Corn is the main feedstock used for producing ethanol fuel
in the United States.
This section needs expansion
. You can help by adding to it
. (November 2018)
Since 2001, corn ethanol production has increased by more than seven times.
Out of 9.50 billions of bushels of corn produced in 2001, 0.71 billions of bushels were used to produce corn ethanol. Compared to 2018, out of 14.62 billions of bushels of corn produced, 5.60 billions of bushels were used to produce corn ethanol, reported by the United States Department of Energy
. Overall, 95% of ethanol is produced from corn.
Currently, corn ethanol is mainly used in blends with gasoline
to create mixtures such as E10
, and E85
is mixed into more than 98% of United States gasoline to reduce air pollution.
Corn ethanol is used as an oxygenate
when mixed with gasoline
. E10 and E15
can be used in all engines without modification. However, blends like E85, with a much greater ethanol
content, require significant modifications to be made before an engine can run on the mixture without damaging the engine.
Some vehicles that currently use E85
fuel, also called flex fuel
, include, the Ford Focus
, Dodge Durango
, and Toyota Tundra
, among others.
The future use of corn ethanol as a main gasoline
replacement is unknown. Corn ethanol has yet to be proven to be as cost effective as gasoline
due to corn ethanol being much more expensive to create compared to gasoline
Corn ethanol has to go through an extensive milling
process before it can be used as a fuel source. One major drawback with corn ethanol, is the energy returned on energy invested (EROI
), meaning the energy outputted in comparison to the energy required to output that energy. Compared to oil, with an 11:1 EROI
, corn ethanol has a much lower EROI
of 1.5:1, which, in turn, also provides less mileage per gallon compared to gasoline.
In the future, as technology advances and oil becomes less abundant, the process of milling
may require less energy, resulting in an EROI
closer to that of oil. Another serious problem with corn ethanol as a replacement for gasoline
, is the engine damage on standard vehicles. E10 contains ten percent ethanol
and is acceptable for most vehicles on the road today, while E15
contains fifteen percent ethanol
and is usually prohibited for cars built before 2001.
However, with the hope to replace gasoline
in the future, E85
, which contains 85% ethanol
, requires engine modification before an engine can last while processing a high volume of ethanol
for an extended period of time. Therefore, most older and modern day vehicles would become obsolete without proper engine modifications to handle the increase in corrosiveness
from the high volume of ethanol
. Also, most gas stations do not offer refueling of E85 vehicles. The United States Department of Energy
reports that only 3,355 gas stations, out of 168,000, across the United States, offer ethanol
refueling for E85
There are two main types of corn ethanol production: dry milling
and wet milling
, which differ in the initial grain treatment method and co-products.
In wet milling
, the corn grain
is separated into components by steeping in dilute sulfuric acid
for 24 to 48 hours.
The slurry mix then goes through a series of grinders to separate out the corn germ
. The remaining components of fiber, gluten
, and starch are segregated using screen, hydroclonic, and centrifugal separators. The corn starch
and remaining water can be fermented into ethanol
through a similar process as dry milling
, dried and sold as modified corn starch
, or made into corn syrup
. The gluten
protein and steeping liquor are dried to make a corn gluten meal
that is sold to the livestock industry. The heavy steep water is also sold as a feed ingredient and used as an alternative to salt in the winter months. Corn oil
is also extracted and sold.
Greenhouse gas emissions
One of the main controversies involving corn ethanol production is the necessity for arable cropland
to grow the corn for ethanol, which is then not available to grow corn for human or animal consumption.
In the United States, 40% of the acreage designated for corn grain is used for corn ethanol production, of which 25% was converted to ethanol after accounting for co-products, leaving only 60% of the crop yield for human or animal consumption.
Economic impact of corn ethanol
The Renewable Fuels Association
(RFA), the ethanol industry's lobbying group, claims that ethanol production increases the price of corn by increasing demand. The RFA claims that ethanol production has positive economic effect for US farmers, but it does not elaborate on the effect for other populations where field corn is part of the staple diet. An RFA lobby document states that "In a January 2007 statement, the USDA Chief Economist stated that farm program payments were expected to be reduced by some $6 billion due to the higher value of a bushel of corn.
Corn production in 2009 reached over 13.2 billion bushels, and a per acre yield jumped to over 165 bushels per acre.
In the United States, 5.6 million bushels of corn were used for ethanol
production out of 14.6 million bushels produced, according to preliminary 2018 USDA
According to the U.S. Department of Energy's Alternative Fuels Data Center, "The increased ethanol [production] seems to have come from the increase in overall corn production and a small decrease in corn used for animal feed and other residual uses. The amount of corn used for other uses, including human consumption, has stayed fairly consistent from year to year."
This does not prove there was not an impact on food supplies: Since U.S. corn production doubled (approximately) between 1987 and 2018, it is probable that some cropland previously used to grow other food crops is now used to grow corn. It is also possible or probable that some marginal land has been converted or returned to agricultural use. That may have negative environmental impacts.
Alternative biomass for ethanol
Remnants from food production such as corn stover
could be used to produce ethanol instead of food corn. Ethanol derived from sugar-beet as used in Europe or sugar-cane in Brazil has up to 80% reduction in well-to-wheel carbon dioxide
. The use of cellulosic biomass
to produce ethanol
is considered second generation biofuel
that are considered by some to be a solution to the food versus fuel debate, and has the potential to cut life cycle greenhouse gas emissions
by up to 86 percent relative to gasoline.
- ^ Smil, Vaclav (2017). Energy Transitions: Global and National Perspectives. Santa Barbara, California: Praeger, an imprint of ABC-CLIO, LLC. p. 162. ISBN 978-1-4408-5324-1. OCLC 955778608.
- ^ Conca, James. "It's Final -- Corn Ethanol Is Of No Use". Forbes. Retrieved 1 April 2019.
- ^ a b Mumm, Rita H; Goldsmith, Peter D; Rausch, Kent D; Stein, Hans H (2014). "Land usage attributed to corn ethanol production in the United States: sensitivity to technological advances in corn grain yield, ethanol conversion, and co-product utilization". Biotechnology for Biofuels. 7 (1): 61. doi:10.1186/1754-6834-7-61. ISSN 1754-6834. PMC 4022103. PMID 24725504. Although 40.5% of corn grain was channeled to ethanol processing in 2011, only 25% of US corn acreage was attributable to ethanol when accounting for feed co-product utilization.
- ^ "Alternative Fuels Data Center: Maps and Data - U.S. Corn for Fuel Ethanol, Feed and Other Use". afdc.energy.gov. Retrieved 16 April 2019.
- ^ a b c "Alternative Fuels Data Center: Ethanol Fuel Basics". afdc.energy.gov. Retrieved 16 April 2019.
- ^ a b "Corn Ethanol Use in the Midwest". large.stanford.edu. Retrieved 16 April 2019.
- ^ Cleveland, Cutler J.; O’Connor, Peter; Hall, Charles A. S.; Guilford, Megan C. (October 2011). "A New Long Term Assessment of Energy Return on Investment (EROI) for U.S. Oil and Gas Discovery and Production". Sustainability. 3 (10): 1866–1887. doi:10.3390/su3101866.
- ^ "Alternative Fuels Data Center: Ethanol Fueling Station Locations". afdc.energy.gov. Retrieved 16 April 2019.
- ^ Bothast, R. J.; Schlicher, M. A. (2014). "Biotechnological processes for conversion of corn into ethanol". Applied Microbiology and Biotechnology. 67 (1): 19–25. doi:10.1007/s00253-004-1819-8. ISSN 0175-7598. PMID 15599517. S2CID 10019321.
- ^ Ethanol Production and Distribution, Alternative Fuels Data Center, US Dept of Energy <http://www.afdc.energy.gov/fuels/ethanol_production.html>
- ^ Verser, D. W.; Eggeman, T. J. Process for producing ethanol from corn dry milling. US7888082B2. https://patents.google.com/patent/US7888082B2/en
- ^ Section, Government of Alberta, Alberta Agriculture and Forestry, Livestock and Crops Division, Crop Research and Extension Branch, Livestock and Crop Research Extension (1 November 2011). "Feeding Distillers Dried Grains with Solubles (DDGS) to Pigs". www1.agric.gov.ab.ca. Retrieved 23 November 2018.
- ^ Jackson, David S.; Shandera, Donald L. (1995), "Corn Wet Milling: Separation Chemistry and Technology", Advances in Food and Nutrition Research, Elsevier, 38: 271–300, doi:10.1016/s1043-4526(08)60085-6, ISBN 9780120164387, PMID 15918293
- ^ a b c d Ethanol Myths and Facts Archived 15 December 2010 at the Wayback Machine
- ^ "Biofuels: The Promise and the Risks, in World Development Report 2008" (PDF). The World Bank. 2008. pp. 70–71. Retrieved 4 May 2008.
- ^ Timothy Searchinger; et al. (29 February 2008). "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change". Science. 319 (5867): 1238–1240. Bibcode:2008Sci...319.1238S. doi:10.1126/science.1151861. PMID 18258860. S2CID 52810681. Originally published online in Science Express on 7 February 2008. See Letters to Science by Wang and Haq. There are critics to these findings for assuming a worst-case scenario.
- ^ "Another Inconvenient Truth" (PDF). Oxfam. 28 June 2008. Archived from the original (PDF) on 19 August 2008. Retrieved 2008-08-06. Oxfam Briefing Paper 114, figure 2 pp.8
- ^ Fargione; Hill, J.; Tilman, D.; Polasky, S.; Hawthorne, P.; et al. (29 February 2008). "Land Clearing and the Biofuel Carbon Debt". Science. 319 (5867): 1235–1238. Bibcode:2008Sci...319.1235F. doi:10.1126/science.1152747. PMID 18258862. S2CID 206510225. Originally published online in Science Express on 7 February 2008. There are rebuttals to these findings for assuming a worst-case scenario.
- ^ "Proposed Regulation to Implement the Low Carbon Fuel Standard. Volume I: Staff Report: Initial Statement of Reasons" (PDF). California Air Resources Board. 5 March 2009. Retrieved 26 April 2009.
- ^ Youngquist, W. Geodestinies, National Book company, Portland, OR, 499p.
- ^ The dirty truth about biofuels
- ^ Deforestation diesel – the madness of biofuel
- ^ United States National Research Council, Committee on Water Implications of Biofuels Production in the United States (2008). Water Implications of Biofuels Production in the United States. The National Academy Press, Washington, D.C. ISBN 978-0-309-11361-8.
- ^ Farrell, Alexander E.; Plevin, Richard J.; Turner, Brian T.; Jones, Andrew D.; O'Hare, Michael; Kammen, Daniel M. (2006). "Ethanol Can Contribute to Energy and Environmental Goals". Science. 311 (5760): 506–508. Bibcode:2006Sci...311..506F. doi:10.1126/science.1121416. ISSN 0036-8075. PMID 16439656. S2CID 16061891.
- ^ Daniel., Sperling (2009). Two billion cars : driving toward sustainability. Gordon, Deborah, 1959-. Oxford: Oxford University Press. ISBN 9780199704095. OCLC 302414399.
- ^ Liska, Adam L.; Yang, Haishun S.; Bremer, Virgil R.; Klopfenstein, Terry J.; Walters, Daniel T.; Erickson, Galen E.; Cassman, Kenneth G. (2009). "Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn‐Ethanol". Journal of Industrial Ecology. 13: 58–74. doi:10.1111/j.1530-9290.2008.00105.x. S2CID 18630452.
- ^ Brown, Lester Russell (2003). Plan B: Rescuing a Planet Under Stress and a Civilization in Trouble. W. W. Norton & Company. ISBN 9780393325232.
- ^ "Ethanol Facts: Agriculture". www.ethanolrfa.org. 12 January 2010. Retrieved 4 April 2010.
- ^ "2009 Crop Year is One for the Record Books, USDA Reports". Nass.usda.gov. 12 January 2010. Archived from the original on 14 January 2010. Retrieved 4 April 2010.
- ^ a b "Alternative Fuels Data Center: Maps and Data - Corn Production and Portion Used for Fuel Ethanol". afdc.energy.gov. Retrieved 29 August 2019.
Last edited on 31 March 2021, at 15:15
Content is available under CC BY-SA 3.0
unless otherwise noted.