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 Introduction to Anaerobic Digestion Process

3 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

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

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

6 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

7 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% 7

8 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 8

9 Composition and Associated Problem with Lignocellulosic Biomass Biomass composition: 35-55% cellulose, 10-25% hemicellulose, and 5-30% lignin Three steps: Pretreatment (delignification): most challenging task Hydrolysis Fermentation 9

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

11 Methods of Pretreatment of Lignocellulosic Biomass (1) Mechanical: Mainly size reduction (2) Chemical: Alkali and acids (3) Hydrothermal: Water at high temperature (4) Biological: Bacteria and fungal 11

12 Effect of particle size on methane production yield Wheat Straw Rice Straw Methane yield, L/kg VS a mm mm mm mm mm mm Fractional composition? Level of particle size reduction? Substrates 12 Chandra et al., Applied Energy, 2013 (submitted)

13 Mechanical Pretreatment: Level of Particle Size Reduction Coarse grinding Fine grinding Ultra fine grinding Total carbohydrate and glucose 13

14 Energy consumption in biomass grinding process A case of size reduction for rice straw Particle size (mm) Energy consumption (MJ/kg) (3%) (32%) 12.6 (84%) Heating value of rice straw = 15.0 MJ/kg Chandra et al., Applied Energy, 2013 (submitted) 14

15 Hydrothermal Pretreatment of Biomass Macromolecule Breakdown 15

16 Methane and Ethanol Production Potential of Agricultural Residue Biomass Sl. no. Biomass Methane production Ethanol production 1 Maize crop waste Yield, kg/tonne Energy, MJ Yield, kg/tonne Energy, MJ Wheat straw Rice straw Sugarcane crop waste Methane properties: relative density = 0.72, higher heating value = 50.0 MJ/kg, Ethanol properties: relative density = 0.79, higher heating value = 26.8 MJ/kg

17 Biomethane or Bioethanol? Two important parameters; 1. Overall contents of biomass utilization. 2. Overall input-output energy in the process.

18 Overall components of biomass utilization

19 Overall input output energy analysis in bioethanol production system Energy use (MJ/L) Luo [1] Patzek [2] Pimentel [3] Shapouri [4] Graboski [5] De Oliviera [6] Wang [7] Average of 1 7 Agriculture Biorefinery Total input Ethanol 21.2 Total output 21.2 Net energy value Source: L. Luo, E. van der Voet, G. Huppes, An energy analysis of ethanol from cellulosic feedstock-corn stover, J. Renewable & Sustainable Energy Reviews, 13(2009):

20 Present Energy Scenario 31.7 GW 238 MMT 1. Petroleum Domestic production 38 MMT Import 200 MMT (85%) 2. Electricity 245 GW Wind GW (66.7%) Small hydro 3.80 GW (12.0%) Solar PV 2.65 GW (8.4%) Biomass 4.11 GW (12.9%) Thermal GW 68.7% Hydro 40.5 GW 16.5% Nuclear 4.78 GW 1.95% Renewables GW 12.9% Sources: Ministry of Power; MP&NG; and MNRE, Govt. of India (values as on 31 st March 2014). 20

21 Swachh Bharat Abhiyan All forms of organic wastes should be properly and efficiently utilized for bio-energy production. To provide rural and urban energy security and bio-fertilizer for improving soil health. 21

22 THANK YOU