About biomass and bioenergy

1. Energy from biomass
by
K.BHAVANA

2.  Introduction
 Biomass conversion technologies
 Photosynthesis
 Biogas generation
 Factors affecting bio digestion
 Classification of biogas plants
 Advantages and disadvantages of bio
digestion plants

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. 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. 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. 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. 1) Direct conversion
2) Thermo chemical conversion
a) Gasification and
b) Liquification
3) Bio chemical conversion
A) Anaerobic digestion
B) Fermentation

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. 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. 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. 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. 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. 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. 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. 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. 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. Continuous plants
Single stage process Double stage process

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.