Lars Angenent, Ph.D.!Dept. of Biological & Environmental Engineering!!BEE 4870!

http://angenent.bee.cornell.edu!

Goal and outline of Bioenergy Chapter 14:!!1. Current or close-to-adaptable technology!2. Decision making process!

A.  Policies!B.  Net energy balance ratio and life cycle assessment!C.  Productivity (cropland and time)!D.  Environment, etc.!

3. Biomass!4. Bioenergy platforms!5. Ethanol – sugarcane vs. corn grain!6. Biodiesel!7. Methane and hydrogen!!

Vanek F. M., Albright L. D. and Angenent L. T. Energy Systems Engineering: Evaluation & Implementation, 2nd edition, McGraw Hill, New York, NY.!!

Policies!!•  Laissez fair (but then subsidies for fossil fuels

should be disbanded)!

•  Mandates: 36 billion gallons of ethanol equivalent fuel in 2020 (US Energy Independence and Security Act of 2007)!

•  Feed-in Tarrifs: 20 cents per unit electricity (kWh) for 20 years for renewable energy.!

Life cycle assessment (LCA)!!•  Environmental impact from cradle to grave!!!•  Net energy balance (NEB) ratio:!

! ! Energy in fuel and other credits (animal feed)! = -------------------------------------------------------------------------------------------!

!All energy needed to produce fuel (growing, processing, transporting)!!!!= < 1 (more fossil fuel energy going in than biofuel energy out!= 10-20 = sustainable?!!But, oranges with oranges; and remain critical, but open minded!!!!!!!!

Biomass Sources:!!1. Plant materials:!

A.  Starches/sugars/oils!B.  Lignocellulose!

2. Algae!3. Organic wastes!

A.  Agricultural (crop and animal waste)!B.  Urban (food and wood waste)!

!

Sugarcane plantation in Brazil!

Energy density in source!

Lignocellulosic feedstock and hydrolysis (pretreatment)!

Pretreatment!1.  Milling!2.  Dilute-sulfuric acid – toxic byproducts = furfurals!3.  Hot water!4.  Alkaline!

Algae!!NEB ratio < 1 even with advanced reactors and extracting oil plus digestion rest of cells to methane!!

Biomass to bioenergy (biorefinery platforms) !Sugar platform!(enzymes-yeast)!

Syngas platform!(thermochemical)!

Carboxylate platform!(undefined mixed cultures)!

Acetate: CH3COOH!Propionate: CH3CH2COOH!Butyrate: CH3CH2CH2COOH!

Syngas: H2 + CO!

Bio-oil platform!(thermochemical)!

Syngas and bio-oil platforms:!!Gasification (anaerobic combustion) products:!!•  Biochar!•  Syngas (carbon monoxide, hydrogen)!•  Bio-oil!

Gas Engine, MicroturbineFuel Cell!

Gasification unit!

Syngas!Biomass! Electrical Power!

Heat!Heat!

Methanation Unit!

Gasification unit!

Syngas!Biomass! Synthetic Natural Gas (SNG)!

Heat!Heat!

Syngas

Methane

Q Q

Utilization of syngas besides fermentation!

Ethanol!

Ethanol from sugar cane in Brazil (7 billion gallons)!

Ethanol from corn grain in US (14 billion gallons)!

20% of energy value in ethanol itself is used for distillation (recovery)* * Shapiro et al. (2010) evaluated several dry milling plants based on 2008 data gathering.

NEB ratio now around 2: biomass combustion/other fuel!

Biodiesel mostly from plant-derived oils (0.8 billion gallons)!

POLYMERS!proteins, polysaccharides, lipids!MONOMERS & OLIGOMERS!amino acids, sugars, fatty acids!

INTERMEDIATES!propionate, butyrate, alcohols!

CH!4! !+ CO!2!

H!2! + CO!2! ACETATE!

Fermenters!

Acetogens!

Hydrogen-utilizing!Methanogens!

Acetate-utilizing!Methanogens!

70%!30%!

Anaerobic food web!

Carboxylic acids!

Undefined mixed cultures!(1000s of different species)! •  Who are they?!

•  Improve function (stability)!

Thanks!