Steam power plant, nuclear power plant, gas power plant, hyro power plant, thermoelectric generator, thermionic generator

1. Energy and Environment Engineering
(BTES105/205)
Hi-Tech Institute of Technology
Aurangabad
Course by
Dr. Laxman Mishra
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2. UNIT-1
Conventional Power Generation
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3. Introduction
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Conventional and Non-conventional Energy resources
• Energy implies the capacity or ability to work vigorously. It has a significant role to play in our day to day
life, in fact, it is predominantly required in every field, whether it is a household, industry, communication,
transport, defense or agriculture.
• Energy resources are broadly classified as Conventional and Non-conventional sources of energy.
• Conventional sources of energy are not present in the environment in abundance, however there uses are
unlimited.
• On the contrary, non-conventional energy sources are the sources present in the environment in large
quantity but are used for limited purposes only.
• Conventional sources of energy are the natural energy resources which are regularly used for many years
and are accepted as fuel to produce heat, light, food and electricity.
• The energy sources include firewood, fossil fuels, cow dung cake etc. Of these sources, fossil fuel is the
greatest conventional source, wherein fossil implies the remains of plants and animals, that got buried
under the earth and transformed into rocks over the years. These fossil fuels are coal, oil (petroleum), and
natural gas.
• Conventional sources of energy are generally non-renewable sources of energy as the accumulation or
creation of conventional sources of energy takes years, once they are exploited or consumed. As these
sources are used on a large scale, the reserves have been depleted.
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4. Introduction
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• An alternative to conventional sources of energy is the non-conventional sources of energy, that achieved
popularity in recent years, after the oil crisis in 1973 and since then they are in use on a large scale. The
energy can be obtained from various sources such as the sun, wind, biological wastes, hot springs, tides,
etc. to generate heat and power.
• These are not only renewable sources of energy but are also pollution free. These sources are present in
abundance in nature, and they are constantly generated, so it cannot be exhausted easily, and used again
and again.
• There are several types of conventional power plants such as,
1. Steam power plant
2. Nuclear power plant
3. Gas turbine power plant
4. Hydro power plant
5. Thermoelectric generators
6. Thermionic generators, etc.
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5. 1. Steam Power Plant-Schematic
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6. Steam Power Plant-Components
It consists of several components such as
1. Boiler: It produces high temperature, high pressure steam by burning fuel such as coal,
2. Steam turbine: Here, the high pressure steam coming from the boiler is expanded which produces mechanical
work. This work is then used to run the generator which produces electricity.
3. Generator: It is the component which used mechanical work output from turbine and converts it into electrical
energy.
4. Condenser: It condenses the steam from the turbine by removing its heat with the help of the cooling tower.
5. Feed water pump: It supplies the water to the economizer at the boiler pressure.
6. Ash handling system: It consists of several other components which together handle the ash produced during
combustion of the fuel.
7. Cooling tower: It supplies cool water to the condenser and helps in condensation of the steam
8. Economizer: Here, the feed water is pre-heated using flue gases before sending to the boiler to save energy in the
boiler
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7. Steam Power Plant-Working
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• The boiler produces high temperature steam through the combustion of fuel like coal, oil or natural
gas
• The steam then passes through the turbine where it produces mechanical energy in the form of
rotation of the turbine.
• The turbine is connected to the electric generator which produces electrical energy.
• The steam from the turbine is then sent to the condenser where it is cooled and converted into liquid
form
• It is then sent back to the boiler through the use of a feed water pump.
• The condenser is connected to the cooling tower which helps in faster cooling of the steam.
• Components like air preheater and economizer are used to increase the overall efficiency
• Waste produced such as ash is handled using different sub-component of the ash handling system

8. Steam Power Plant-Advantages & Disadvantages
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Advantages
1. Cost of fuel is less
2. It can respond quickly to changes in load
3. It needs less space as compared to hydro power plant
Disadvantages
1. It has high operation and maintenance cost
2. Consumes large amount of water
3. Installation time is large
4. It has low plant efficiency
5. Coal and ash handling is a difficult challenge
6. It causes pollution in nearby areas
7. It produces different pollutants harmful for human beings, plants, animals and buildings
8. Causes greenhouse effects that leads to global warming
9. Affects the health of nearby inhabitants, flora and fauna
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9. Steam Power Plant-Site Selection Criteria
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• Availability of raw material and fuel
• Availability of labour
• Geology and soil type
• Availability of water
• Land availability and its cost
• Economic issues
• Load center
• Pollution
• Ash disposal facility
• Transport facility
• Distance from populated areas
• Archaeological and historical sites
• Future expansion
• Away from air fields
• Environmental issues
• Social issues
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2. Nuclear Power Plant-Schematic
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11. Nuclear Power Plant-Components
It consists of several components such as
1. Reactor vessel: It is constructed to handle the high pressure that is generated during the nuclear reaction. It is made of low
carbon steel for strength and stainless steel for corrosion resistance.
2. Moderator: It reduces the speed of the neutrons so that they can be captured by other surrounding atoms.
3. Control rods: They are used for controlling the rate of nuclear reaction at the safe level. They absorb the required number of
neutrons to maintain a desired level of operation.
4. Fuel: The most commonly used nuclear materials are 92U235, 94Pu239 and 92U233.
5. Coolant: Coolants are used for absorbing the heat generated in the reactor core and transfer it to the water for generation of
steam in heat exchanger.
6. Heat exchanger: The heat carried by the coolant is transferred to water for generating steam which is then sent to the
turbine.
7. Steam turbine, condenser, generator: These components work in similar fashion as in steam power plant
8. Shielding: A thick shielding is provided to save human workers from the effect of harmful alpha, beta and gamma particles
9. Reflector: It prevents protons from escaping the core of the reactor thereby facilitating proper chain reaction
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Nuclear Power Plant-Working
Fission of nuclear material in the reactor core generates large quantity of heat. This heat is carried away
by the coolant from the reactor to the heat exchanger. In the heat exchanger, this heat is used for heating
the water coming from the condenser. The water is sufficiently heated to produce high temperature, high
pressure steam. The steam is then passed through the turbine which converts the heat energy into
mechanical energy required for driving the generator/alternator. The steam is then discharged into the
condenser where it is converted into liquid water. This water is then recirculated to the heat exchanger
with the help of feed pump.
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Nuclear Power Plant- Site Selection Criteria
1. Land availability
2. Geology and soil type
3. Access to electrical grid
4. Transportation facility
5. Skilled manpower
6. Water availability
7. Disposal of nuclear waste
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3. Gas Turbine Power Plant - Schematic
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Gas Turbine Power Plant - Working
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• A gas turbine power plant consists of a compressor, combustion chamber, gas turbine, fuel pump,
generator, starting motor and other lubricating mechanism.
• The air from the surrounding is compressed by the compressor to a high pressure. It is then supplied to
the combustion chamber/combustor.
• At the same time, the fuel pump supplies the fuel in the form of spray at high pressure into the
combustor.
• The fuel is then ignited in the combustion chamber which increases its temperature.
• The high temperature, high pressure gas is then passed through the gas turbine where adiabatic
expansion of gas takes place; producing mechanical power.
• The mechanical power from the compressor is converted into electric power by the generator.
• The hot gases after expansion in the turbine are exhausted into the surroundings.
• Gas turbines are not self starting, hence, a starting motor is needed at the beginning of the cycle.

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Gas Turbine Power Plant - Advantages
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1. Its construction is simple
2. It is vibration free, therefore, does not affect combustion process
3. It runs at high speed
4. It is smallest in size with less weight to power ratio
5. It can use any type of fuel
6. It can be started and stopped quickly and with ease
7. It produces less pollution as the combustion process is complete
8. It requires less space
9. It requires less capital cost and maintenance cost
10. Lubrication requirement is lesser as compared to diesel power plant
11. Its ignition system is simple
12. It requires less water as compared to steam, nuclear or diesel power plant

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Gas Turbine Power Plant - Disadvantages
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1. It has low efficiency
2. It has shorter life of 5 to 7 years
3. It produces noise causing noise pollution
4. Special metals are required for manufacturing the gas turbine

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Gas Turbine Power Plant – Site Selection Criteria
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1. Land availability and its cost
2. Availability of labour
3. Geology and soil type
4. Transport facilities
5. Availability of water
6. Distance from populated areas
7. Load centre
8. Archaeological and historical sites
9. Future expansion
10. Social issues

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4. Hydro Power Plant - Schematic
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Hydro Power Plant - Components
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1. Reservoir: A reservoir stores water and supplies it to run the turbine
2. Dam: A dam is a structure built across the river. It is used to provide workable head to
the water for power generation and increase the water storage capacity of the
reservoir.
3. Gate: It is used to control the flow of water from the reservoir to the turbine through
penstock.
4. Surge tank: It is used for countering the sudden change in pressure in the penstocks
called ‘water hammer’ when there is increase or decrease in the load demand in the
turbine.
5. Penstock: The pipes that carry water from the dam to the turbine are called penstocks.
6. Turbine: It converts the kinetic energy of the water into mechanical energy used for
driving the generator.
7. Tail race: It is the path that leads the water discharged from the turbine into the river.

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Hydro Power Plant - Working
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• Water flows from the reservoir to the turbine. During the passage its potential energy
is converted into kinetic energy.
• This high velocity water strikes the turbine vanes where its kinetic energy is converted
into mechanical energy.
• The turbine is coupled to a generator which converts the mechanical energy into
electrical energy.
• The speed of the turbine and generator depends on the head and water speed
• The power generated is controlled by the governing mechanism attached to the turbine
which controls the amount of water supplied to the turbine according to the load
demand.

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Hydro Power Plant – Site Selection Criteria
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1. Availability of water head
2. Water storage facility availability
3. Slope of the hill
4. Transport facility
5. Land availability and its cost
6. Distance to nearest locality
7. Availability of construction material
8. Geology and soil type
9. Water pollution
10. Sedimentation
11. Social and environmental effects
12. Economic issues
13. Archaeological and historical sites
14. Future expansion

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Hydro Power Plant - Advantages
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1. Its operation cost is very low. Hence cost per unit of power is less
2. It is highly reliable
3. Starting and stopping is quick and easy
4. They have no issues of air pollution
5. It has longer life of up to 30 years
6. They have high efficiency as compared to other power plants
7. They can be used as base load or peak load power plants
8. It requires less manpower
9. They can also be used for irrigation and flood control in addition to power generation
10. It does not require any fuel for power generation

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Hydro Power Plant - Disadvantages
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1. It is dependent on water availability and rainfall
2. They need long distance power transmission as they are located far away
3. Time requirement for installation of these plants is large
4. They have high capital cost
5. It causes deforestation
6. Stagnant water in the reservoir affects the health of the river
7. Larger possibility that stretches of the river become dry
8. Increased sedimentation in the river
9. Submerged vegetation release methane which causes global warming
10. Displacement of local population may be required

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5. Thermoelectric Generators
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Thermoelectric Generators
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When two different materials are joined together and their ends are maintained at different temperatures, then two types
of thermoelectric effects are seen.
1. Seebeck Effect: It gives rise to an electromotive force in the circuit due to temperature difference between the two
junctions.
The reverse of this effect is called Peltier effect where heat is emitted at one junction and absorbed at the other
junction when electric current flows through the network.
2. Thomson Effect: The evolution or absorption of heat when electric current passes through a circuit composed of a
single material that has a temperature difference along its length.

27. • It converts heat energy into electrical energy directly
• It is environmental friendly
• It has no moving parts and therefore has long life
• It has very low efficiency of 2-5%
• It is mainly used for power generation and air conditioning
• The efficiency of the thermoelectric generator depends on the semiconductor materials
used.
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Important Characteristics of Thermoelectric Generators

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Thermoelectric Generators - Working
• A combination of P and N type semiconductors are used for electricity
generation.
• One end of the junction is maintained at higher temperature (hot junction) and
the other end acts as the cold junction.
• As long as the temperature difference is maintained across two junctions
electricity is generated and can be measured across the ends.
• Larger number of thermo elements are connected in series to increase the
voltage. While they are connected in parallel to increase the thermal
conductivity.
• These type of generators are light weight and are very useful for space missions
and for powering rovers.

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6. Thermionic Generators
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Thermionic Generators
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• Thermionic emission (also known as thermal electron emission or the Edison effect) is the liberation of electrons from
an electrode by virtue of its temperature (releasing of energy supplied by heat). This occurs because the thermal energy
given to the charge carrier overcomes the work function of the material. The charge carriers can be electrons or ions.
• All metals have free electrons which can be liberated from the parent atom by applying heat energy which is greater
than the band gap energy.
• The liberated electrons travel to the cooler metal electrode.
• The two electrodes are separated by vacuum or plasma. This gap is very narrow, usually few millimeters only.
• When the hot and the cold electrodes are connected externally through a load, the electrons travel back to the hot
electrode through this circuit, thus generating electricity.
• The emitter electrode is called cathode and the receiver electrode is called anode.
Work Function: The minimum energy needed for an electron to be liberated from a material is called its work function.
Work function is different from metal to metal.