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About biomass and bioenergy

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  1. 1. Energy from biomass by K.BHAVANA
  2. 2.  Introduction  Biomass conversion technologies  Photosynthesis  Biogas generation  Factors affecting bio digestion  Classification of biogas plants  Advantages and disadvantages of bio digestion plants
  3. 3. BIOMASS  Biomass means organic matter produced by plants, which harnesses the solar energy by photosynthesis.  The plants which produce the organic matter are both terrestrial and aquatic and their derivatives.
  4. 4. BIOMASS RESOURCES  Biomass with traditional solid mass (in solid form)  Biomass in a non traditional form (in liquid form)  Biomass fermentation (in gas form)
  5. 5. THE HEAT CONTENT OF VARIOUS FUELS FUEL HEAT CONTENT UNIT GAS Hydrogen 12 MJ/m3 Fuel gas 15-20 MJ/m3 Biogas 20-25 MJ/m3 Methane 38 MJ/m3 LIQUID Methanol 21 GJ/te Ethanol 27 GJ/te Crude oil 44 GJ/te SOLID Refuse 9 GJ/te Straw 16 GJ/te Wood 12-15 GJ/te Char 20 GJ/te coal 22-32 GJ/te
  6. 6. ENERGY PLANTATION  It is the method of tapping maximum solar energy by growing plants.  Energy forms are ideal solar collectors, which are economical and non polluting and no need to maintain.  To increase the forest land area the social forestry programme comprises the schemes 1)Mixed plantation on waste land 2)Reforestration of degraded forests
  7. 7. 1) Direct conversion 2) Thermo chemical conversion a) Gasification and b) Liquification 3) Bio chemical conversion A) Anaerobic digestion B) Fermentation
  8. 8. Anaerobic digestion  It is the process of production of biogas by the decomposition of wastage in the absence of oxygen.  The optimum temperature 35˚c and time required to decomposition is 10 days.
  9. 9. Biomass conversion technologies {wet process} Conversion process solids Principles products liquids gasses Further treatment Premium fuels Anaerobic digestion Methane and co2 Co2 removal methane fermentation ethanol distillation Ethanol Chemical reduction Mixture of oils Fractional distillation Hydro carbon liquids
  10. 10. Conversion process solids Principle products liquid gases Further treatment Premium fuels liquefication Gasification Steam gasification Char Char Char Pyroligneous Acids oils and tars Fuel gas Fuel gas methane Steam reforming and /or shift reaction Methane methanol or higher alchohols hydrogenation Mixture of olis Fractional distillation Hydro carbon liquids Oil extraction Vegetable oil esterificatio n Diesel substitute
  11. 11. PHOTOSYNTHESIS  It is the chemical reaction of sunlight and green plants. 6CO2+12H2O  C6H12O6+6H2O+6O2  Photosynthesis essentially a reduction and oxidation processes.  The O2 is liberated from H2O and not from CO2. This processes is called carbonfixation.  LIGHT REACTION: Splitting of H2O molecule into H2 and O2 in the presence of chlorophyll and sunlight.  DARK REACTION: Formation of starch from CO2 and H2 molecule.
  12. 12. Conditions necessary for photosynthesis  Light: The plants use radiation between 400 to 700 A˚ only a part of this energy used in photosynthesis. This range of light is called photo-synthetically active radiation.  CO2 concentration: CO2 is main source for photosynthesis the main sources for CO2 are, 1) Animal respiration 2) Combustion of fuel 3) The decay of organic matter by bacteria 4) Ocean  Temperature: Generally plants can resist a temperature of 0-60˚c for the process of photosynthesis.The photo chemical part is not effected by temperature. The bio chemical part is high sensitive to temperature.
  13. 13. Biogas generation  Biogas is produced by animal,plant and human waste.  Biogas contains 55-65% of CH4 30-40% CO2 and other being H2,H2S and N2.  Biogas is also called as Gobar Gas.  The calorific value is 38,131 KJ/m3.  DIGESATION: It is a biological process that occurs in the absence of oxygen and in the presence of anaerobic organisms at ambient pressure and temperature of 35-70˚C  Biogas is produced by anaerobic digestion which is digested by micro organisms(harmful and benificiable)
  14. 14. Factors affecting biodigestation 1) pH or the hydrogen-ion concentration 2) Temperature 3) Total solid content of the fluid material 4) Loading rate 5) Seeding 6) Uniform feeding 7) Diameter to depth ratio 8) Carbon to nitrogen ratio 9) Nutrients 10) Agitation of the content of the digester 11) Rate of heating 12) Type of feed stocks 13) Toxicity due end product 14) Pressure 15) Acid accumulation inside the digester
  15. 15. Classification of biogas plants • The drum and dome type • Differential variations in the drum type • Continuous and batch type Advantages of floating drum plant: • High gas production. • No problem of gas leakage and constant gas pressure Disadvantages: • It has high cost • Heat is lasted through the metal gas holder • Gas holder requires painting once or twice a year
  16. 16. Fixed dome type • Advantages: It has low cost and it uses only cement. It has no corrosion trouble Temperature will be constant No maintenance • Disadvantages: Gas production is less There is problem of seum formation It has variable gas pressure
  17. 17. Continuous plants Single stage process Double stage process
  18. 18. Batch plant • The features of batch plant: 1) The gas production in this is intermittent, depending upon the clearing of the digester. 2) It needs several digesters for continuous gas production. 3) Batch plants are good for long fibrous materials. 4) This plant is expensive and easy to operate.