Biomass.ppt

Biomass Energy
 Introduction
 Biomass Resources
 Bio Fuel
 Bio Gas
 Producer Gas
 Liquid Fuel (Ethanol)
 Biomass Conversion Techniques
 Biomass Gasification
 Biogas Technology and Biogas Plants
 Ethanol from Biomass and Bio Diesel

Biomass
 Biomass refers to solid carbonaceous material derived
from plants and animals. These include residues of
agriculture and forestry, animal waste and discarded
material from food processing plants
 Biomass being organic matter from terrestrial and marine
vegetation, renews naturally in a short span of time,
thus, classified as a renewable source of energy
 It is a derivative of solar energy as plants grow by the
process of photosynthesis by absorbing CO2 from the
atmosphere
 Biomass does not add CO2 to the atmosphere as it
absorbs the same amount of carbon in growing the
plants as it releases when consumed as fuel
 It is a superior fuel as the energy produced from biomass
is ‘carbon cycle neutral’

Biomass continued….
 Biomass fuel is used in over 90% of rural households
and in about 15% urban dwellings
 Agriculture products rich in starch and sugar like wheat,
maize, sugarcane can be fermented to produce ethanol
(C2H5OH)
 Methanol (CH3OH) is also produced by distillation of
biomass that contains cellulose like wood and biogases
 Both these alcohols can be used to fuel vehicles and can
be mixed with diesel to make biodiesel
 Biomass resources for energy production are widely
available in forest areas, rural farms, urban refuse and
organic waste from agro- industries. Biomass
classification is illustrated in the next slide
 India produces over 550 million tones of agricultural and
agro-industrial residues every year. Similarly, 290 million
cattle population produces about 438 million tones of
dung annually

Biomass Resources
 Forests
 Agricultural crop residues (rice husk, wheat
straw, corn cobs, cotton sticks, sugarcane
biogases, groundnut shell, coconut shell etc)
 Energy crops (fast growing plants)
 Vegetable oil crops (rapeseed, sunflower, cotton
seed, palm, groundnut, coconut etc)
 Aquatic crop (water plants)
 Animal waste
 Urban waste
 Industrial waste

Biofuels
 Charcoal (smokeless dry solid fuel with high energy
density)
 Briquetting (densification of loose biomass into a high
density solid fuel)
 Vegetable oil (rapeseed, palm, coconut and cotton seed
oil)
 Biogas (can be produced by digestion of plant, animal and
human waste)
 Producer gas (mixture of a few gases - obtained by partial
combustion of wood or any cellulose organic material of
plant origin)
 Liquid fuel (ethanol – inflammable colorless biofuel –
produced by fermentation of any feedstock which contains
sugar or starch and even cellulose material)

Advantages of Biomass Energy
 It is a renewable source
 Energy storage is an inbuilt feature of it
 It is an indigenous source requiring little or no foreign
exchange
 The pollutant emissions from the combustion of
biomass are usually lower than those from fossil fuels
 Commercial use of biomass may avoid the problems
of waste disposal in urban centers
 Use of biogas plants leads to improved sanitation and
better hygienic conditions
 It is available in all the seasons
 The nitrogen rich slurry and sludge from a biogas
plant improves the fertility of the soil
 The forestry and agricultural industries associated with
biomass provide substantial economic development
opportunities in the rural areas

Disadvantages of Biomass Energy
 It is dispersed and land intensive
 It is of low energy density
 It is labour intensive
 The cost of collecting large quantities of biomass is
significant
 It is not suitable for varying loads
 It is not feasible to set up biomass power plants in all
locations

Biomass Conversion Technologies
• Densification
• Direct combustion and incineration
• Thermo-chemical conversion
• Bio-chemical conversion
Densification :
 In this process bulky biomass is reduced to a better
volume - to -wait ratio by compressing in a die at a high
temperature and pressure.
 The biomass pressed into briquettes or pellets (either to
transport and store) can be used as clean fuel in
domestic chulhas, bakeries and hotels.

Cont.,
Direct Combustion:
 This is the main process adopted for utilizing biomass
energy. It is burnt to produce heat utilized for cooking,
space heating, industrial processes and for electricity
generation.
 This utilization method is very inefficient with heat
transfer losses of 30 – 90 % of the original energy
contained in the biomass. The problem is addressed
through the use of more efficient cook-stove for burning
solid fuels
Incineration:
It is the process of burning completely the solid masses
to ashes by high temperature oxidation.

Cont.,
Incineration (Cont.,):
 Although the terms combustion and incineration are
synonymous, yet the combustion process is applicable to
all fuels (i.e., solid, liquids, and gases): incineration is a
special process which is used for incinerating municipal
solid waste to reduce the volume of solid refuse (90 per
cent ) and to produce heat steam and electricity.
Pyrolysis:
 Wood, dung, vegetable waste can be dried and burnt to
provide heat or converted into low calorific value by
pyrolysis.
 In the pyrolysis process, the organic material is
converted to gases, solids and liquids by heating to 500
to 900 degree celcius in the absence of oxygen.

Cont.,
Thermo-Chemical Conversion:
It is a process to decompose biomass with various
combinations of temperatures and pressures.
Thermo-Chemical conversion in two forms
i) Gasification:
It is the process of heating the biomass with limited
oxygen to produce low heating value or by reacting it
with steam and oxygen at high pressure and
temperature to produce medium heating value gas.
ii) Liquification:
 Biomas can be liqiufied through fast or flash pyrolysis
called pyrolytic oil which is dark brown liquid of low
viscosity and a mixture of hydrocarbons.
 Biomass can also be liquified by methanol sysnthesis.

Cont.,
Bio-Chemical Conversion:
In biochemical conversion there are two principal
conversion process
(i) Anaerobic Digestion:
 This process involves microbial digestion of biomass and
is done in the absence of oxygen.
 The process and end products depend upon the micro-
organisms cultivated under culture conditions.
 This process generates mostly methane (CH4) and CO2
gas with small impurities such as hydrogen sulphide.
Aerobic Decomposition : is done in the presence of oxygen
and it produces CO2 , NH3 and some other gases in
small quantities and large quantity of heat. The final by
product of this process can be used as fertilizer.

Cont.,
Bio-Chemical Conversion (Cont.,)
(ii) Fermentation:
 In this process of decomposition of organic matter by
micro-organisms especially bacteria and yeasts.
 It is well establish and widely used technology for
conversion of grains and sugar crops into ethanol (ethyl
alcohol).
 Ethanol can be blended with gasoline (petrol) to produce
gasohol (90% petrol and 10%ethanol). Processes have
been developed to produce various fuels from various
types of fermentations.

Biomass Gasifiers (Thermo Chemical)
 Biomass gasification is thermo-chemical conversion of
solid biomass into a combustible gas fuel through
partial combustion with no solid carbonaceous residue.
Gasifiers use wood waste and agriculture residue.
 Gasifiers (fixed bed type) can be of ‘updraft’ or
‘downdraft’ type depending upon the direction of the air
flow.
 In the updraft gasifier, fuel and air move in a
countercurrent manner.
 In the downdraft gasifier, fuel and air move in co-current
manner. However, the basic reaction zones remain the
same.
 A typical downdraft gasifier is shown in the next slide.

Downdraft Gasifiers continued….

Downdraft Gasifiers
 Fuel is loaded in the reactor from the top.
 As the fuel moves down, it is subjected to drying (120c)
and then pyrolysis (200-600C) where solid char, acetic
acid, methanol and water vapour are produced.
 Descending volaties and char reach the oxidation zone
where air is injected to complete the combustion. It is the
reaction zone and the temperatures rises to 1100ºC.
This helps in breaking down the heavier hydrocarbons
and tars.
 As these production move downwards, they enter the
‘reduction zone’ (900-600ºC, reaction being
endothermic) where producer gas is formed by the
action of CO2 and water vapour on red hot charcoal.

Downdraft Gasifiers continued….
 Producer gas formed in the reduction zone contains
combustible products like carbon monoxide (CO),
Hydrogen (H2)and methane (CH4 ). Hot gas flowing out
is usually polluted with soot, tar and vapour. For
purifying, it is passed through coolers. Tar is removed by
condensation, whereas soot and ash are removed by
centrifugal separation.
 Clean producer gas provides the process heat to operate
stoves (for cooking), boilers, driers, ovens and furnaces.
The major applications is in area of electric power
generation. A biomass gasifier-based electricity
generation system costs from Rs. 4.0 crores to 4.5
crores per MW.
 Fixed bed gasifiers can attain efficiency up to 75% for
conversion of solid biomass to gaseous fuel. However,
the performance depends on fuel size, moisture content,
volatiles and ash content.

Fluidized Bed Gasifier
 Fluidized Bed Combustion (FBC) is a better option to
use for the problematic biomass of farm residues like
rice husk (high ash content), bagasse , industrial waste
such as saw dust and pulping effluents, sewage sludge
etc.
 FBC constitutes a hot bed of inert solid particles of sand
or crushed refractory support on a fine mesh or grid.
 The bed material is fluidized by an upward current of air
as shown in the next slide.
 Pressurized air starts bubbling through the bed and the
particles attain a state of high turbulence, and the bed
exhibits fluid like properties.
 A uniform temperature within the range of 850-1050C is
maintained.

Fluidized bed gasifier continued….
 Large surface area is created in the fluidized bed and the
constantly changing area per unit volume provides a
higher conversion efficiency at low operating
temperatures compared to the fixed beds.
 High heating capacity of sand and the uniform
temperature of fluidized bed makes possible to gasify
low-grade fuels of even non-uniform size and high
moisture content.
 When the gasifier is put in use, the bed material is
heated to ignition temperature of the fuel and biomass is
then injected causing rapid oxidation and gasification.
 Fuel gas so produced contains impurities, dust, char
particles and tar. It needs conditioning and cleaning for
utilization as an engine fuel.

Biogas Plant (Anaerobic)
 Biogas is an inflammable gas derived from organic
wastes such as cattle dung, human waste etc. It is a safe
fuel for cooking and lighting.
 Biogas consists of Methane (CH4), CO2 and traces of
other gases such as H2, Carbon Monoxide (CO), N2, O2
and Hydrogen Sulfide (H2S). The methane content of
biogas is about 60% which provides a high calorific value
to find use in cooking, lighting and power generation.
 Biogas plant converts cattle dung and other organic
matter into biogas and good quality organic manure.
 There are two popular designs of biogas plants:
(i) Floating drum (constant pressure) type
(ii) Fixed dome (constant volume) type

Floating Drum Type Biogas Plant
(KVIC Model)
 A popular model, shown in the next slide, comprises an
underground cylindrical masonry digester having an inlet
pipe for feeding animal dung slurry and an outlet pipe for
sludge.
 There is a steel dome for gas collection which floats over
the slurry. It moves up and down depending upon
accumulation and discharge of gas guided by the dome
guide shaft.
 A partition wall is provided in the digester to improve
circulation necessary for fermentation.
 The floating gas holder builds gas pressure of about 10
cm of water column, sufficient to supply gas up to 100
metres. Gas pressure also forces out the spent slurry
through a sludge pipe.

Cont.,
Advantages:
 Gas pressure is constant
 Less scum problem
 No gas leakage problem
 No danger of explosion since there is no possibility of
mixing of biogas and external air.
Disadvantages:
 High cost
 High maintenance cost
 There is a loss of heat through gas holder
 The outlet pipe, which should be flexible, requires
regular attention.

Fixed Dome Type Biogas Plant
(Janata Model)
 It is an economical design where the digester is
combined with a dome-shaped gas holder as shown in
the next slide.
 It is known as Janata model. The composite unit is made
of brick and cement masonry having no moving parts,
thus ensuring no wear and tear and longer working life.
 When the gas is produced, the pressure in the dome
changes from 0 to 100 cm of water column.
 It regulates gas distribution and outflow of spent slurry .

Cont.,
Constructional Features
 Foundation
 Digester
 Dome
 Inlet chamber
 Outlet chamber
 Mixing Tank
 Gas outlet pipe.

Site Selection
 The site should be as far as possible near the cattle
shed and points of gas utilization.
 It should be at least 2 meters away from the foundation
of the house/building.
 The sun light should be available during whole of the day
round the year.
 The site should be at least 10-15 meters away from the
any water drinking sources.
 There should not be any big tree near plant whole roots
may cause any harm with the passage of time.
 There should be an easy availability of water near the
plant.
 To avoid carrying spent slurry to a very far distance there
should be some space for making compost pit.
 The earth should have adequate bearing stress to avoid
any possibility of caving in or collapse of the plant.

PRODUCTION OF BIOFUELS
 Non-petroleum liquid fuels find use when petroleum fuels
are scarce or costly. Methanol (CH3OH), Ethanol
(CH5OH) and Biodiesel are used as fuels in I.C engines.
 Ethanol (or ethyl alcohol) can be produced by
“fermentation of carbohydrates” which occur naturally
and abundantly in some plants like sugarcane and
starchy materials like corn and potatoes.
 Methanol can be produced from municipal solid wastes
and specially grown biomass.
 Biodiesel is produced from non-edible oil seeds.
 Producer gas is obtained by partial combustion of wood
or any cellulose organic material of plant origin.

Ethanol Production (Fermentation)
 Ethanol is ethyl alcohol (C2H5OH), a colourless,
flammable liquid
 It is a renewable energy source which can substitute
petroleum products
 Ethanol can be produced from a variety of biomass
materials containing sugar, starch and cellulose
The best-known feedstock under three categories are:
 Sugars: sugarcane, sugar beet, sweet sorghum, grapes,
molasses
 Starches: maize, wheat, barley, potatoes, cassava, rice
 Cellulose: wood, straw, stems of grasses, bamboo,
sugarcane bagasse

Ethanol Production continued….
Production Process:
 Sugar rich crops, especially the sugarcane which contains
the valuable raw material for crystal sugar, and by-products
from sugar mills are molasses that contain 50 to 55% sugar
content.
 It is monosaccharide form of sugar which refers to the
glucose (C6H12O6) and fructose (C6H12O6) content in cane
 Sweet fruits like ripe grapes, mangoes, etc. contain glucose
in natural form.
 Juice containing sugar can easily be fermented into ethanol
by adding yeast. Yeasts are micro-organisms, which
produce enzymes that convert sugar to ethanol.

Methanol Production
Production Process:
 Methanol can be produced from municipal solid wastes and
specially grown biomass.
 The wastes are shredded and passed through magnets to
remove iron.

Cont.,
 The iron –free wastes are gasified with O2.
 The product synthesis gas is scrubbed by water to remove
particulars, entrained oil, H2s and CO2.
 Co-shift conversion for H2 / CO2 / CO ratio adjustment,
methanol synthesis and methanol purification are
accomplished to produce methanol.

Biodiesel
 Biodiesel is a liquid fuel produced from non-edible oil
seeds such as Jatropha, pongamia pinnata (Karanja),
etc. which can be grown on wasteland.
 However, the oil extracted from these seeds has high
viscosity (20 times that of diesel) which causes serious
lubrication, oil contamination and injector chocking
problems.
 These problems are solved through trans-esterification,
a process where the raw vegetable oils are treated with
alcohol (methanol or ethanol with a catalyst) to form
methyl or ethyl esters. The monoesters produced by
trans-esterifying vegetable oil are called ‘biodiesel’
having low fuel viscosity with high octane number and
heating value.
 Endurance tests show that biodiesel can be adopted as
an alternative fuel for existing diesel engines without
modifications.

Biodiesel continued…
The advantages of biodiesel as engine fuel:
 Renewable
 Higher octane number
 Can be used as neat fuel (100 % biodiesel) or mixed in
any ratio with petroleum diesel
 Higher flash point (making it safe to transport)
 Biodegradable and produces 80 % less CO2 and 100 %
less SO2 emissions

Producer Gas
 It is obtained by partial combustion of wood or any
cellulose organic material of plant origin.
 It is a mixture of a few gases (CO2, CH4, H2, CO, N2),
hydrogen and methane keep heating value between 4.5
MJ/ m3, depending upon the volume of its constituents.
 It can be burnt in a boiler to generate steam.
 It is used as fuel in “I.C. engines” for irrigation pumps and
gas turbines for power generation.

Energy Recovery From Urban Waste and Wood
 The Urban Waste is disposed off suitably by Waste –to-
Energy conversion systems including:
1. Landfill Gas Energy Plants
2. Waste Incineration Cogeneration Plants
3. Biochemical Conversion Plants
 One of the most important biomass conversion
technologies is Incineration (Combustion). The
application of “ Incineration Process” are given below

Cont.,
 In cold countries heat is supplied by the utilities
for heating the houses. Steam is required for
process industries.
 Following are the other processes of waste –to-
energy and wood-to-energy.
1. Production of biomass from waste by
methane formation process.
2. Production of wood gas from wood
3. Production of biogas from landfills, etc.

Urban Solid Waste (Municipal Waste,
Municipal Refuse)
 The domestic waste (Refuse) in the cities is usually sent
to landfill sites located away from the centre of the city.
 Large cities like Delhi, Bombay have large amount of
waste and increasing waste disposal problems.
 The emerging solution is to produce useful thermal and
electrical by waste-to-energy plants (WTE) located in the
heart of city.
 Such energy plants are rated in MW (50 to 500 MWe)
and serve the following functions.
1. Safe and economical disposal of urban waste.
2. Supply of electrical and thermal energy to the
consumers in the city.
3. Environmental protection from urban waste.

Waste-to-Energy Incineration Process
 The energy route of the waste-to-electrical energy by
incineration process is given below
Biomass Energy Thermal Energy Electrical Energy
(From nature) (From Incinerator) (From Generator)
Electrical Energy
(to users or grid users)
 The incineration process accepts a wide variety of
biomass inputs including
1. Semi-dried wood, trees, tree residues, wood chips,
saw-dust.
2. Semi-dried garbage (urban waste).
3. Semi-dried farm waste (dried cow-dung, straw,
sugar, biogases, etc.
4. Mixtures of fossil fuels and biomass for higher heat
content of the in feed.
5. Steam is supplied to steam –turbine power plant (50
to 150 MW)

Cont.,
6. Heat (hot water) is supplied for district heating in
cold countries.
7. Steam is supplied to process industry.
 Waste incineration power plant is usually located
near the source of water. Table below gives the
locations of Waste-to-Power Plants.

Waste Incineration Energy Plant
Processing of wood and wood-waste (fuel) for
feeding to the incineration plant

Cont.,
 The incineration plant is usually located in the forest and
near saw mill.
 This reduces the expenditure of transportation of wood
and makes it competitive as a fuel for producing
electricity.
 The various steps involved in the process are
1. Felling of trees in the forest
2. Segregating logs, tree barks, leaves etc.
3. Transporting the logs and other residue to central
store.
4. Storing the logs in a circular store.
5. Collecting dried wood by means of central crane in
the circular store and transporting the wood power
plant for incineration.
6. Shredding (making smaller pieces)
7. Feeding to the furnace.

Power Generation From landfill Gas

Cont.,
 In this method power generation, a large pit at the
outskirt is prepared and a pipe system for gas collection
is laid down the waste is filled.
 Municipal solid waste is then buried for anaerobic
digestion.
 The gas is then stored in a storage tank.
 The gas after passing through gas regulator, runs gas
turbine which in turn runs a generator, producing
electrical power.
Landfill Gas Collection System:
 It consists of wells comprising vertical pipes of in the
landfill.
 The well-pipes and collection pipes are of polythene.
 Knockout drums are installed in the pipelines for removal
of water.
 The wells are connected to manifolds by the piping
system.

Cont.,
 Land fill gas constrains predominantly methane (54% by
volume).
 The landfill gas is used in the following applications
directly(without purification)
1. As a fuel for burning in boilers.
2. As a fuel for kilns, furnaces.
 The purified methane obtained from landfill gas is used
as follows
1. As a vehicle fuel
2. As a fuel for diesel engines
3. As a fuel for diesel engine, to produce electrical
energy
4. After upgrading supplied as a fuel gas to
domestic customers

Power Generation From Liquid Waste
 Liquid waste may be of following types
1. Sewage
2. Distillary waste
3. Pulp and paper mill black liquor waste
1.Sewage:
 Anaerobic digestion is used to produce gas for
extracting energy from sewage.
 Anjana sewage treatment plant (at Surat) has three
sludge digesters with a total capacity of 82.5 million liters
per day; each digester generates about 2500 m3 biogas
daily.
 A scrubber system is employed to clean the gas, to
make it suitable for use in a 100 percent biogas engine
to generate electricity.

Cont.,
2. Distillary waste:
 Power generation from distillary liquid waste (carrying
rich raw material for producing gas).

Cont.,
 Distillary liquid waste is collected in a decantation tank
where the suspended solids settle down.
 Decanted liquid / effluent containing fermented molasses
is pumped into a digester through a heat exchanger,
where it (effluent) is cooled to maintain the digester
temperature at 36-38 degree Celsius.
 Effluent is than allowed to be digested anaerobically for
about 12-15 days, during which gas is produced.
 The biogas accumulates in a biogas holder and is stored
under pressure using a pressure control device.
 The gas is used to run the I.C engine (s) which in turn
generate electrical power through generators.

Cont.,
3. Pulp and paper mill black liquor waste:
 A large amount of energy and water is consumed by the
pulp and paper industry.
 The waste discharge water contains compounds of
wood and raw material which are useful for recovery of
energy.
 A plant for biomethanation of biogases wash effluent is
installed at Karur (in Tamil Nadu), based on USAB
technology.
 Biochemical Oxygen Demand (BOD) and Chemical
Oxygen Demand (COD) removal is 94% and 89%
respectively, with gas production of 0.37 m3 / kg.
 At present , about 1500 m3 of gas is generated per day,
which is used in a lime-mud reburning kiln.
 The gas output from the plant meets 50% heat load of
the kiln, equivalent to about 12.5 *103 liters of furnace
oil.

Biomass.ppt

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Biomass.ppt