Biogas Production from Lignocellulosic Biomass

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1 Biogas Production from Lignocellulosic Biomass Dr. Ram Chandra Scientist, Energy Bioscience Overseas Fellow Centre for Rural Development & Technology Indian Institute of Technology Delhi 1

2 Biomass to Energy Conversion Processes 1) Thermochemical conversion: (i) Combustion, (ii) Pyrolysis, (iii) Gasification In all above processes only part of thermal energy is utilized (10-20%). There is no any emission reduction in actual. 2) Biochemical conversion: (i) Alcoholic fermentation is most energy intensive process. (ii) Anaerobic digestion: Most efficient process Clean and Green Fuel and Bio-fertilizer 2

3 Introduction to Anaerobic Digestion Process

4 Anaerobic Digestion Process Complex Organic Substrates HYDROLYSIS: Performed by hydrolytic bacteria (facultative anaerobes and anaerobes) Simple Substrates ACID PRODUCTION: Including acetogenesis (facultative anaerobes and anaerobes) Acetate, Formate, CO 2, CO, H 2, Methanol, Ethanol, Methyl Amine, Propionate, Butyrate METHANE PRODUCTION: Methanogenesis CH 4 + CO 2 + Other minor gases

5 Stage I- Hydrolysis Complex Carbohydrates Simple Sugars Complex Lipids (Fat) Fatty Acids Complex Proteins Amino Acids

6 Stage II- Acid Production Simple Sugars + Fatty Acids + Amino Acids Organic acids, including acetate + Alcohols Acetogenesis (acetate production): Organic acids + Alcohols Acetate

7 Stage III- Methane Production Acetoclastic Methanogenesis Acetate CH 4 + CO 2 Hydogenotrophic Methanogenesis H 2 + CO 2 CH 4 Methyltrophic Methanogenesis Methanol CH 4 + H 2 O

8 Overview of Microbial Transformation Biodegradable Acetate waste % COD % Large Org acids organic alcohols molecules 20% H 2 and CO 2 17% 13% 72% CH 4 and CO 2 28% 8

9 Agricultural Biomass Residue Resources for second generation of biofuel production Crop waste Total cultivated area, Mha Estimated dry biomass production, MT Rice (27.3%) Wheat (13.3%) Sugarcane (19.5%) Maize (5.5%) ~ 700 MT biomass/year (13% of the world) 1) Thermochemical conversion: Combustion, Pyrolysis, Gasification, Bio-oils 0.38 kw/ha or 9 kwh/day from surplus biomass (50% biomass use, 4 tonne/ha/year,15 MJ/kg, ɳ = 20%). 33 GW potential from only 4 major crop residue (50% biomass use and ɳ = 20%). 2) Biochemical conversion: Alcoholic fermentation, Anaerobic digestion Biomethane and Bio-fertilizer 9

10 Open Field Burning of Paddy Straw in Punjab 10

11 Efficient biomethane production from agricultural biomass Biomass composition: 35-55% cellulose, 10-25% hemicellulose, and 5-30% lignin Three steps: Pretreatment (delignification): most challenging task Hydrolysis Fermentation 11

12 Cell wall Pretreatment Lignocellulosic structure and role of pretreatment Macrofibrill Hemicellulose Plant cell Plant Lignin Cellulose Edward MR, Nature,2008, 454: Chandra et al., Renewable & Sustainable Energy Reviews, 2012, 16:

13 Types of pretreatment: (1) Mechanical (2) Chemical (3) Hydrothermal (4) Biological 13

14 1.50 mm 0.75 mm 0.30 mm 1.50 mm 0.75 mm 0.30 mm Effect of particle size on methane production yield Wheat Straw Rice Straw Methane yield, L/kg VS a Fractional composition? Level of particle size reduction? Substrates Chandra et al., Applied Energy, 2013 (submitted) 14

15 Effect of level of particle size reduction Coarse grinding Fine grinding Ultra fine grinding Total carbohydrate and glucose 15

16 Energy consumption in biomass grinding process A case of size reduction for rice straw Particle size (mm) Energy consumption (MJ/kg) (3%) (32%) (84%) Heating value of rice straw = 15.0 MJ/kg Chandra et al., Applied Energy, 2013 (submitted) 16

17 Hydrothermal Pretreatment of Biomass Macromolecule Breakdown 17

18 ph of sludge Effect of Hydrothermal Pretreatment Rice straw Rice husk Wheat straw Temperature, 0 C 18

19 WT ; 5.7 2%NaOH ; 19.7 HT+3%NaOH ; 36.5 WT ; %NaOH ; 74.1 HT+5%NaOH ; WT ; %NaOH ; HT+5%NaOH ; 94.1 Effect of NaOH and HT pretreatment on methane yield Rice Husk Rice Straw Wheat Straw Energy input in HT Methane yield, L/kg VS a pretreatment Temp: C, TS 20% Q = MJ/kg of TS 22% of feedstock energy Biomass compaction in reactor reduces input energy requirement 1 L batch feed AD Substrates Chandra et al., Applied Energy, 2012, 94: Chandra et al., Energy, 2012, 43:

20 THANK YOU