Biomass Energy Resources
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Questions and Answers

What is the primary function of chlorophyll in plants?

  • To absorb water from the soil
  • To absorb green light
  • To release oxygen into the atmosphere
  • To convert solar energy into carbohydrates (correct)

    • What is the approximate percentage of energy used in the world that is accounted for by biomass?

  • 20%
  • 10%
  • 25%
  • 15% (correct)

    • What is the name of the process by which plants convert solar energy into carbohydrates?

  • Respiration
  • Photosynthesis (correct)
  • Decomposition
  • Fermentation

    • What is the gaseous fuel produced from biomass through anaerobic fermentation?

    <p>Biogas</p> Signup and view all the answers

    What is the range of wavelengths of visible light used by plants for photosynthesis?

    <p>0.4 to 0.7 ?m</p> Signup and view all the answers

    What is the purpose of adding certain portions of digested slurry to the fresh slurry during anaerobic digestion?

    <p>To seed the digestion slurry with methane-forming bacteria</p> Signup and view all the answers

    What is the ideal pressure range for the proper functioning of the anaerobic digester?

    <p>6-10 cm of water column</p> Signup and view all the answers

    What is the primary purpose of energy crops?

    <p>To produce biofuels</p> Signup and view all the answers

    What is the temperature range at which anaerobic bacteria grow and work best?

    <p>20-65°C</p> Signup and view all the answers

    What is the major component of biogas?

    <p>Methane</p> Signup and view all the answers

    What is the term for the process of converting biomass into biogas?

    <p>Anaerobic fermentation</p> Signup and view all the answers

    What is the primary advantage of anaerobic digestion over other methods of energy production?

    <p>It helps to conserve complete nitrogen content of the biomass</p> Signup and view all the answers

    What is the ideal temperature range for anaerobic digestion?

    <p>Lower than 65°C</p> Signup and view all the answers

    What is the primary function of hydrolysis in the biochemical process of converting biomass to biogas?

    <p>To break down complex compounds into simpler soluble compounds</p> Signup and view all the answers

    What is the primary advantage of using biomass energy?

    <p>It is a renewable source of energy</p> Signup and view all the answers

    What is the optimal temperature range for photosynthesis to occur at its maximum rate?

    <p>20-30°C</p> Signup and view all the answers

    What is the energy density of charcoal?

    <p>30 MJ/kg</p> Signup and view all the answers

    What is the main component of biogas, produced through anaerobic digestion?

    <p>Methane</p> Signup and view all the answers

    What is the process of converting woody biomass into producer gas?

    <p>Thermochemical method</p> Signup and view all the answers

    What is biodiesel produced from?

    <p>Vegetable oils and normal diesel</p> Signup and view all the answers

    What is the temperature range in which anaerobic bacteria can digest biomass?

    <p>25-75°C</p> Signup and view all the answers

    What is one of the methods used to overcome the problem of low temperature in hilly regions for biogas production?

    <p>Hot water circulation</p> Signup and view all the answers

    What is one of the considerations for locating a biogas plant?

    <p>Availability of water source</p> Signup and view all the answers

    What is one of the benefits of community biogas plants?

    <p>All of the above</p> Signup and view all the answers

    What is one of the suggestions to improve the productivity and efficiency of biogas plants?

    <p>Using additional materials to generate biogas</p> Signup and view all the answers

    What is the ideal solid content of biomass for better digestion?

    <p>9-10%</p> Signup and view all the answers

    What is the purpose of seeding in anaerobic digestion?

    <p>To start or accelerate the digestion process</p> Signup and view all the answers

    What is the effect of faster feeding rate on the digestion process?

    <p>It accumulates acids and stops the digestion process</p> Signup and view all the answers

    What is the classification of biogas plants based on their operation?

    <p>Batch type and continuous type</p> Signup and view all the answers

    What is the purpose of mixing and stirring in the digester?

    <p>To mix the floating masses of biomass</p> Signup and view all the answers

    What is the purpose of pyrolysis in biomass conversion?

    <p>To convert biomass into more valuable and convenient fuels</p> Signup and view all the answers

    What is the product obtained by catalytic liquefaction process at low temperature and high pressure?

    <p>Liquid in the form of oil such as acetic acid, acetone, methanol, oil and tar</p> Signup and view all the answers

    What is the purpose of gasification in biomass conversion?

    <p>To obtain a combustible gas mixture</p> Signup and view all the answers

    What is the purpose of leachate collection system in landfilling?

    <p>To collect and recycle leachate for biogas production</p> Signup and view all the answers

    What is the ideal moisture content of garbage for biogas production in landfilling?

    <p>60%</p> Signup and view all the answers

    What is the purpose of the partition wall in the digester chamber of a floating drum type biogas plant?

    <p>To provide optimum conditions for growth of acid forming and methane forming bacteria</p> Signup and view all the answers

    What is the advantage of using a displacement tank in a modified fixed dome type biogas plant?

    <p>It helps in maintaining a constant pressure inside the digester</p> Signup and view all the answers

    What is the calorific value of biogas?

    <p>4250 kcal/m3</p> Signup and view all the answers

    Why can't biogas be used alone in an IC engine?

    <p>It needs some modification in the IC engine</p> Signup and view all the answers

    What is the stoichiometric air-fuel ratio of biogas?

    <p>5.27 by volume</p> Signup and view all the answers

    Study Notes

    Biomass Energy Resources

    • Biomass is organic material that can be converted into energy through combustion or metabolic processes
    • Main sources of biomass energy: wood, agricultural waste, urban waste, and forest waste

    Photosynthesis

    • Process by which plants convert solar energy into chemical energy (carbohydrates)
    • Requires chlorophyll, carbon dioxide, and water
    • Plants absorb red and blue light, but not green light, which is why they appear green
    • Biomass production efficiency: 28% of used energy is converted into carbohydrates

    Conditions for Photosynthesis

    • Temperature: 20-30°C for maximum rate
    • Carbon dioxide concentration: increases photosynthesis
    • Oxygen concentration: reduces photosynthesis
    • Water: increases photosynthesis
    • Intensity and wavelength of solar radiation: increases photosynthesis with PAR (photo synthetically active radiation)

    Biomass

    • Can be used in its original form or transformed into solid, liquid, or gaseous fuels
    • Examples of biomass fuels: fuel wood, charcoal, fuel pellets, bioethanol, biogas, producer gas, and biodiesel

    Biofuels

    • Fuel wood: most common source of biomass energy, energy density of 16-20 MJ/kg
    • Charcoal: obtained from wood, energy density of 30 MJ/kg
    • Fuel pellets: formed from crop residues, energy density of 16-20 MJ/kg
    • Bioethanol: derived from sugarcane, starch, or cellulose, energy density of 26.9 MJ/kg
    • Biogas: gaseous fuel produced from biomass, energy density of 23 MJ/m3

    Biomass Resources

    • Forests: source of fuel wood, charcoal, and producer gas
    • Agricultural residues: straw, rice husk, groundnut shell, coconut shell, and sugarcane bagasse
    • Energy crops: sugar plants, starch plants, and oil-producing plants
    • Urban waste: garbage, sewage, and liquid waste
    • Aquatic plants: water hyacinth, seaweed, algae, and kelp

    Advantages and Disadvantages of Biomass Energy

    • Advantages: renewable, storable, waste management, indigenous, economic development, sanitation, and fertilizers
    • Disadvantages: low energy density, labor-intensive, and large land area required

    Biogas

    • Gaseous fuel produced from biomass through anaerobic digestion
    • Composition: 50-60% methane, 25-35% carbon dioxide, and 5% hydrogen and other gases
    • Energy density: 23 MJ/m3
    • Uses: cooking, heating, lighting, and running small IC engines

    Anaerobic and Aerobic Processes

    • Anaerobic: process occurring in absence of oxygen, used in biogas production
    • Aerobic: process occurring in presence of oxygen

    Anaerobic Digestion

    • Process of biogas production from biomass slurry
    • Factors favoring digestion: wetness, warmness, and darkness
    • Three stages: hydrolysis, acid formation, and methane formation
    • Digester: airtight equipment used for anaerobic digestion

    Advantages of Anaerobic Digestion

    • Energy production from waste materials
    • Fertilizer production
    • Waste management
    • Improved sanitation and hygiene
    • Containment of odors

    Raw Materials for Biogas

    • Waste: industrial, agricultural, urban, and forest waste
    • Cultivated materials: rice, wheat, and cereals
    • Harvested materials: agricultural crops and residues

    Factors Affecting Biogas Production

    • Temperature: 20-65°C

    • Pressure: 6-10 cm of water column

    • Water: 9-10% solid content

    • pH value: 6-7.5

    • Feeding rate: uniform feeding rate

    • Presence of nutrients: carbon, nitrogen, and other nutrients

    • Seeding: adding digested slurry to fresh feed

    • Mixing and stirring: mixing of biomass slurry

    • Retention time: 50-60 days

    • Toxic substances: presence of pesticides, detergents, and ammonia

    • Type of biomass: cow dung, poultry manure, etc.### Advantages and Disadvantages of Fixed Drum Type Biogas Plant

    • Lower cost

    • No corrosion problem

    • Better heat insulation

    • No maintenance required

    Disadvantages of Fixed Drum Type Biogas Plant

    • Gas production per cubic meter of the digester is less
    • Variable pressure of biogas
    • More risk of leakage due to higher pressure of gas
    • More risk of explosion
    • Complex installation

    Properties of Biogas

    • Composition: 60% methane, 40% carbon dioxide, and traces of hydrogen, hydrogen sulphide, and other gases
    • Calorific value: 5,600 kcal/m3 or 4,250 kcal/kg
    • Stoichiometric air-fuel ratio: 5.27 by volume
    • Calorific value of mixture: 767 kcal/m3, equivalent to 85% of gasoline

    Application of Biogas in IC Engine

    • Biogas cannot be used in IC engine without modification
    • Blending biogas with petrol and diesel can run IC engine with small modification
    • A mixture of biogas and gasoline containing 5-10% biogas can be used as IC engine fuel, reducing gasoline consumption by 5-10% and fuel cost

    Models of Biogas Plants

    • Common circular digester with floating gas holder without water seal (KVIC design, India)
    • Common circular fixed dome digester (China)
    • Flexible gas type combined digester and gas holder
    • Taper digester with floating gas holder (Nepal)
    • Two-chamber rectangular digester with floating gas holder and water seal (Philippines)
    • Jet digester with separate gas holder (Thailand)
    • KVIC model
    • PRAD model
    • ASTRA model
    • Ganesh model

    Biogas Plant in Hilly Area

    • Average temperature remains below 15°C in hilly regions
    • Anaerobic bacteria grow and digest biomass in the temperature range of 25-75°C
    • Methods to overcome temperature limitations:
      • Hot water circulation
      • Use of chemicals (e.g., urea and urine)
      • Solar energy system

    By-Product of Digestion

    • By-products of digestion are shown in Figure

    Location of Biogas Plant

    • Considerations for locating a biogas plant:
      • Distance from well or spring used for drinking water purposes
      • Proximity to biomass generation area
      • Availability of water source
      • Open and exposed site for better performance
      • Proximity to point of gas consumption

    Size of Biogas Plant

    • Considerations for deciding the size of the plant:
      • Waste generation and animal/people population
      • Gas requirements
      • Volume of digester tank needed
      • Size and shape of digestion tank
      • Size of floating drum of the digester

    Community Biogas Plants

    • Advantages of community biogas plants:
      • Efficient cooking fuel
      • Electricity generation for various purposes
    • Suggestions for improving productivity and efficiency:
      • Using biogas in dual fuel engine to generate power
      • Using hot exhaust to operate biogas plants at higher temperature
      • Using additional materials (e.g., water plants with animal waste) to generate biogas
      • New methods of biogas generation using bacterial support structures and recycling of spent slurry

    Biomass Conversion Technologies

    • Basic technologies to convert biomass into:
      • Direct energy
      • More valuable or convenient products
    • Technologies:
      • Incineration
      • Thermochemical (pyrolysis)
      • Biochemical

    Incineration

    • Burning or combustion of biomass to obtain useful heat
    • Heat can be used for:
      • Space heating and cooking
      • Generating steam in boiler to run turbine with electric generator

    Thermochemical (Pyrolysis)

    • Conversion of biomass into more valuable and convenient fuels
    • Process:
      • Heating biomass in absence of air or partial combustion
    • Products:
      • Gaseous mixture (H2, CO, CO2, CH4, N2)
      • Liquid (acetic acid, acetone, methanol, oil, and tar)
      • Pure carbon char

    Biomass Gasification

    • Conversion of solid biomass into combustible gas mixture (carbon monoxide and hydrogen)
    • Process:
      • Partial combustion of biomass in absence of sufficient air
    • Types of gasifiers:
      • Fixed bed updraft gasifier
      • Fixed bed down draft gasifier
      • Cross draft gasifier
      • Fluidized bed gasifier

    Energy Recovery from Urban Waste by Landfill Reactors

    • Municipal solid waste (MSW) disposal by controlled sanitary landfilling
    • Biodegradable urban wastes are segregated and compacted to generate biogas
    • Preparing the landfill site:
      • Lining with plastic liner and clay to prevent groundwater contamination
      • Leachate collection system to collect and recycle leachate
    • Optimum moisture content of garbage: 60%
    • Biogas production using anaerobic bacteria
    • Temperature rises to 60°C during digestion

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    Explore the use of biomass energy, primarily obtained from wood, for cooking and heating purposes, particularly in rural areas.

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