Module 3
Module 3
Module 3
ENERGY RESOURCES
ENERGY RESOURCES
Energy may be defined as "any property which can be converted into work"
It is the "the capacity to do work".
Energy is available on earth in a number of forms and some forms may be used immediately while others might
require some transformation. All the developmental activities in the world are directly or indirectly dependent
on energy. Both energy production and energy utilization indicate a country's progress. At the same time,
energy production has its impact on environment due to pollution and finally affects the quality of life of
people.
For Example:
(1) Burning coal to produce electrical energy or mechanical energy
(2) Chemical to electrical by dry cell batteries
(3) Using water in dams to produce electricity through mechanical energy.
Energy is essential to the existence of mankind. All industrial processes like mining, transport, lighting, heating
and cooling in buildings need energy. With the growing population, the world is facing an energy deficit.
Almost 95% of commercial energy is available from fossil fuels like coal and natural gas. These fossil fuels will
not last for more than a few years. Hence, we must explore alternative fuel/energy options.
CLASSIFICATION OF ENERGY
Based on continual utility, energy resources can be classified into three types:
1. Renewable energy sources: These resources can be generated continuously and are inexhaustible.
Ex: Wood, Solar energy, Wind energy, Hydro power, tidal energy, Geo-thermal energy, etc
2. Non-renewable energy sources: Non-renewable energy sources are natural resources that cannot be
regenerated once they are exhausted. They cannot be used again.
Ex: Coal, Petroleum, Natural gas, etc.
3. Sustainable sources: Sources of energy which are not renewable but they will last for a very long time.
Example: Nuclear Energy.
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Energy resources can be further classified into conventional and non-conventional categories
We use energy faster than it can be produced - Coal, oil and natural gas - the most utilised sources take
thousands of years for formation.
Energy resources are limited - India has approximately 1% of world’s energy resources but it has 16% of world
population.
Most of the energy sources we use cannot be reused and renewed - Non renewable energy sources constitute
80% of the fuel use. It is said that our energy resources may last only for another 40 years or so.
We save the country a lot of money when we save energy - About 75 per cent of our crude oil needs are met
from imports which would cost about Rs.1, 50,000 crore a year
We save our money when we save energy - Imagine your savings if your LPG cylinder comes for an extra week
or there is a cut in your electricity bills
We save our energy when we save energy - When we use fuel wood efficiently, our fuel wood requirements are
lower.
Save energy to reduce pollution - Energy production and use account to large proportion of air pollution and
more than 83 percent of greenhouse gas emissions.
Reduce Consumption on Non-Renewable Sources.
1. Resource Depletion: By using these resources in excess, they are going to deplete one day and will take
another millions of years to form again.
2. Save Money: Usage of fluorescent bulbs, solar electricity may cost expensive initially but prove to be cost-
effective in the long run.
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3. Reduce Carbon-dioxide: If Non-Renewable resources are used up to the limit they may also help in
reducing the carbon-dioxide. Pollution from nuclear and coal power plants cause diseases like asthma,
emphysema etc.
4. Climate Change : Due to increase in the rate of these resources it also affect the climate greatly, Drought,
Severe storms, floods, land loss, erosion of soil and heat deaths are few examples of climate change.
5. Ozone Layer Depletion: Ozone layer in the atmosphere protect us from ultraviolet rays from reaching the
earth thus, making life on the earth possible.
6. Adverse effect on humans and the environment : Extraction of Uranium and Coal from beneath the earth
cause huge effect to the lives of coal miners. These people have high cancer death rates. They also harm the
environment and agricultural lands.
7. Acid Rain: Coal power plants and vehicles emit sulphur dioxide (SO2) and nitrous oxides. When they mix
with water vapour under certain conditions, sulphuric acid and nitric acid, known as acid rain, are formed. This
is very harmful to the lungs. It kills fish in lakes, corrodes property (buildings, monuments, cars), harms the soil
(releasing toxins), and harms trees and crops.
8. Global Warming: With so much dependence on Non-renewable sources, global warming is taking place all
over the world and the result which is glaciers are melting which is causing the rise in the sea level.
Renewable energy sources are natural resources that can be regenerated continuously and are inexhaustible.
They can be repeatedly used.
SOLAR ENERGY:
Every day, the sun radiates (sends out) an enormous amount of energy—called solar energy. It radiates more
energy in one day than the world uses in one year. The sun makes energy in its inner core in a process called
nuclear fusion. It takes the sun’s energy just a little over eight minutes to travel the 93 million miles to Earth.
Solar energy travels at the speed of light 3.0 x 108 meters per second. Only a small part of the visible radiant
energy (light) that the sun emits into space ever reaches the Earth. Solar energy is considered a renewable
energy source. Solar energy is used to heat buildings and water and to generate electricity.
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Listed below are the various devices used to harvest solar energy.
Solar cells or Photovoltaic cells or PV cells: Solar cells consist of a p-type semiconductor (Silicon doped with
Boron) and n-type semiconductor (Silicon doped with Phosphorus) in close contact with each other. When solar
rays fall on the top p-type semiconductor, the electrons from the valence band move to the conduction band and
cross the p-type junction into the n-type semiconductor. A potential difference is created causing an electric
current to flow. These cells are widely used in calculators, electronic watches, street lights, water pumps to
radio and television. In 2015, the Desert Sunlight solar project in California opened. It is the largest
photovoltaic plant in the world, generating 550 megawatts of electricity—enough to power over 150,000
homes.
Solar battery: When several solar cells are connected in series, it forms a solar battery. These solar batteries
generate enough electricity to run water pumps, street lights, etc. They are mainly used in remote areas where
electricity supply is a problem.
Solar Space - Heating System: Solar space - heating system consist of natural materials like stones, bricks, or
materials like glass, which absorb heat during the day time and release it slowly in the night. It is generally used
in cold places where houses are kept in hot condition using solar space - heating systems. A solar space-heating
system consists of a passive system, an active system, or a combination of both. Passive systems are typically
less costly and less complex than active systems. A passive solar home is designed to let in as much sunlight as
possible. It is like a big solar collector. Sunlight passes through the windows and heats the walls and floor inside
the house. The light can get in, but the heat is trapped inside. A passive solar home does not depend on
mechanical equipment, such as pumps and blowers, to heat the house, whereas active solar homes do.
Solar water Heaters: It consists of an insulated box, in which is painted black on the inside. It is provided with
a glass lid to receive and store solar heat. The box contains a copper coil painted in black through which cold
water flows in, gets heated in the copper coil and flows into a storage tank. Finally, water from storage tanks is
supplied.
Solar energy is currently used to power satellites, watches, calculators, etc
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A few applications of solar energy are: (i) solar water heater, (ii) solar cooker, (iii) solar dryer and (v) solar
refrigerator.
WIND ENERGY
Wind is defined as moving air. Energy recovered from the force of wind is called wind energy. Wind energy is
harnessed by the use of wind mills.
Wind mills: The force of blowing wind strikes the blades of the wind mill thereby causing it to rotate
continuously. This rotational energy of the blades is used to drive several machines like water pump, flour mill
and electric generators.
Wind farms: Several wind mills joined together in a definite pattern forms a wind farm. Wind farms generate
large amounts of electricity.
The minimum speed required for satisfactory working of a wind generator is 15 kmph.
A wind turbine has three main parts, the tower, the blades, and nacelle. Nacelle is the part where major actions
are performed including turning motion into electricity. Wind turns the turbine blades causing the shaft to spin,
thereby generating electricity. An inverter in the nacelle converts electricity to AC, which then moves towards
storage space or main power line.
To maintain the frequency and voltage of current generated constant speed turbines are installed. Energy
produced by each wind turbine depends on some external factors like size of blades, style or turbine, diameter
and power of wind.
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ADVANTAGES
DISADVANTAGES
When electricity is generated from flowing water, this is called hydroelectric energy. Hydroelectric energy is
a renewable energy resource because it's an energy resource that regenerates in a short time period.
Hydropower represents about 16% of total electricity production. China is the largest producer of
hydroelectricity, followed by Canada, Brazil, and the United States.
GENERATING POWER
A dam is built on a river that has a large drop in elevation. The dam stores lots of water behind it in the
reservoir. Near the bottom of the dam wall there is the water intake. Gravity causes it to fall through the
penstock inside the dam. At the end of the penstock there is a turbine propeller, which is turned by the
moving water. When flowing water from the rivers turns blades in a turbine, the kinetic energy in flowing water
is changed to mechanical energy. The shaft from the turbine goes up into the generator, which produces the
power. Power lines are connected to the generator that carry electricity to houses. The water continues past the
propeller through the tailrace into the river past the dam.
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ADVANTAGES
DISADVANTAGES
BIOMASS ENERGY
Biomass is organic matter produced by plants or animals. It is used as a source of energy. The biomass is fast
renewable forms of energy and available freely as waste and discarded matters.
Biomass is generally burnt for heating, cooling and industrial purposes.
Ex: wood, crop residues, seeds, cattle dung, sewage, agricultural wastes, etc.
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Burning biomass is only one way to release its energy. Biomass can be converted to other useable forms of
energy like methane gas or transportation fuels like ethanol and biodiesel.
a) Methane gas is a component of landfill gas or biogas that forms when garbage, agricultural waste, and human
waste decompose in landfills or in special containers called digesters.
b) Crops such as corn and sugar cane are fermented to produce fuel ethanol for use in vehicles. Biodiesel, another
transportation fuel, is produced from vegetable oils and animal fats.
1. Biogas: Biogas is a mixture of gases such as methane, carbon dioxide, hydrogen sulphide, etc. Biogas is
obtained by the anaerobic fermentation of animal dung or plant wastes in the presence of water. Bio-gas is a
sustainable source of energy by virtue of its production from available natural organic wastes of cattle dung,
human excreta, poultry waste, plant leaves, paddy husk etc. Bio-gas is a mixture of methane (68%), CO2 (31%)
and N2 (1%). Methane gas (CH4) is produced by bio-gas plants and this gas is utilized as cooking gas. Heat
value of bio gas can be improved by reducing its CO2 content.
Bio-gas production is carried out in an enclosed bio-gas plant made of bricks or steel. Slurry of waste
organic matter is fed into the plant through an inlet and gas formed is tapped by an inverted drum. As gas is
produced the drum rises and the gas may be drawn through an outlet. Bio-gas is commonly produced from
cattle dung in a bio gas plant known as Gobar Gas plant. Bio-gas is a clean, cheap fuel that can be used for
lighting purpose, lifting water through small pumps.
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The fermentation process is carried out by bacteria living in a mixed culture in the fermenter.
Convert of the end products of hydrolysis into methane CH4, carbon dioxide CO2 and water H2O.
Fermentation types
2. Biofuels: Biofuels are the fuels, obtained by the fermentation of biomass. Examples are Ethanol, Methanol.
(i) Ethanol: Ethanol can be produced by sugarcane. Its calorific value is less when compared to petrol and
therefor produces much less heat than petrol.
(ii) Methanol: Methanol can be easily obtained from ethanol or sugar containing plants. Its calorific value is
also too low when compared to gasoline and petrol.
(iii) Gasohol: Gasohol is a mixture of ethanol and gasoline.
Energy sources are classified as non-renewable if they cannot be replenished in a short period of time.
Renewable energy sources such as solar and wind can be replenished naturally in a short period of time. The
non-renewable energy resources are Fossils and Nuclear energy. Fossil energy sources,
including oil, coal and natural gas, are non-renewable resources that formed when prehistoric plants and
animals died and were gradually buried by layers of rock.
COAL
Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and
hydrocarbons. It is a source of energy and is used to produce electricity in thermal power plants. Almost 27350
billion metric tons of known coal deposits occur on earth. Out of which about 56% are located in Russia, 28%
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in USA and Canada. India has about 5% of world’s coal reserve and that too not of vary good quality in term
of heat capacity.
1. Coal is milled to a fine powder, allowing it to burn more quickly. It is blown into the combustion chamber of
a boiler where it is burnt at high temperature.
2. The hot gases and heat energy produced converts water in tubes lining the boiler into steam.
3. The high-pressure steam is passed into a turbine containing thousands of propeller-like blades. The steam
pushes these blades causing the turbine shaft to rotate at high speed. The steam is condensed and returned to the
boiling chamber where it is heated again.
4. The shaft rotation engages the wire coils and magnets in a generator connected to it. This charged magnetic
field produces electricity
5. Electricity is sent to the switchboard (transformer) where it is regulated and sent via on-land cables to homes.
Using coal to produce energy causes many some problems, usually on a greater scale than the use of oil or gas.
These problems include acid rain, sulphur oxide emission, carbon dioxide emission, poorer land, hazardous
waste and others.
Several forms of coal exist in the world. Anthracite, bituminous coal, lignite, and sub-bituminous coal are all
different types that are used by humans.
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Crude oil (a non-renewable resource) is usually found in underground areas called reservoirs. It is liquid in
nature and yellowish black in colour. They are composed mainly of hydrocarbons and organic compounds.
Petroleum products include transportation fuels, fuel oils for heating and electricity generation, asphalt and road
oil etc.
Sometimes, petroleum and crude oil are used to mean the same thing, but petroleum itself is a broad range of
petroleum products including crude oil itself.
Crude oil can exist either deep down in the earth's surface or deep below the ocean beds. Saudi Arabia, USA,
Russia, China and Iran are among the top crude oil producers in the world, and the USA is the world's biggest
consumer of crude oil, followed by China.
1. Oil is burnt in turbines in power stations to produce extreme heat, which is used to create high-pressure
steam.
2. This steam is used to spin a turbine very fast by pushing against metal blades.
3. The blades turn a generator containing wires and magnets and magnetic field produces electricity.
4. The electricity flows to a transformer, which changes it to very high voltage electricity. The transformer also
regulates the amount of electricity that is produced and supplied.
NATURAL GAS
Natural gas is a gas that occurs deep beneath the earth’s surface. Natural gas consists mainly of methane, a gas
(or compound) with one carbon atom and four hydrogen atoms. Natural gas also contains small amounts of
hydrocarbon liquids and non-hydrocarbon gases. Natural gas can be used as a fuel or to make materials and
chemicals.
Natural gas is used as a fuel to produce steel, glass, paper, clothing, brick, and electricity.
Natural gas is a major fuel used to heat buildings. Natural gas is also used in homes and businesses for cooking,
for heating water, for drying clothes, and for outdoor lighting.
Natural gas is essentially a mixture of methane (70-90%), butane (20%), ethane, propane and other gases like
Co2, H2S and N2.
Natural gas containing mainly methane but not higher hydrocarbons is said to be lean or dry gas, where as it
containing appreciable amount of propane, butane and other liquid hydrocarbons like pentane and hexane is
called wet gas or rich gas.
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LPG: Liquefied Petroleum Gas is a mixture of propane and butane liquefied and stored under pressure in steel
container.
To detect possible leakage of the gas it is usually to add Tetrahydrothiophen (because of strong smell).
ADVANTAGES
NUCLEAR ENERGY
Nuclear power is the use of nuclear reactions that release nuclear energy to generate heat, which most
frequently is then used in steam turbines to produce electricity in a nuclear power plant. It is the energy which is
trapped inside the atom. It is non–renewable source of energy which is released during fission or fusion of
certain radioactive elements. The most important advantage of atomic power is the production of an enormous
amount of energy from a small quantity of radioactive element. For eg: 1 kg of Uranium liberates energy
equivalent to 30000 kgs of coal. Energy released during nuclear reaction (mass – energy equation as per Albert
Einstein’s formula E = mc2).
(1)Nuclear Fission: The nucleus in atoms is split by fast moving neutrons and in turn a tremendous amount of
energy in the form of heat, light etc is released by a chain of reactions.
Uranium is used as fuel. The energy released slowly in this process is utilized to generate electricity or else
released suddenly all at once, results a tremendous explosion as in the case of Atom bomb.
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In a nuclear power plant, water is turned into steam, which in turn drives turbine generators to produce
electricity. The heat to make the steam is created when uranium atoms split – called fission. Fission occurs in a
reactor core, where uranium rods are placed. The reaction of neutrons with uranium atoms split them releasing
energy. The excess neutrons are absorbed by the control rods, regulating a chain reaction, releasing huge
amount of energy, thereby heating the water in the reactor core. Reactor core will keep the water under pressure
so that it heats, but does not boil. This heated water is circulated through tubes in steam generators, allowing
the water in the steam generators to turn to steam, which then turns the turbine generator.
(2)Nuclear Fusion: Nuclear energy can be generated by fusion process which involves two hydrogen atoms
combine to produce one helium atom. Eg: hydrogen bomb, Sun, stars.
The disposal of nuclear wastes during mining, fuel production and reactor operation for a long time period
resulting in adverse effects on environment. Disposable of nuclear waste is a national and global problem.
Currently the generation of electricity in nuclear reactors is done by nuclear fission reactions. For the
moment, nuclear fusion is not valid to generate electric power. Once developed, if nuclear fusion is
really practicable, it will provide great advantages over nuclear fission:
Virtually inexhaustible sources of fuel.
No accidents in the reactor due to the chain reactions that occur in fissions.
The waste generated will be much less radioactive.
ADVANTAGES
Reduces the amount of energy generated from fossil fuels (coal and oil).
Less greenhouse gas emissions.
Less fuel offers more energy.
The cost of nuclear fuel (overall uranium) is 20% of the cost of energy generated.
The production of electric energy is continuous.
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DISADVANTAGES
Chances for nuclear accidents. Two good examples are Chernobyl (Russia) nuclear disaster 1986, Fukushima
Nuclear disaster 2011.
Difficulty in the management of nuclear waste.
Nuclear plants have a limited life.
Nuclear power plants are objectives of terrorist organizations.
Use of the nuclear power in the military industry - creation of two nuclear bombs dropped on Japan during
World War II.
STEAM REFORMING:
Methane reacts with steam under 3-25 bar pressure in the presence of a catalyst to produce HYDROGEN,
carbon monoxide, and a relatively small amount of carbon dioxide.
Steam reforming reaction is endothermic, i. e. heat must be supplied to the process for the reaction to proceed.
Steam-Methane Reforming Reaction
CH4 + H2O (+heat) → CO + 3H2
ELECTROLYSIS
Electrolysis is a process that splits Hydrogen from water, which results in no emission but is very expensive at
present, It accounts for only 4-5% of Hydrogen production today, due mostly to the greater cost.
A fuel cell combines hydrogen and oxygen to produce electricity, heat, and water. Fuel cells are often compared
to batteries. Both convert the energy produced by a chemical reaction into usable electric power.
The Hydrogen Fuel cells are made up of four parts- the Anode, the Cathode, the Catalyst, and the Electrolyte.
Pressurized hydrogen gas enters the fuel cell on the anode side.
The gas is forced through the catalyst, separating it into to H+ ions and two electrons.
The ions go through the catalyst (because they’re positive) and the electrons are forced through an external
circuit (where they generate power).
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Oxygen gas is forced through the cathode past the catalyst. It forms two highly negatively charged Oxygen
ions, which attract the two H+ ions.
Each oxygen atom combines with two H2 ions, as well as electrons that have returned from the external circuit,
to form water molecules.
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