Biomass Energy and Photosynthesis
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Questions and Answers

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

  • 35-40°C
  • 10-15°C
  • 20-30°C (correct)
  • 45-50°C

    • What is the byproduct of anaerobic digestion or fermentation of biomass?

  • Fuel wood
  • Bioethanol
  • Biodiesel
  • Biogas (correct)

    • What is the energy density of charcoal per unit mass?

  • 10 MJ/kg
  • 30 MJ/kg (correct)
  • 20 MJ/kg
  • 40 MJ/kg

    • What is biodiesel primarily produced from?

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

    What is the primary source of biomass energy?

    <p>Fuel wood</p> Signup and view all the answers

    What is the primary source of biomass energy?

    <p>Solar energy</p> Signup and view all the answers

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

    <p>15%</p> Signup and view all the answers

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

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

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

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

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

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

    What is the purpose of using hot water circulation in biogas plants in hilly areas?

    <p>To maintain the biomass slurry at a high temperature in the digester</p> Signup and view all the answers

    What is the consideration for locating a biogas plant near the area where biomass is generated?

    <p>To reduce transportation cost of biomass</p> Signup and view all the answers

    What is the advantage of using biogas in dual fuel engine to generate power?

    <p>To sell power to the state electricity boards</p> Signup and view all the answers

    What is the benefit of using solar energy system in biogas plants in hilly areas?

    <p>To heat the biomass slurry in the digester</p> Signup and view all the answers

    What is the purpose of considering the number of animals and people in deciding the size of a biogas plant?

    <p>To determine how much waste is generated</p> Signup and view all the answers

    What is the primary purpose of incineration of biomass?

    <p>To produce steam for electricity generation</p> Signup and view all the answers

    What is the term for the process of converting biomass into a gaseous fuel?

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

    What is the purpose of the leachate collection system in a landfill reactor?

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

    What is the ideal moisture content of garbage in a landfill reactor?

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

    What is the primary application of producer gas?

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

    What percentage of energy from the dry converted biomass is provided by the biogas during combustion?

    <p>60-75%</p> Signup and view all the answers

    What is the ideal pH value for the digestion of biomass slurry?

    <p>7-8</p> Signup and view all the answers

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

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

    What is the purpose of seeding the digestion slurry with methane forming bacteria?

    <p>To obtain maximum biogas generation rate</p> Signup and view all the answers

    What is the benefit of anaerobic digestion in terms of waste management?

    <p>It helps in the waste management of an industry and urban waste</p> Signup and view all the answers

    What is the primary purpose of gasifying crop residues?

    <p>To obtain producer gas</p> Signup and view all the answers

    What is the main component of biogas?

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

    What is the name of the microorganism that grows on biomass during anaerobic digestion?

    <p>Anaerobe</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 energy density of biogas?

    <p>23 MJ/m3</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 optimize conditions for growth of acid forming and methane forming bacteria</p> Signup and view all the answers

    What is the advantage of a fixed dome type biogas plant compared to a floating drum type?

    <p>Lower cost</p> Signup and view all the answers

    What is the calorific value of biogas?

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

    What is the minimum percentage of biogas required to be blended with petrol or diesel to run an IC engine?

    <p>5%</p> Signup and view all the answers

    What is the purpose of the stirrer in the digester tank of a fixed dome type biogas plant?

    <p>To mix the slurry inside the digester and scum floating on the slurry</p> Signup and view all the answers

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

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

    What is the purpose of seeding in biogas production?

    <p>To add a small amount of methane forming bacteria to the digester</p> Signup and view all the answers

    What is the effect of pesticides, detergents, and ammonia on the digestion process?

    <p>They affect the digestion process negatively</p> Signup and view all the answers

    What is the characteristic of a batch type biogas plant?

    <p>It consists of multiple digesters that are charged and emptied one by one</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 for bacterial action</p> Signup and view all the answers

    What is the primary force responsible for global winds?

    <p>Differential heating of the earth's surface</p> Signup and view all the answers

    What is the direction of the global winds?

    <p>Towards the westerly direction</p> Signup and view all the answers

    What is the primary reason for the generation of local winds?

    <p>Uneven heating of the earth's surface</p> Signup and view all the answers

    What is the direction of the wind at night in local winds?

    <p>From land to water</p> Signup and view all the answers

    What is the energy available in the wind proportional to?

    <p>The cube power of the wind speed</p> Signup and view all the answers

    What is the primary factor affecting the nature of wind at a specific site?

    <p>Physical geometry of the locality and terrain around the site</p> Signup and view all the answers

    What is the term for the rate of change of wind speed with height?

    <p>Wind shear</p> Signup and view all the answers

    At what height is the wind speed uniform and unaffected by ground conditions?

    <p>2000 m</p> Signup and view all the answers

    What is the minimum requirement for a successful wind turbine installation?

    <p>High annual mean wind speed</p> Signup and view all the answers

    What is the purpose of an anemometer?

    <p>To measure wind speed</p> Signup and view all the answers

    What is the primary function of the axial force in a wind turbine?

    <p>To waste energy that cannot be extracted</p> Signup and view all the answers

    What is the main difference between a horizontal axis wind turbine (HAWT) and a vertical axis wind turbine (VAWT)?

    <p>The direction of the axis of rotation</p> Signup and view all the answers

    What is the purpose of twisting the turbine blades from tip to root?

    <p>To maintain a constant pitch angle</p> Signup and view all the answers

    What is the benefit of using a three-bladed rotor compared to a two-bladed rotor?

    <p>It generates more power output</p> Signup and view all the answers

    What is the purpose of the hub in a wind turbine?

    <p>To attach the blades to the nacelle</p> Signup and view all the answers

    What is the main advantage of the Savonious rotor over the cup type rotor?

    <p>It has high starting torque at low wind speed.</p> Signup and view all the answers

    What is the main limitation of the Darrieus rotor?

    <p>It is not self-starting due to lower starting torque.</p> Signup and view all the answers

    What is the primary reason for using energy storage systems with wind turbines?

    <p>To compensate for variations in wind speed.</p> Signup and view all the answers

    What is the main advantage of the Musgrove (H-shaped) rotor over the Darrieus rotor?

    <p>Its blades are foldable to control power.</p> Signup and view all the answers

    What is the primary application of the cup type rotor?

    <p>Wind speed measurement.</p> Signup and view all the answers

    What is the primary purpose of considering the nearness to load centre in wind turbine installation?

    <p>To reduce the cost of transmission of the generated power</p> Signup and view all the answers

    What is the significance of rotor solidity in wind turbine design?

    <p>It affects the speed of rotation of the rotor</p> Signup and view all the answers

    What is the effect of a large angle of incidence on the airflow over the aero foil?

    <p>The airflow is separated from the aero foil</p> Signup and view all the answers

    What is the purpose of pitch angle or blade setting angle in wind turbine design?

    <p>To control the output power, speed or torque of the turbine</p> Signup and view all the answers

    What is the result of resolving the total force exerted by the wind on the aero foil?

    <p>Two forces acting parallel and perpendicular to the airflow</p> Signup and view all the answers

    What is the primary function of the yaw control system in a wind turbine?

    <p>To adjust the nacelle around the vertical axis to face the wind stream</p> Signup and view all the answers

    What is the primary advantage of using a Vertical Axis Wind Turbine (VAWT)?

    <p>It can accept wind from any direction, eliminating the need for yaw control</p> Signup and view all the answers

    What is the primary purpose of the gearbox in a wind turbine?

    <p>To regulate the output rotation from the rotor with the speed of the generator</p> Signup and view all the answers

    What type of rotor is suitable for applications where high starting torque is needed?

    <p>Multi-bladed rotor</p> Signup and view all the answers

    What is the primary function of the tower in a wind turbine?

    <p>To support the nacelle and rotor</p> Signup and view all the answers

    What is the primary purpose of yaw and tilt control in wind turbines?

    <p>To shift the rotor axis out of wind direction</p> Signup and view all the answers

    What is the environmental impact of wind turbines on bird's life?

    <p>The rotating rotors pose a threat to bird's life</p> Signup and view all the answers

    What is the purpose of electrolysis of water in wind energy storage?

    <p>To produce hydrogen and oxygen gases which can be stored and converted into electric energy using fuel cells</p> Signup and view all the answers

    What is the environmental impact of large-scale wind energy interception on the ecosystem?

    <p>It causes an adverse impact on the ecosystem</p> Signup and view all the answers

    What is the purpose of stall control in wind turbines?

    <p>To shift the blades to a position in which high winds cannot damage the machines</p> Signup and view all the answers

    What is the primary advantage of a variable speed drive system in wind turbines?

    <p>It helps in capturing more power compared to the fixed speed drive system.</p> Signup and view all the answers

    Which of the following factors has contributed to the acceleration and development of wind power?

    <p>Availability of high-strength fiber composites and low-cost power electronics.</p> Signup and view all the answers

    What is the purpose of yaw control in wind turbines?

    <p>To regulate the direction of the wind turbine according to the wind direction.</p> Signup and view all the answers

    Which of the following is a major factor that has led to the acceleration and development of wind power?

    <p>Larger wind turbines generating significant power output.</p> Signup and view all the answers

    What is the primary benefit of using a variable speed drive system in wind turbines?

    <p>It helps in capturing more power compared to the fixed speed drive system.</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

    Wind Energy

    • Wind is air in motion, and its energy is proportional to the cube of its speed.
    • Wind energy is an indirect form of solar energy, generated by the differential heating of the earth's surface.

    Origin of Winds

    • Global winds are caused by the differential heating of the earth's surface at the equator and polar regions.
    • The rotation of the earth creates the Coriolis force, which makes global winds move towards the westerly direction.
    • Local winds are generated by uneven heating of land and water surfaces.

    Nature of Wind

    • Wind varies from place to place, depending on the climate, geography, and terrain.
    • Knowledge of wind behavior and structure is essential for installing wind turbines.

    Wind Speed Variations

    • Wind speed increases with height, but falls to zero at the earth's surface.
    • The rate of change of wind speed with height is called wind shear.
    • The gradient height is the height at which wind speed no longer increases with height.

    Wind Turbine Siting

    • Key considerations for selecting a wind turbine site include:
      • High annual mean wind speed
      • No obstruction within a certain distance
      • Open plain or coastal area
      • Height to take advantage of increased wind speed
      • Proximity to load centers and transportation links
      • Availability of wind data

    Rotor Design

    • A rotor extracts energy from the wind by transforming kinetic energy into rotational motion.
    • Rotor design parameters include:
      • Solidity: the ratio of projected blade area to swept area
      • Chord: the width of the blade
      • Angle of incidence: the angle between the blade and the wind direction
      • Pitch angle: the angle between the blade and the direction of motion
      • Different velocities: wind velocity, incident wind velocity, blade linear velocity, and relative velocity

    Wind Energy Conversion

    • The principle of wind energy conversion is to extract energy from the wind by partially decelerating and expanding the airstream.
    • The rotor collects wind from the whole area swept by the rotor, and the energy is extracted through the deceleration of the airstream.

    Aerodynamic Considerations

    • Lift and drag forces are created when wind moves over an aerofoil.
    • The shape of the aerofoil determines the relative magnitude of lift and drag forces.
    • Lift devices are more efficient due to their lower drag forces.

    Types of Windmills

    • Horizontal Axis Wind Turbine (HAWT): axis of rotation is parallel to the airstream.
    • Vertical Axis Wind Turbine (VAWT): axis of rotation is perpendicular to the airstream.
    • HAWTs are commonly used for electric power generation.
    • VAWTs are suitable for applications where low speeds are required, such as piston pumps.

    Rotors of HAWT and VAWT

    • HAWT rotors can be single-bladed, two-bladed, three-bladed, or multi-bladed.
    • VAWT rotors can be cup-type, Savonious, Darrieus, Musgrove, or Evans-type.
    • Darrieus rotors are commonly used for large power generation due to their good power coefficient.### Advantages of Darrieus Wind Turbine
    • Simple in construction
    • Low cost of construction and installation
    • Higher power coefficient and tip speed ratio compared to S-rotor

    Disadvantages of Darrieus Wind Turbine

    • Not self-starting machine
    • Works on drag force, leading to low efficiency in converting wind energy
    • Limited height, unable to utilize high wind speeds available at higher levels
    • Unable to yaw out of the wind, requires special high torque braking system during high wind speeds

    Starting Arrangements for Darrieus Rotor

    • Attaching S-rotors at the top and bottom of the shaft to help start up
    • Designing the generator to run as a motor to start up the wind turbine initially
    • Partly shielding the rotor from the wind stream to behave as an unsymmetrical rotor and develop starting torque

    Wind Energy Storage

    • Chemical energy storage through batteries
    • Thermal energy storage through heating water
    • Compressed air storage
    • Electrolysis of water to produce hydrogen and oxygen gases
    • Pumping water to a high tank for storage
    • Integration to electric grid

    Environmental Impacts of Wind Turbine

    • Zero emission during operation
    • Threat to bird's life due to rotating rotors
    • Noise disturbance due to aerodynamic noise
    • Interference to transmission of TV and communication signals
    • Visual intrusion due to high towers
    • Safety concerns due to rotating blades
    • Impact on ecosystem due to large-scale interception and use of wind energy

    Recent Developments in Wind Turbines

    • Yaw and tilt control for safety and speed control
    • Pitch control to regulate rotor blades for maximum output
    • Stall control to shift blades to a safe position during high winds
    • Fixed blades with constant pitch for constant turbine speed
    • Eddy current braking system to control speeds
    • Variable speed drive system to capture maximum power

    Factors Accelerating Wind Power Development

    • Improved materials for large-sized rotor blades
    • Power electronics for regulation and control
    • Variable speed drive system for maximum energy capture
    • Larger wind turbines for economical power output
    • Short energy payback period
    • Improved plant operations for high power supply
    • Increased expertise in development and operation
    • Renewable resource competing with conventional power sources

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    Learn about biomass energy sources, including wood and agricultural waste, and the process of photosynthesis, where plants convert solar energy into chemical energy.

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