Bioenergy-butanol

Agenda Bioethanol versus biodiesel Butanol (CH3CH2CH2CH2OH)

» Chemical properties» How to make it?

Butanol

Feedstock Any starch/sugar rich biomass

» Agricultural biomass– Corn– Wheat– Sugar cane – Sugar beets– Straws– Corn stover

» Woody biomass

History 1916 utilization of Clostridia acetobutylicum

for acetone production by Chime Wizemann (fermentation process)» Smokeless gun powder

1945 the second most important commercial fermentation process

1960 growth of petroleum industry» Butanol production via petrochemical pathway

1980-2008» Biological pathway

Ethanol versus butanol

Energy efficiency» Butanol 96% of gasoline

Less volatile than ethanol Less corrosive than ethanol Water-tolerant alternate fuel

» Less hydroscopic than ethanol (it doesn't pick up water)

– pipeline High viscosity

» 2x ethanol» 5-10x gasoline» Problems in the fuel systems of butanol-fueled cars

Lower octane number compared to ethanol » Lower compression ratio and efficiency

Butanol-properties Sweet smelling solvent Industrial solvent High melting point of 25.5°C causes it to

gel and freeze near room temperature » Additive in gasoline

Industrial commodity » 370million gallon/year» $3.75/gallon» Petrochemical route

Production of butanol (1)

Fermentation» Weizmann organism

(chemist Weizmann)» Anaerobic bacteria » Starch, sugars» Extracellular amylolytic

enzymes and amylase– Glucoamylase etc.

» Distillation (boiling point)

Clostridium acetobutylicum, the "Weizmann Organism"

ABE fermentation (2) ABE fermentation (butanol, acetone,

ethanol) butanol:acetone:ethanol (6:3:1)» Other by-products:

– Acetic acid– Lactic acid– Propionic acids– Isopropanol

1 bushel of corn: » 1.3 gallons of butanol» 0.65 gallons of acetone» 0.22 gallons of ethanol (each 1-2%)

Ethanol versus butanol fermentation (1)

Ethanol» S. cerevisiae (yeast)» Temp 30°C» pH 6

» No extracellular enzymes» Monomeric sugars (6C)» Products: 50% ethanol,

50% CO2

» Toxicity of the final product over 100g/L of ethanol

Butanol» Clostridium (bacteria)» Temp 30-40°C» pH 6.8-7 drops to 5.0

(acidogenesis) and increases to 7.0 (solventogenesis)

» Presence of extracellular enzymes

» Starch, cellobiose and monomers (5 and 6C)

» Variety of products» Toxicity of the final products

– 20g/L max of acetone, butanol, and ethanol

Ethanol versus butanol fermentation (2)

Butanol ClostridiumEthanol S. cerevisiae

Pure sugar source» Toxicity of butanol to C.acetobutylicum» ethanol, thus butanol, higher recovery

cost of butanol Lignocellulosic substrate

» More inhibitors generated during pretreatment

» Lower butanol yields

ABE fermentation (3)

Cars running on butanol

Over 10,000 miles around and across US