Unit III. Part -b. Energy and Environmental Engineering

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Portion UNIT III Part – b: Energy and environmental engineering: Conventional and non-conventional fuels, per capita and global consumption pattern, their environmental impacts, alternative energy sources, vehicular emission standards of fuel consumption, green buildings and rating systems. 03 Hrs Energy: Energy is defined as the ability or the capacity to do work. Energy is the integral part of our life. It is the energy that produces work, heat and power. Energy and power are measured in diff
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  PortionUNIT III Part – b: Energy and environmental engineering: Conventional and non-conventional fuels, per capita andglobal consumption pattern, their environmental impacts, alternative energy sources, vehicular emission standards of fuelconsumption, green buildings and rating systems. 03 Hrs Energy: Energy is defined as the ability or the capacity to do work. Energy is the integral part of our life. It is theenergy that produces work, heat and power. Energy and power are measured in different units which makes thethings confusing sometimes. Let us have look at various units of measurement of energy and power and their conversion. Units of Measurement of Energy Energy is defined as the ability to do work i.e. energy produces work. As per the second law of thermodynamics, whenever the work is done by absorbing the energy (heat) from the reservoir, some heat isalways rejected to the sink. The work and heat are also forms of energy; hence the units of measurement of energy, work and heat are same.A number energy measurement systems exist at present but most commonly used system is SI. Here arethe units of measurement of energy, work and heat in various systems:1) MKS system (Metric system): Calories or cal : This unit is very commonly used to indicate the energycontent of the fuel and food, capacity of refrigeration and air-conditioning system, etc. One calorie is the amountof heat required to raise the temperature of one gram of water by one degree Celsius. As such calorie is a verysmall unit hence larger unit Kilocalories or Kcal is more commonly used. 1Kcal = 1000 cal2) SI unit system: Joule : This system is most commonly used now. Joule unit has been named after the famousscientist Joule who has made very important contributions in the field of thermodynamics especially in work andenergy. Even Joule is a small unit; hence kilo Joule or KJ is used commonly. 1KJ = 1000J3) British thermal unit: Btu : One Btu is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Conversion from One Unit to the other 1Btu = 1055J or 252cal1cal = 4.187J or 0.003969 Btu1J = 0.2388cal or 0.0009481 Btu. Units of Measurement of Power The rate at which the work is produced from the energy is called as power. For instance let us suppose thatthere are two engines, both of which consume two gallons of gasoline and produce same amount of work i.e. 5KJ.Let us suppose that the first one produces this work in five seconds and the seconds one produces this work in 10seconds. Accordingly the power produced by the first engine is 5/5 = 1KJ/s = 1KW and the power produced bysecond engine is 5/10 = 0.5KW.Here are various units of power:1) SI unit: The SI unit of power is W. It is the amount of power produced by consumption of one Joule of energyin one second. The unit W is very small, larger unit like KW and MW are used commonly. 1KW = 1000W and1MW = 1000KW. SI unit is most commonly used now.2) Horsepower (hp): This unit is more commonly used to denote the power produced by the engine of theautomobiles. 1hp = 746W or 0.746KW  Classes / forms of Energy ãPotential Energy – storedenergy or energy of positionGravitational – energy an object or substance has because of its position. Anything “up high”Stored Mechanical - stored in an object by the application of force. Must push or pull on an object Nuclear - energy stored in the nucleus of an atom. Holds the atom together Chemical - energy stored in the bonds between atoms. Holds molecules together ãKinetic Energy – energy of motionMechanical (Motion)– movement of objects or substances from one place to another Electrical - movement of electrons. NOT AN ELECTRON PARADE!Sound - movement of energy through substances in the form of longitudinal/compression wavesRadiant – electromagnetic energy that travels in transverse wavesThermal/Heat – internal energy of a substance due to the vibration of atoms and molecules makingup the substance Energy Transfers ãEnergy can not be created nor destroyed, only changed.ãEnergy always transfers from high to low.ãEnergy transfers are never 100% efficient. Types of energy:-conventional and non-conventional Conventional : Power provided by traditional means such asFossil fuels, Nuclear energy,etc., Fossil fuels: 1. Coal: Coal is a hard, black coloured, rock like substance. It is made up of carbon, hydrogen, oxygen,nitrogen and varying amounts of sulfur. There are three main types of coal – anthracite, bituminousand lignite. Anthracite coal is the hardest and has more carbon, which gives higher energy content.Lignite is the softest and is low in carbon but high in hydrogen and oxygen content. Bituminous isin between. The precursor to coal – peat is still found in many countries and is also used as anenergy source.Coal is mined out of the ground using various methods. Some coal minesare dug by sinking vertical or horizontal shafts deep under ground and coal miners travel byelevators or trains deep under ground to dig the coal. Other coal is mined in strip mines where hugesteam shovels strip away the top layers above the coal. The layers are then restored after the coal istaken away. The coal is then shipped by train and boats and even in pipelines. In pipelines, the coalis ground up and mixed with water to make what is called slurry. This is then pumped many milesthrough pipelines. At the other end, the coal is used to fuel power plants and other factories.2. Oil: Oil is another fossil fuel. It was also formed more than 300 million years age. Diatoms are seacreatures in the size of a pin head and the dead diatoms settle on the sea floor. Here they were buried under sediment and other rock. The carbon from the dead organisms eventually turned intooil under great pressure and heat. The demand for oil increased with the increasing of the population. Oil and natural gas are found under ground between folds of rock and in areas of rock that are porous and contain the oils within the rock itself.3. Natural gas:  Natural gas is lighter than air. Natural gas is mostly made up of a gas called methane.Methane is a simple chemical compound that is made up of carbon and hydrogen atoms. This gas ishighly flammable. Natural gas is usually found near petroleum underground. It is pumped from below the ground and distributed to larger areas. Natural gas usually has no odour. Before it is sentto the pipelines and storage tanks, it is mixed with a chemical that gives a strong odour. The odour smells almost like rotten eggs. The odour makes it easy to smell if there is a leak. Nuclear energy:  Nuclear power plants provide about 17% of the world’s electricity. Some countries dependmore on nuclear power for electricity than other. In France, about 75% of the electricity is generated fromnuclear power. In the United States, nuclear power supplies about 16% of the electricity overall, but some  states get more power from nuclear plants than others. There are more than 400 nuclear power plantsaround the world, with more than 100 in the United States. per capita and global energy consumption pattern  The standard of living of the people of any country is considered to be proportional tothe energy consumption by the people of that country. In one sense, the disparity one feelsfrom country to country arises from the extent of accessible energy for the citizens of eachcountry. Unfortunately, the world energy demands are mainly met by the fossil fuels today. The geographical non equi-distribution of this source and also the ability to acquire and alsocontrol the production and supply of this energy source have given rise to many issues andalso the disparity in the standard of living. To illustrate the points that have been mentioned,it is necessary to analyze some data. Energy Use by Sector 37%: Industry (agriculture, mining, manufacturing,20%: Personal and commercial transportation11%: Residential heating, lighting, and appliances5%: Commercial uses (lighting, heating and cooling of commercial buildings, and provision of water andsewer services)27%: Energy losses in generation and transmission In Table 1, the proved reserves of some of the fossil fuels are given on the basis of regions.   The world energy consumption pattern is also increasing as shown in the Fig.1. The energyconsumption has been increasing and it will triple in a period of 50 years by 2025 as seenfrom Fig.1.Data on fossil fuel consumption by fuel type are given in Table 2. Energy Consumption Per capita (GNP) (2004) ãIndia: 0.7 kW; Bangladesh: 0.2 kW(least)ãThe US consumes 25% of the world's energy (with a share of the world populationat 5%).
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