Corn Puck
William Carr January 17, 2007
Okay, as I understand it "retting" is the process of breaking down
fuel fibers so you can bind fuel together in pellets or briquettes.
This can be done by sheer mechanical force, or by letting the fuel
fibers decay somewhat. Then the fuel can be compressed into a
briquette.
I understand some low-tech approaches use manure as a binder instead.
I freely admit, I delete these posts immediately. I'm not going
there, period. Let someone more qualified handle that, um, end, of
the research.
**********************
Well, I had never thought of trying retting with corn. Corn
stalks, certainly: stover would make pretty good biomass.
Put back 30% of it for the soil, use the rest for fuel.
*********************
Where I keep my bagged corn for our pellet stove in our garage,
there's a leak running down the cement block wall.
I discovered this, of course, when I finally got to the bags of corn
stacked against the wall.
Sigh. I scooped out what wasn't soaked and threw out about 1/4 of
each bag. Except for the last bag, I didn't get to it.
Now, the ground water got into the bags of cracked corn, and of
course fermentation began. The bags were slightly warm and smelled
like peanut butter gone bad, that old smell of sileage down on the farm.
My uncle used to feed the cattle on his dairy farm sileage. YUCK.
That's a smell you won't forget.
Well, when I was all out of corn but that last bag, I had to switch
to wood pellets. I am sort of frugal, so I checked that last bag
of corn before chucking it.
Lo and behold, it wasn't wet and smelly anymore.
In fact, the fermentation had completed, the corn had solidified
into a solid, lightweight mass, and was mostly dried out.
I decided not to toss it out after all...
I left it a couple of weeks and tonight I took a hoe handle and broke
up that solid mass.
It was pretty hard to do. This stuff was solidly glued together.
I finally bashed it into chunks and picked one up.
HMMMM. A circular chunk three inches across and an inch thick
weighed out at only 30 grams.
Hefting it in my hand, I'm reminded of a Wasp nest.
Oh, it's not THAT light, but it's probably as light as a cork the
same size.
A zip-lock bag of corn kernels the same volume would probably weigh
twice as much....
**********
This "puck" is solid, made of something that looks just like paper
mache´ with some few corn kernels stuck in it.
Call it corn mache´.
I tried to squeeze it, and despite it's light weight, it's bulk
modulus is pretty high and it won't dent, and as I said, it was kind
of hard to shear apart too.
I just tried to stretch the puck, but it won't stretch and I couldn't
get it to break. This stuff is pretty tough.
So, what do we have here ?
Bacteria from the groundwater leaked onto a woven fiberglass mesh bag
filled with cracked corn.
The corn fermented, the bacteria ate the oils and sugars in the corn,
reproduced themselves, effectively converting carbohydrates into
proteins, gave off alcohol and water vapor, and eventually died.
So some of the fuel value was lost to the alcohol evaporating. Not
that much, but some.
Afterward, as the corn mash sat in the porous bag in a cold garage,
it dehydrated. All the bacteria are still in there, but they're dead.
Bacteria are made of proteins, and protein burns. Not as fast as
sugars or oils, but nice and steady. Like peat.
And don't forget the glue factor. Wouldn't it be nice to convert
corn kernels into a binder that we could use to hold loose fuel
aggregate together?
Then there's moisture content. If the corn had started at 13.5%
moisture, then been cracked, it would dry over time to about 12%MC.
And stop there.
But once digested by the bacteria, the mash mysteriously dehydrated
on it's own until it's much lighter.
I can't afford to send this puck out to a lab, but I find it
interesting that it dehydrated without adding any external heat at all.
Drying fuel costs money. I ain't got any money. I need fuel that
either comes dry or dries on it's own.
**********************
So, now you're wondering, "But Bill, does the stuff burn???".
Yes... yes, it does.
I took a few chunks over to the pellet stove and tossed them in.
I got out my stopwatch and waited.
About eight seconds later flame started to lick up the sides of the
chunks.
At two minutes the little briquettes were not only aflame, patches of
them were glowing red hot.
Please note: regular store-bought briquettes don't start that fast.
(My charcoal starter chimney will get charcoal briquettes burning in
ten minutes with one or two pieces of newspaper and they last 45
minutes.)
I watched and waited. And waited. It took eight full minutes for
the 1" by 1 1/4" by 1" chunk I was watching to finally burn down to
the size of a marble, and then I lost track of it.
*******************
So, interesting.
(Avocado peels also dry on their own, the USA imports an ungodly
number of metric TONNES of Avocados each year, and Avocado peel burns
like so much kerosene: but an Avocado peel also burns out in less
than forty seconds. Woosh! But hey, maybe there's a use for a
slow-burning fuel too. )
If I'd thrown in an equal volume of corn kernels, I would have gotten
about ten seconds of smoke, then the kernels would have started
blackening.
Eventually the kernels would start contributing heat to the fire, and
they would have burnt out in, say, five minutes, tops. That's a
guess, I don't have any corn left to test for a benchmark.
*******************
So, I don't know if this is groundbreaking research or anything.
Add it to the Archive of Kooky Ideas.
Anyone looking for a new binder for briquettes might try replicating
the effect.
Getting the groundwater bacteria should be child's play. Go dig up
some dirt, preferrably in a forest, shovel into a bucket.
Put bucket in a sunny, warm, spot.
Add water, stir, add molasses, stir, drop in an aerating tube from a
fish tank bubbler, and bubble air into the mess for a few days.
For the sake of thoroughness, repeat the experiment without the extra
aeration. Could be it was anaerobic bacteria that did the magic trick.
At the end of that time, you should have something like "Manure
tea". I use compost to make this stuff and spray it on my plants
every year to help them resist infection.
************
Add the MT to cracked corn, and I bet you dollars to doughnuts the
mash will ferment. Keep it wet, in a woven fiberglass bag to let
the bacteria breathe.
The whole mass was two inches thick: it's possible that the
thickness was limited by available oxygen for the bacteria.
I suppose stirring or bubbling air through the mash would help and
overcome the thickness problem.
Pour sticky mash into a mix of aggregate fuel, mix, press into a form
with a hole in the middle, and stack.
To dry, you'll need what I accidentally used, a porous filter mesh to
set the briquette on, that same fiberglass mesh bag.
William CarrAir Jordan