Corn ethanol

It is debatable whether the production and use of corn ethanol results in lower greenhouse gas emissions than gasoline.

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.

[10] In the dry milling process, the entire corn kernel is ground into flour, or "mash," which is then slurried by adding water.

The entire process takes 40 to 50 hours, during which time the mash is kept cool and agitated to promote yeast activity.

The remaining silage is processed into a highly nutritious livestock feed known as distiller's dried grains and solubles (DDGS).

[citation needed] In wet milling, the corn grain is separated into components by steeping in dilute sulfurous acid for 24 to 48 hours.

The remaining components of fiber, gluten, and starch are segregated using screen, hydroclonic, and centrifugal separators.

The heavy steep water is also sold as a feed ingredient and used as an alternative to salt in the winter months.

[citation needed] Corn ethanol results in lower greenhouse gas emissions than gasoline and is fully biodegradable, unlike some fuel additives such as MTBE.

[14] 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.

Other issues relate to pollution, water use for irrigation and processing, energy balance, and emission intensity for the full life cycle of ethanol production.

[15][16][17][18][19][20][21][22][23][24] 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.

[14][25][26][27] 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.

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.