Ethanol-Gasoline Fuels: Are they Effective? Presented by Steve Cavadeas

Outline  Background  Ethanol production process  Pros and Cons  Conclusions

1990 Ammendment to Clean Air Act  An attempt to reduce severe smog areas  Reduce CO emissions in winter –Requires an oxygenate  Allows more complete combustion  Ethanol, MTBE  The federal RFG program was introduced in 1995  RFG is currently used in 17 states  About 30 percent of gasoline sold in the U.S. is reformulated.  Each oil company prepares its own formula.

Options  MTBE vs. Ethanol  Corn vs. Biomass  Dry milling vs. Wet milling Wet milling

Dry Milling Process

Wet Milling Process

Biomass Process

Wet Milling Details  Steeping –Grain is soaked in sulfurous acid for 24 to 48 hours  Grinding and Separation –Grain is separated into gluten, fiber, starch, and germ –Oil is extracted from germ using benzene

By-Products  Feed product –Fiber is extruded and heavy steep water is added, then dried. –Sold as feed for livestock  Gluten Meal –Gluten is filtered and dried –Sold as feed ingredient to poultry boiler operations

Products  Starch –Can be processed further to produce 1. Modified or dried corn starch 2. Corn syrup (dextrose, fructose) 3. Ethanol

Ethanol from Corn Starch Liquification –-amylase added to cleave random -1,4 and -1,6-glucosidic bonds –Gluco-amylase added to digest -1,4-glucosidic bond from non-reducing end

Ethanol from Corn Starch  Yeast then added to resulting sugar for fermentation (40-50 hours). C 6 H 12 O O 2  2 C 2 H 6 O + 2 CO 2 (6 separate reactions, ∆G = kcal/mol) (6 separate reactions, ∆G = kcal/mol) however, there is a problem…

Ethanol from Corn Starch  Respiration can occur! C 6 H 12 O O 2  6 CO H 2 O (G = -686 kcal/mol)  Solution? –Get rid of O 2 –Use organisms that preferentially ferment

Ethanol from Corn Starch  After fermentation, 8-10% EtOH in water –Distilled to approximately 190 proof –Dehydrated to 200 proof using molecular sieves  Finally, 5% denaturant is added to render undrinkable (usually gasoline) –Avoid beverage alcohol tax  Product is sent to be mixed as 10 vol% gasoline

Ethanol Production Facilities Source: U.S. Energy Information Administration/Renewable Fuels Administrations

U.S. Ethanol Production Source: U.S. Energy Information Administration/Renewable Fuels Administrations

Benefits  Octane Booster –Raises octane 2.5~3 numbers  Allows for higher combustion rates  Reduces harmful emissions –CO emissions decrease by 26% –Fewer higher order hydrocarbons emitted  Large number of jobs for production –32% of corn harvested goes to production of ethanol

Drawbacks  Additional emissions –15% NO x –65% Organic emissions –46% aldehydes –10% PAN, PPN Potent lachrymators and mutagens Data from Performance Evaluation of Alcohol-Gasoline Blends in 1980 Automobiles. Coordinating Research Council. No 527. July, 1982.

But then again…  New study from EPA suggests air quality is highest in three decades  Depends on who you ask Millions of Tons * CO NO x PPN SO VOC Lead *preliminary data

Other Drawbacks  Energy loss! –1 acre corn field creates ~ 330 gal EtOH –Planting, growing, harvesting 1 acre requires ~1,000 gal fossil fuels –1 gal EtOH = 77,000 Btu –1 gal Gasoline = 114,000 Btu  Possible vapor lock in engines (older cars) –Not an issue with “forward pumping”

More Drawbacks  Cost of production (2003) –EtOH ~ $1.74 / gallon –Gasoline ~ $1.14 / gallon  State and Federal Subsidies –~$1 Billion/year given to ethanol producers –This is added cost to consumer

Conclusion  Environmental benefits vs. cost/performance  Other oxygenates available? –ETBE (Ethyl Tert-Butyl Ether) –TAME (Tertiary Amyl Methyl Ether) –MTBE (Methyl Tert-Butyl Ether)

What do you think?  References 1.Performance Evaluation of Alcohol-Gasoline Blends in 1980 Automobiles. Coordinating Research Council. No 527. July, Ethanol from Corn Wastes Energy? Social Science. October Pg 6. 3.Potential Air Quality Effects of Using Ethanol-Gasoline Fuel Blends: A Field Study in Albuquerque, New Mexico. Environ. Sci. Technol. Vol. 31, No Pgs Renewable Fuels Association. 5.U.S. Department of Energy. 6.American Corn Growers Association.