Ethanol alcohol (EtOH) is the same alcohol that is in beer, wine, and distilled spirits, namely CH3CH2OH.
In dry milling the entire kernel of corn or other starchy grain such as wheat, barley or sorghum is processed without separating out the various component parts of the grain. Water is added to form a mash to which enzymes are added to convert the starch to dextrose, a simple sugar. The mash is cooked at high temperatures to reduce bacteria, and is then cooled and fermented with yeast to convert the sugar to alcohol. The yeast die off when the alcohol content rises to about 15%. Distillation converts the mixture to about 180-proof (90%). Dehydration with benzene produces 200-proof (100%) alcohol. Then a small amount of a denaturant, such as unleaded gasoline, is added to ensure that it cannot be consumed as a beverage before being shipped off to be used as a fuel.
The Environmental Protection Agency ruled in the Clinton years that gasoline manufacturers were required to use ethanol as an oxygenate to produce a cleaner burn previously provided by MTBE (methyl tertiary-butyl ether) which proved to be a ground water contaminant. While Chemical & Engineering News explained that cars produced after 1995 no longer needed an additive to produce a cleaner burn, the requirement continues to this date, as a result of extremely effective lobbying by agricultural trade groups.
Their success is indicated by the fact that ethanol received a 51-cent per gallon subsidy through 2008 and 45 cents a gallon ever since. In addition, cheaper EtOH made in Brazil from sugar cane suffers a 54-cent tariff. But wait! There is more! An escalating government mandate that runs through 2022 requires the production of 37 billion gallons of biofuel (primarily ethanol) in the United States.
All of this support for an unnecessary fuel even before the U.S. became the energy capital of the world, was exposed in 1998 by the late Dr. David Pimentel of Cornell University. While chairing the U.S. Department of Energy Panel to investigate the economics of ethanol production, the panel found that 131,000 British Thermal Units (BTUs) were required to produce a single gallon of ethanol, which only produced 77,000 BTUs when burned. That is a net energy loss of 54,000 BTUs per gallon. But it gets worse.
While some cost is captured by selling the residual dry distillers grain for animal feed, the panel determined that water use and soil erosion required by growing corn had their costs as well.
Pimentel ended his report by all but gloating when he stated that if all the automobiles in the U.S. were fueled by ethanol, 97% of our land area would have to be devoted to growing corn.
In reality one can recognize that growing corn to produce ethanol is a way to harvest solar energy, all of which initially comes from the sun’s radiation. How much strikes the earth at any one time depends on the season and latitude of the location. A reasonable year-long average across the earth is that solar energy averages 200 watts per square meter of the earth surface (think in terms of the heat and light provided by the familiar 100 watt light bulb).
To get some perspective on corn-ethanol, let us consider two other ways to harness solar energy: direct conversion to electricity via photoelectric (PV) cells, and conversion of wind energy into electricity.
These days, commercially available PV cells can convert about 15%-20% of the sunlight falling on them into electricity. In a place averaging 200 watts of sunlight per square meter, they produce 30-40 watts per square meter of land area, averaged around the year.
Wind turbines in excellent sites are spread out over huge tracts of land. On average, they produce about 12.5 kW/hectare, or 1.25 watts per square meter of the enclosed land.
Photosynthesis is the mechanism by which solar energy becomes stored in plants, and it is nowhere near as efficient as people believe. To make a long story short, energy crops of various kinds can be produced at the rate of about 10 tons (9 metric tons) of drymatter per acre (4047 square meters) of land per year. In energy units, it amounts to a year-round average conversion rate of sunlight to biomass of 1.2 watts per square meter, or about the same as wind power.
There is a big difference, however, between wind and biomass. Wind machines produce electricity directly. If drymatter is simply burned to produce steam to turn a turbine to produce electricity, it will do so at about 35% efficiency, resulting in 0.42 watts per square meter. But that’s also an overestimate, because we are neglecting the energy involved in harvesting, drying, and delivering the biomass to the electricity plant.
For corn, the conversion of solar energy into plant energy is no better than for generic drymatter. It takes a lot of energy to convert that energy into EtOH, as noted above. The Renewable Energy Association has argued that the production of EtOH is energy net-positive, but their figures amount to about 0.6 watts (thermal) per square meter of land. (Converted to electricity at 35% efficiency, that would be 0.21 watts per square meter.) In any case, the use of fertile land to produce a fuel means that less agricultural land can be used to produce food.
At last the forces of economics brought on by the unfortunate pandemic may be shining a light on the illogical continuous federal support for a fuel that makes no sense. With less fuel being used, less ethanol is being bended into gasoline. Profit on the production of ethanol, even with its subsidies, has disappeared. More than a million gallons a day are being produced, according to the U.S. Energy Information Administration, as stockpiles total over 24 million barrels.
Last year more than 10 ethanol plants cut production rates or closed down. Many more are yet to follow. Time is long overdue to end the ethanol industry as we have known it for more than three decades. Let them turn to producing a more useful product, namely pure grain alcohol for the liquor industry.