Term Paper on Energy

Here is a term paper on ‘Energy’. Find paragraphs, long and short term papers on ‘Energy’ especially written for school and college students.

Term Paper # 1. Introduction to Energy:

Energy is one of the most vital resources considered for the sustainable development of mankind. Energy consumption is considered as an indication of the prosperity of a nation. With the growth of the civilization and the improvement of the living standards of mankind, the requirement of power has increased tremendously.

The quality of life is directly related to the per capita energy consumption. Our demand for energy is increasing with the progress in every sphere of life. In early times, the energy was used in three forms: human power, animal power, and heat. The need for human power has been the cause of slavery in all the periods.

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With the passage of times, the work of muscles has been transferred to machines driven by energy from coal, oil, gas, wind, or water. Consequently, the demand for energy has increased at an accelerated rate and started depleting the fossil fuel energy sources. In recent years, there has been a growing emphasis on the utilization of new energy sources such as solar, tidal, geothermal, ocean thermal, etc.

It is, therefore, important to know the global energy processes that give rise to a variety of energy resources on Earth. To meet this enormous requirement of power, a large number of power- producing systems have been developed. Most of the energy that we are having at our disposal mainly comes from relatively cheaper sources such as coal, petroleum, and natural gas found within the earth.

The high rate of consumption and the rate of depletion of these sources have been found not suitable to meet our demands. This situation has forced us to search for the alternative sources of energy such as solar energy, wind energy, biomass, and other forms of non-conventional sources of energy.

The energy resources include traditional fossil fuel, nuclear energy, and hydrostatic and renewable sources of energy (solar, wind, biomass, geothermal, and tidal).

2. Term Paper on Fossil Fuels:

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Fossil fuel, that is, solid (mainly coal including anthracite, bituminous, lignite, and peat), liquid, and gaseous fuel including petroleum and its derivatives and natural gas, is the primary conventional source of energy. Coal has the potential to contribute substantially to supply energy in future. Coal reserves are abundant.

Fossil fuels contain the various combustible elements such as nearly 80-90% carbon, 12% hydrogen, and rest may be sulfur, ash, and a small percentage of oxygen. They use oxygen for the combustion. Hence, on combustion, they produce heat which can be utilized to produce steam to run steam prime movers which in turn drive the electrical generator in thermal power plants.

High-pressure steam generated by the boiler can be used to run turbo generator to produce electrical energy for the mankind. Modern boilers, generating steam, burn coal in any of its forms (lump or pulverized) as a primary fuel. Coal, oil, gas, uranium, and hydel are commonly known as commercial or conventional energy sources.

There are three major classifications of fossil fuels:

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(i) Solid fuel (coal including anthracite, bituminous, lignite, etc.)

(ii) Liquid fuel (petroleum products such as petrol, diesel, and kerosene oil)

(iii) Gaseous fuel (coal gas, natural gas, etc.)

(i) Solid Fuels:

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Coal is formed by the decomposition of vegetable matter buried under the earth for millions of years in an anaerobic condition. It is the most universal source of energy. Since the development of industrialization in based on the power requirement, the coal has been found the most common source of energy. Modern boilers burn coal in any form (mostly in pulverized form) to produce steam and it is being used for industrial application like making of iron and steel.

(ii) Liquid Fuels (Oil/Petroleum Products):

In the last three decades, the world switched over from coal to oil as a major source of energy because of ease in handling and clean operation. Almost 38% of the energy requirements of the world are met by oil. The rising trend has brought a considerable strain on it.

In India, important crude oil fields are found in Assam, Bombay high, and Gujarat. The crude oil after refinement is useful in producing oil fuels which are used for running internal combustion (IC) engines, diesel power plants, and furnaces. The byproducts of the crude oil are useful in producing fertilizers, synthetic rubber, etc.

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Liquid fuels are more advantageous than solid fuels.

The advantages of liquid fuels are as follows:

(a) The handling of liquid fuel is easier.

(b) Liquid fuels require less space for storage.

(d) More heat can be produced and there by more temperature can be achieved within a short period of time.

(e) Combustion is uniform and stable.

(f) No residues are left after combustion.

The disadvantages of liquid fuels are as follows:

(a) Liquid fuels are costlier than solid fuels.

(b) There is danger of fire in storage.

(d) Proper attention is required in handling.

(iii) Gaseous Fuels:

Gaseous fuels are the most convenient to use. They require least number of gas- handling equipments. They are the simplest and the most maintenance-free burner systems. The gaseous fuel mixes with air uniformly and hence combustion is most effective and heat production is even more effective. Even though the gaseous fuels are the most ideal for power plants, storage and handling of gas pose a lot of problems.

Generally, the gases used as a fuel cannot be stored. Storing of gas is very expensive and risky also.

The pipeline can only deliver the gas directly to the site. It is also a very costly affair. The power plants using gas fuel are located only near the source of gas.

The advantages of gaseous fuels are as follows:

(a) No ashes are left after burning; hence the problem of ash disposal is completely eliminated.

(b) It is much convenient to use.

(d) Less amount of excess air is required for complete combustion.

(e) Complete combustion due to proper mixing of air and fuel.

(f) Combustion is pollution-free.

(g) Smokeless combustion is observed.

(h) The transportation of gas by pipeline is easy but very costly. For a long-distance pipeline, compressors are used to boost-up the pressure at intermediate stage which causes increase in the cost of fuel as compared to coal and oil.

(a) Natural Gas:

Natural gas is available in natural resources. During the process of preparing oil in oil fields, natural gas is obtained. It is a mixture of various compounds of hydrogen and carbon. The main constituents are methane and ethane. The composition of gas is 83% CH₄, 15% C₂H₆, 1% CO₂, and 1% N₂.

In addition to the gas components mentioned above, the gas may also contain hydrogen and carbon monoxide. It also contains volatile matters.

In natural gas, methane (CH₄) is the main constituent. The heating value of the gas depends upon the composition of the fuel. The average heating value is about 40,000 kJ/m³. It gives excellent combustion as the gas mixes properly with the air.

Natural gas is available in wells, and the working site must be installed near the well where natural gas is available in order to avoid difficulties in pipelines to make the system economical.

The arrangement of storing natural gas is a very costly affair and dangerous as well. In petroleum mines, gas is not utilized in an effective manner and hence a large quantity of the gas is burnt in oil production process. The gases are seen burning with yellow flame in oil field.

(c) Prepared Gas:

The gaseous fuel of importance is prepared gas. It is obtained as the byproduct of some process of reaction in chemical industries such as producer gas, coke-oven gas, and blast furnace gas. It can also be prepared from agriculture waste such as paddy husk, cow dung, etc.

(d) Producer Gas:

The gas is produced due to the partial oxidation of coal. In this case, the partial combustion of coal is derived from air and water. It is in fact a mixture of CO, H₂, N₂, and CO₂. It contains about 33% CO, 64% N₂, and rest H₂ and CO₂. They may have sometimes in their composition hydrocarbon and oxygen.

It has very low heating value approximately 5000 kJ/m³ which is less as compared to that of gasoline.

Handling and storing of the gas is very difficult. The vessel must be large enough and the source of supply and distribution system must be available. There should be a layout of the piping to get the gas supplied in an effective manner.

(e) Coke-Oven Gas:

It is produced as a byproduct, during the process of making coke in coke-oven plant. The composition of gas depends upon the quality of coal and its composition and also on the method of operating condition of the furnace. Its main constituents are H₂ and CH₄ but it may have a trace of C₂H₆, CO, CO₂, and N₂.

A sample of coke-oven gas has the composition as follows:

H₂(49%), CH₄(30%), C₂H₆(4%), CO(7%), CO₂(2%), and N₂(8%).

The heating value of the fuel is approximately 20,000 kJ/m³.

Blast Furnace Gas:

It is obtained as a by-product of making iron from its ore in blast furnace.

The composition of the blast furnace gas is as follows:

H₂(3%), CO(27%), CO₂(1.5%), N₂(58%), and CH₄(0.5%).

Heating value of the blast furnace gas is much less as compared to other gaseous fuels. It is about 5000 kJ/m³. It contains considerable amount of dust and fly ash, and therefore, it must be properly cleaned before use, otherwise it will give abrasion to the equipment metal surface.

3. Term Paper on Nuclear Energy:

Nuclear energy is a recent entrant in the field of power production. It has considerable potential. There is a common trend throughout the world to use nuclear energy as a source of power. The nuclear energy is produced by fission reaction. Atoms of certain heavy metals are in the precarious state of unbalancing.

When a free neutron enters the nucleus of U²³⁵, the nucleus splits into two fragments and releases two to three neutrons. There is a self-sustaining chain reaction and during this reaction, a large amount of heat energy is produced. This process is known as nuclear fission. The neutrons released during the process cause further self-sustaining chain reaction, as shown in Fig. 1.2.

Neutron + Heavy nucleus → Fission fragments + Neutrons (2-3) + Energy

Nuclear reactor is a vessel where self-sustaining controlled chain reaction takes place with a release of a large quantity of heat. The heat produced in the reaction is utilized to produce steam to operate turbo generator. The fission reaction produces tremendous amount of heat. The energy released by the fission of 1.0 kg of U²³⁵is equivalent to the energy obtained by burning of 4500 tons of high-grade coal or 2200 tons of oil. However, there are some limitations in the use of nuclear energy.

These are as follows:

(a) High capital cost involved.

(b) Limited availability of fissionable raw material.

(d) Non-availability of well-trained personals to run nuclear plants.

4. Term Paper on Wind Energy:

Wind energy is the form of energy available with the force exerted by the blow of air (wind) across the earth. Wind possesses energy by virtue of its motion. Wind power generation is the indirect method of electrical power generation. Air in motion arises from gradient. The solar radiation heats the air near the equator and this low-density heated air rises up. At the surface, it is displaced by cold dense high-pressure air flowing from the poles.

In the upper atmosphere near the equator, the air thus tends to flow back towards the poles and away from the equator. The net effect is a convective circulation with surface wind from north to south. The wind speed is greater in hilly and coastal areas than plain ground, inferring that the wind speed increases with altitude. The standard height is selected as 10 m.

The conversion of the kinetic energy of the wind into mechanical energy can be utilized to perform useful work and in turn to generate electricity. Most of the systems for converting wind energy into mechanical energy consist of a number of vanes or blades mounted on a hub.

When wind blows through the vanes, they rotate about the axis and the rotational energy can be used to develop useful work. The wind energy conversion device is known as wind turbine/wind mill. The system to rotate is known as rotor. The wind turbine produces rotational motion which is utilized to produce electrical energy.

The power output of the wind mill depends on three factors:

(a) Wind speed

(b) Cross-sectional area of wind swept by rotor

The main components of a wind energy conversion system are shown in Fig. 1.3. Because wind turbine produces rotational motion, wind energy is readily converted into electrical energy by connecting the shaft of turbine to an electrical generator.

The sub-components of a wind mill are as follows:

(a) Wind turbine or rotor

(b) Wind mill head

(d) Supporting structure

(e) Tail vane

Wind turbine converts the kinetic energy of the wind motion to mechanical energy transmitted at the shaft. The wind mill head supports the rotor, housing the bearings. The control devices are also incorporated to change the pitch of the blade. A tail vane is fitted to orient the rotor to face the wind.

Power in Wind:

The power in wind can be calculated by using the basic principles. The wind mill is based on the principle of converting the kinetic energy of wind into the mechanical energy.

KE = 1/2 mV²

Where m is the amount of air passing through the area A and V is the wind velocity. Amount of air passing per unit time, m= pAV

KE = 1/2 (ρAV) V² = 1/2 ρAV³ W

Wind power (P) per unit area = 1/2 ρV³ W/m²

Thus, this may be concluded that a wind mill is the device built to convert the wind energy to mechanical energy. The mechanical energy produced can be utilized for running water pumps, etc. It consists of a rotor fitted with large size vanes/blades. The efficiency of such unit is very less. The attempts are being made to improve the performance of the wind mills by the application of modern technology of aerodynamic and its transmission ability.

5. Term Paper on Solar Energy:

Solar energy, despite its limitations, can prove to be the most promising amongst all types of the renewable energy in order to fill the energy gap, if efficient harnessing and utilization systems are developed. It is the most abundant, pollution-free, and inexhaustible form of energy available on the earth. The earth receives radiant energy from the sun which is a vast and hot mass of hydrogen and helium gases. In the sun, energy is generated in its central core like a nuclear reactor.

The energy is released as per the following reaction:

4¹H₁ → ²He₄ + 26.7 MeV

All forms of energy on the earth are derived from the sun. The sun is a large sphere of hot gases, the heat being generated by various kinds of fusion reactions which convert hydrogen atoms to helium as shown in the reaction above. The energy produced and radiated by the sun refers to its energy that reaches the earth. The energy keeps the temperature of the earth more than that in colder space; this causes a natural flow of air in atmosphere.

The solar power where the sun hits atmosphere is 10¹⁷ W, whereas the solar power on the earth surface is 10¹⁶ W. The total worldwide power demand is 10¹³ W. Therefore, the sun gives us 10³ times more power than we need.

Figure 1.4 represents the distribution of solar radiations that reach the earth. On an average, about 30% is reflected back or scattered back into space, and 23% is consumed in the evaporation, convection, and the precipitation of the water in the hydrological cycle.

The remaining energy, 47%, is absorbed by the atmosphere, land surface, and oceans, and is converted into heat at ambient temperature. The intensity of the incoming solar radiation at any point on the earth’s surface depends on many factors such as the time of the day and year, latitude, season, cloud condition, atmospheric pollution, and height above the sea level.

The solar radiation that has not been absorbed or scattered and reaches the earth directly from the sun is called direct radiation. Diffused radiation is that part of solar radiation which is received from the sun after its direction has been changed by reflection and scattering by the atmosphere. The total solar radiation received at any point on the earth’s surface is the sum of the direct and the diffused radiation.

Solar energy has the potential of all sources of renewable energy. It will be of great importance, if only a small amount of this form of energy could be used. The energy radiated by the sun on a bright sunny day is approximately 1.0 kW/m². Attempts have been made to make use of this form of energy. It may be regarded as an inexhaustible source of useful energy.

The main drawbacks for its use are as follows:

(a) The intermittent and variable energy arriving at the earth’s surface.

(b) The large area required to collect the energy at a useful rate.

The utilization of solar energy is of great importance especially to India where the sunlight is abundant for a major part throughout the year. The climatic conditions are also favorable. Attempts have been made to use this energy in raising steam for driving steam prime movers for the purpose of the generation of electrical energy.

However, on account of the large space required, uncertainty on the availability of solar energy at a constant rate due to clouds, wind, haze, etc., makes it less feasible to be captured. Experiments are underway to use this energy for power production, house heating, air conditioning, water heating, solar cooking, electrical energy for lighting, etc.

Following are the applications of solar energy:

(a) Heating of residential buildings

(b) Solar water heating

(d) Solar distillation

(e) Solar cooker

(f) Salt production by the evaporation of sea water

(g) Biomass conversion

(h) Solar cells

(i) Solar electric power generation

Solar Power Plant:

The basic components used for a solar power plant are exactly identical to that of a thermal power plant, except the fact that the boiler is replaced by solar plate collectors. The energy from solar radiation is collected and utilized to generate steam or any other low-temperature working fluid to run prime movers.

As the temperature required for steam generation is considerably high (200°C) for getting high efficiency, concentrated type collectors are used. The cost of concentrated type collectors is more than that of flat plate collectors. The arrangements are shown in Fig. 1.14.

The power generation system is based on Rankine cycle as in the case of conventional system using steam as a working fluid. The only difference will be that instead of steam as a working fluid, organic fluids such as R11, R113, etc., have been used.

The efficiency of the system is found as low as 7-8%. The solar radiation will be captured by solar plate collector and storage tank which replaces boiler. A 10-MW plant was installed at IIT Madras in 1979-80 under the Indo-German collaboration with R11 and R113 as working fluids. The solar plate collector acts as a boiler.

Solar Cell:

The solar energy can be directly converted into electrical energy by means of the photovoltaic effect. The photovoltaic effect is the generation of an electromagnetic field as a result of the ionized radiation. The device, to make use of photovoltaic effects to convert sunlight to electricity, is called solar cells. Photovoltaic cells are made of semiconductors which generate electricity by absorbing light energy.

The modern solar cells are made of semiconductors usually based on single crystal silicon when doped with phosphorus. In this case, silicon becomes an n-type semiconductor and when doped with boron, aluminium, it forms a p-type semiconductor. A semiconductor with p-n junction is the most important configuration.

A semiconductor device is made either from a p- or n-type base material into which one or more impurities of positive polarity are introduced to form p-n layers. The interface between the layers having opposite polarity is called p-n junction and this is the most important configuration which provides an electrical field with the absorption of sunlight.

In a p-n junction, free electrons from n side tend to diffuse into p side where they readily recombine because of very large hole concentration. Similarly, all holes from p side of the junction tend to diffuse into n side and rapidly combine with free electrons. The movement of free electrons from n to p side leaves a net positive charge behind in the n side of the function, while migrating holes from p side leave a negative charge on the p side of the junction.

The charge distribution near the junction gives rise to an electric field and hence a potential difference across the junctions. The electric field generates mainly due to chemical composition difference in the material on the two sides of the junction as shown in Fig. 1.15. When a p-n junction of a semiconductor is exposed to sunlight, some of the solar radiations (photons) are absorbed in p-n junction.

The photons absorbed in p-n junction will have high energy to dislodge an electron in the material and gives enough energy to move freely in the material. This produces a positive charge on p side and a negative charge on n side. If an external load is applied, this charge will draw a current.

The best–known application of photovoltaic cells for electric power generation has been in aircrafts.

6. Term Paper on Biomass:

Biomass is the organic matter produced by plants, both terrestrial (those produced on land) and aquatic (those produced in sea water). It includes forest crops and residues. In fact, it can also be considered as a form of solar energy which is indirectly used to grow these plants by photosynthetic process. Solar energy is stored in the form of chemical energy.

Hence,

Solar energy → Photosynthesis → Biomass → Energy generated

Biomass is categorized in three groups:

(a) Biomass present in the form of solid mass such as wood and agriculture waste.

(b) Biomass present in the form of converted liquid fuels.

(c) The gas is produced from cow dung and other wastes such as rice husks, leaves, garbage, human excreta, and sewage. Biomass is fermented anaerobically to obtain a gaseous fuel called biogas.

The first category of biomass is burnt directly in the presence of air to produce heat energy. In the second category, the biomass is converted into ethanol and methanol which can be used as liquid fuel in IC engines. The third category is to form gaseous fuel known as biogas which is obtained from biomass. Biogas or methane is produced by the anaerobic decomposition of organic matters.

Ethyl alcohol may be obtained by the fermentation of sugarcane, potatoes, corn, etc. Biogas consists of 60% methane which on combustion gives mainly CO₂. Methane gas has good fuel value.

CH₄ + 2O₂ → CO₂ + 2H₂O + 21000 Calories

Methane can be produced from animal waste, human waste, industrial waste, and crop waste such as cattle, horse, and pig manures, municipal garbage, etc. The conversion of these compounds into methane is caused by bacterial action in an atmosphere where there is no oxygen in anaerobic conditions.

The reactions are as follows:

The above reaction is accomplished in a device called digester, as shown in Fig. 1.16. Biogas is a clean and efficient fuel generated from cow dung, human waste, or any kind of biological material derived through anaerobic fermentation process. It is safe for cooking and lighting. The byproduct of biogas is usable as high-grade manure. At present, there are millions of biogas plants in the world.