Corn ethanol

Corn ethanol is ethanol produced from corn as a biomass through industrial fermentation, chemical processing and distillation. It is primarily used in the United States as an alternative to gasoline and petroleum (first-generation biofuel). Corn ethanol is the most common type of ethanol in the United States, but is considered less efficient than other types of ethanol (sugar cane, etc.) because only the grain is used and many petroleum-based products (fertilizer, pesticides, etc) are used in it's production.

Ethanol production may occur through two corn processing methods: dry and wet corn milling; the main difference between the two is the initial treatment of grain. In dry milling operations, liquefied corn starch is produced by heating corn meal with water and enzymes. A second enzyme converts the liquefied starch to sugars, which are fermented by yeast into ethanol and carbon dioxide; released CO₂ during fermentation can be captured and sold for use in carbonating beverages and in the manufacture of dry ice, but it is often released to the atmosphere because carbon capture for food use requires specialized and expensive equipment. Wet milling operations separate the pericarp, germ (oil), and protein from the starch before it is fermented into ethanol.

Environmental efficiency

Despite CO₂ (a greenhouse gas) being released during ethanol production and combustion, it is recaptured as a nutrient to the crops that are used in its production. Approximately 75% of ethanol production is performed via the dry corn milling process, since dry corn mills are less expensive to construct. The problem with traditional grain based ethanol is that it utilizes fossil fuels to produce heat during the conversion process, generating substantial greenhouse gas emissions.

There is also controversy over the production of corn in many equatorial regions with rain forests, and South Africa. Farmers and agriculture businesses are burning down rain forests (which are natural CO2 sequesters already). While CO2 studies assume no co2 sequestration if the corn is not planted. Scientists say that this will mean that ethanol will end up contributing to global warming more than if we used oil, where rainforests are destroyed to produce it. This is also an issue in other biofuels such as biodiesel.

Problems associated with corn-derived ethanol

The cost of building 100 million gallon ethanol plants is $140 million; the cost of natural gas to operate these plants is estimated at $15-$25 million per year, while the amount of water required in the production of ethanol is roughly 2 million gallons per day.(Approximately 1700 gallons of water for every gallon of ethanol) And since corn is one of the most water-intensive crops to grow, the volume of water involved in production makes it imperative that the water used be treated sewage water, rather than the Ogallala aquifer beneath the great plains, which is being drawn down at rates exceeding 100 times replacement rate.

Others argue that the benefits versus rewards, from an environmental perspective, are substantially less. Whether or not ethanol production from corn is efficient is debatable. Proponents of corn-derived ethanol point to studies emphasizing an overall net positive energy gain, whereas others claim that when the complete production costs of farming, seed, fertilizer, pesticides, fuel, ethanol distillation, etc., are taken into consideration, ethanol requires 30% more energy to produce than it creates. Ethanol proponents say that ethanol simply puts back the same carbon dioxide that the plants from which it is made absorbed while growing, and hence does not add to the world's balance of greenhouse gases. A 2006 University of Minnesota study shows a positive energy balance for ethanol of around 25%, but also highlights many environmental and economic limitations affecting the viability of corn ethanol.

There are also ethical challenges in deciding the best use of natural resources. The "fuel or food debate" rages over the loss of dedicating more land to ethanol crops would squeeze the supply of land for food production. Demand for biofuels is raising the price of crops which may adversely affect food supplies. In June 2008, corn was selling at an all time high of well over $7.36/bushel (compared with the recent norm of around $2/bushel). Poultry and Pork producers are feeling the pinch of rising corn prices, which may soon be felt as higher bills at the grocery check-out counter. Moreover, government-sponsored efforts to cull forest lands for "biomass" fuel stocks could deplete habitats. For example, dedicating more land to ethanol crops would squeeze the supply of land for food production. There is currently 349 million acres (1,410,000 km²) of available farmland, and an additional 388 million acres (1,570,000 km²) of idle land. The amount of land required to plant enough corn to replace imported fuels is 238 million acres (963,000 km²). Realistically, peak corn-ethanol would likely top out at between 11 and 15 billion US gallons (42 and 57 million m³) per year - only a fraction of the 140 billion US gallons (530 million m³) of gasoline consumed each year in the United States.

Producing corn is very energy intensive, and uses fossil fuels in virtually every step of the crop cycle: transporting and planting the seeds; operating farm equipment; making and applying fertilizer; and transporting the corn to market. Fertilizer, herbicide, and insecticide production consume the most fossil fuels. Fossil-fuel based fertilizers also contaminate the soil and groundwater, but they can not be replaced by natural fertilizer: there are not enough animals to provide the fertilizer to grow the corn necessary to produce all the grain-based ethanol needed to run American cars. And the herbicides and pesticides necessary to grow corn at an industrial scale leach into the groundwater, too.

There is an ongoing debate concerning the amount of energy it takes to produce ethanol from corn. For example, it takes energy equivalent to about one gallon of gasoline to make four pounds of nitrogen, the main ingredient in most fertilizer, and every one of the more than 15 million acres (61,000 km²) planted in corn is dusted with about 58 pounds of nitrogen. Given the variety of factors that go into growing corn, estimates vary widely about the amount of energy used: one estimate contends that it would require 1.5 gallons of ethanol to provide the same amount of energy as a gallon of gasoline. Others challenge these conclusions, asserting that this analysis is based on obsolete data and miscalculated key energy values and does not account for the useful by-products, such as animal feed, of making ethanol; taking all that into account, ethanol could provide up to 40% more energy than is consumed in making it.

The question of sustainability arises when we consider that ethanol from corn can't possibly be grown forever because growing corn depletes the soil even if sustainable farming methods such as crop rotation are used. Some researchers argue that ethanol production from corn could wear out the soil within 30 years. Although farmers in the midwest have been growning corn on the same land for the past 200 years and are getting a larger crop today then they did 30 years ago.

Ethanol, even in gasoline blends, cannot be shipped through the country's existing gasoline pipeline system because it is easily contaminated by water and corrodes the pipes; there is no ethanol pipeline anywhere in the world, although Brazil's Petrobras claims to have one in the planning stages. Ethanol is currently shipped by truck or rail car to fuel distributors, who then mix it with gasoline before delivering it to filling stations in more trucks. This adds to the cost of ethanol and to its overall CO₂ emissions. In order to use ethanol on any large scale, transport vehicles will either have to be retrofitted for ethanol, or the government be forced to build or subsidize pipelines.

For ethanol to be currently economically viable requires massive Federal subsidies and price supports. Even the biggest of proposed ethanol supports - an increase in mandated ethanol consumption from 7.5 billion gallons a year to 15 billion gallons a year, as called for in the energy bill Congress is currently (10/07) debating - would barely dent America’s oil consumption, which is approximately 150 billion gallons annually.

Another issue concerning ethanol as a gasoline substitute includes the fact that only around 5 million automobiles currently in America are “flexible-fuel vehicles” - cars that are equipped to run on a blend of 85 percent ethanol and 15 percent gasoline (known as E85). That’s out of 135 million registered passenger cars in the United States. Moreover, as the Dallas Morning News reported last year, the owners of almost all of these flex-fuel vehicles tend to fill them up with regular gas, owing to a scarcity of gas stations that sell E85.

There is no shortage of disagreement on the pros and cons of using corn-ethanol as a petroleum substitute. What does emerge from the discussion is that while corn-derived ethanol may be a short term solution to America's energy problem, it casts doubt on corn-based ethanol's long-term viability, and begs the need for a long term solution: enter cellulosic ethanol.

There is actually a debated possibility that (indirectly) corn and other ethanols cause rainforests to be slashed and burnt. This happens because the fields that were formally used for corn are now used for ethanol. Thus the corn grown for eating is grown on what were grazing lands for farmers and ranchers. These people start cutting rainforest for grazing ground and also use the fertile grasslands.