Ming W Lau

AN INTEGRATED BIOREFINERY APPROACH UTILIZING AFEX-PRETREATED CORN STOVER FOR ETHANOL, NATIVE YEAST AND SACCHAROLYTIC ENZYME PRODUCTION

Ming W Lau

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Operating Cost Based on NREL Economic Model (2008) •

In Percentage (%) Electricity

-8.4%

Waste Disposal

1.3%

Other Raw Materials

1.8%

Ammonia

13.2%

Sulfuric Acid

2.6% 22.3%

Cellulase CSL (Nutrients)

9.9% 57.3%

Feedstock 0

20

40

60

Operating Cost (cents/gal EtOH)

80

Detoxification (ammonia), nutrient supplementation and cellulase = 45% of the total processing cost • Ammonia to biomass ratio = 75 g: 1 kg • Electricity generated from residual unhydrolyzed solids • The actual cost of enzyme is still uncertain

Modified from Humbird and Aden (2009) 2

Conventional Approach in Cellulosic Ethanol Production •

Dilute acid solubilizes hemicellulose • Detoxification using ammonia to reduce inhibitory levels • Commercial nutrients and enzymes are added for bioconversion Modified from Humbird and Aden (2009)

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4

Strategies to Improve Overall Economics of Cellulosic Ethanol

Preserve Lignin for CoProduction Generation

Eliminate Detoxification

Find Highly Robust Strain/s for High Ethanol Yield

Improved Paradigm for Biomass Processing and Conversion

Evaluate Biomass Nutrients and Minerals

Reduce Cost of Enzymes

Ammonia Fiber Expansion (AFEX) and Dilute Acid Pretreatment Untreated CS

SOLIDS

AFEX

Dilute Acid

Catalyst

Anhydrous ammonia as catalyst

Sulfuric acid as catalyst

Hemicellulose solublization