COAL:
Occurrence: It is found in nature in solid form. Appearance: Its colour is dark brown or black. Its basic component is carbon, some organic and inorganic substances.
FORMATION OF COAL:
Coal is formed by different pale ontological plants. Millions of years ago, it was formed by the decomposition of many layers of soil on the plants. During this period, the absence of air and the prevalent high temperature changed these plants gradually into carbon. Along with carbon, there are some other substances present whose reduction is not yet complete: The mixing of these solid matters and carbon resulted in the formation of coal. The older is the deposit, the greater is the amounts of carbon in the coal. Good quantity of coal is used not only as fuel, but also for the synthesis of many valuable organic compounds. Coal tar obtained from fractional distillation is the basic raw material for the preparation of various chemical compounds, like naphthalene, dyes and insecticides. Coke used in the manufacture of iron and steel is also derived from coal.
Petroleum:
Like coal petroleum, is also obtained from blow the soil. Petroleum was formed by the deposition of the skeleton of marine animals in the mud. A lot of pressure and high temperature acted on these skeletons and changed them into the petroleum. It is obtained from soil as a black colour viscous liquids lid which contains many other
impurities. Petroleum obtained from below the soil is not pure. To purify it, it is set to refineries. So it is first refined in the refineries by such as petrol, diesel, kerosene oil, etc. Petrol and diesel are used as source of energy to run motor cars and rail engines while kerosene oil is used as a common fuel and to obtain energy. The fuel used in aero planes is also obtained from the fractional distillation of raw material. Another oil obtained from petroleum is called lubricating oil. It is used to minimise the friction between the parts of the machines.
Natural Gas:
Pakistan has huge reserves of natural gas at Sui, in Ballochistan and at other places. The same are commercially exported. The chemical analysis of the gas show that it is formed by many organic compounds such as methane, ethace, propane and butane. Apart from this, some toxic compounds such as compounds of sulphur, carbon-dioxide and nitrogen, etc. are also preset. These toxic and useless compounds are separated from the gas before supplying the main pipe-lines. Natural gas is not only the source of energy but is also used as a raw material for producing many chemicals such as the production of an artificial fertilizer like urea. It is also used as a source of heat energy by which the water is boiled into steam in the turbines or generators to obtain the electric energy.
Water:
Water occurs abundantly around us in liquid form or as solid (ice and sow). Moreover % Of the earth surface is covered with water. Water is found under the earth in combination with salt and minerals and entrapped between empty spaces in rocks and certain crystalline structures. Water due to its great dissolving power, occurs in natural in an impure state. Water is must for life, and wherever living organisms are preset, water is invariably found with them. Human body contains nearly 70% Water. In vegetable kingdom, water is present in various plants from 500-80%. Water can be described as a colourless liquid. We should remember, that water may sometimes be a solid, in the form of ice. Sometimes it is invisible gas (water vapour). Water has chemical formula of H2Owhich means that it is made up of two elements. Two parts (atoms) of hydrogen and one atom of oxygen for every molecules of water. Hydrogen and Oxygen taken by themselves are gases present in the air. When these two gases are mixed and made to burn, they bum with an explosion and form water.
Conventional Sources of Energy
Uses:
Water is collected in big lakes and dams and then allowed to fall under pressure on the turbines during which the potential energy of water is converted into mechanical energy.The mechanical energy runs the turbine and electricity is produced by the generators attached to the turbine. Heat and nuclear energy could also be the source of electric energy but electricity produced by water is cheaper. Non-Conventional Sources of Energy Mankind has always used whatever sources of energy he has found useful. Solar energy has been used since earliest times for drying various things. Sail-boats, and sail ships were the only means to travel and transport till the invention of steam engines. Availability of cheap fossil fuels and electricity, which are very convenient to distribute and use, have led to disuse of wind mills. With rising prices for fossil fuels and real danger of their depletion, interest in non- conventional and discarded energy sources has been revived. With massive input of sophisticated science and technology in researches into non-conventional source like solar, wind, biomass, tidal and geothermal, a breakthrough is expected. In the next century, these sources will successfully compete with the conventional ones, for supplying the ever-increasing energy needs of the humanity. Now we shall discuss some non- conventional energy sources as appear in the next coming headings.
Bio-Gas:
In rural areas, animal dung and crops wastes have been and are being used to meet fuel With the help of bio-gas, plants, dung, poultry dropping and human faces can be mixed needs. with plant wastes to generate natural gas and Odourless fertilizer.
Solar Energy:
All life on the earth owes its existence to solar energy in one way or the other. The use of solar energy is not new. However its use in homes and for commercial And industrial purposes is a recent phenomenon. Its use to generate electricity, commercially is all
very recent. In artificial space satellites, all energy needs are met by the electricity generated by solar Sola-cells. Photovoltaic cells can convert solar energy into electricity directly. The photovoltaic cells release electrons when they receive sunlight on their surface. With the reduction in cost of solar cells, its use will become more common. The source of solar energy is the conversion of mass into energy in the interior of the the sun due to nuclear fusion. In this process, hundreds of thousands of tonnes of matter is being converted into heat light and other types of radiations. It is estimated that every square kilometer of earth's surface receives approximately 1500 megawatts of solar energy. Even if a fraction of energy received on earth's surface is converted into useable energy, it can meet all the requirements of energy for the entire world. The problem are many but they are expected to be solved in coming years.
Wind energy:
Wind energy is one of the famous forms of energies. Sailboats and windmills have been used since long. But it is only in recent times that windmills are being used to generate electricity on a commercial scale. Wind energy is produced in the places where wind speed is high, large blades can be used to capture wide energy. The motion of the blades is used to run electric generators. In many parts of the world, many windmills are being erected together to generate large amounts of electricity. Windmill can also be used to lift water from deep wells.
Tidal Energy:
Twice during twenty-four hours, huge amount of water rushes towards and recedes away from the sea-shores. Making use of this phenomenon, cheap electricity can be generated. How to produce electricity from tidal energy? A dam is constructed at the mouth of a creek situated at the sea coast. A high tide, the is water is stored at the back of the dam. When the water recedes at low tide, the water in the dam is allowed to flow out through the dam. The outgoing water drives the turbine located inside the dam and the turbine rotates the generator to produce electricity. One such plant is generating 240 megawatt of electricity in France. Tidal power stations have been installed in Alaska, Argentina and the U.S.S.R.
Geothermal Energy:
The source of this energy is molten lava in the interior of the earth. In certain regions of the earth, this lava is situated near to earth's surface. Some times water deposits are found around this lava.
Nuclear Energy:
At present, energy is obtained from nuclear reactions using uranium as fuel. Significant amount of encre, used in the world is obtained from this source. However, the problems connected with disposal of waste from nuclear reactor as well as with safety, have slowed down the growth of nuclear industry.
FOSSIL FUELS:
Since the beginning of the 20th century most of the world's energy has been derived from the burning of fossil fuels. The fossils fuels are mainly coal, petroleum and natural gas.
Conventional Sources of Energy
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