E&S:Lecture 12

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  1. Biofuels are created through....
    photosynthesis
  2. the chlorophyll pigments absorbs photons at _____and _____wavelengths
    blue and red
  3. Photosynthesis equation
    6CO2 + 6H2O +hv = C6H12O6 + 6O2
  4. Plants can't take in CO2 for photosynthesis without
    loosing water vapor, which saturates their pores when closed
  5. Plants in dry climates
    • 1.Can't afford to lose water
    • -let in very little CO2
    • -grow very slowly
  6. The net photosynthetic efficiency of most ecosystems
    1%
  7. the residence time for surface organic carbon
    20 years
  8. Carbon cycle steps
    • 1. Plants and ocean remove CO2 from atmosphere
    • 2. animals eat plants and release waste
    • 3. Plant and animal organic matter get buried underground
    • 4. after millions of years, turn into fossil fuels
    • 5. animals respire and release CO2 and fossil fuels burned
  9. "Dry" Biomass compostion
    • 1.Cellulose
    • 2.Hemi-Cellulose
    • 3.Lignin
    • 4.Other: oils, sugars, minerals
  10. Cellulose
    • 1.Linear chain of thousands of linked glucose units
    • -only digestible by bacteria (termites)
  11. Hemi-Cellulose
    • 1. Non-starch component of plants
    • 2. only digestible by plants
  12. Lignin
    • 1. Fills the spaces between cell wals to make them stiff and water proof
    • 2. Common in wood
    • 3. Only digestible by bacteria
  13. Biomass energy
    16-20 MJ/kg
  14. Diesel fuel can be produced from
    • 1. Rapeseed
    • 2.Soybean oils
    • 3.Animal fats
    • 4. Waste
  15. Production process of Biodiesel
    • 1. Removing water and contaminants
    • 2. Treat with a solution of methanol and KOH
    • 3. Purify
  16. why is Biodiesel superior to conventional diesel fuel?
    • 1.Low sulfur content
    • 2. Pleasant aroma
  17. Biogas
    1. Anaerobic decomposition of organic matter can be a source of methane gas
  18. Biogas Reaction
    C6H12O6 ------3CO2 + 3CH4
  19. Fermentation
    • 1. Incomplete oxidation of organic compounds
    • -electron acceptor is another organic molecule
  20. Examples of fermentation
    • 1.Fermentation of sugar by yeast or bacteria to make ethanol (beer, wineetc.)
    • 2. Creation of lactic acid in animal muscles when oxygen supply is low
    • 3. Anaerobic digestion of organic by bacteria to produce methane and hydrogen gas(cows)
  21. Fermentation reactions are generally
    anaerobic and exothermic, thus producing their own heat
  22. Ethanol power
    31.1MJ/kg
  23. E10 or less is
    Gasohol
  24. E85
    Highest mixture sold in USA
  25. What proof is pure distilled ethanol?
    190
  26. Issues with Ethanol
    • 1.minimal to negative net energy production
    • 2.displaces food production and water resources
    • 3.increases corn prices
  27. Future of ethanol
    • 1. Lies in cellulosic ethanol
    • -Enzymes convert cellulose----sugar(fermented)----ethanol
    • -can be harvested from grass
    • -requires no cultivation or irrigation
  28. Algal fuels
    1.Oils and fuels produced by algae
  29. Issues with Algal fuels
    1.High infrastructure costs
  30. Process:Algal fuel production
    • 1.Grow algae
    • 2.Starve it of nutrients
    • 3.Break alage open
    • 4. Use solvents to separate the fats from sugars
    • 5. Evaporate solvent
    • 6. Transform fat to biodiesel

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Author:
dante01
ID:
158128
Filename:
E&S:Lecture 12
Updated:
2012-06-11 03:31:57
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