BIOENERGYFlame Institute

The energy obtained from biological sources is called bioenergy. Bioenergy is the use of biomass (organic matter) to produce electricity, transportation fuels or chemicals. Bioenergy sources include agriculture and forestry residues and the organic components of municipal and industrial wastes. Fossil fuels (coal, petroleum and natural gas) is not included under bioenergy.

Only 0.2% of solar radiations reaching the earth is converted into biomass. This amount is about-10 times the energy produced from nonbiomass sources. Being a tropical country, India receives more solar radiations and therefore has high potential for biomass synthesis to meet the requirement of energy.

Bioenergy is obtained from following types of biological sources:

Animal energy : Animal energy is basically of two forms :

(1) Human muscle power (HMP) : It is the form of animal energy, which is used throughout the world in the form of physical work by human race like farmers in the field, women in house work and non agricultural labourers like artisans in wood work, gardeners, etc. A major part of the energy utilized today belongs to this type and it constitutes about 1/5^th of the total generated electricity in India. Thus, it constitutes the significant part of energy used.

(2) Draught animal power (DAP) : Animals are domesticated not only for providing us with food, hides and bones but they are also used in agriculture and transport. These animals play an important role in villages. India has about 84 million of work animals; 70 million bullocks; 8 million buffaloes and one million each to horses and camels. In addition mules, donkeys, elephants and yaks are also used. 50 percent of the Indian farmers have holdings less than two acres each, as a result they cannot use tractors. More than 15 million animal-drawn carts are use in India. Carts have the advantage that they can be used on all types of roads in all terrains. The energy potential of DAP is enormous. Suppose if each animal generates 0.5 horse power then the installed capacity of animals comes about 42 million horse power or 30,500 MW. This value is almost equal to total electric power generation in India. Because of poor quality of animals and outmoded designs of carts and agricultural machinery, full potential of DAP has not been realised in India. Methods recommended to achieve this are :

(i) Improved breeds of draught animals.

(ii) Use of better carts.

(iii) Proper management of grazing lands and pastures.

(iv) Supply of nutritious fodder.

Biofuels and Biomass : They are fuels of biological origin. Biofuels are major source of energy. They are renewable and if used properly and efficiently they can solve the energy problems of developing countries.

Biomass is the term applied to all materials whose origin can be traced to photosynthesis. Biomass can be used to generate producer gas, to run water pumps for irrigation, to obtain alcohol, to replace petrol, to generate biogas for cooking and lighting and to generate electricity.

Table : 10.12-1 Ways of utilising biomass as fuel

Biomass	Process	Form / Source of energy produced
Wood	Direct burning, Gasification, Carbonisation, Pyrolysis, Hydrolysis, Fermentation and Synthesis.	Heat, Producer gas, Charcoal gas, Oil and Charcoal, Methanol, Ethanol,
Agro-industrial residues.	Fermentation/Distillation, Anaerobic digestion.	Ethanol., Biogas
Petroleum and Oil producing plants	Cracking and direct use.	Petroleum products, Heating, Running engines.
Energy cropping	Fermentation/ Distillations.	Ethanol.

Wood : It is the renewable and most common source of energy in use since time immemorial. Wood which is used as source of energy is called fuel wood and about 2 billion people in world are dependent upon wood as source of fuel. Excessive use of wood as fuel has led to deforestation, soil erosion, loss in fertility of soil and hence deterioration of environment.

The consumption of fuel wood was estimated at 1.7 billion m³ in 1984 of which more than two third was consumed in Asia and Africa.

Characteristics of good fire wood

(1) It should be highly combustible and catch fire easily.

(2) It should have high calorific value and should be free of disagreeable odour.

(3) The fuel wood plants should be present every where.

(4) These should be easy to dry and should not split when burnt.

(5) Should be non-resinous in nature and smokeless.

Table : 10.12-2 Good fire woods and bad fire woods

Good fire-woods	Bad fire-woods
Acacia senegal (Gum Arabic)	Pinus roxburghii (Chir Pine)
Acacia nilotica (Kikar)	Mangifera indica (Mango)
Albizzia (Siris)	Madhuca indica (Mahua)
Azadirachta indica (Neem)	Bauhinia racemosa (Kachnar)
Quercus (Oak)	Bombax (Red silk cotton)
Casuarina equisetifolia (Jhau)	Michelia excelsa (Champak)
Adina cordifolia (yellow teak) Hopea (Dammar tree) Dalbergia sisso (Shisham) Prosopis (Jand) Anogeissus latifolia (Axle wood, Dhawra) Ceripos tagal (Goran) Gmelina arborea (Gumhar) Terminalia tomentosa (Asna) Syzygium cumini (Jambolana Jamun)

The angiospermic wood (hard wood) is generally better than gymnospermic wood (soft wood). Soft wood produces intense heat but for shorter periods and hard wood gives uniform heat for longer periods. Bad fuel wood does not catch fire quickly, has low flame, low calorific value, gets burnt quickly, is full of smoke with offensive odour.

Due to increase in population, the demand of fuel wood is increasing day by day and this has led to fuel wood crises. In order to overcome fuel wood crisis, following methods have been suggested :

(1) To grow more fuel wood trees, i.e., energy plantations.

(2) Proper designing of wood stoves or chullahs in order to increase efficiency of these and hence to save energy loss.

(3) Electric cremation should be enhanced.

(4) Energy production from woods by different processes like carbonisation (Change of wood into carbon/charcoal by heating), gasification (change of wood into producer gas by passing steam over incandescent coke), pyrolysis (thermochemical conversion of wood into charcoal, pyroligneous acid (10% acetic acid), wood gas, wood tar, wood alcohol, etc.).

Energy plantations : Energy plantations mean to grow more trees for fuelwood. The uses of energy plantations are :

(1) Solar energy can be stored continuously.

(2) Minimum technology is required for raising the trees.

(3) They are ecologically safe, economical, renewable and sufficient manpower is available to raise them.

(4) Green plant’s are the best source of renewable energy.

(5) They do not require new technologies and major input.

Mobilisation of land resources : To minimise the danger of loss of agricultural land for growing fuelwood, trees should be grown for fuelwood on :

(1) On farmer’s own land where cultivation is not done.

(2) Village common lands

(3) Along both sides of road, canals and railway tracks

(4) On degraded forests and

(5) On wastelands

Over 30 million hectares of land is available in India for energy plantations, without affecting land under agricultural and industrial use.

Selection of suitable species : While selecting suitable species following criteria can be considered :

(1) The saplings should establish quickly and rapidly.

(2) The species should be preferably local and well adapted to local climatic and soil conditions.

(3) It should have high coppicing ability or regenerative potential. Coppicing means thick growth of branches from the stump after the aerial branches have been removed. Coppiced growth is faster as compared to the growth of new saplings because they have already established root system.

(4) The plant should be able to grow with minimum water and fertilizer requirement.

(5) The plant should draw minimum quantity of nutrients from soil.

(6) Plants should be able to improve the soil quality like sterilisation, correction of alkalinity or acidity etc.

(7) Plants should have the xerophytic character when grown under xeric conditions.

(8) Plants should be resistant to pests and diseases.

(9) Plants grown along both the sides of roads and railway tracks should be able to tolerate water logging.

Development of suitable agro-technology : Techniques of growing particular species in particular habitat must be carried out to get maximum yield. Cultivating grasses and fodder crops along with fuel wood species brings out maximum land use.

Producer gas : It is mixture of mainly CO, H₂, O₂. Producer gas is produced due to incomplete combusion of coal and wood. With restricted supply of air, coal and wood is burnt. Mixture gas thus produced is passed through filter to remove shoot and ashes. Now the gas is passed through coolers to condense other waste residue. Now the gas is released for industrial use. This gas is free from pollution. Raw material for producer gas is easily available and can be produced at normal temperature. The gas produced is inflammable but otherwise costly and generates less power.

Agro-industrial residues : Some methods have been devised for bioconversion of agricultural residues, industrial waste materials and animal wastes into energy. This is very important in solving the environmental pollution problems. About 28 percent of population in the developing countries uses dung and crop residues as fuel for cooking food. Thus potential fertilizer of the agricultural fields is wasted in burning. The problem can be solved by using dung to produce gobar gas (biogas) and residue can be used as manure. The aerobic fermentation of dung yields fuel as well as fertilizer.

Biogas (Gobar gas) : Biogas is methane rich fuel gas produced by anaerobic breakdown and fermentation of biomass. Biogas consists of 50- 70% CH₄ (methane), 30- 40% CO₂, 1% H₂S and traces of and CO. Calorific value of biogas is 4,429 kcal/m³(23-28 MJ/m³), when its CH₄ content is 50%.

Table : 10.12-3 Composition of biogas

S.No.	Name of gas	Chemical formula	Percentage
(1)	Methane	CH₄	50-68%
(2)	Carbon dioxide	CO₂	25–35%
(3)	Hydrogen	H₂	1–5%
(4)	Nitrogen	N₂	2–7%
(5)	Oxygen	O₂	0–0.1%
(6)	Hydrogen sulphide	H₂S	Rare

Biogas generation is a three stage anaerobic digestion of animal and other organic wastes.

First stage : The facultative anaerobic micro-organisms breakdown the polymers into soluble monomers with the help of enzymatic hydrolysis. The complex carbohydrates such as cellulose and hemicellulose are degraded by celluloytic enzymes. Proteins are broken by proteolytic enzymes and lipids by lipolytic enzymes. Lignin cannot be broken down by micro-organisms, so it remains as residue along with inorganic salts.

Second stage : Here the monomers become the substrate for micro-organisms. These are then converted into organic acids.

Third stage : In this stage soluble organic acids (acetic acid) are formed for the substrates of the last stage. Finally methanogenic anaerobic bacteria (e.g., Methanobacterium, Methanobacillus, Methanosarcina and Methanococcus) produce methane (biogas).

Biogas plants : Biogas (gobar gas) generation has been taken up in India on a large scale. One such plant is already existing at Okhla near New Delhi which generates a total of about 0.6 million cubic feet of gas per day. About 1.95 lakh biogas plants were set up during 1985-86 under the National Biogas Development Programe.

Important substrates in biogas production : Animal wastes like dung of cattle, urine and slaughter house wastes; agroindustrial wastes like oil cakes, sugar industry wastes, wastes from fruits and vegetables processing; agricultural or crop residues; human wastes (night soil); urban solid wastes and also aquatic plants like Eichhorina (water hyacinth), Wolffia, Hydrilla, Salvinia, Azolla and algae, etc.

In biogas production, water content is maintained at 90% at which most methanogenic bacteria are active.

The biogas so produced can be used for different purposes, can be efficiently used and stored easily. Further pathogens of faecal matter can be reduced (sanitation) and thus disease cycles are broken.

Energy cropping and petroplants : These are renewable resources of energy. Growing of crops from which alcohol and other energy fuels can be produced, constitute energy cropping. Important plants of energy cropping (i.e., energy crops) are :

(a) Saccharum officinarum (Sugarcane)

(b) Beta vulgaris (Beet root or Chukandar)

(d) Zea mays (Maize)

(e) Manihot glaziovii (Tapioca)

These plants are efficient users of solar energy. These plants can be easily changed into ethanol (ethyl alcohol). In Brazil, ethanol fuel is used in automobiles (95% alcohol), where as in USA, 85-90% petrol is mixed with 10- 15% alcohol to form a new fuel called gasohol, which is used as fuel in automobiles. But slight modification is required in conventional engines to use these new fuels, i.e., ethanol and gasohol.

Petroplants or Petrocrops : Latex of some plants containing long chain hydrocarbons is considered to be a good substitute for liquid fuels or petroleum. Such plants having large amount of latex with long chain hydrocarbons are called petroplants. Cultivation of petroplants is also a part of energy-cropping. Cultivation of these petrocrops was first of all done by Italians in Ethiopia about fifty years back, although actual credit for identifying the petrocrops goes to Dr. Melvin Calvin.

Dr. Calvin was first to identity few petroleum plants whose products can be used in place of petrol and oil. Most of such plants belong to families asclepiadaceae, euphorbiaceae and apocynaceae. These plants are able to convert a substantial amount of photosynthates into latex.

Latex contains long chained liquid hydrocarbons. These can be used directly or broken to hydrocarbons of chain length similar to the ones present in petrol.

Their hydrocarbon contents can be increased by genetic manipulations (genetic engineering). But commercial production of petroleum or liquid fuel alternative (through petroplants) is in early stage.

Most common petrocrops are :

(a) Euphorbia antisyphilitica

(b) E. caudicifolia

(d) E. royleana

(e) Calotropis procera

(f) Copaifera langsdorfii (A Brazilian tree and its sap is a good alternative for diesel. About 3 litres of sap per month is produced per tree, which can be filled directly in fuel tank of diesel engine automobile).

(g) Cryptostegia grandiflora

(h) Pittosporum resiniferum (Petroleum nut)

The use of these petroplants may reduce the pressure on liquid fuel or petroleum.

? Per hectare potential production of alcohol 4000 litres for Sugarcane, 1800 litres for Sugarbeet, 1650 litres for Potato and 1125 litres for Maize.

? Fuel wood consumption provides 43% of total energy consumed in developing countries and amounts to about 14% of total world’s energy production.

? Pyrolysis is heating of wood and waste wood to high temperature. The products are charcoal, pyroligneous acid, tar, oil, wood alcohol and wood gas.

? The energy potential of DAP is enormous.

? Hardwood is better as a fuel than softwood.

? Fuel gas (methane) is obtained by anaerobic fermentation of gobar gas

? Fuel wood is a renewable energy source.

? Gosohol. Brazil is obtaining alcohol from Sugarcane while USA is from Maize.

Bioenergy

With the exception of water, which one of the following is possibly the most important accessory chemical substance in industrial processes [CBSE PMT 1994]

(a) Petroleum (b) Rubber

Non-conventional energy source is [CET Chd. 1993]

(a) Tidal energy (b) Biogas

Energy source of this earth is

(a) Sunlight (b) Respiration

The rate of biogas production can be limited by

(a) Methane production

(b) Cellulose digestion

(d) None of these

Non-renewable source of energy is

(a) Forest wealth (b) Wild life

Biogas can be a good substitute for [BHU 2000]

(a) Fuel wood (b) Petroleum and oil

One of the following bacterial groups are exploited in biogas production [JIPMER 2000]

(a) Methogens (b) Methanotrophs

Major autotrophic biomass in oceans is contributed by

[CBSE PMT 2000]

(a) Forests

(b) Algae and phytoplanktons

(d) None of these

The energy generated by hydel power plant is

[MP PMT 1994]

(a) Renewable and non-polluting

(b) Renewable and polluting

(d) Non-renewable and non-polluting

LPG cooking gas is

(a) Low price gas (b) Low pressure gas

A non-polluting source of energy is

(a) Wood (b) Coal

Major source of liquid hydrocarbon is

(a) Calotropis gigantea (b) Cocos nucifera

Energy plantations vary from energy cropping in being

(a) Substitute for petroleum (b) Source of fuel wood

Which wood burns for short period of time

[Haryana PMT 1996]

(a) Gymnosperms (b) Angiosperm

What type of fuel are coal, petrol and natural gas

[CBSE PMT 1990]

(a) Biofuels (b) Electrical fuels

Cultivation of more fuel wood trees is known as

(a) Afforestation (b) Energy plantations

A good fodder [CBSE PMT 1991]

(a) Contains high dry matter

(b) Is free from disease and pest

(d) All of these

The incorrectly matched pair is

(a) Biogas produced from dung

(b) Latex source of liquid hydrocarbons

(d) Animal energy used most efficiently

The value of solar energy or Extra terrestrial light reaching the biosphere is

(a) 2 g cal/cm²/min (b) 30 g cal/cm²/min

Solar energy transducer is

(a) Agaricus (b) Rhizobium

The black wood tree of India is [Haryana PMT 1997]

(a) Acacia nilotica (b) Dalbergia sissoo

It is possible to extract maximum energy from wood through

(a) Biomass (b) Cracking

Energy from wood must be extracted more efficiently through

(a) Carbonisation (b) Pyrolysis

The fuel wood crisis can be overcome by [KCET 1997]

(a) Efficient forest extractions (b) Afforestation

An ideal good fuelwood is obtained from

(a) Bauhinia racemosa (b) Dalbergia sissoo

Advantage of energy plantations is

(a) Running nuclear plants

(b) To reduce pressure on forests

(d) Both (b) and (c)

In developing countries, the heaviest demand on forests is for [BHU 1996]

(a) Fuel wood (b) Furniture wood

Citric acid production is by action of [CBSE PMT 1995]

(a) Aspergillus niger (b) Acetobacter

Non-renewable substance or resource is [RPMT 1992]

(a) Planktons and fishes (b) Fossils and minerals

Thermal power generation is

(a) Conventional, renewable, polluting

(b) Conventional, renewable, non-polluting

(d) Non-conventional, non-renewable and non-polluting

Most common biofuel, being used nowadays is

(a) Cellulose (b) Charcoal

Petroplants were first recognized by [MP PMT 1999]

(a) Lamarck (b) Darwin

Growing of plants for alcohol production is called

(a) Energy plantation (b) Energy cropping

Gasohol mixture is useful as

(a) Fermenter (b) Manure

Which of the source of energy is non-renewable [RPMT 1990]

(a) Wild life (b) Forest wealth

The energy obtained from biological resources is called

[RPMT 1990]

(a) Electrical energy (b) Mechanical energy

Fuel wood is [APMEE 1990; EAMCET 1990]

(a) Source of petroleum products

(b) Renewable resource of energy

(d) Source of alcohol

Which of the following is more efficient in converting solar energy

(a) Chlorella (b) Cuscuta

Petroleum resource is [CBSE PMT 1992]

(a) Renewable

(b) Non-renewable

(d) Infinite and unconventional

Which one of the following is a renewable source of energy

[MP PMT 1995]

(a) Petroleum (b) Coal

Biogas is a mixture of [MHCET 2002]

(a) (b)

A major component of gobar gas is [CBSE PMT 2004]

(a) Ethane (b) Butane

Producer gas differs from biogas in having [MHCET 2004]

(a) Methane (b) Carbon monoxide

The current consumption on domestic fire wood in India is about [CBSE PMT 1990]

(a) 18.6 million tonnes (b) 146.5 million tonnes

Energy plantation refers to [Haryana PMT 1995]

(a) Setting up new electricity plants

(b) Growth of fuel wood trees

(d) Erection of more dams

While India’s population is 15 percent of the world, its annual energy consumption is only

(a) 0.2% (b) 2%

The wood considered unfit as fuel is

(a) Bombax ceiba (b) Madhuca indica

Sap of which plant is considered as a good substitute for diesel oil

(a) Euphorbia sp (b) Copaifera longsdorfii

Biogas produced by anaerobic fermentation of water biomass consists of [CPMT 2005]

(a) Methane (b) Traces of H₂, H₂S and N₂

[

The calorific value of biogas is [Pb. PMT 1992]

(a) 10 – 20 mj/m³ (b) 23 – 28 mj/m³

One of the following aquatic weed has been exploited for biogas production [CPMT 1995]

(a) Cryptostegia (b) Ceratophyllum

One of the following is not the petroleum plant

(a) Sugarcane (b) Maize

A species selected for energy transplantation must not be

(a) Slow growing (b) Pest resistant

The energy obtained from 42 million animal power is equivalent to

(a) 350 MW (b) 3500 MW

‘Sun basket’ is [AMU 1997]

(a) The device to utilize sunrays directly to meet the requirement of heat energy

(b) The sufficient amount of sunlight stored in a cell

(d) All of these

A Bioenergy source obtained by fermentation to supplement fossil fuel petrol is [CET Chd. 1998]

(a) Kerosene (b) Ethanol

For biogas production besides dung which one of the following weed is recommended in our country [Kerala PMT 2004]

(a) Eichhornia crassipes

(b) Coffea arabica

(d) Solanum nigrum

Daily input of sunlight per square per day on the earth is

(a) 100 gm cal (b) 400 gm cal

A source of good firewood is

(a) Pinus (b) Cedrus

The best source of alcohol is

(a) Wood (b) Noble cane

Gasohol is

(a) 90% alcohol + 10% petrol

(b) 10% alcohol + 90% petrol

(d) 100% ethanol

Producer gas is produced by ……… of wood

(a) Carbonization (b) Gasification

One of the following plants have contributed to coal formation [AFMC 2000]

(a) Pteridophytes (b) Gymnosperms

Read the assertion and reason carefully to mark the correct option out of the options given below :

(a) If both the assertion and the reason are true and the reason is a correct explanation of the assertion

(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion

(c) If the assertion is true but the reason is false

(d) If both the assertion and reason are false

(e) If the assertion is false but reason is true

Assertion : Bioenergy is the energy available from biological sources.

Reason : Fossil fuels are examples of bioenergy.

Assertion : Wood is an excellent fuel.

Reason : The average calorific value of seasoned wood is half to coal.

Assertion : Sugar crops and strach crops are valuable as solar energy converters.

Reason : They provide both liquid and solid fuels.

Assertion : Dalbergia sisso is a good fire wood.

Reason : The wood is able to produce good flame.

Assertion : Biogas is ecofriendly fuel.

Reason : Biogas is cheep source of energy.

Bioenergy

1	a	2	d	3	a	4	b	5	d
6	a	7	a	8	b	9	a	10	d
11	c	12	c	13	b	14	a	15	c
16	b	17	d	18	d	19	a	20	d
21	a	22	d	23	d	24	a	25	b
26	d	27	a	28	a	29	b	30	c
31	c	32	d	33	b	34	c	35	c
36	c	37	a	38	a	39	b	40	d
41	c	42	d	43	b	44	b	45	b
46	b	47	d	48	b	49	d

Critical Thinking Questions

1	b	2	c	3	d	4	a	5	c
6	a	7	b	8	a	9	c	10	c
11	b	12	b	13	b	14	b

Assertion and Reason

Bioenergy

(a) Main source of energy is solar light. Only 0.2% solar energy trapped in biomass.
(b) Organic wastes consist of cellulose, hemicellulose, lignin, lipids, and protein. Decomposer microbes convert complex organic compounds to soluble compound.
(a) Conversion of organic acid into gas by activity of methanogenic bacteria (anaerobes).
(c) Euphorbia antisyphilitica, yields large amount of latex which containing long chain of hydrocarbons.
(b) Wood used as a source of energy is called fuel wood / fire wood. So energy plantation is must for production of renewable energy.
(a) Woods of dicots serve as better fuel wood than gymnospermous woods, because the former provide uniform heat for a long time.
(b) Wood gives a good flame with sufficient heat, which source is green plants is called energy plantations.
(a) Acacia nilotica or kikar or black wood is good fire wood. They should be easy to dry and catch fire quickly.
(d) Gasification – Change of wood into producer gas by passing steam over incandescent coke.
(d) Carbonisation – Change wood into carbon / charcoal by heating.

Pyrolysis – Thermochemical conversion of wood into charcoal, Pyroligneous acid (10% acetic acid) wood gas etc.

Gasification – change of wood into producer gas by passing stem.

(b) Good fuel wood are easy to dry, quickly catch fire, having good flame with high caloric value, e.g., Albizzia, Casuarina, Hopea, Dalbergia sisso etc.
(a) Wood which is used as source of energy is called fuel wood and about 2 billion people in world are dependent upon wood as a source of fuel.
(d) Melvin Calvin recognised that certain plant of family Euphorbiaceae convert a substantial amount of photosynthate into latex containing liquid hydrocarbon which are potential substitutes for petroleum.
(c) Energy obtained from biological sources is called bioenergy. Which is two types (i) Animal energy (ii) Biofuels.
(d) Biofules are the fuels of biological origin (like plants). These constitute renewable form of energy.
(c) Biogas / Gobar gas production by anaerobic respiration & fermentation of animal dung. Which consists 50–70% ,30–40%,,1%, and trace,, .
(b) Biogas is methane rich fuel gas produced through anaerobic breakdown and fermentation of biomass. It contains CH₄, CO₂ and trace of H₂, H₂S and N₂, where as producer gas mainly contains CO, H₂ and N₂.
(b) Energy plantation mean to grow more trees for fuel wood, solar energy stored, safe for ecologically, renewable etc.
(b) Copaifera longsdorfii / Brazilian tree and its sap is good alternative for diesel. About 3 litres of sapper month produced per tree.
(d) Result of anaerobic fermentation of animal dung produced gobar gas

Critical Thinking Questions

(b) Calorific value of biogas is 4.429 K cal/m³ or 23–28 mj/m³, when its content is 50%.
(a) Green plants is called sun basket because they stored solar energy into chemical energy by the help of photosynthesis.
(c) Albizzia, Azadirachta, Acacia etc. are good fuel / fire wood. The wood should be easy dry, quickly catch fire and high calorie value.
(b) Gasohol programme of U.S.A. uses mixture of alcohol (10 – 15%) and petrol (85 – 90%).
(b) Producer gas is produced by gasification process. The producer gas consists , , .

Assertion and Reason

(c) Bioenergy is the energy available from biological sources, both living and their immediate remains eg. wood, gobar gas. It does not include fossil fuels (coal, petroleum, natural gas) etc.
(b) Wood is an excellent fuel since 99% of the over dried wood is combustible, leaving behind about 1%. The average calorific value of seasoned wood is around 4600 calories/kg, two kilograms of, which yield approximately the same heating value as produced by one kilogram of good coal.
(a) Sugar crops (like sugarcane and sugar beet) and starch crops (like corn) are efficient as solar energy converters. These crop not only give sugar which may be used directly or converted into ethanol (liquid fuel), but also give valuable byproducts such as bagasse, which can be used as solid fuels.
(a) Dalbergia sisoo is a good fuel. The characteristics of good fire wood are – (I) It should be free from offensive odours, (II) It should not produce smoke, (III) It should be free from resin or contain only small quantity of it, (VI) The wood is able to produce good flame with high calorific value.
(b) Using organic wastes for biogas generation has several advantages.

(I) It provides both energy and manure,

(II) Biogas is a storable form of energy which can be used more efficiently and economically,

(III) Biogas has wider applications than the direct burning of organic wastes etc. Due to being non pollutant and usage of organic waste for the production of biogas, it is called eco-friendly fuel.

(84)