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Power Plant Engineering chap-1 ppt.pptx

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Power Plant Engineering discusses various types of power plants and energy conversion systems. It introduces the concepts of power, different energy sources like fossil fuels, nuclear and renewable energy. Power plants are classified based on their primary energy source, prime mover used and operational duty. Energy can be converted directly using methods like fuel cells, photovoltaics and indirectly in systems like coal fired steam plants. The document emphasizes the need for environmentally friendly and economically feasible energy production to meet growing demand while reducing pollution. It provides an overview of energy sources, power plants and conversion methods.

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Power Plant Engineering By:- Tsegaye Paulos (MSc.) @WSU, Mechanical Engineering Department
Chapter-1: INTRODUCTION The whole world is in the grip of energy crisis and the pollution manifesting itself in the spiraling cost of energy and uncomforted due to increase in pollution as well as the depletion of conventional energy resources and increasing curve of pollution elements. To meet these challenges one way is to check growing energy demand but that would show down the economic growth as first step and to develop nonpolluting energy conversion system as second step. It is commonly accepted that the standard of living increases with increasing energy consumption per capita. Thus energy production system must be: Economically feasible Demand satisfying and suitable for the purpose Environmentally friend 2
Energy is the capacity of a physical system to do work (units : joule, ergs).or it is the amount of work that can be done by a force. Work is the amount of energy transferred by a force acting through a distance (units : N.m) W = F . d Power is the time rate at which work is done (units : J/s , watt)horse power is the British unit of power. power = energy / time 3 1.1. Concept of Power Plant
A power plant (also referred to as a power generating station, power plant, power house) is an industrial facility for the generation of mechanical or electric power. A power plant is assembly of systems or subsystems to generate electricity, i.e., power with economy and requirements. The power plant itself must be useful economically and environmental friendly to the society. A power plant may be defined as a machine or assembly of equipment that generates and delivers a flow of mechanical or electrical energy. The main equipment for the generation of electric power is generator. When coupling it to a prime mover runs the generator, the electricity is generated. 4
Schematic diagram of Coal Fired Power Plant 5
1.2. Classification of Power Plant i. Based the potential of energy 6
ii. On the basis of primary source or fuel Nuclear power plants Geothermal power plants Fossil-Fuel power plants Biomass-Fuelled power plants Solar thermal power plants 7
iii. On The Basis of Prime Mover Steam Turbine Power Plants Gas Turbine Power Plants Combined Cycle Power Plants Internal combustion reciprocating engines: are used for small cogeneration plants likes - Hospitals, office buildings, industrial plants, and other critical facilities. Micro turbines: Stirling engine and internal combustion reciprocating engines are low-cost solutions for using opportunity fuels, such as landfill gas, digester gas from water treatment plants and waste gas from oil production 8
iv. On the basis of duty 1. Base Load Power Plants: Base Load Power Plants run nearly continually to provide that component of system load that doesn't vary during a day or week. 2. Peaking Power Plants: Peaking power plants meet the daily peak load, which may only be for a one or two hours each day. While their incremental operating cost is always higher than base load plants 3. Load Following Power Plants: Load following power plants can economically follow the variations in the daily and weekly load, at lower cost than peaking plants and with more flexibility than base load plants. 9
1. 3. Raw Sources of energy Sources of energy are those, which can supply adequate amount of energy in a suitable form for long periods of time. The major sources of energy, aside from human and animal power, are fossil fuel (petroleum resources, natural gas, coal), biomass, geothermal, nuclear, wind and solar. 10
i. The sun (solar energy) Sun is the source of many forms of energy available to us. The most abundant element in sun is hydrogen. This hydrogen at high temperature, high pressure and high density undergoes nuclear fusion and hence releases an enormous amount of energy. This energy is emitted as radiations of different forms in the electromagnetic spectrum. Out of these X-rays, gamma rays and most of ultraviolet rays do not pass through the earths atmosphere. 11
2. Solar collectors 12
ii. Petroleum Fossil fuels are the carbon-based fuels (coal, petroleum, and natural gas) found in fossil-bearing strata of the geologic column which represent the remains of plant and animal life that are preserved in the sedimentary rock. Most researchers believe that natural gas and petroleum are biogenic and derived from marine life. However, in Australia there is evidence that the source rocks for some of the oil and gas deposits were underlying coal beds. Petroleum products constitute 5095 % of commercial energy supplies and almost all the needs of transportation sector and mobile equipment are currently met by petroleum products. They also constitute the basic fuel for electric power plants while coal, natural gas and hydro resources are used in those locations where they are available. Kerosene and LPG are the favored cooking fuels and kerosene is the major lighting fuel in areas where there is no electricity. 13
Cont There are three steps in recovering petroleum. -The first step is the primary recovery, which is when oil flows by natural pressure or simple pumping. The maximum recovery is usually 30% of the oil available in the well. -The next step is the secondary recovery, which is when water or gas is pumped into the well to force oil out. This adds an additional 1020% to be recovered. -The third step is the tertiary recovery, where hot gases and chemicals are pumped into the well to make the oil less viscous for easier pumping. Petroleum refining separates different components of petroleum. It changes the chemical composition of petroleum component to produce desirable fuels and chemicals.14
Cont Petroleum refining has 3 major processes. The first process is a physical process called fractional distillation, which separates components according to their boiling points. The second step is the cracking, which breaks down long chains to make more gasoline, diesel, and jet fuel. This is a chemical process using a catalyst. The third process is the reforming process, where it converts straight chains into branched chains for better performance in gasoline engines. 15
iii. Natural Gas This is usually formed in the Earth along with petroleum. Its main constituent is methane. It also contains small quantities of Ethane and Propane. Natural gas liquefied by applying high pressure is CNG (Compressed Natural Gas). In automobiles, houses and factories, CNG is used as a fuel. It is also used as a source of hydrogen required in the manufacture of fertilizers. Natural Gas (CNG) is generally a mixture of the lighter hydrocarbons with methane (CH4) predominating, often with varying fractions of nitrogen and impurities such as hydrogen sulfide. Natural Gas meets nearly 20% of worlds energy needs. 16
iv. Coal Coal is composed mainly of carbon though it also contains hydrogen and oxygen and varying small amounts of nitrogen, sulfur and other elements. It was formed by the decomposition of the remains of vegetation growing in swamps or in large river deltas undergoing intermittent subsidence. The decomposed material from plants and trees was transformed first by bacterial action into peat which becomes buried by later sedimentary deposits. Later under the movement of the earths crust, the layers of peat become more deeply buried, and under the influence of heat and biochemical reactions they were transformed into various types of coal or lignite, during this coalification process, the carbon content increased as oxygen and hydrogen were released. 17
Cont Coals are ranked according to their carbon content. Under mild conditions of heat and pressure, the lowest rank coals were formed, consisting of brown coal and lignite. At higher temperatures and pressures, sub-bituminous and bituminous coals were formed, and under very high pressures, the highest rank coals, called anthracites, were formed. The anthracites contain more than 92% carbon, 2 3% hydrogen together with oxygen, volatile matter and impurities. Bituminous coal contains about 5% hydrogen and has a carbon content of 7080%. The lowest ranks of lignite and brown coal may have less than 50% carbon content. The rank by carbon content approximates to a ranking by heat content though with some overlap between classes. ----Peat---lignite --butimine --anthracite 18
V. Nuclear Energy Nuclear power production is based on the energy released when an atomic nucleus such as uranium undergoes fission following the absorption of a neutron to form a compound nucleus. This compound nucleus is unstable and may break into two or three smaller atomic nuclei with the simultaneous emission of several neutrons together with the release of considerable amount of energy. These neutrons may themselves be absorbed by other nuclei, and if enough of these are uranium nuclei, it is possible for a chain reaction to develop. Natural uranium consists of 99.3% 238U and only 0.7% of lighter isotope 235U, but it is the latter that provides the most readily available fission energy in nuclear reactor. Fission of a Uranium-235 atom produces a cesium-140 atom, a rubidium-93 atom, 3 neutrons, and 3.210-11 J of energy. In practical terms, the complete fission of 1 kg of uranium-235 releases 6.731010 kJ of heat, which is more than the heat released when 3000 tons of coal are burned. 19
vi. Other sources of energy ALCOHOL Spirit lamp is used in classrooms for experiments. The spirit being used in spirit lamp is alcohol. This is a good fuel. Atmospheric pollution is much less when it is burnt. In certain countries a mixture containing alcohol and petrol is used as fuel in automobiles. GASOHOL A mixture of petrol (gasoline) and alcohol is being used as fuel in automobiles in Brazil and Zimbabwe. This fuel is gasohol. gaso from gasoline and hol from alcohol. HYDRO POWER Water is the only non-conventional energy source that has been exploited by man on a large scale. The technology is well established and simple. The industrial infrastructure for the manufacture of water turbines, valves, gates, generators and associated electrical equipment are well established in many countries. Geothermal energy These are areas where there are volcanoes, hot springs, and geysers, and methane under the water in the oceans and seas. In some countries, such as in the USA water is pumped from underground hot water deposits and used to heat peoples houses. 20
1.4. Classification of energy sources Energy can be classified into several types based on the following criteria: 1) Primary and Secondary energy 2) Commercial and Non commercial energy 3) Renewable and Non-Renewable energy 4) Conventional and Non-conventional energy 21
1. Primary and Secondary Energy Primary and Secondary Energy ( Based on Usability of Energy) Primary energy sources are those that are either found or stored in nature. Common primary energy sources are coal, oil, natural gas, and biomass (such as wood). Other primary energy sources available include nuclear energy from radioactive substances, thermal energy stored in earth's interior, and potential energy due to earth's gravity. Primary energy sources are costly converted in industrial utilities into secondary energy sources; for example coal, oil or gas converted into steam and electricity. Primary energy can also be used directly. 22
2. Commercial Energy and Non Commercial Energy sources The energy sources that are available in the market for a definite price are known as commercial energy. By far the most important forms of commercial energy are electricity, coal and refined petroleum products. Commercial energy forms the basis of industrial, agricultural, transport and commercial development in the modern world. In the industrialized countries, commercialized fuels are predominant source not only for economic production, but also for many household tasks of general population. Examples: Electricity, lignite, coal, oil, natural gas etc. Non-commercial energy sources include fuels such as firewood, cattle dung and agricultural wastes, which are traditionally gathered, and not bought at a price used especially in rural households. These are also called traditional fuels. Non-commercial energy is often ignored in energy accounting. 23
3. Renewable & non renewable energy sources (Based on Long-term Availability) (a) Non-renewable Resources: which are finite and do not get replenished after their consumption are called non-renewable, e.g., fossil fuels, uranium, etc. (b) Renewable Resources: which are renewed by nature again and again and their supply is not affected by the rate of their consumption 4. Conventional & Non Conventional Energy sources (Based on Traditional Use) (a) Conventional Energy resources: which are being traditionally used for many decades and were in common use around the oil crisis of 1973, are called conventional energy resources e.g., fossil fuels, nuclear and hydro resources (b) Non-conventional Energy resources: which are considered for large-scale use after the oil crisis of 1973, are called non energy sources, e.g. solar, wind, biomass, etc. 24
1.5 Energy Conversion system Energy conversion system is the process of converting primary or natural energy resources to other forms of energy that is suitable for the purpose, economically feasible. Energy conversion system is divided as: Direct energy conversion system and indirect energy conversion system i. Direct energy conversion system Direct energy conversion system is direct conversion of one form of energy to the required form of energy without intermittent process or conversion. Example: Fuel cell Thermionic conversion Thermoelectric system Photovoltaic 25
Electrochemical Effects And Fuel Cells Fuel cells produce electricity from an electrochemical reaction between hydrogen and oxygen. Fuel cells are efficient, environmentally benign and reliable for power production. The use of fuel cells has been demonstrated for stationary/portable power generation and other applications. Fuel cell is device that converts the chemical energy stored in a fuel directly to electricity. 26
Thermoelectric Systems A loop of two dissimilar metals develops an e.m.f. when the two junctions of the loop are kept at different temperatures. This is called Seebeck effect. This effect is used in a thermocouple to measure temperature. Thermoelectric generator is a device which directly converts heat energy into electrical energy using the Seebeck thermoelectric effect. The device is very simple but thermal efficiency is very low of the order of 3%. Efficiency of thermoelectric generator depends upon the temperature of hot and cold junctions and the material properties. 27
Photovoltaics Solar photovoltaic (PV) convert light into electricity using semiconductor materials. Photovoltaic cell is a solar cell, which is a solid state electrical device that converts the energy of light directly into electricity. Solar energy is one of the most important renewable energy sources that has been gaining increased attention in recent years. Solar energy is plentiful; it has the greatest availability compared to other energy sources. The amount of energy supplied to the earth in one day by the sun is sufficient to power the total energy needs of the earth for one year. 28
Solar energy is clean and free of emissions, since it does not produce pollutants or by- products harmful to nature. The conversion of solar energy into electrical energy has many application fields. Such as Residential, vehicular, space and aircraft, and naval applications are the main fields of solar energy. Have further Study on Structures of Photovoltaic Cells/Modules/Arrays, solar invertors, solar battery and solar potential analysis for better understanding of solar based power plants. 29
ii. Indirect Energy Conversion System Indirect energy conversion system is a conversion of one form of energy to the required form of energy with one or more intermittent energy conversion process or conversion. E.g.: Coal fired steam power plant Chemical energy-heat energy-mechanical energy- electrical energy 30
Energy Consumption The energy consumption of a nation can be broadly divided into the following areas or sectors depending on energy-related activities. These can be further:- Domestic sector (houses and offices and commercials) Transportation sector Agriculture sector Industrial power 31
Project work Write the detail Report for the following energy sources in the concern of international and Ethiopia status. Hydroelectric Power Plant Steam Power Plant Geothermal Power Plant Wind power plant Nuclear power plant Solar/Photovoltaic power plant Gas Turbine Power Plant Biomass power plant .. 32
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Power Plant Engineering chap-1 ppt.pptx

  • 1. Power Plant Engineering By:- Tsegaye Paulos (MSc.) @WSU, Mechanical Engineering Department
  • 2. Chapter-1: INTRODUCTION The whole world is in the grip of energy crisis and the pollution manifesting itself in the spiraling cost of energy and uncomforted due to increase in pollution as well as the depletion of conventional energy resources and increasing curve of pollution elements. To meet these challenges one way is to check growing energy demand but that would show down the economic growth as first step and to develop nonpolluting energy conversion system as second step. It is commonly accepted that the standard of living increases with increasing energy consumption per capita. Thus energy production system must be: Economically feasible Demand satisfying and suitable for the purpose Environmentally friend 2
  • 3. Energy is the capacity of a physical system to do work (units : joule, ergs).or it is the amount of work that can be done by a force. Work is the amount of energy transferred by a force acting through a distance (units : N.m) W = F . d Power is the time rate at which work is done (units : J/s , watt)horse power is the British unit of power. power = energy / time 3 1.1. Concept of Power Plant
  • 4. A power plant (also referred to as a power generating station, power plant, power house) is an industrial facility for the generation of mechanical or electric power. A power plant is assembly of systems or subsystems to generate electricity, i.e., power with economy and requirements. The power plant itself must be useful economically and environmental friendly to the society. A power plant may be defined as a machine or assembly of equipment that generates and delivers a flow of mechanical or electrical energy. The main equipment for the generation of electric power is generator. When coupling it to a prime mover runs the generator, the electricity is generated. 4
  • 5. Schematic diagram of Coal Fired Power Plant 5
  • 6. 1.2. Classification of Power Plant i. Based the potential of energy 6
  • 7. ii. On the basis of primary source or fuel Nuclear power plants Geothermal power plants Fossil-Fuel power plants Biomass-Fuelled power plants Solar thermal power plants 7
  • 8. iii. On The Basis of Prime Mover Steam Turbine Power Plants Gas Turbine Power Plants Combined Cycle Power Plants Internal combustion reciprocating engines: are used for small cogeneration plants likes - Hospitals, office buildings, industrial plants, and other critical facilities. Micro turbines: Stirling engine and internal combustion reciprocating engines are low-cost solutions for using opportunity fuels, such as landfill gas, digester gas from water treatment plants and waste gas from oil production 8
  • 9. iv. On the basis of duty 1. Base Load Power Plants: Base Load Power Plants run nearly continually to provide that component of system load that doesn't vary during a day or week. 2. Peaking Power Plants: Peaking power plants meet the daily peak load, which may only be for a one or two hours each day. While their incremental operating cost is always higher than base load plants 3. Load Following Power Plants: Load following power plants can economically follow the variations in the daily and weekly load, at lower cost than peaking plants and with more flexibility than base load plants. 9
  • 10. 1. 3. Raw Sources of energy Sources of energy are those, which can supply adequate amount of energy in a suitable form for long periods of time. The major sources of energy, aside from human and animal power, are fossil fuel (petroleum resources, natural gas, coal), biomass, geothermal, nuclear, wind and solar. 10
  • 11. i. The sun (solar energy) Sun is the source of many forms of energy available to us. The most abundant element in sun is hydrogen. This hydrogen at high temperature, high pressure and high density undergoes nuclear fusion and hence releases an enormous amount of energy. This energy is emitted as radiations of different forms in the electromagnetic spectrum. Out of these X-rays, gamma rays and most of ultraviolet rays do not pass through the earths atmosphere. 11
  • 13. ii. Petroleum Fossil fuels are the carbon-based fuels (coal, petroleum, and natural gas) found in fossil-bearing strata of the geologic column which represent the remains of plant and animal life that are preserved in the sedimentary rock. Most researchers believe that natural gas and petroleum are biogenic and derived from marine life. However, in Australia there is evidence that the source rocks for some of the oil and gas deposits were underlying coal beds. Petroleum products constitute 5095 % of commercial energy supplies and almost all the needs of transportation sector and mobile equipment are currently met by petroleum products. They also constitute the basic fuel for electric power plants while coal, natural gas and hydro resources are used in those locations where they are available. Kerosene and LPG are the favored cooking fuels and kerosene is the major lighting fuel in areas where there is no electricity. 13
  • 14. Cont There are three steps in recovering petroleum. -The first step is the primary recovery, which is when oil flows by natural pressure or simple pumping. The maximum recovery is usually 30% of the oil available in the well. -The next step is the secondary recovery, which is when water or gas is pumped into the well to force oil out. This adds an additional 1020% to be recovered. -The third step is the tertiary recovery, where hot gases and chemicals are pumped into the well to make the oil less viscous for easier pumping. Petroleum refining separates different components of petroleum. It changes the chemical composition of petroleum component to produce desirable fuels and chemicals.14
  • 15. Cont Petroleum refining has 3 major processes. The first process is a physical process called fractional distillation, which separates components according to their boiling points. The second step is the cracking, which breaks down long chains to make more gasoline, diesel, and jet fuel. This is a chemical process using a catalyst. The third process is the reforming process, where it converts straight chains into branched chains for better performance in gasoline engines. 15
  • 16. iii. Natural Gas This is usually formed in the Earth along with petroleum. Its main constituent is methane. It also contains small quantities of Ethane and Propane. Natural gas liquefied by applying high pressure is CNG (Compressed Natural Gas). In automobiles, houses and factories, CNG is used as a fuel. It is also used as a source of hydrogen required in the manufacture of fertilizers. Natural Gas (CNG) is generally a mixture of the lighter hydrocarbons with methane (CH4) predominating, often with varying fractions of nitrogen and impurities such as hydrogen sulfide. Natural Gas meets nearly 20% of worlds energy needs. 16
  • 17. iv. Coal Coal is composed mainly of carbon though it also contains hydrogen and oxygen and varying small amounts of nitrogen, sulfur and other elements. It was formed by the decomposition of the remains of vegetation growing in swamps or in large river deltas undergoing intermittent subsidence. The decomposed material from plants and trees was transformed first by bacterial action into peat which becomes buried by later sedimentary deposits. Later under the movement of the earths crust, the layers of peat become more deeply buried, and under the influence of heat and biochemical reactions they were transformed into various types of coal or lignite, during this coalification process, the carbon content increased as oxygen and hydrogen were released. 17
  • 18. Cont Coals are ranked according to their carbon content. Under mild conditions of heat and pressure, the lowest rank coals were formed, consisting of brown coal and lignite. At higher temperatures and pressures, sub-bituminous and bituminous coals were formed, and under very high pressures, the highest rank coals, called anthracites, were formed. The anthracites contain more than 92% carbon, 2 3% hydrogen together with oxygen, volatile matter and impurities. Bituminous coal contains about 5% hydrogen and has a carbon content of 7080%. The lowest ranks of lignite and brown coal may have less than 50% carbon content. The rank by carbon content approximates to a ranking by heat content though with some overlap between classes. ----Peat---lignite --butimine --anthracite 18
  • 19. V. Nuclear Energy Nuclear power production is based on the energy released when an atomic nucleus such as uranium undergoes fission following the absorption of a neutron to form a compound nucleus. This compound nucleus is unstable and may break into two or three smaller atomic nuclei with the simultaneous emission of several neutrons together with the release of considerable amount of energy. These neutrons may themselves be absorbed by other nuclei, and if enough of these are uranium nuclei, it is possible for a chain reaction to develop. Natural uranium consists of 99.3% 238U and only 0.7% of lighter isotope 235U, but it is the latter that provides the most readily available fission energy in nuclear reactor. Fission of a Uranium-235 atom produces a cesium-140 atom, a rubidium-93 atom, 3 neutrons, and 3.210-11 J of energy. In practical terms, the complete fission of 1 kg of uranium-235 releases 6.731010 kJ of heat, which is more than the heat released when 3000 tons of coal are burned. 19
  • 20. vi. Other sources of energy ALCOHOL Spirit lamp is used in classrooms for experiments. The spirit being used in spirit lamp is alcohol. This is a good fuel. Atmospheric pollution is much less when it is burnt. In certain countries a mixture containing alcohol and petrol is used as fuel in automobiles. GASOHOL A mixture of petrol (gasoline) and alcohol is being used as fuel in automobiles in Brazil and Zimbabwe. This fuel is gasohol. gaso from gasoline and hol from alcohol. HYDRO POWER Water is the only non-conventional energy source that has been exploited by man on a large scale. The technology is well established and simple. The industrial infrastructure for the manufacture of water turbines, valves, gates, generators and associated electrical equipment are well established in many countries. Geothermal energy These are areas where there are volcanoes, hot springs, and geysers, and methane under the water in the oceans and seas. In some countries, such as in the USA water is pumped from underground hot water deposits and used to heat peoples houses. 20
  • 21. 1.4. Classification of energy sources Energy can be classified into several types based on the following criteria: 1) Primary and Secondary energy 2) Commercial and Non commercial energy 3) Renewable and Non-Renewable energy 4) Conventional and Non-conventional energy 21
  • 22. 1. Primary and Secondary Energy Primary and Secondary Energy ( Based on Usability of Energy) Primary energy sources are those that are either found or stored in nature. Common primary energy sources are coal, oil, natural gas, and biomass (such as wood). Other primary energy sources available include nuclear energy from radioactive substances, thermal energy stored in earth's interior, and potential energy due to earth's gravity. Primary energy sources are costly converted in industrial utilities into secondary energy sources; for example coal, oil or gas converted into steam and electricity. Primary energy can also be used directly. 22
  • 23. 2. Commercial Energy and Non Commercial Energy sources The energy sources that are available in the market for a definite price are known as commercial energy. By far the most important forms of commercial energy are electricity, coal and refined petroleum products. Commercial energy forms the basis of industrial, agricultural, transport and commercial development in the modern world. In the industrialized countries, commercialized fuels are predominant source not only for economic production, but also for many household tasks of general population. Examples: Electricity, lignite, coal, oil, natural gas etc. Non-commercial energy sources include fuels such as firewood, cattle dung and agricultural wastes, which are traditionally gathered, and not bought at a price used especially in rural households. These are also called traditional fuels. Non-commercial energy is often ignored in energy accounting. 23
  • 24. 3. Renewable & non renewable energy sources (Based on Long-term Availability) (a) Non-renewable Resources: which are finite and do not get replenished after their consumption are called non-renewable, e.g., fossil fuels, uranium, etc. (b) Renewable Resources: which are renewed by nature again and again and their supply is not affected by the rate of their consumption 4. Conventional & Non Conventional Energy sources (Based on Traditional Use) (a) Conventional Energy resources: which are being traditionally used for many decades and were in common use around the oil crisis of 1973, are called conventional energy resources e.g., fossil fuels, nuclear and hydro resources (b) Non-conventional Energy resources: which are considered for large-scale use after the oil crisis of 1973, are called non energy sources, e.g. solar, wind, biomass, etc. 24
  • 25. 1.5 Energy Conversion system Energy conversion system is the process of converting primary or natural energy resources to other forms of energy that is suitable for the purpose, economically feasible. Energy conversion system is divided as: Direct energy conversion system and indirect energy conversion system i. Direct energy conversion system Direct energy conversion system is direct conversion of one form of energy to the required form of energy without intermittent process or conversion. Example: Fuel cell Thermionic conversion Thermoelectric system Photovoltaic 25
  • 26. Electrochemical Effects And Fuel Cells Fuel cells produce electricity from an electrochemical reaction between hydrogen and oxygen. Fuel cells are efficient, environmentally benign and reliable for power production. The use of fuel cells has been demonstrated for stationary/portable power generation and other applications. Fuel cell is device that converts the chemical energy stored in a fuel directly to electricity. 26
  • 27. Thermoelectric Systems A loop of two dissimilar metals develops an e.m.f. when the two junctions of the loop are kept at different temperatures. This is called Seebeck effect. This effect is used in a thermocouple to measure temperature. Thermoelectric generator is a device which directly converts heat energy into electrical energy using the Seebeck thermoelectric effect. The device is very simple but thermal efficiency is very low of the order of 3%. Efficiency of thermoelectric generator depends upon the temperature of hot and cold junctions and the material properties. 27
  • 28. Photovoltaics Solar photovoltaic (PV) convert light into electricity using semiconductor materials. Photovoltaic cell is a solar cell, which is a solid state electrical device that converts the energy of light directly into electricity. Solar energy is one of the most important renewable energy sources that has been gaining increased attention in recent years. Solar energy is plentiful; it has the greatest availability compared to other energy sources. The amount of energy supplied to the earth in one day by the sun is sufficient to power the total energy needs of the earth for one year. 28
  • 29. Solar energy is clean and free of emissions, since it does not produce pollutants or by- products harmful to nature. The conversion of solar energy into electrical energy has many application fields. Such as Residential, vehicular, space and aircraft, and naval applications are the main fields of solar energy. Have further Study on Structures of Photovoltaic Cells/Modules/Arrays, solar invertors, solar battery and solar potential analysis for better understanding of solar based power plants. 29
  • 30. ii. Indirect Energy Conversion System Indirect energy conversion system is a conversion of one form of energy to the required form of energy with one or more intermittent energy conversion process or conversion. E.g.: Coal fired steam power plant Chemical energy-heat energy-mechanical energy- electrical energy 30
  • 31. Energy Consumption The energy consumption of a nation can be broadly divided into the following areas or sectors depending on energy-related activities. These can be further:- Domestic sector (houses and offices and commercials) Transportation sector Agriculture sector Industrial power 31
  • 32. Project work Write the detail Report for the following energy sources in the concern of international and Ethiopia status. Hydroelectric Power Plant Steam Power Plant Geothermal Power Plant Wind power plant Nuclear power plant Solar/Photovoltaic power plant Gas Turbine Power Plant Biomass power plant .. 32
  • 33. 33