9.

BIOMASS ENERGY
Topics:
✔ Biomass types
✔ Characterization
✔ Conversion routes-pyrolysis and gasification
✔ Bio chemical
 BIOMASS
Biomass is biological/organic material derived from
photosynthesis directly or indirectly.
The term is equally applicable to both animal and vegetation
derived material, but in the context of energy, it refers to
plant based material.
Renewable energy source.
Solar energy stored in the form of complex organic
compounds of Carbon, Hydrogen, Oxygen and Nitrogen etc.
Is a source of ‘5F’: food, fodder, fuel, fiber and fertilizer-
organic farming.
Can be converted into useful forms of energy through
different conversion routes.
Gets converted into fossil fuels after several million years
under certain conditions of pressure, temperature etc. Fossil
fuels are not renewable, hence, are not biomass.
 EXAMPLES OF BIOMASS
Wood: Trees, bushes, wood residue
(Sawdust, bark etc. from forest clearings
and mills)
Wastes: Municipal Solid Waste (Paper, food
and yard wastes, plastics, tires etc.),
Livestock Waste, Process Waste, Sewage
Crops: Starch crops (Corn, wheat and
barley), Sugar crops (sugar cane and beet),
Forage crops (Grasses, alfalfa, and clover),
Oilseed crops (soybean, sunflower,
safflower)
Aquatic Plants: Algae, water weeds, water
hyacinth, reed etc.
BIOMASS AND CARBON EMMISIONS
Living biomass in plants
and trees absorbs carbon
dioxide from the
atmosphere through
photosynthesis
Biomass emits carbon
dioxide when it naturally
decays and when it is
used as an energy source
Biomass causes a closed
cycle with no net
emissions of greenhouse
gases
 BIOMASS ENERGY
Energy obtained from biomass is called
biomass energy.
Produced by green plants through
photosynthesis in presence of sun light

Other living organisms consume green plants

or their byproduct and generate biomass
ORIGIN OF BIOMASS ENERGY
 BIO-FUEL
Derived from biological carbon fixation of
biomass
Examples are
✔ Bioalcohols-ethanol:liquid
✔ Biodiesel:liquid
✔ Biogas: gas
✔ Solid bio-fuels:solid
 BIO-FUEL (contd…)
Bioalcohol
✔ Produced by the action of microorganisms and
enzymes through the fermentation of sugars or
starches or cellulose
Biodiesel
✔ Produced from oils or fats using
transesterification
Green diesel- Only R & D
✔ Produced from traditional fractional distillation
to process the oils of canola, algae, jatropha and
salicornia
 BIO-FUEL (contd…)
Biogas
✔ Produced by the process of anaerobic
digestion of biodegradable waste materials
or energy crops
✔ The solid byproduct can be used as a
biofuel or a fertilizer.
Solid biofuels
Raw biomass is burnt directly in a stove or
furnace to provide heat
Loose biomass (saw dust, rice husk) is
densified by palletization/briquetting.
 BIOMASS ENERGY RESOURCE
The raw biomass for extracting secondary energy
(fuel, organic chemicals, etc.) is called biomass
energy resources.
Biomass Energy Resource are broadly classified into
two categories:
✔ Nurtured/Cultivated: Biomass from cultivated
fields, crops, forests and harvested periodically,
aquatic/marine plants.
✔ Waste Organic Material: Biomass from waste e.g.
municipal waste, animal excreta/dung, forest
waste, agricultural waste, bioprocess waste,
Industrial waste, butchery waste, fishery wastes,
processing waste etc.
PRINCIPAL BIOMASS ENERGY RESOURCES
AND CONVERSION PROCESSES

Category Name of the Conversion Process

Biomass Resource
Cultivated Trees, (Wood chips, Burning to produce heat
Energy saw dusts) and electricity
Resource Aquatic crops, Producing biogas and
algae, green plants biochemicals
Agricultural crops Production of gas (Wood
gasification)
Fruit farms Production of wood oil
and charcoal (Wood to oil
process)
PRINCIPAL BIOMASS ENERGY RESOURCES
AND CONVERSION PROCESS (contd…)
Category Name of the Biomass Resource Conversion
Process
Waste – Rice and wheat husk Production of
Biomass Baggase of sugar cane ethyl alcohol
resources by
Coconut husk, groundnut shell, straw
from fermentation
of rice, wheat etc.
farms and of molasses,
bio-indust Waste of furniture industry, wood beet root,
ry industry fruits,
Waste of poultry industry, fishery potatoes,
industry, food industry, brewery, cereals
tannery, butchery etc.
Carbohydrates, glucose, fructose etc.
ADVANTAGES OF BIOMASS ENERGY
Renewable and inexhaustible (theoretically) source
of energy
Biomass is very abundant.
It is easy to convert to a high energy portable fuel
such as alcohol or gas which are efficient, viable and
relatively clean-burning.
It is cheap in contrast to the other energy sources.
Biomass production can often mean the restoration
of waste land (e.g. deforested areas)
Commercial use of biomass may reduce the problem
of waste disposal
ADVANTAGES OF BIOMASS ENERGY (contd…)
It may also use areas of unused agricultural land and
provide jobs in rural communities.
When direct combustion of plant mass is not used
to generate energy (i.e. fermentation, pyrolysis, etc.
are used instead), there is minimal environmental
impact
If it is produced on a renewable basis using biomass
energy, it does not result in a net carbon dioxide
increase as plants absorb it when they grow.
Nitrogen-rich bio-digested residue from a biogas
plant is a good soil conditioner and improves the
fertility of soil
DISADVANTAGES OF BIOMASS ENERGY
A dispersed and land-intensive source
Low energy density
Could contribute a great deal to global
warming and particulate pollution if directly
burned
Still an expensive source, both in terms of
producing the biomass and converting it to
alcohols
On a small scale there is most likely a net loss
of energy
 SCOPE OF BIOMASS ENERGY
Scope of biomass energy
✔ Rural applications of biomass energy.
✔ Urban and industrial applications of biomass energy.
✔ Biomass as a primary source for large scale electrical
power generation.
India has vast land based, aquatic, forest, agricultural
biomass resources. Biomass energy processes serve
many purposes:
✔ Energy supply: Fuel, Biogas, Organic chemicals
✔ Rural development
✔ Waste disposal
✔ Environment balance
ENERGY PLANTATIONS (TERRESTRIAL)
Growing of selected species of tree and plants on a short
rotation basis on waste or arable land for energy generation
point of view e.g.
✔ Acacia nilotica (Babul, grows even in wasteland)
✔ Dalbergia Sissoo (Sheesham, high calorific value up to 20.5
MJ/kg)
✔ Prosopis Juliflora (Vilayati Babul, Root up to 50m)
✔ Albizzia Lebbeck (Siris)
✔ Gujarat state – biggest supplier of charcoal to chemical industry
ENERGY PLANTATIONS (AQUATIC)
Growing of floating water plants e.g., water hyacinth
in rivers, lakes, ponds etc in tropical / sub-tropical
area (yield 25 T(dry)/ha/yr)
 BIOMASS FROM WATER BODIES
Algae biomass is an important renewable source of
energy produced by photosynthesis.
BIOMASS FROM WATER BODIES (contd…)
The algae is produced in algae farms. Algae contains
organic matter which can be converted into methane gas
(a useful fuel) in a simple biogas plant by the process
called anaerobic digestion. Algae crops are likely to be
cultivated on large scale to obtain renewable energy.
After extracting the biogas, the organic residue from the
biogas-plant is added to the algae pond. This acts as a
food to the bacteria in algae pond. The algae-bacterial
combination consumes the waste organic water in the
pond, absorbs solar energy and results in rapid growth
of algae.
BIOMASS ENERGY CONVERSION PROCESSES
The biomass can be converted to useful energy
forms such as:
✔ Heat
✔ Gaseous, Liquid and Solid fuels
✔ Organic chemicals
The biomass conversion process has several routes
depending upon temperature, pressure,
micro-organisms, and process conditions. These
routes are classified in following three broad
categories.
✔ Direct combustion (Incineration)
✔ Thermo-chemical conversion:
pyrolysis, gasification
 BIOMASS ENERGY CONVERSION
PROCESSES AND END PRODUCTS
Conversion
Biomass Resource Products Market
Process
Solid biomass (Wood, Combustion Heat Heat/CHP, Electricity
Stem) Pyrolysis Bio oil, Fuel gas Transportation fuel
Gasification Fuel gas Transportation fuel
Wet biomass Anaerobic Biogas Electricity
(Organic waste, digestion
Manure)
Sugars and starch Hydrolysis and Bio-ethanol Transportation fuel,
Plants (Sugarcane, Fermentation Chemical
beet, cereals)
Oil crops (rapeseed, Extraction and Bio-diesel Transportation fuel
sunflower) Esterification
 DIRECT COMBUSTION
Direct combustion (rapid oxidation accompanied by
heat and light) of biomass is the most straightforward
method of energy production.
Generally direct combustion is applicable to solid
biomass including cultivated biomass and waste
biomass.
The heat released by direct combustion can be used for
several useful purposes such as cooking, industrial heat,
steam generation etc.
The direct burning of biomass is the cause of a great
deal of pollution and has contributed to global
warming.
DISPOSAL OF PADDY STRAW
 SATELLITE PHOTOGRAPH ON GOOGLE
EARTH SNAPSHOT OF NORTHERN INDIA

November 4, 2008
Source: Earth Observatory (NASA)

Smoke due to improper combustion

(Damage to environment and loss of
huge source of energy)
A TYPICAL POWER-PLANT
An electrostatic precipitator (ESP) controls
particulate emissions
Only Boiler & ESP
need to be
redesigned
BIO-MASS STORAGE METHODS (contd…)

EURO BAGGING
THERMO-CHEMICAL CONVERSION
Biomass is converted into another chemical form by
thermo-chemical processes in which heat is the dominant
mechanism.
These processes include gasification and pyrolysis and are
separated principally by the availability of oxygen and conversion
temperature.
Gasification is the conversion of a solid biomass into a gaseous
fuel at a high temperature with controlled air.
Pyrolyisis involves the heating of biomass such as wood or
agricultural waste at around 500-900 oC in the absence of oxygen
to decompose it into gas and charcoal (carbon). A major
advantage of pyrolysis is that carbon dioxide, one of the main
drawbacks to most biomass energy conversion processes, is not
produced. A disadvantage, however, is that the biomass must be
heated to relatively high temperatures, a process that itself
requires significant amounts of energy.
Same technologies as applicable to coal are used
 BIO-CHEMICAL CONVERSION
The process makes use of the enzymes of
bacteria and other micro-organisms to break
down biomass to produce liquid and gaseous
fuels
In most cases micro-organisms are used to
perform the conversion process: anaerobic
digestion, fermentation and composting.
Other chemical processes such as converting
vegetable or animal oils into biodiesel is
transesterification.
 ANAEROBIC DIGESTION
Biological treatment can be done either in presence
of oxygen (aerobic) or in absence of oxygen
(anaerobic).
In India, anaerobic digestion plants are commonly
known as Biogas Plants or Gobar Gas Plants. In such
plants slurry of cow dung and water is fed to the
digester and is allowed to ferment for a few weeks.
The biogas is released. The biogas contains methane
(CH4) as fuel gas component.
There are two types of Biogas Plants
✔ Fixed head/dome
✔ Floating head/dome
ENERGY ROUTE OF BIOGAS
 BIOGAS HISTORY

1776 : Marsh gas, By Volta

1808 : Humphry Davy, Methane
1859 : Leper colony, Mumbai, Digester
1895 : Gas lamp in Exeter, England
1907 : Patent, Germany
1930 : R&D
TYPICAL BIOGAS COMPOSITION, %

Methane, CH4 50–75

Carbon dioxide, CO2 25–50
Nitrogen, N2 0–10
Hydrogen, H2 0–1
Hydrogen sulfide, H2S0–3
Oxygen, O2 0–2
 STAGES IN BIOGAS PRODUCTION

BIOLOGICAL AND CHEMICAL STAGES OF ANAEROBIC DIGESTION

Hydrolysis: Complex molecules break down to simpler molecules
Acidogenesis: Carbonic acid etc.
Acetogenesis: Acetic acid, Hydrogen?
Methanogenesis: Methane and carbon dioxide gas forming
SCHEMATIC OF A FIXED DOME TYPE
BIOGAS PLANT
 SCHEMATIC OF A FLOATING DOME TYPE
BIOGAS PLANT

Position a of dome with less gas in the dome. Position b of dome with more gas in the dome.
COMPARISON OF FIXED AND FLOATING
HEAD/DOME BIOGAS PLANT
Janta/Fixed dome type Floating Dome type Biogas Plant
1 Gas is released at variable pressure Gas is released at constant pressure
2 Identifying defects is difficult Identifying the defects in gas holder
easy
3 Cost of maintenance is low Cost of maintenance is high
4 Capital cost is low Capital cost is high (for same capacity)
5 Space above the drum can be used Floating drum does not allow the use
of space for other purpose
6 Temperature is high during winter Temperature is low during winter
7 Life span is comparatively longer Life is short
8 Requires move excavation work Requires relatively less excavation
 SIZES OF BIOGAS PLANTS
Biogas Size of
Category Application
Delivery Digester
Very small 0.65 - For small family of 3
Biogas plant m3/day members having 2 cattle.
Small biogas 2 m3/day - For family of 6 members
plant having 8 cattle.
Medium (family 3 m3/day 1.6 m dia, For family of 12 persons
size) biogas 4.2 m height having 12 heads of
plant cattle.
Large (farm 6 m3/day 3.3 m dia, For a farm having poultry
size) biogas 4.65 m height diary etc., 20 cattle.
plant
Very Large 2600 1000 m3 Cattle 1000
(community m3/day
size)
ADVANTAGES AND DISADVANTAGES OF
FLOATING DOME DESIGN
Advantages Disadvantages
• The slurry is constantly • Higher cost due to fabricated
submerged below the dome. dome construction.
• The pressure is naturally • Dome upper surface is exposed
equalised. to sunlight and external
• No danger of excessive pressure. atmosphere. The heat is lost
• No danger of mixing between during winters.
biogas and external air. Hence no • The outlet pipe between the
danger of explosion. floating dome and fixed external
• Gas is obtained at uniform and connection should be of flexible
constant pressure. hose type. It is subjected to sun
• Gas does not leak through the rays, rain and movement. It
dome as the slurry provides needs regular attention and
natural screen. maintenance.
TYPICAL GAS PRODUCTION FROM DIFFERENT FEEDSTOCK
Sl. Typical Gas Yield Typical Methane Content
Feedstock
No. (liters/kg) (%)
1. Paper Waste 480 53
2. Bagasse 330 57
3. Spent Tea Waste 235 57
4. Food Waste 160 62
5. Bamboo Pulp 145 54
6. Dry Leaves 118 60
7. Green leaves & twigs 100 65
8. Fruit waste 91 50
9. Bamboo dust 53 72
10. Distillery effluent 31 75
11. Black liquor (Paper Mill) 22 69
12. Animal Excreta
- Cow/Bullock 36 60-65%
- Buffalo 36 “
- Pig 78 “
- Chicken 62 “
13. Human Excreta 70 “
LARGE BIOGAS PLANT AT VIJAYAVADA
MUNICIPAL CORPORATION
 FERMENTATION
Process of production of ethyl alcohol from any
feedstock containing sugar or starch or also from
cellulose materials.
Feedstock:
✔ Sugar: Sugar beets, sugar cane, sweet sorghum,
Fruits etc
✔ Starches: Grains like corn, wheat, potatoes etc.
✔ Cellulose: Wood, solid waste, agricultural wastes
etc.
Process of production:
✔ Fermentation of fermentable sugar solution
✔ Fermentation of sugar solution to Ethyl alcohol
✔ Separation of ethanol from other by – products.
PROCESS OF PRODUCTION OF FUEL ALCOHOL
Feedstock
↓
Milling
↓
Sterilization
↓
Cooking (enzymes & water added to form mess)
↓
Cooling
↓
Fermentation (yeasts addition)
↓ (2 days)
Bear (10% ethyl alcohol)
↓
Distillation
↓
Dehydration
↓
Denaturation↓
Fuel alcohol
ENERGY ROUTES OF URBAN WASTE TO
ENERGY
PYROLYSIS OF URBAN WASTE