A Cheaper Maize Harvest
Herein, by cobcorn is meant an ear of maize sans its enveloping wrap of leaves, a naked ear. ..It is comprised of these major components — starch.., xylans .., cellulose.., and lignin. ..All the starch is in the kernels of grain, as the cob or core to which the kernels are attached has none.
Somewhat over 70% of the dry matter of the kernels is starch, which amounts to ~60% of the dry matter of a cobcorn, the cob itself being circa 15% of its dry matter.
Currently, harvesting maize for the grain is mostly done by a combine harvester, ..which typically is a general purpose harvester not specific to the crop, except for the front unit (called a header) which is a separate item.
The maize header does not require much power to function and it delivers cobcorn into the maw of the harvester.
The combine’s threshing rotor requires a great deal of power to function, and in consequence the harvester needs a large engine that necessarily consumes much fuel. ..Many a combine is a big expensive beast of a machine both to buy and to operate. ..The maize header costs far less in comparison.
Attaching a maize header to the front of a truck and running it with an hydraulic motor [or some other way], plus a means of conveying cobcorn into a box behind the cab, would result in a much less expensive harvest.
Alternatively, the header and conveyor may be a pull~type unit offset behind a tractor and delivering cobcorn into a wagon hitched directly behind that tractor. ..This was once the common way of harvesting maize in North America, even up to the 1970s. ..Self~propelled units were also available, some having a dumpbox that was emptied periodically into a truck.
But however cobcorn is harvested, what would complete the scenario is someone to buy it from the farmer, to save him the expense of threshing out the grain. ..In short, what is wanted is a reliable market for cobcorn. _And that depends ultimately on someone having use for the cobs.
A Market for Cobcorn
The most obvious buyer of cobcorn would be an aggregator who would assemble shipload quantities, separating grain from cobs and selling each separately. ..The machine used is specific to maize and does not require much power to strip kernels from the cob, leaving the cobs intact. (This process has been called shelling, though stripping is more descriptive.)
By way of contrast, what a combine harvester does is threshing, which is much more aggressive, breaking the cobs into pieces and using more power in doing so.
But the grain must be sufficiently dry to meet trade standards, and it is not in that condition when coming off the combine harvester on a farm. ..So that farmer must dry it, an extra expense. ..Similarly, cobcorns coming from the field also need drying, though not immediately, and may be sold as is, the buyer then needing to dry them in order to get grain dry enough to meet trade standards.
An inexpensive method is air drying, though this may take some weeks. A locale whose air is usually dry and hot is ideal for this. ..Many places around the Mediterranean fit this description well enough.
Major Buyer of Cobcorn … in a hot, sunny locale:
- Simple scenario —
- strip grain from cobs;
- bin drying of grain with air heated by sun;
- grain sent in shiploads;
- [storage of cobs outdoors for natural dry down];
- grind and pellet cobs: _ship those.
- << Other scenarios for a major buyer appear below.>>
Fermenters
The most likely use of pelleted cobs is in production of a biofuel thru fermentation. ..Only, not ethanol, which simply is a poor choice as a transport fuel, and rather restricted in the matter of ferment substrates. ..Far better instead are microbes that can utilise both starch and xylans [or at least xylose]. ..That way, maize cobs alone can be the substrate of choice for the fermenter, avoiding the grain entirely, which some years may be pricey.
Butanol is well known as something to be mixed in with gasoline, and it also blends with diesel fuel. ..Its energy density per litre is ~50% greater than for ethanol, and nearly matches that of regular gasoline. ..So it may seem itself an obvious choice as a ferment product. However, the choice is not so simple.
Making butanol by fermentation is a two.step process, in which butanoic acid is first produced and then later it gets transformed into butanol by the same microbes. ..But butanol is inhibiting to them, and in consequence must be removed from the broth more or less continuously, if the process is to be economical.
Certain advantages obtain by stopping the ferment at the acids stage and making butanoic acid the main product. ..It is then a shorter ferment, so the equipment is better utilised, making more product per month. ..The acid is also much easier to deal with and may be recovered as such, else as its calcium salt [as an example].
Of course, it is not itself a transport fuel. ..However, it can be made into a transport fuel in a separate operation, for which there are several choices. ..One of these is simple hydrogenation to make normal butanol of it. Another is use of immobilised bacteria to do likewise.
So maize cobs would be of interest to savvy biofuel makers who don’t limit themselves to considering only ethanol. ..Why perpetuate such an exceedingly poor choice, anyway? ..Doing only what others have done is timid management rather than sound management.
Furfural Maker
Furfural is an industrial chemical made from various agricultural materials having a relatively high content of xylans (say, 25% or so). ..Some plants use the bagassee from sugar cane processing, some use maize cobs. ..One such is a new plant in Kenya capable of making 5000 tons of furfural each year solely from maize cobs. (see item on this site: Furfural, on the ‘More Enviro’ menu.)
Some Other Choices
- Better scenario — for a major buyer of cobcorn _(hot, sunny locale)
- kernels being tightly packed on cob, slit or abrade their tops, [perhaps heat using radiant heat or microwaves], then remove much of the starch (say 75%), likely by suction, possibly by water jet or by rolling;
- dry [perhaps agglomerate] starchy bits removed;
- pack and sell containerloads as animal feed or perhaps also as human food;
- air dry cobs [if needed], then grind and pellet the cobs;
- sell to fermenters making biofuel; ..also to furfural makers.
- the cost of equipment is likely less, while sales revenues would be more.
- Extension —
- of the cobs after starch extracted, strip kernels from some of these;
- add this material to other such cobs when pelleting them;
- this provides pellets with more fermentables, thus worth more to fermenters;
- naked cobs may be sold to furfural makers, likely as pellets; …or ….
- extract much of the xylans from some cobs and add to others when pelleting them, which provides pellets with more xylan, worth more to furfural makers;
- compost these extracted cobs for later local sale as ‘natural fertiliser’.
Other Ferments —
Butanediol as a ferment product is another good choice since it is readily transformed into butanone in one simple step.
Perhaps better known as MEK [methyl.ethyl.ketone], ..butanone is a widely used solvent. It would fetch more sold as such, though it can also be [or become] a fuel component. ..As instance, it is readily hydrogenated to form isobutanol, which is also well known as something blendable with gasoline.