Podcast Beta
Questions and Answers
What percentage of the energy used in the world is accounted for by biomass?
What is the wavelength range of visible light used by plants for photosynthesis?
What is the percentage of energy lost during photosynthesis due to the absorption of green light?
What is the efficiency of converting incident solar energy into chemical energy in plants?
Signup and view all the answers
What is the percentage of carbohydrates energy used in respiration?
Signup and view all the answers
What is the optimal temperature range for photosynthesis to occur at its maximum rate?
Signup and view all the answers
Which of the following factors increases photosynthesis?
Signup and view all the answers
What is the energy density of charcoal in MJ/kg?
Signup and view all the answers
What is the primary component of biogas?
Signup and view all the answers
What is the purpose of anaerobic digestion in biogas production?
Signup and view all the answers
What is the primary function of seeding digestion slurry with methane-forming bacteria?
Signup and view all the answers
What is the ideal pressure range for the proper functioning of a digester?
Signup and view all the answers
What is the primary benefit of anaerobic digestion in waste management?
Signup and view all the answers
What is the optimal temperature range for the growth and functioning of anaerobic bacteria?
Signup and view all the answers
What is the primary role of hydrolysis in the biochemical process of anaerobic digestion?
Signup and view all the answers
What is the primary compositions of biogas in terms of percentage?
Signup and view all the answers
What is the primary advantage of biomass energy in rural areas?
Signup and view all the answers
What is the ideal temperature range for anaerobic digestion to occur?
Signup and view all the answers
What is the primary role of anaerobe microorganisms in biogas production?
Signup and view all the answers
What is the primary factor that favors anaerobic digestion in biogas production?
Signup and view all the answers
What is the primary consideration for locating a biogas plant near the area where biomass is generated?
Signup and view all the answers
What is the purpose of using a solar energy system in a biogas plant in hilly areas?
Signup and view all the answers
What is the primary benefit of community biogas plants?
Signup and view all the answers
What is the purpose of using hot exhaust from a power generating system in a biogas plant?
Signup and view all the answers
What is the primary consideration for deciding the size of a biogas plant?
Signup and view all the answers
What is the primary purpose of thermochemical conversion of biomass?
Signup and view all the answers
What is the purpose of gasification in biomass conversion?
Signup and view all the answers
What is the ideal moisture content for biogas production in landfills?
Signup and view all the answers
What is the purpose of the leachate collection system in landfilling?
Signup and view all the answers
What is the primary benefit of using biomass gasification for power generation?
Signup and view all the answers
What is the ideal pH range for the methane forming stage of anaerobic digestion?
Signup and view all the answers
What is the purpose of seeding in anaerobic digestion?
Signup and view all the answers
What is the primary function of the partition wall in the digester chamber of a floating drum type biogas plant?
Signup and view all the answers
What is the main advantage of continuous type biogas plants over batch type plants?
Signup and view all the answers
Why is the pressure inside the digester of a floating drum type biogas plant constant?
Signup and view all the answers
What is the effect of faster feeding rate on the digestion process?
Signup and view all the answers
What is the purpose of mixing and stirring in the digester?
Signup and view all the answers
What is the primary advantage of using a fixed dome type biogas plant over a floating drum type biogas plant?
Signup and view all the answers
What is the stoichiometric air-fuel ratio of biogas?
Signup and view all the answers
What is the maximum percentage of biogas that can be blended with gasoline to run an IC engine?
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
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Learn about biomass energy resources, main sources, and the process of photosynthesis, including the role of chlorophyll and plant energy production.
