{{Short description|Ethanol produced from corn biomass}} {{Use dmy dates|date=May 2023}} [[File:Combine-harvesting-corn.jpg|thumb|400px|Corn is the main feedstock used for producing ethanol fuel in the United States.]]
'''Corn ethanol''' is ethanol produced from corn biomass and is the main source of ethanol fuel in the United States, mandated to be blended with gasoline in the Renewable Fuel Standard. Corn ethanol is produced by ethanol fermentation and distillation. It is debatable whether the production and use of corn ethanol results in lower greenhouse gas emissions than gasoline.<ref>{{cite book | last=Smil | first=Vaclav | title=Energy Transitions: Global and National Perspectives | publisher=Praeger, an imprint of ABC-CLIO, LLC | location=Santa Barbara, California | year=2017 | isbn=978-1-4408-5324-1 | oclc=955778608 |page=162}}</ref><ref>{{Cite web|url=https://www.forbes.com/sites/jamesconca/2014/04/20/its-final-corn-ethanol-is-of-no-use/|title=It's Final -- Corn Ethanol Is of No Use|last=Conca|first=James|website=Forbes|access-date=2019-04-01}}</ref> Approximately 45% of U.S. corn croplands are used for ethanol production.<ref>{{Cite web |title=USDA ERS – Feedgrains Sector at a Glance |url=http://www.ers.usda.gov/topics/crops/corn-and-other-feed-grains/feed-grains-sector-at-a-glance |access-date=2022-12-15 |website=ers.usda.gov}}</ref>
== Uses == {{Expand section|date=November 2018}} Since 2001, corn ethanol production has increased by more than several times.<ref>{{Cite web|url=https://afdc.energy.gov/data/10339|title=Alternative Fuels Data Center: Maps and Data – U.S. Corn for Fuel Ethanol, Feed and Other Use|website=afdc.energy.gov|access-date=2019-04-16}}</ref> 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 billion bushels were used to produce corn ethanol, reported by the United States Department of Energy. Overall, 94% of ethanol in the United States is produced from corn.<ref name=":0">{{Cite web|url=https://afdc.energy.gov/fuels/ethanol_fuel_basics.html|title=Alternative Fuels Data Center: Ethanol Fuel Basics|website=afdc.energy.gov|access-date=2019-04-16}}</ref>
Currently, corn ethanol is mainly used in blends with gasoline to create mixtures such as E10, E15, and E85. Ethanol is mixed into more than 98% of United States gasoline to reduce air pollution.<ref name=":0" /> 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.<ref name=":1">{{Cite web|url=http://large.stanford.edu/courses/2014/ph240/parry2/|title=Corn Ethanol Use in the Midwest|website=large.stanford.edu|access-date=2019-04-16}}</ref> Some vehicles that currently use E85 fuel, also called flex fuel, include, the Ford Focus, Dodge Durango, and Toyota Tundra, among others.{{Citation needed|date=January 2021}}
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.<ref name=":1" /> 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.<ref>{{Cite journal|last1=Cleveland|first1=Cutler J.|last2=O'Connor|first2=Peter|last3=Hall|first3=Charles A. S.|last4=Guilford|first4=Megan C.|date=October 2011|title=A New Long Term Assessment of Energy Return on Investment (EROI) for U.S. Oil and Gas Discovery and Production|journal=Sustainability|volume=3|issue=10|pages=1866–1887|doi=10.3390/su3101866|bibcode=2011Sust....3.1866G |doi-access=free}}</ref> 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.<ref name=":0" /> 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 vehicles.<ref>{{Cite web|url=https://afdc.energy.gov/fuels/ethanol_locations.html#/find/nearest?fuel=E85&country=U%20S|title=Alternative Fuels Data Center: Ethanol Fueling Station Locations|website=afdc.energy.gov|access-date=2019-04-16}}</ref>
Beyond its role as a transportation fuel, ethanol from corn can be dehydrated to ethylene or coprocessed in fluid catalytic cracking units. A 2025 cradle to gate life cycle assessment reported lower greenhouse gas emissions for such bioethylene pathways than for fossil-derived ethylene production.<ref>{{cite journal |last1=Benavides |first1=Prasanna T. |last2=Gracida-Alvarez |first2=Ubaldo R. |last3=Richa |first3=Kriti |last4=Port |first4=John |last5=Hawkins |first5=Troy R. |year=2025 |title=Cradle-to-gate greenhouse gas emissions of bioethylene produced from U.S. corn ethanol and comparison to fossil-derived ethylene production |journal=Bioresource Technology |volume=430 |article-number=132565 |doi=10.1016/j.biortech.2025.132565 |pmid=40268097 |doi-access=free }}</ref> In this pathway, ethanol is catalytically dehydrated to produce ethylene, a key feedstock for polyethylene and other plastics. Under certain configurations, life cycle modeling found that bioethylene from corn ethanol could achieve more than a 100% reduction in greenhouse gas emissions compared to fossil derived ethylene, due to coproduct credits and carbon capture.<ref name="Cradle-to-gate greenhouse gas emiss">{{cite journal |last1=Benavides |first1=Prasanna T. |last2=Gracida-Alvarez |first2=Ubaldo R. |last3=Richa |first3=Kriti |last4=Port |first4=John |last5=Hawkins |first5=Troy R. |year=2025 |title=Cradle-to-gate greenhouse gas emissions of bioethylene produced from U.S. corn ethanol and comparison to fossil-derived ethylene production |journal=Bioresource Technology |volume=430 |article-number=132565 |doi=10.1016/j.biortech.2025.132565|doi-access=free }}</ref> The study also examined coprocessing ethanol with petroleum derived feedstocks in refinery units to produce renewable gasoline blendstocks, finding this pathway could achieve significant greenhouse gas savings relative to conventional refining.<ref name="Cradle-to-gate greenhouse gas emiss"/>
==Production process== {{See also|Corn wet-milling|Dry milling and fractionation of grain|l1=}}[[File:Ethanol plant.jpg|thumb|left|350px|An ethanol fuel plant in West Burlington, Iowa.]]
Biofuels can be produced through biological or thermochemical routes, with bioethanol among the most common.<ref>{{cite journal |last1=Chen |first1=Wei-Hsin |last2=Lee |first2=Keat Teong |last3=Ong |first3=Hong Chyuan |year=2019 |title=Biofuel and Bioenergy Technology |journal=Energies |volume=12 |issue=2 |page=290 |doi=10.3390/en12020290 |doi-access=free |hdl=10453/136901 |hdl-access=free }}</ref> Recent plant upgrades have incorporated energy saving measures such as heat integration, improved distillation efficiency, and advanced enzymes that increase starch to ethanol conversion rates.<ref name="Life-cycle greenhouse gas emissions">{{cite journal |last1=Xu |first1=Hao |last2=Lee |first2=Uisung |last3=Wang |first3=Michael |year=2022 |title=Life-cycle greenhouse gas emissions reduction potential for corn ethanol refining in the USA |journal=Biofuels, Bioproducts and Biorefining |volume=16 |issue=3 |pages=671–681 |doi=10.1002/bbb.2348}}</ref> Examples of such measures include replacing natural gas with biomass derived syngas, installing combined heat and power systems, and capturing CO₂ from fermentation or distillation.<ref name="Life-cycle greenhouse gas emissions"/> 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.<ref>{{Cite journal|last1=Bothast|first1=R. J.|last2=Schlicher|first2=M. A.|date=2014|title=Biotechnological processes for conversion of corn into ethanol|journal=Applied Microbiology and Biotechnology|volume=67|issue=1|pages=19–25|doi=10.1007/s00253-004-1819-8|pmid=15599517|s2cid=10019321|issn=0175-7598}}</ref>
=== Dry milling === The vast majority (≈90%) of corn ethanol in the United States is produced by dry milling.<ref>{{Cite web |title=Alternative Fuels Data Center: Ethanol Production |url=https://afdc.energy.gov/fuels/ethanol-production |access-date=2026-05-21 |website=afdc.energy.gov |language=en-US}}</ref> In the dry milling process, the entire corn kernel is ground into flour, or "mash," which is then slurried by adding water.<ref>Verser, D. W.; Eggeman, T. J. Process for producing ethanol from corn dry milling. US7888082B2. https://patents.google.com/patent/US7888082B2/en</ref> Enzymes are added to the mash to hydrolyze the starch into simple sugars. Ammonia is added to control the pH and as a nutrient for the yeast, which is added later. The mixture is processed at high temperatures to reduce the bacteria levels. The mash is transferred and cooled in fermenters. Yeast are added, which ferment the sugars into ethanol and carbon dioxide. The entire process takes 40 to 50 hours, during which time the mash is kept cool and agitated to promote yeast activity. The mash is then transferred to distillation columns, where the ethanol is removed from the silage. The ethanol is dehydrated to about 200 proof using a molecular sieve system. A denaturant such as gasoline is added to render the product undrinkable. The product is then ready to ship to gasoline retailers or terminals. The remaining silage is processed into a highly nutritious livestock feed known as distiller's dried grains and solubles (DDGS).<ref>{{Cite web|url=https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex13760|title=Feeding Distillers Dried Grains with Solubles (DDGS) to Pigs|last=Section|first=Government of Alberta, Alberta Agriculture and Forestry, Livestock and Crops Division, Crop Research and Extension Branch, Livestock and Crop Research Extension|date=2011-11-01|website=www1.agric.gov.ab.ca|access-date=2018-11-23}}</ref> The carbon dioxide released from the process can be used to carbonate beverages and to manufacture dry ice .{{Citation needed|date=January 2021}}
=== Wet milling === In wet milling, the corn grain is separated into components by steeping in dilute sulfurous acid for 24 to 48 hours.<ref>{{Citation|last1=Jackson|first1=David S.|title=Corn Wet Milling: Separation Chemistry and Technology|volume=38|date=1995|journal=Advances in Food and Nutrition Research|pages=271–300|publisher=Elsevier|doi=10.1016/s1043-4526(08)60085-6|pmid=15918293|isbn=978-0-12-016438-7|last2=Shandera|first2=Donald L.}}</ref> 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.<ref>{{Cite web |last=AMG |title=Corn Milling: Wet vs. Dry Milling |url=https://blog.amg-eng.com/corn-wet-milling-vs-dry-milling/ |access-date=2026-05-21 |website=blog.amg-eng.com |language=en}}</ref>
==Environmental issues== {{See also|Ethanol fuel in the United States#Environmental and social impacts|l1=Environmental and social impacts of ethanol fuel in the U.S.}}
Corn based ethanol is classified as a first generation biofuel produced from edible crops; later generations derive from lignocellulosic feedstocks or algae.<ref>{{cite journal |last=Tropea |first=Angelo |year=2022 |title=Biofuels Production and Processing Technology |journal=Fermentation |volume=8 |issue=7 |page=319 |doi=10.3390/fermentation8070319 |doi-access=free }}</ref> Corn ethanol results in lower greenhouse gas emissions than gasoline and is fully biodegradable, unlike some fuel additives such as MTBE.<ref name="EERE">[http://www1.eere.energy.gov/biomass/ethanol_myths_facts.html Ethanol Myths and Facts] {{webarchive|url=https://web.archive.org/web/20101215041537/http://www1.eere.energy.gov/biomass/ethanol_myths_facts.html|date=15 December 2010}}</ref> However, because energy to run many U.S. distilleries comes mainly from coal plants, there has been considerable debate on the sustainability of corn ethanol in replacing fossil fuels. Additional controversy relates to the large amount of arable land required for crops and its impact on grain supply and direct and indirect land use change effects. Other issues relate to pollution, water use for irrigation and processing, energy balance, and emission intensity for the full life cycle of ethanol production.<ref name=WorldBank>{{cite web|url=http://siteresources.worldbank.org/INTWDR2008/Resources/2795087-1192112387976/WDR08_05_Focus_B.pdf |title=Biofuels: The Promise and the Risks, in World Development Report 2008 |publisher=The World Bank|year=2008|pages= 70–71|access-date=2008-05-04}}</ref><ref name=Science08>{{cite journal|title=Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change|author=Timothy Searchinger|journal=Science|volume=319 |issue=5867|pages=1238–1240|doi=10.1126/science.1151861|date=29 February 2008|pmid=18258860|bibcode=2008Sci...319.1238S|s2cid=52810681|display-authors=etal|doi-access=free}} 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.</ref><ref name=Oxfam>{{cite web|url=http://www.oxfam.org/files/bp114-inconvenient-truth-biofuels-0806.pdf |title=Another Inconvenient Truth |publisher=Oxfam |date=28 June 2008 |access-date=2008-08-06 |archive-url=https://web.archive.org/web/20080819214631/http://www.oxfam.org/files/bp114-inconvenient-truth-biofuels-0806.pdf |archive-date=19 August 2008 }}Oxfam Briefing Paper 114, figure 2 pp.8</ref><ref name="Fargione08">{{cite journal|title=Land Clearing and the Biofuel Carbon Debt |author=Fargione|journal=Science|volume=319 |issue=5867 |pages=1235–1238 |date=29 February 2008 |pmid= 18258862|doi= 10.1126/science.1152747|bibcode=2008Sci...319.1235F|last2= Hill|first2= J.|last3= Tilman|first3= D.|last4= Polasky|first4= S.|last5= Hawthorne|first5= P.|s2cid=206510225|display-authors=etal}} Originally published online in Science Express on 7 February 2008. There are rebuttals to these findings for assuming a worst-case scenario.</ref><ref name=ARBproposal>{{cite web|url= http://www.arb.ca.gov/regact/2009/lcfs09/lcfsisor1.pdf |title=Proposed Regulation to Implement the Low Carbon Fuel Standard. Volume I: Staff Report: Initial Statement of Reasons|publisher=California Air Resources Board|date=5 March 2009|access-date=2009-04-26}}</ref><ref>Youngquist, W. Geodestinies, National Book company, Portland, OR, 499p.</ref><ref>{{Cite web |url=http://www.oilcrash.com/articles/pf_bio.htm |title=The dirty truth about biofuels |access-date=30 July 2010 |archive-date=4 December 2009 |archive-url=https://web.archive.org/web/20091204053139/http://www.oilcrash.com/articles/pf_bio.htm }}</ref><ref>[http://www.efrc.com/manage/authincludes/article_uploads/Deforestation%20diesel1.pdf Deforestation diesel – the madness of biofuel]</ref><ref name=Wfootprint2010>{{cite journal|title=The water footprint of biofuel production in the USA|last1=Powers|first1=Susan E|last2=Dominguez-Faus|first2=Rosa|last3=Alvarez|first3=Pedro JJ|date=March 2010|journal=Biofuels|volume=1|issue=2|pages=255–260|doi=10.4155/BFS.09.20|s2cid=130923687}}{{dead link|date=August 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name=NRCWater>{{Cite book | author=United States National Research Council, Committee on Water Implications of Biofuels Production in the United States|title = Water Implications of Biofuels Production in the United States| year = 2008 | publisher = The National Academy Press, Washington, D.C.| isbn = 978-0-309-11361-8}}</ref>
=== Greenhouse gas emissions === [[File:ADM corn plant (Columbus, Nebraska).JPG|thumb|Corn-processing plant near Columbus, Nebraska.|alt=|400x400px]]Several full life cycle studies have found that corn ethanol reduces well-to-wheel greenhouse gas emissions by up to 50 percent compared to gasoline.<ref name="EERE" /><ref>{{Cite journal|last1=Farrell|first1=Alexander E.|last2=Plevin|first2=Richard J.|last3=Turner|first3=Brian T.|last4=Jones|first4=Andrew D.|last5=O'Hare|first5=Michael|last6=Kammen|first6=Daniel M.|date=2006|title=Ethanol Can Contribute to Energy and Environmental Goals|journal=Science|volume=311|issue=5760|pages=506–508|doi=10.1126/science.1121416|issn=0036-8075|pmid=16439656|bibcode=2006Sci...311..506F|s2cid=16061891}}</ref><ref>{{Cite book|title=Two billion cars: driving toward sustainability|last=Daniel.|first=Sperling|date=2009|publisher=Oxford University Press|others=Gordon, Deborah, 1959–|isbn=978-0-19-970409-5|location=Oxford|oclc=302414399}}</ref><ref name="Ianrnews.unl.edu">{{cite journal|last1=Liska|first1=Adam L.|last2=Yang|first2=Haishun S.|last3=Bremer|first3=Virgil R.|last4=Klopfenstein|first4=Terry J.|last5=Walters|first5=Daniel T.|last6=Erickson|first6=Galen E.|last7=Cassman|first7=Kenneth G.|date=2009|title=Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol|journal=Journal of Industrial Ecology|volume=13|issue=1 |pages=58–74|doi=10.1111/j.1530-9290.2008.00105.x|bibcode=2009JInEc..13...58L |s2cid=18630452|url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1000&context=ncesrpub|doi-access=free}}</ref> A 2022 life cycle analysis led by Argonne National Laboratory estimated the current U.S. corn ethanol carbon intensity at about 52.4 g CO₂e/MJ. The study found that combining efficiency measures, fuel switching (e.g., syngas or renewable natural gas in place of natural gas), and carbon capture could reduce carbon intensity to as low as −18.4 g CO₂e/MJ, including land use change.<ref name="Life-cycle greenhouse gas emissions"/> The analysis also accounted for credits from co products such as distillers dried grains with solubles (DDGS), which displace conventional animal feed and thereby reduce overall life cycle greenhouse gas emissions.<ref name="Life-cycle greenhouse gas emissions"/> However, more recent research based on an analysis of data from the first eight years of the US Renewable Fuel Standard's implementation suggests that corn ethanol produces more carbon emissions per unit of energy than gasoline, when factoring in fertilizer use and land use change.<ref>{{cite journal |last1=Lark |first1=Tyler |last2=Hendricks |first2=Nathan P. | first3=Aaron |last3=Smith | first4=Nicholas |last4=Pates | first5= Seth A. |last5=Spawn-Lee | first6= Matthew |last6=Bougie | first7=Eric G. |last7=Booth | first8= Christopher J. |last8=Kucharik | first9= Holly K. |last9=Gibbs |date=2022 |title=Environmental outcomes of the US Renewable Fuel Standard |journal=Proceedings of the National Academy of Sciences |volume=119 |issue=9 |article-number=e2101084119 |doi=10.1073/pnas.2101084119 |doi-access=free |pmid=35165202 |pmc=8892349 |bibcode=2022PNAS..11901084L }}</ref>
Ethanol-blended fuels currently in the market – whether E10 or E85 – meet stringent tailpipe emission standards.<ref name="EERE" />
=== Croplands and land use === [[File:Corn vs Ethanol production.webp|thumb|300px|Corn vs ethanol production in the United States {{legend|#FFD932|Total corn production (bushels) (left)}} {{legend|B51700|Corn used for ethanol fuel (bushels) (left)}} {{legend-line|#313131 solid 3px|Percent of corn used for Ethanol (right)}} ]] 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.<ref>{{Cite book|url=https://books.google.com/books?id=TXhQM0Qyol8C&q=rescuing+a+plant+under+stress+and+a+civilization+in+trouble&pg=PR7|title=Plan B: Rescuing a Planet Under Stress and a Civilization in Trouble|last=Brown|first=Lester Russell|date=2003|publisher=W. W. Norton & Company|isbn=978-0-393-32523-2}}</ref> 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.<ref name="Mumm 2014 61">{{Cite journal |last1=Mumm |first1=Rita H |last2=Goldsmith |first2=Peter D |last3=Rausch |first3=Kent D |last4=Stein |first4=Hans H |date=2014 |title=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 |journal=Biotechnology for Biofuels |volume=7 |issue=1 |page=61 |doi=10.1186/1754-6834-7-61 |issn=1754-6834 |pmc=4022103 |pmid=24725504 |bibcode=2014BB......7...61M |quote=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. |doi-access=free }}</ref>
Growing corn to fuel internal combustion vehicles is a highly inefficient use of land. A solar farm generating electricity to power an electric vehicle would power around 85 times as much distance as corn ethanol grown on the same area.<ref>{{Cite web |date=January 19, 2023 |title=Corn Ethanol vs. Solar: Land Use Comparison |url=https://www.cleanwisconsin.org/wp-content/uploads/2023/01/Corn-Ethanol-Vs.-Solar-Analysis-V3-9-compressed.pdf |website=Clean Wisconsin}}</ref>
== 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.<ref>{{cite web|url=http://www.ethanolrfa.org/pages/ethanol-facts-agriculture |title=Ethanol Facts: Agriculture |publisher=ethanolrfa.org |date=12 January 2010 |access-date=2010-04-04}}</ref> Corn production in 2009 reached over 13.2 billion bushels, and a per acre yield jumped to over 165 bushels per acre.<ref>{{cite web |url=http://www.nass.usda.gov/Newsroom/2010/01_12_2010.asp |title=2009 Crop Year is One for the Record Books, USDA Reports |publisher=Nass.usda.gov |date=12 January 2010 |access-date=2010-04-04 |archive-url=https://web.archive.org/web/20100114051806/http://www.nass.usda.gov/Newsroom/2010/01_12_2010.asp |archive-date=14 January 2010 }}</ref> In the United States, 5.05 billion bushels of corn were used for ethanol production out of 14.99 billion bushels produced in 2020, according to USDA data.<ref name="afdc.energy.gov">{{Cite web|url=https://afdc.energy.gov/data/10339|title=Alternative Fuels Data Center: Maps and Data – Corn Production and Portion Used for Fuel Ethanol|website=afdc.energy.gov|access-date=2019-08-29}}</ref> 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."<ref name="afdc.energy.gov"/> 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.{{Citation needed|date=January 2021}}
==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.<ref name="EERE" />
==See also== *Ethanol fuel *Ethanol fuel in the United States
==References== {{Reflist}}
==External links== * [https://web.archive.org/web/20080621101938/http://www.worldwatch.org/node/5391 Better Than Corn? Algae Set to Beat Out Other Biofuel Feedstocks] (Worldwatch Institute). *The End of Cheap Food. (Cover Story). 2007 Economist 385(8558):11–12. *Energy Policy Act of 2005. 2005 Public Law {{nat|109-58}}. *Pimentel, David. 2009 Corn Ethanol as Energy. Harvard International Review 31(2):50–52. *Scully, Vaughan. 2007 Effects of the Biofuel Boom. BusinessWeek Online:26-26. *Waltz, Emily. 2008 Cellulosic Ethanol Booms Despite Unproven Business Models. Nature Biotechnology 26(1):8–9. *[https://www.thekitchenrevival.com/cornstarch-substitute/ Cornstarch Substitute] *[https://www.ucsusa.org/sites/default/files/attach/2017/02/Fueling-Clean-Transportation-Future-Biofuels.pdf Martin,Jeremy. 2017. Fueling a Clean Transportation Future.] Union of Concerned Scientists.
{{DEFAULTSORT:Corn Ethanol}} Category:Ethanol fuel Category:Ethanol Category:Maize products