and fall apart. It may need a binder added.


What others sayd. Most certainly not a beginers project.

I wuld encourage you to try a Simplefire gasifier with good charcoal first. You will soon notice what vast amount of slag it makes (molten ash) and how it over time deteriorates performance. Cardboard contains probably 10 times the ash. It has a lot of fillers and binders like limestone powder and clay.


Oh Im with you on the learning curve! I just can’t help wondering how deep the deep end is! :cowboy_hat_face: and Ive been making charcoal for the garden for years
Im building a downdraught charcoal gasifier. Its about a week away. Im just doing the plumbing now.
Thing is- I know what is coming petroleum wise. here in NZ, the Gubbermunt has dismantled our only oil refinery and sold it off to China. we hold reserves of refined products onshore for 17-25 days. That is all we have.
Im pretty well in with the guy who used to run our municipal recycling centre. He is going out on his own and he wants me to make him a commercial brickette press to process cardboard and sawdust. So this seemed like a natural progression if it was worthwhile.
Ive had 25 years in wood stoves and 50 years in agricultural engineering so if something is worthwhile I can make it happen. Stuie


There are some videos from india where they do commercial briquette stuff. But honestly, it might be more profitable to feed it to the worms. Worm castings have a higher margin.


Are you doing worms Sean? I have gotten away from shredded paper and cardboard myself. I shred the leaf mold out of the compost bins that isn’t fully converted to useable compost yet. Already full of microbes so the worms quickly finish it off into castings. For no-till, a layer of cardboard before applying more compost is good. For some reason earthworms love cardboard and you will find them gathered just underneath it after it’s been down a while. If I had access to enough cardboard I’d probably quit using weed cloth to cover the beds.


You are going to need diving weights and a scuba set up. Might need helium /air mix to avoid the bends coming back to the surface. :grin:


There is a fellow on youtube, who has done extensive work with sawdust briquettes, etc. I have enjoyed watching his videos over the years, he has solved a lot of “home” scale production issues. This is his channel, once there, search for “briquette”.

Wade into the shallows of the deep end. :thinking: