Corn in Your Tank?

America and most of the world seem to be held hostage by middle eastern oil kingdoms in collusion with big oil companies. Pollution from petroleum based fuels is ruining our environment and contributing to the global warming that may destroy humanity. Finding a way to kick our oil dependency is crucial to reducing the influence that these unsavory nations and their petroleum have over our future.

            Many people believe that the US could become self sufficient in auto fuel by converting our cars to burn ethanol. Some even suspect that a conspiracy between oil companies has suppressed the development of ethanol as fuel. But, while ethanol has the potential to supplement gasoline, it can never supplant it primarily due to the enormous magnitude of the gasoline usage in the USA.

            Let's look at some figures. Brazil has received favorable attention recently because it produces enough ethanol to provide 40% of its gasoline requirement, making it self sufficient. Note that even here ethanol has not completely supplanted gasoline, which still accounts for 60% of the auto fuel requirement.

            Before concluding that the US could reach the same level of ethanol usage, let's compare the two nations' demands. Brazil's auto usage is 10 billion (with a "B" – 10,000,000,000) gallons per year, which sounds like a lot until you consider that gasoline use in the US is 170 billion gallons per year. How much sugar cane would be required to produce the USA's auto fuel demand with ethanol, and how much land would have to be devoted to growing it?

            According to Lester R. Brown in, Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble there are two crucial measures of biofuel production, fuel yield per acre and net energy yield (the energy produced above that required to produce it).

            First we have to understand that different fuels contain different amounts of combustion energy. That's no conspiracy, just the facts of chemistry and thermodynamics. Unfortunately ethanol provides significantly less energy than gasoline, meaning that it takes more gallons of ethanol than gallons of gasoline to propel a car 100 miles. This makes it hard to evaluate statistical claims. For example, how do we know whether any particular report includes this energy penalty that ethanol has compared to gasoline?

            Assuming for argument's sake that ethanol gives 85% of the combustion energy of gasoline, then we need 1,200 gallons of ethanol for every 1,000 gallons of gasoline, meaning we need 200 billion gallons of ethanol per year to supplant gasoline in America.

According to Brown, Brazil tops the world's efficiency in turning sugar cane to ethanol, producing 662 gallons from each acre under cultivation and providing an 8 to one return on the energy investment. In other words, Brazil gets 8 units of ethanol energy for each unit of energy required to produce it. American ethanol from corn produces 354 gallons per acre and returns only 1.5 units of energy for each unit required to produce it.

Because a unit of energy is required for each 8 units of energy returned, the ethanol required becomes 225 billion gallons. At Brazil's rate of production, the USA would need over 340 million acres devoted to growing sugar cane to produce 225 billion gallons of ethanol. To put this in perspective, all the existing corn fields in every state amount to about 800 million acres.

If we rely instead upon corn we must invest 2 units of energy for every 3 units of ethanol we produce. Consumption increases to a whopping 330 billion gallons requiring almost a billion acres or 1.5 million square miles of corn in addition to the current corn crop! Every square foot of land between Chicago and Denver from Canada to Mexico would have to grow corn. No cities, no parks, no homes or freeways, only corn fields.

Before deciding to push for huge increases in ethanol production, we may want to consider the consequences. As ethanol displaces gasoline, its price will increase, forcing the price of the corresponding crop to rise. Sugar, corn and other crops that can produce ethanol will rise along with the price of the fuel and the food they produce. Corn as food must compete with corn as fuel.

Where will ethanol crops grow? To the extent that existing farmland is converted to such production, the world's food supply will decrease. Clearly vast new areas will have to be cultivated. Will this accelerate the destruction of Brazilian rainforest?

What resources are required to harvest and process 300 million acres of sugar cane; 930 million acres of corn? Already the giant agribusinesses compete with oil companies for America's enmity. And what happens if a cane blight or corn weevils or tornadoes or floods wipes out much of the crop? And what about fertilizer? Good farmers know that you must rotate crops. If you plant the same crop year after year, the soil is depleted of the nutrients required by that crop. Will we devastate the land by growing corn or sugarcane, then have to apply ever greater volumes of fertilizer?

Ethanol from cellulose such as wheat straw and sawgrass have been discussed recently. These require enzymes to break down the cellulose into ethanol. Much work needs to be done to determine the rate and total yield of this breakdown.

It is clear that ethanol represents an extender to supplement existing petroleum stocks, and a temporary one at that. It cannot replace gasoline. Until we come up with a viable solution to future petroleum shortages and environmental degradation, we must depend primarily upon conservation. Whatever the fuel, the less we use of it the better. Devoting enormous new resources to ethanol production will undoubtedly produce unintended consequences detrimental to the environment. Like it or not, gasoline is the best worst choice for decades to come.