Biofuels: Food versus Fuel?

Dr. Tapsak, HSC203, x4893National Teach-in on Global Warming, Feb. 5, 2009

How green are biofuels?

Interesting ethanol facts!

• In 1908, Ford’s Model T had a carburetor adjustment that allowed the vehicle to run on ethanol.

• In the 1930s, more than 2000 service stations in the Midwest sold ethanol made from corn.

• By the 1940s, WW2 prompted governments to commandeer whiskey distilleries for ethanol fuel production.

• During the 1970s oil crisis, ethanol was blended into gasoline to form gasohol (E10).

http://www.nesea.org/greencarclub/factsheets_ethanol.pdf, accessed 2/3/09

How is ethanol currently produced

from corn?

• Milling • Liquefying the Cornmeal • Enzyme Hydrolysis • Yeast Fermentation • Distillation• Dehydration

https://www.eere-pmc.energy.gov/PMC_News/images/ethanolmythpic.jpg, accessed 2/3/09

Where is ethanol currently produced?

Switch grass and wood byproducts contain fermentable sugars, but they are locked up in complex structures. Plant matter (biomass) consists of three key polymers: Cellulose (35 to 50%), hemicellulose (20 to 35%), and lignin (10 to 25%).

http://genomicsgtl.energy.gov/benefits/cellulosicethanol.shtml, accessed 2/3/09

How is ethanol currently produced

from biomass?

• Mechanical Preprocessing• Pretreatment• Solid-Liquid Separation• Fermentation of Hemicellulosic Sugars • Enzyme Production • Cellulose Hydrolysis • Fermentation of Cellulosic Sugars (Glucose) • Distillation • Dehydration

http://genomicsgtl.energy.gov/benefits/cellulosicethanol.shtml, accessed 2/3/09

What are the challenges we face?

• According to Dr. David Pimental, Cornell University, powering the average U.S. automobile for one year on ethanol (blended with gasoline) derived from corn would require 11 acres of farmland.

• Ethanol can not be effectively transported by pipeline.

• More energy is required to produce ethanol than the energy that actually is in it.

• Ethanol subsidies are highly politicized.

http://genomicsgtl.energy.gov/benefits/cellulosicethanol.shtml, accessed 2/3/09