An Open Letter to Ethanol Factories

The manufacture of ethanol for fuel from corn is wasteful of energy because the energy required to plant and harvest the corn, plus the energy to ferment and distill it, approximates the energy in the product ethanol. All green plants produce sugar (almost always glucose) by photosynthesis in the leaves.  This is transported to their seeds and the inner layer of bark (cambium layer) where it is converted (polymerized) to starch for storage.  This is why peas are at their best when freshly picked before the new sugar arriving from the leaves has been converted into starch.  Starch is easily converted back to sugar for use by the embryo plant or in the mother plant for its own new growth especially in the spring.  


Ethanol production whether whiskey, vodka or as a gasoline additive utilizes embryo plants (almost always barley) to digest other starch from corn, potatoes, rice, etc.  The resulting sugar is fermented by yeast to ethanol and carbon dioxide--hence the fizz in beer and champagne.  When glucose is polymerized to cellulose (woody fibers) instead of starch, this is a one-way street as far as the plant is concerned.  Cellulose is degraded biologically only by soil bacteria whether in the soil or inhabiting termites or other animal intestines.  If we could devise an industrial scale artificial termite intestine, crop wastes and sawdust would be the feedstock instead of cornstarch (the only portion of the corn converted to ethanol in our present ethanol factories—the remainder is used for animal feed).  How do tiny termite bodies manage to retain the bacteria needed to digest cellulose by a continuous process (as opposed to a batch process like the fermentation followed by distillation in an ethanol plant)? Continuous processes are almost always much more efficient than batch processes—an axiomatic precept in chemical engineering.   It would seem that the bacteria that do the work for termites would be expelled from such a small insect body long before they got the job done.  The interesting answer is that the bacteria inhabit spaces among the hairs of a hairy paramecium (a one celled animal much larger than bacteria and much smaller than termites).  The paramecia swim up stream in the termite intestine like miniature spawning salmon, carrying the bacteria forever upstream where the chemical action is happening.


A team containing microbiologists and chemical engineers should promptly solve the straightforward assignment of devising an industrial scale termite intestine.  They probably wouldn’t even need the paramecia because of economies of scale.  It also happens that termite digestion can be tuned in the laboratory to produce various chemical entities from methane to hydrogen and in a rather pure state. Methane is easily converted to methanol (wood alcohol), which is interchangeable with ethanol as a fuel additive.  So, when (if) the hydrogen economy blossoms, our new factories could be adapted to become geographically distributed producers of hydrogen, incidentally obviating some problems in transporting the hydrogen to its users.


It is notable that 10% ethanol in gasoline is an excellent and sufficient octane enhancer.  Also, unlike tetraethyl lead and methyl tertiary butyl ether, it is totally nontoxic in the environment. (Don’t drink anything that is mixed with gasoline).


In summary, in spite of the byproduct of animal feed, non-beverage ethanol production is wasteful of energy unless the ethanol can be produced from a feedstock of waste material.  I ascertained that Monroe’s ethanol plant could be adapted in this manner before voting with the rest of the Aldermen in favor of the plant coming to Monroe.


John A. Frantz, MD

July 14, 2005

More about Fermentation Producing Ethanol

In the previous article I mentioned the use of barley malt to convert starch to glucose, the first step in making beer, and about how embryo barley plants are so rich in this enzyme that much more starch from any other source can also be converted to glucose simultaneously.  Yeast, Saccharomyces cervesiae, is then added to ferment the sugar to alcohol and carbon dioxide (CO2). Baker’s yeast, brewer’s yeast, and various wine yeasts are all strains of one species, S. cervesiae. The differences among the strains are in the amounts of trace byproducts, producing slightly different ancillary flavors. 


In the case of beer manufacture hops are added for flavor before fermentation.  Beer results with no further processing except bottling.  Carbonation occurs naturally from fermentation if the beer is sealed in bottles at just the right stage of fermentation – too much carbonation will explode the bottles.  Modern brewers frequently pasteurize the beer to inactivate (kill) the yeast.  The beer is then carbonated much more accurately with tanks of compressed CO2.  Home brewers can get accurate carbonation by letting the fermentation go to completion and adding just the right amount of sugar at the time of bottling (3/4 teaspoon per quart).


In a whiskey distillery the hops are omitted and only wheat or rye for starch is added to the malting barley.  After fermentation, distillation concentrates the alcohol along with distinctive volatile flavors.  The malt (which produces the “body” in beer) remains behind and is converted to animal feed, as also occurs in ethanol factories like the one in Monroe.  Vodka is much more easily made because the distillation is tuned to produce alcohol and water only.  Any source of starch produces the same product, technical grade industrial alcohol, also known as vodka when diluted about 50%.  Another way to concentrate alcohol instead of distillation is freezing a fermented solution and discarding the ice.   This is how applejack used to be made, which incidentally prevented olfactory detection by revenue agents.


Wine is produced by fermenting sweet juices by using different strains of  S. cervesiae.  To be precise, wine is fermented grape juice – other fermented juices are “false wines”.  The percentage of alcohol in wine is exactly half the original sugar concentration (up to over 25%).  This is a coincidence of the atomic weights in the chemical reaction equation (I checked this out).  A concentration of 11% alcohol in wine is required for it to keep well enough to age properly--various slow bacterial reactions must be inhibited.   The greatest possible concentration of alcohol that can be produced from fermentation alone is 15%--too close to 15% may result in what had been intended to be a dry wine remaining slightly sweet.  So 15% alcohol inhibits yeast.  What concentration of CO2 inhibits yeast?  The answer is 75 pounds per square inch.  This is the reason that champagne bottles are so thick.  Champagne is slightly sweet.  The fermentation will stop by the excess CO2--greater than “normal” carbonation, in case you hadn’t noticed. 


In the case of baker’s yeast, a tiny amount of fermentation results in an enormous amount of CO2--hence teetotalers can conscientiously eat bread.  All of us get about one alcoholic drink per day from fermentation in our intestines, anyway.  When told about this, I suspect that some teetotalers are thinking “My intestines wouldn’t do that to me!”.  Baking powder produces CO2 from baking soda and a weak acid such as cream of tartar but only in the presence of water; double acting baking powder also produces CO2 when heated.


John A. Frantz, MD

November 7, 2005