Hydrogen, as a clean, efficient and sustainable energy source, has been accelerated to develop and utilize. Agricultural wastes can be converted into hydrogen to realize high

1. BIOGAS TECHNOLOGY
A Utilization of Waste Energy from Waste Materials
(USEFUL OPTION FOR COMMON HOUSE ENERGY)
Presented by:-
Dr. Emad S S Belal

2. Biomass
The material of plants and animals, including their
wastes and residues, is called biomass.
It is organic, carbon-based, material that reacts with
oxygen in combustion and natural metabolic processes
to release heat.
Biomass is a renewable energy resource derived from
the carbonaceous waste of various human and natural
activities. It is derived from numerous sources,
including the by-products from the wood industry,
agricultural crops, raw material from the forest,
household wastes etc.

3. Such heat, especially if at temperatures >400 C, may be used to
generate work and electricity.
The initial material may be transformed by chemical and
biological processes to produce biofuels, i.e. biomass processed
into a more convenient form, particularly liquid fuels for
transport.
Examples of biofuels include methane gas, liquid ethanol,
methyl esters, oils and solid charcoal.
The term bioenergy is sometimes used to cover biomass and
biofuels together
Biomass provides about 13% of mankind’s energy
consumption, including much for domestic use in developing
countries but also significant amounts in mature economies;
this percentage is comparable to that of fossil gas. The
domestic use of biofuel as wood, dung and plant residues for
cooking is of prime importance for about 50% of the
world’s population.

4. Solar radiation
Domestic and
industrial biofuels
photosynthesis
Biomass energy store
Co2
Natural humus
natural
Energy
release

5. The carbon in biomass is obtained from CO2 in the
atmosphere via photosynthesis, and not from fossil sources.
When biomass is burnt or digested, the emitted CO2 is
recycled into the atmosphere, so not adding to atmospheric
CO2 concentration over the lifetime of the biomass growth.
The heat energy available in combustion, equivalent in
practice to the enthalpy or the net energy density, ranges from
about 8MJkg−1 (un dried ‘green’ wood) 15MJkg−1 (dry
wood), to about 40MJkg−1 (fats and oils) and 56MJkg−1
(methane). Biomass is, however, mostly carbohydrate material
with a heat of combustion of about 20MJkg−1 dry matter;

6. The photosynthetic process
• Photosynthesis is the making (synthesis) of
organic structures and chemical energy stores
by the action of solar radiation (photo). It is by
far the most important renewable energy
process, because living organisms are made
from material fixed by photosynthesis, and our
activities rely on oxygen in which the solar
energy is mostly stored.
• The continuous photosynthetic output flux on
the Earth is about 09×1014W (i.e. about 15kW
per person; the power output of 100 000 large

7. Solar radiation incident on green plants and other photosynthetic
organisms relates to two main effects:
(1) temperature control for chemical reactions to proceed, especially in
leaves, and
(2) photo excitation of electrons for the production of oxygen and carbon
structural material
The energy processes in photosynthesis depend on the photons
(energy packets) of the solar radiation, labeled ‘h’, where h is
Planck’s constant and is the frequency of the radiation. The organic
material produced is mainly carbohydrate, with carbon in a medium
position of oxidation and reduction (e.g. glucose, C6H12O6).
The fixation of one carbon atom from atmospheric CO2 to
carbohydrate proceeds by a series of stages in green plants,
1 Reactions in light, in which photons produce protons from H2O, with
O2 as an important by-product, and electrons are excited in two stages to
produce strong reducing chemicals.
2 Reactions not requiring light (called dark reactions), in which these
reducing chemicals reduce CO2 to carbohydrates, proteins and fats.

8. Combining both the light and the dark reactions gives an overall
reaction, neglecting many intermediate steps:
CO2+2H2˙O light −−−−→ ˙O2+CH2O+H2O
Here CH2O represents a basic unit of
carbohydrate, so the reaction for sucrose production is
12CO2 +24H2˙O light −−−−→12 ˙O2 +C12H22O11 +13H2O

9. During photosynthesis CO2 and H2O are absorbed to form
carbohydrates, proteins and fats. The generalized symbol CH2O
is used to indicate the basic building block for these products.
CO2 is released during respiration of both plants and animals,
and by the combustion of biological material. This simplified
explanation is satisfactory for energy studies, but neglects the
essential roles of nitrogen, nutrients and environmental
parameters in the processes.
The net energy absorbed from solar radiation during
photosynthesis can be measured from combustion, since
Δ H +CO2 +2H2O photosynthesis −−−−−−−→
←−−−−−−−combustion CH2O+O2 +H2O
ΔH = 460 kJ per mole C = 48eV per atom C ≈ 16MJkg−1of dry
carbohydrate material

10. Home work
• Energy and Environmental issues are tow
sides of a coin considering advantages and
disadvantages of renewable energy wright
an easy of about 4-5 pages discussing this
issue?
The terms energy and power are essentially
synonyms, distinguish between them?

11. Biofuels production processes.

12. Biochemical
4 - Aerobic digestion.
In the presence of air, microbial aerobic metabolism of
biomass generates heat with the emission of CO2, but
not methane. This process is of great significance for the
biological carbon cycle, e.g. decay of forest litter, but is
not used significantly for commercial bioenergy.
5- Anaerobic digestion.
In the absence of free oxygen, certain microorganisms
can obtain their own energy supply by reacting with
carbon compounds of medium reduction level to produce
both CO2 and fully reduced carbon as CH4. The process
(the oldest biological ‘decay’ mechanism) may also be
called ‘fermentation’, but is usually called ‘digestion’
because of the similar process that occurs in the
digestive tracts of ruminant animals. The evolved mix of CO2
CH4 and trace gases is called biogas as a general term, but may be
named sewage gas or landfill-gas as appropriate.

13. Alcoholic fermentation.
Ethanol is a volatile liquid fuel that may be used in
place of refined petroleum. It is manufactured by the
action of micro-organisms and is therefore a
fermentation process. Conventional fermentation has
sugars as feedstock.
Biophotolysis.
Photolysis is the splitting of water into hydrogen and
oxygen by the action of light. Recombination occurs
when hydrogen is burnt or exploded as a fuel in air.
Certain biological organisms produce, or can be made
to produce, hydrogen in bio photolysis. Similar results
can be obtained chemically, without living organisms,
under laboratory conditions. Commercial exploitation of
these effects has not yet occurred,.

14. Agrochemical
Fuel extraction.
Occasionally, liquid or solid fuels may be obtained
directly from living or freshly cut plants. The materials
are called exudates and are obtained by cutting into
(tapping) the stems or trunks of the living plants or by
crushing freshly harvested material. A well-known similar
process is the production of natural rubber latex. Related
plants to the rubber plant Herea, such as species of
Euphorbia, produce hydrocarbons of less molecular
weight than rubber, which may be used as petroleum
substitutes and turpentine.

15. Biodiesel and esterification.
Concentrated vegetable oils from plants may be
used directly as fuel in diesel engines; indeed
Rudolph Diesel designed his original 1892
engine to run on a variety of fuels, including
natural plant oils. However, difficulties arise with
direct use of plant oil due to the high viscosity
and combustion deposits as compared with
standard diesel-fuel mineral oil, especially at low
ambient temperature ≤∼5C. Both difficulties are
overcome by converting the vegetable oil to the
corresponding ester, which is arguably a fuel
better suited to diesel engines than conventional
(petroleum-based) diesel oil.

16. Energy farming
We use this term in the very broadest sense to mean the production
of fuels or energy as a main or subsidiary product of agriculture
(fields), silviculture (forests), aquaculture (fresh and sea water), and
also of industrial or social activities that produce organic waste
residues, e.g. food processing, urban refuse.. The main purpose of
the activity may be to produce energy (as with wood lots), but more
commonly it is found best to integrate the energy and biofuel
production with crop or other biomass material products.
An outstanding and established example of energy
farming is the sugarcane industry. The process depends
upon the combustion of the crushed cane residue
(bagasse) for powering the mill and factory operations.
With efficient machinery there should be excess energy
for the production and sale of by-products, e.g.
molasses, chemicals, animal feed, ethanol, fibre board
and electricity.

17. Anaerobic digestion for biogas
Decaying biomass and animal wastes are broken
down naturally to elementary nutrients and soil
humus by decomposer organisms, fungi and
bacteria.
The processes are favoured by wet, warm and
dark conditions. The final stages are
accomplished by many different species of
bacteria classified as either aerobic or anaerobic.
Aerobic bacteria are favoured in the presence of oxygen with the
biomass carbon being fully oxidised to CO2
In closed conditions, with no oxygen available from the
environment, anaerobic bacteria exist by breaking down
carbohydrate material. The carbon may be ultimately divided
between fully oxidised CO2 and fully reduced CH4,

18. Biomass Applications
• Direct combustion for heat
• Biomass is burnt to provide heat for
cooking, comfort heat (space heat),crop
drying, factory processes and raising
steam for electricity production and
transport. Traditional use of biomass
combustion includes
• (a) cooking with firewood, with the latter
supplying about 10–20% of global energy
use (a proportion extremely difficult to
assess) and
• (b) commercial and industrial use for heat

19. Domestic cooking and heating
A significant proportion of the world’s population depends
on fuel wood or other biomass for cooking, heating and
other domestic uses. Average daily consumption of fuel is
about 0.5–1 kg of dry biomass per person, i.e. 10–20MJd−1 ≈
150W. Multiplied by, say, 2×109 people, this represents
energy usage at the very substantial rate of 300GW.
Crop drying
The drying of crops (e.g. fruit, copra, cocoa, coffee, tea), for
storage and subsequent sale, is commonly accomplished by
burning wood and the crop residues, or by using the waste heat
from electricity generation. The material to be dried may be
placed directly in the flue exhaust gases, but there is a danger of
fire and contamination of food products. More commonly air is
heated in a gas/air heat exchanger before passing through the
crop.

20. Process heat and electricity
Steam process heat is commonly obtained for factories
by burning wood or other biomass residues in boilers,
perhaps operating with fluidized beds. It is physically
sensible to use the steam first to generate electricity
before the heat degrades to a lower useful temperature.
The efficiency of electricity generation from the biomass
may be only about 20–25% due to low temperature
combustion, so 75–80% of the energy remains as process
heat and a useful final temperature is maintained.
Wood resource
Wood is a renewable energy resource only if it is grown
as fast as it is consumed. Moreover there are ecological
imperatives for the preservation of natural woodland and
forests.

21. Pyrolysis (destructive distillation)
Pyrolysis is a general term for all processes whereby organic
material is heated or partially combusted to produce secondary
fuels and chemical products.
The input may be wood, biomass residues, municipal waste or
indeed coal. The products are gases, condensed vapours as
liquids, tars and oils, and solid residue as char (charcoal) and
ash. Traditional charcoal making is pyrolysis with the vapours
and gases not collected.
Gasification is pyrolysis adapted to produce a maximum
amount of secondary fuel gases.
The fuel products are more convenient, clean and transportable
than the original biomass. The chemical products are important as
chemical feedstock for further processes or as directly marketable
goods. Partial combustion devices, which are designed to
maximise the amount of combustible gas rather than char or
volatiles, are usually called gasifiers. The process is essentially
pyrolysis, but may not be described as such.

22. Pyrolysis systems. (a) Small-scale pyrolysis unit. (b) Traditional charcoal kiln

23. Alcoholic fermentation
Alcohol production methods
Ethanol, C2H5OH, is produced naturally by certain micro-organisms
from sugars under acidic conditions, i.e. pH 4 to 5. This alcoholic
fermentation process is used worldwide to produce alcoholic drinks.
The most common micro-organism, the yeast Saccharomyces
cerevisiae, is poisoned by C2H5OH concentration greater than 10%,
and so stronger concentrations up to 95% are produced by distilling
and fractionating When distilled, the remaining constant boiling
point mixture is 95% ethanol and 5% water. Anhydrous ethanol is
produced commercially with azeotropic removal of water by co-
distillation with solvents such as benzene

24. Ethanol fuel use
Liquid fuels are of great importance because of their ease of
handling and controllable combustion in engines. Anhydrous
ethanol is a liquid between −117 and+78C, with a flash point of 130
Cand an ignition temperature of 423C, and so has the
characteristics of a commercial liquid fuel, being used as a direct
substitute or additive for petrol (gasoline), and is used in three
ways:
 As 95% (hydrous) ethanol, used directly in modified and
dedicated spark-ignition engines;
 Mixed with the fossil petroleum in dry conditions to produce
gasohol, as used in unmodified spark-ignition engines, perhaps
retuned;
 as an emulsion with diesel fuel for diesel compression engines
(this may be called diesohol, but is not common).

25. Energy Forms
Primary energy sources
(A) Fossil energy sources (B) Renewable energy sources (C) Nuclear fuels
• Hard coal • Water Uranium
• Brown coal • Sun Plutonium
• Petroleum • Wind Thorium
• Natural gas • Geothermal heat
• Oil shale • Tides
• Tar sand
• Gas hydrate
Biomass
Secondary
Energy
Sources
• Biogas
• Landfill gas

26. Biogas
is the CH4/ CO2 gaseous mix evolved from digesters,
including waste and sewage pits; to utilise this gas, the
digesters are constructed and controlled to favour
methane production and extraction (Figure 11.7). The
energy available from the combustion of biogas is
between 60 and 90% of the dry matter heat of
combustion of the input material.

27. Composition and properties of biogas
Biogas is a mixture of gases that is composed
chiefly of:
· methane (CH4): 40-70 vol.%
· carbon dioxide (CO2): 30-60 vol.%
· other gases: 1-5 vol.%
including
· hydrogen (H2): 0-1 vol.%
· hydrogen sulfide (H2S): 0-3 vol.%
Like those of any pure gas, the characteristic properties of biogas
are pressure and temperature-dependent. They are also affected
by the moisture content

28. Biogas Calorific Value
E =  Hm Fm Vb
Where:
Hm – Heat combustion of Methane (65m/kg,
28Mj/m2).
Fm
_ Percentage Fraction of Methane in Biogas
(0.7).
Vb – Volume of Biogas, m3.
  The efficiency of biogas burners, (0.6

29. Calorific Value of Biogas
The calorific value of biogas is about 6 kWh/m3 - this
corresponds to about half a liter of diesel oil. The net
calorific value depends on the efficiency of the burners or
appliances. Methane is the valuable component under the
aspect of using biogas as a fuel.
Biogas properties
Constituent By volume By mass
CO2 19% 37.38%
N2 6.5% 8.14%
O2 1.5% 2.15%
CH4 73% 52.34%
H2S 20 ppm
Density 0.9145 kg/m3 (273 K, 1 at)
LHV 26.17 MJ/kg
(A/F)s,CH4 17.23

31. Pure methane at standard temperature and pressure has a lower
heating value of approximately 912 Btu/ft3. Typical biogas of 65%
methane has a heating value of approximately 600 Btu/ft3 since only
the methane portion will burn. Approximate equivalents of biogas to
other fuels arc presented in Table.
. Fuel Equivalents of Biogas (per 1000 ft3)'
600 fts of natural gas
6.6 gal. of propane
5.9 gal. of butane
4.7 gal. of gasoline
4.3 gal. of #2 fuel oil
44 Ib. of bituminous coal
100 Ib. of medium-dry wood
* Biogas with 65% methane

32. Application 1m3 biogas equivalent
Lighting
Cooking
Fuel replacement
Shaft power
Electricity generation
equal to 60 -100 watt bulb for 6 hours
can cook 3 meals for a family of 5 - 6
0.7 kg of petrol
can run a one horse power motor for 2 hours
can generate 1.25 kilowatt hours of electricity
Table 1: some biogas equivalents
Source: adapted from Kristoferson, 1991.

33. Anaerobic digestion proceeds in three distinct steps:
1. A group of deferent reactions mediated by several types of
fermentative bacteria degrade various substances into
fragments of lower molecular mass (polysaccharides into sugars,
proteins into peptides and amino acids, fats into glycerin and
fatty acids, nucleic acids into nitrogen heterocycles, ribose, and
inorganic phosphates).
2. Further degradation is promoted by acetogenic bacteria that
convert the alcohols and higher acids into acetic acid, hydrogen
and carbon dioxide.
3. The acetic acid, hydrogen and carbon dioxide produced in
Steps 1 and 2 are used by methanogenic bacteria y to produce
methane and carbon dioxide from the acid and methane and
water from the hydrogen and carbon dioxide.

34. Biochemistry
 Methanogens use a number of different ways
to produce methane
Using ethanoate (acetate) that may be derived
from the decomposition of cellulose:
CH3COO+ + H-  CH4 + CO2 +36 kJ mol-1
Or using hydrogen and carbon dioxide produced
by the decomposers:
4 H2 + CO2  CH4 + 2 H2O +130.4 kJ mol-1
© 2008 Paul Billiet ODWS

35. Factors Controlling the Conversion of Waste to Gas
 The rate and efficiency of the anaerobic digestion process is
controlled by:
 The type of waste being digested,
 Its concentration,
 Its temperature,
 The presence of toxic materials,
 The pH and alkalinity,
 The hydraulic retention time,
 The solids retention time,
 The ratio of food to microorganisms,
 The rate of digester loading,
 And the rate at which toxic end products of digestion are
removed

36. Requirements
 a fermenter, which is supplied with an innoculum of
bacteria (methanogens and decomposers)
 anaerobic conditions
 an optimum temperature of 35°C
 an optimum pH of 6.5 to 8
This needs to be monitored as the decomposers
produce acids and they work faster than the
methanogens consume the acids
 organic waste (biomass) e.g. sewage, wood pulp
© 2008 Paul Billiet ODWS

39. Anaerobic Digestion Advantages
 Reduce
- Smell
- Greenhouse gas
- Pathogen level
 Produce biogas
 Improve fertilizer value of manure
 Protect water resources

40. • Biogas typically refers to a gas produced by the
biological breakdown of organic matter in the
absence of oxygen.
• It is clean environment friendly fuel that can be
obtained by anaerobic digestion of animal
residues and domestic and farm wastes,
abundantly available in the countryside.

41. • Biogas generally comprise of 55-65 % methane, 35-45 %
carbon dioxide, 0.5-1.0 % hydrogen sulfide and traces of
water vapor.
• Average calorific value of biogas is 20 MJ/m3 (4713 kcal/m3).
• Critical temperature required for liquefaction of methane is
-82.1oC at 4.71MPa pressure, therefore use of biogas is
limited nearby the biogas plant.
• An estimate indicates that India has a potential of
generating 6.38 X 1010 m3 of biogas from 980 million tones
of cattle dung produced annually.
• The heat value of this gas amounts to 1.3 X 1012 MJ. In
addition, 350 million tones of manure would also produce
along with biogas.

42. POTENTIAL OF BIOGAS IN Sudan
* Cattle population : 30 million
* Farm families : 23 million
* Own 4 or more cattle : 10 million
* Potential of setting up
family size BGP : 12 million
* Established till 2011 none but pilot educational plants
* Dung collection (55% efficiency) : in million kg/day
*Gas production : 39.85million cu.m.gas/day
*Assuming 60% eff. equivalent to = 112695 million K.cal/day
= 12.37 million lit.of kerosene
= 14.54 million lit. of crude oil
= 16.26 million Kg.of coal
= 23.94 million lit. of fire wood
= 131.04 million kWh.of electricity

43. ORGANIC WASTES & THEIR ESTIMATED
AVAILABILITY IN Sudan
Sr.
No.
Organic Wastes Estimated Quantity
1. Municipal Solid waste 30 million tons/year
2. Municipal liquid waste 12000 million litres/day
3. Distillery (u nits) 8057 kilolitres/day
4. Press mud 9 million tons/year
5. Food & fruit processing wastes 4.5 million tons/year
6. Animal waste 30000 tons/year
7. Dairy industry waste 50-60 million litres/day
8. Paper & pulp industry waste (mills) 1600 m3/day
9. Tannery (units) 52500 m3 waste water/day
Source: MNES Report, Renewable Energy in India and business opportunities, MNES. Govt. of India, New Delhi, 2001

44. BIOGAS PRODUCTION PROCESS
Biogas production process (Anaerobic digestion) is a multiple-stage process in
which some main stages are:
Chemical reactions involved in biogas production:
C6H12O6 → 3CO2 + 3CH4
CO2 + 4H2 > CH4 + 2H2O
CH3COOH > CH4 + CO2

45. THE QUANTITY, RATE AND COMPOSITION
OF BIOGAS GENERATED DEPENDS ON
–The nature and concentration of the substrate,
or material.
–Feed rate,
–pH value,
–Bacterial population,
–Temperature, and
–Chemical inducers.

46. biochemical processes
The biochemical processes occur in three stages, each facilitated
by distinct sets of anaerobic bacteria:
 1 Insoluble biodegradable materials, e.g. cellulose,
polysaccharides and fats, are broken down to soluble
carbohydrates and fatty acids (hydrogenesis). This occurs in
about a day at 25 C in an active digester.
 2 Acid forming bacteria produce mainly acetic and propionic acid
(acidogenesis). This stage likewise takes about one day at 25 C.
 3 Methane forming bacteria slowly, in about 14 days at 25C,
complete the digestion to a maximum ∼70%CH4 and minimum
∼30%CO2 with trace amounts of H2 and perhaps H2S
(methanogenesis). H2 may play an essential role, and indeed
some bacteria, e.g. Clostridium, are distinctive in producing H2
as the final product.
The methane forming bacteria are sensitive to pH, and conditions should be
mildly acidic (pH 6.6–7.0) but not more acidic than pH 6.2. Nitrogen should be
present at 10% by mass of dry input and phosphorus at 2%. A golden rule for
successful digester operation is to maintain constant conditions of
temperature and suitable input material. As a result a suitable population of
bacteria is able to become established to suit these conditions.

47. Fats
Protein
s
Cellulose
Fat decomposing
organism Stage (2)
Organic
acids
Methane
bacteria
CH4 – CO2
Cellulose decomposing
organism
Proteins decomposing
Organism
Soluble
compound
Acid
bacteria
Stage (1) Stage (3)
Three stage anaerobic digestion

48. BIOGAS PRODUCTION POTENTIAL FROM
DIFFERENT WASTES

49. UTILIZATION OF BIOGAS
• Cooking: Biogas can be used in a specially designed burner for
cooking purpose. A biogas plant of 2 cubic metres capacity is
sufficient for providing cooking fuel needs of a family of about
five persons.
• Lighting: Biogas is used in silk mantle lamps for lighting purpose.
The requirement of gas for powering a 100 candle lamp (60 W)
is 0.13 cubic metre per hour.
• Power Generation: Biogas can be used to operate a dual fuel
engine to replace up to 80 % of diesel-oil. Diesel engines have
been modified to run 100 per cent on biogas. Petrol and CNG
engines can also be modified easily to use biogas.
• Transport Fuel: After removal of CO2, H2S and water vapor,
biogas can be converted to natural gas quality for use in
vehicles.

50. Overview of commercially viable
technologies
• Family size biogas plants (1 to 10 m3 )
• Large scale biogas plants (10 to 140 m3)
• Large scale plants above 1000 m3 –

51. Fertilizer
Add- food
Production
Cooking
Waste –
sewage
manure .etc
Water
Biogas plant
Slurry
Better
sanitation
Biogas
Manure
Lighting
Water
Pumping
Water
heating
Industries
Misc. uses
‫الشكل‬
(
2.1
)
‫الحيوي‬‫الغاز‬‫استخدامات‬‫مخطط‬
[
17
]

52. Out let
In let
Gas Out let Dome
Digester
FIXED DOME TYPE
BIOGAS PLANT

53. An outline of fixed dome biogas plant
Detailed structural design of fixed dome biogas plant

54. Out let
Pipe
In let
Pipe
Digester
Drum
FLOATING DRUM TYPE
BIOGAS PLANT
Gas
outlet
Inlet
Outlet
Benefits:
Capacity to maintain steady
pressure of biogas by the
movement of gas holder
Inbuilt provision for scum
breaking
Volume of gas is known just by
observing the position of the drum

55. SUITABLE ORGANIC MATERIAL
• Grass
• Bio wastes from slaughter houses
• Breweries and distilleries
• Fruit and wine press houses
• Dairies
• The cellulose industry or sugar production

56. Anaerobic Digesters Types
Calculations and sizing
• Hydraulic Retention Time (HRT)
• The number of days the materials stays in the tank
or digesters is called the Hydraulic Retention Time
or HRT.
• The Hydraulic Retention Time equals the volume of the
tank divided by the daily flow
• (HRT=V/Q).
• The hydraulic retention time is important since it
establishes the quantity of time available for
bacterial growth and subsequent conversion of
the organic material to gas.

57. • Solids Retention Time (SRT)
• The Solids Retention Time (SRT) is the most
important factor controlling the conversion of
solids to gas. It is also the most important factor
in maintaining digester stability. Although the
calculation of the solids retention time is often
improperly stated, it is the quantity of solids
maintained in the digester divided by the quantity
of solids wasted each day.
• SRT =(V ) (Cd )/ (Qw ) (Cw )
• Where
• V is the digester volume; Cd is the solids concentration in the
digester; Qw is the volume wasted each day
• and Cw is the solids concentration of the waste.

58. Calculations
Digesters sizing
• The energy available from a biogas digester is given by:
• E =η HbVb
• Where η is the combustion efficiency of burners, boilers, etc.
(∼60%).
• Hb is the heat of combustion per unit volume biogas
(20MJm−3 at 10 cm water gauge pressure, 0.01 atmosphere)
• V b is the volume of biogas.
• E =η HmfmVb
• where Hm is the heat of combustion of methane (56MJkg−1,
28MJm−3 at STP) and fm is the fraction of methane in the
biogas. As from the digester, fm should be between 0.5 and
0.7, but it is not difficult to pass the gas through a counter
flow of water to dissolve the CO2 and increase fm to nearly
1.0

59. • The volume of biogas is given by
• where C is the biogas yield per unit dry
mass of whole input 02–04m3 kg−1
• m0 is the mass of dry input.
• The volume of fluid in the digester is given
by
• Vf= m0/pm
• Where pmis the density of dry matter in the
fluid (∼50 kgm−3).
Vb= Cm0

60. • The volume of the digester is given by
• Vd= ˙Vf tr
• where
• ˙Vf is the flow rate of the digester fluid and
• tr is the retention time in the digester (∼8–20
days).
•

62. Home work
• Calculate
• (1) the volume of a biogas digester
suitable for the output of 6000 pigs,
• (2) the power available from the
digester,
• assuming a retention time of 20 days
and a burner efficiency of 0.6.

64. • Example: a 2000 tons of cow dung with 8% DM
and 80% total organic matter in dry fraction
• Find the gas volume if the unit weight of dry DM
450m3/ ton?
• Solution;
• 1-DM dry=(total DM X % weight in DM)
• Dry weight= 0.08*2000= 160 ton
• 2-Gas volume
• Vgas= DM X %DM X OM (% CH4) XVBM
• = 0.80*450*160=57600 m3 of Biogas
• Or Vgas= Ms*DM*Fb*C=2000*0.08*0.8*450=
• =57600 m3

65. • The Wet weight of waste or manure; This weight
depends on animals type and their daily waste
production & its density
• Wm=Wa* n* 365/1000
• Where
• Wm- the manure wright ton/year
• Wa- animal waste kg/day
• N- number of animals
• Example:
• A farmer have a 20 cows the daily waste production of
the cow is2 kg/day find the total waste ton/year?
• Solution
• Wm=Wa* n* 365/1000 =2*20*365/1000=14.6 ton/year
• 2- if the manure density is 50kg/m3 and the waste needs 25
days to digest find the digester size?
• Manure volume
• Vman=Wm/p =14.6*1000/50= 292 m3
• Digester volume or size
• Vdig= Vman* t ret/365 = 292*25/365=20m3

66. • 3- if the biogas has a 0.25 m3/kg production rate
and 80% of CH4
Find the daily gas production for this farmer?
• Dry weigt=n*Wa- animal waste kg/day=40 kg
• biogas volume/day=Dm* production rate *%CH4=
• =40*0.25*0.8= 8 m3/day
• 4-
• If the calorific value of biogas in the previous example is
28000 kj/m3
• Find total heat energy of the efficiency of burning gas is
70%?
• E methan= Vbiogas*Hm*ηcomp = 8*28000* 0.7= 156800 kj/day
• =156.8 MJ/day

67. Design & Specification
ITEM QTY. RATE AMT.
TANK(500 ltr) 1 1500 1500
TANK(400 ltr) 1 1200 1200
90mm “T” 1 90 90
90mm Female Adapter 1 60 60
90mm Male Adapter 2 60 120
End Cap 1 50 50
90mm PVC pipe 10ft 6/ft 60
63mm Elbow 1 50 50
63mm Check nut GI 1 100 100
63mm Male Adapter 2 50 100
63mm PVC Pipe 10ft 3/ft 30
Ball Valve 1 750 750
90mm Barrel Piece 1 100 100
63mm Barrel Piece 1 80 80
Bill of material for biogas plant

68. ITEM QTY. RATE AMT.
50 mm barrel piece 1 80 80
½” Barrel piece 1 25 25
½: Pvc male adapter 1 10 10
½” Metal elbow 1 40 40
Epoxy hardener 30gms 50
Pvc solution 100ml 50
Gas collector hdpe(250 ltr) 1 500 500
Fabrication charges 2000 2000
Foundation and support 1000 1000
Total 8045/-
Bill of material for biogas plant

69. CAPACITY TABLE
USABLE
BIOGAS(Hr
. RS)
KITCHEN
WASTE
(GMS)
WATER
(LTS)
DIGESTER
(LTS)
GAS
HOLDER
(LTS)
1 500 7 500 300
1.5 700 10 750 500
2 1000 10 1000 750
2.5 1500 12 1500 1000

70. DESIGNS
3/7/2024 YCCE 70

72. Fabrication
Saquib 72

73. Digester
3/7/2024 YCCE 73

74. Gas Collector
3/7/2024 YCCE 74

75. Gas Valve
3/7/2024 YCCE 75

76. Biogas flame

77. USABLE
BIOGAS(HRS)
KITCHEN
WASTE
WATER
(LTS)
DIGESTER GAS
(GMS) (LTS) HOLDE
R
(LTS)
1hr (350 liters) 500 7 500 400
1.5 hrs (425 liters) 700 10 750 500
2 hrs (700 liters) 1000 10 1000 750
2.5 hrs (875 liters) 1500 12 1500 1000
BIOGAS PRODUCTION PROCESS

78. 3/7/2024 YCCE 78

79. Table - Quantity of Diesel oil saved by running a 5 hp
dual fuel engine on biogas.
Size of biogas 5 hp engine is Quantity of dies
run twice a day Diesel oil (lit./day)
8 4 hour 3.6
15 6.5 hour 5.8
25 12 hour 10.8

80. TABLE :- Comparison of various Fuels.
Name of Calorific value Thermal To replace Useful heat
Fuel (k cal/kg) Efficiency (%)(1m3) Biogas (k cal/kg)
Gobar gas (m3) 4713 60 1 2770
Kerosene (lit.) 9600 50 0. 62 lit. 4800
Fire wood (kg) 4700 10 3. 474 kg 470
Cow dung cake (kg) 2090 10 12. 29 kg 209
Char coal (kg) 6930 28 1. 458 kg 2079
Soft cake( kg) 6292 28 1. 605 kg 1887
Indane (kg) 10882 60 0. 433 kg 6529
Furnace oil (lit) 9041 75 0. 417 6780
Coal gas (m3) 4004 60 1.177 2400
Electricity 860 70 4. 698 602

81. Conclusion
• 400 liters of gas collection, 350 can be
used effectively which is available for
about 1 hour continuously.
• Much useful for a family for reduction of
conv. Energy use.
• The gas is clean and odorless.

82. Conclusion
• The slurry is an excellent fertilizer.
• The gas production is high in summers
while the efficiency is reduced in winters.
• Water droplets present in the gas chokes
the passage of gas.

83. Future Improvements
• The plant of large capacity can be built in
order to get high amount of gas as the waste
available is in very high quantity.
• A solar water heater can be attached to
ensure that hot water is provided in feed. It
helps greatly during winters for bacteria
production.

84. Future Improvements
• The gas collector if fabricated must have a
dome shape; it ensures uniform flow of gas.
• The length of delivery pipe can be decreased
by selecting proper layout of burner. It
avoids losses during transportation of gas.
• A water separator can be incorporated near
the gas cork. It ensures separation of water
droplets.

86. BIOGAS UTILIZATION
TECHNOLOGIES
• There are several viable options for the
utilization of biogas , Foremost among these are:
• direct combustion
• fueling engines
• sales to natural gas pipelines

87. Direct Combustion
• Direct combustion is inarguably the simplest
method of biogas utilization. Conversion of
combustion systems to biogas combustion is
basically a matter of fuel orifice enlargement and
intake air restriction, with attendant modification
of the fuel delivery and control system.
• However, when implementing these modifications
with either new or retrofitted systems, a number of
variables should be considered; including the heat
input rate, the fluid handling capabilities, flame
stability, and furnace atmosphere

88. • Burner Conversion
• Burner conversion to fire biogas rather than natural gas
or propane involves insuring that an exit velocity and
corresponding pressure drop of the biogas is maintained
for proper fuel and air mixing. The pressure drop across
a burner orifice will increase with decrease in heating
value and specific gravity of biogas relative to natural
gas and propane.
• Absorption Chillers
• A biogas conversion method with limited application to
date involves absorption heating and cooling. Utilizing
biogas in a gas burner, a double-effect absorption
chiller-heater can be used to provide chilled water for
refrigeration and space cooling and hot water for
industrial processes and space heating.

89. • Gas Turbines
• These machines and their peripheral equipment
require fuel gases with very low concentrations
of particulates and moisture.
• Many manufacturers recommend gas qualities
similar to those required by utilities for pipeline
quality natural gas.

90. Engines Systems
• Internal combustion engines have been fueled by biogas from municipal
digester systems for more than 40 years with varying degrees of success.
In recent years, this application has been extended to agricultural and
industrial systems for a variety of power requirements. Stationary spark
ignition engines can supply power
• for many loads including:
•cogeneration.
•pumps,
•fans and blowers,
•elevators and conveyors, and
•heat pumps and air conditioners.
• There is also the potential for biogas fueling of cars, trucks and
industrial 'equipment including tractors.
• Evaluation of which system would provide optimum economic use of a
biogas source hinges on a number of considerations including:

91. Cogeneration
• cogeneration is best defined as the simultaneous
production of two or more forms of energy from a
single fuel source. In the following discussion, the
two forms of energy exemplified are electricity and
thermal energy in the form of hot water. Other
applications include fueling an engine for shaft
horsepower (for pumps, blowers, etc.) and thermal
energy (space heating, hot water, absorption
chilling, etc.). Additionally, cogeneration can take
the form of using biogas to fuel a steam boiler for
producing steam for a steam turbine for
producing shaft horsepower, electricity, and hot
water.

92. Spark Ignition Engines
• Engine Modification
• Spark ignition (SI) engines are the easiest engines to
convert to biogas due to the wide availability of natural
gas fired units and the relative similarity of biogas to
natural gas. There is also a large selection of diesel
powered cogeneration systems in the higher output
ranges (over 500 kW).
• Engine conversion to biogas fueling involves engine
modification in the following areas:
• - carburetion,
• - spark gap settings,
• - spark timing, and
• - maintenance requirements.

93. Diesel Engines
• Biogas fueling of diesel engines requires the use
of diesel fuel for ignition, since there is no
spark and biogas has a low cetane rating.
• This requires some modification of the engine
including a carburetor for the mixing of biogas
with intake air and a means for maintaining the
desired diesel fuel setting on the injection
pump, and for advancing the ignition timing

96. Test 2
• Q1:-
• 1-define the following terms?
• 1- biomass 2- anaerobic digestion -
• 3- biodiesel
• 2- Sugar cane agro-industry is out standing example of farm energy show the
process flow diagram of energy generation sugar cane?
3- Ethanol used as a fuel for I.C engines in three ways
briefly show them?
4- many processes are used to extract energy from
biomass show the and give example product of each
process

97. • How Do Wind Turbines Work?
• What are the Basic Components of a
wind turbine system for electricity
generation and water pumping?
• Define the terms
• Wake – power coefficient – tip speed
ratio – lift and drag forces?
• Classify wind turbines?

98. THANK YOU