[Stoves] Retting... corn?

[William Carr]

This post is regarding fuel treatment and preparation:   ( It's a bit  
long, sorry. )


BTW, where do we post pictures for this group?




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 Carr