Energy resources play very important role in our life. They are vital for all development activities (for example, cooking, heating, cooling, lighting, travelling, etc.). Also they are required in maintaining present living standards as well as developing further in all spheres of human life. Therefore, there is a great need to study the energy resources.
Humans first obtained energy from biomass (wood and cow dung), then coal and finally oil and natural gas. These fossil fuels (coal, oil and natural gas) were formed roughly 300 million years ago in the carboniferous period. Carboniferous period was part of Paleozoic Era i.e., a period even before dinosaurs lived on earth in Jurassic Period. At the time of carboniferous period the land was covered with huge trees, ferns and other large leafy plants. The trees and plants were buried in the oceans and pressed down by dirt and rocks over a long period. Gradually the dead trees and plants which were buried under the pressure, transformed into peat and then to coal. Likewise sea animals buried under enormous water pressure and remained there for millions of years. Then they were transformed into oil and natural gas (petroleum).
In addition to these conventional/fossil fuels (coal, oil and natural gas) nuclear and hydro-power are also used for generating electricity. Large Hydro Power Plants are being used for over a hundred years.
They use energy of moving water, which is a renewable source of energy as the water is not consumed up but replenished or filled up again and again. Though the large hydro power plants are renewable energy sources they come under the category of conventional energy sources. It is so because they are being used to produce electrical energy commercially for over a hundred years. It will be appreciated later that Small Hydro Power (SHP) Plants are classified as non-conventional energy source.
Thus, we can recognise the fact that thermal, large hydro and nuclear are the base of conventional energy. However, the main drawbacks of the fossil-fuel based thermal power plants are limited supply of fuels and environmental pollution. Global Warming is caused by greenhouse gas (GHG) emissions from fossil fuel based generating systems. Main drawbacks of large hydro power plants are long gestation periods, submergence of large area along with vegetation, shifting of people and other environmental effects. Main problem in nuclear power plants is danger of nuclear radiations causing health hazards.
You are aware that our standards of living are rising rapidly. As more and more people now have many electrical gadgets. Many people who were not having electricity connections in their homes are now connected with electric supply. Though some of them may not be having continuous regular supply of electricity for 24 hours a day (i.e., 24 × 7 regular supply).
It is hoped that the quality and quantity of electric supply will improve greatly. The demand for electricity will also increase as the number of electrical gadgets used by a common household is ever-increasing.
To overcome the problem of conventional energy sources and to meet huge demand of energy in future, most countries including India have focused to develop energy from renewable sources. Renewable energy sources are also called non-conventional sources of energy. These sources are continuously regenerated (renewed or replenished) by natural processes. Solar energy, wind energy, biomass energy, tidal energy, Ocean Thermal Energy Conversion (OTEC) are various forms of renewable energy resources. Various other sources of renewable energy are also available substantially.
It may be stated that the future of solar, wind, biomass, small hydropower, tidal and other renewable energy sources is bright and these will play an important role in the world energy scenario.
BASICS OF ENERGY AND POWER
Energy is the ability to do work. In other words, each and every work needs a fixed amount of energy. The rate of energy is called power. With more power, the same work can be completed in a lesser time and with less power the same work will take more time to complete. Energy, power and time are related as given by following expression:
Energy = Power × Time
Power is the rate of energy at which it is generated or consumed. So mathematically, it can be expressed as
p = e/t
where,
p = power, e = energy, and t = time
SI unit of energy, power and time are joule, watt and second respectively.
Main Energy Types
Law of conservation of energy states that energy can neither be created nor be destroyed. Only the one form of energy can be converted to other forms of energy. The main forms of energy are:
1. Mechanical energy
2. Heat energy
3. Electrical energy
These forms of energy can be easily converted from one form to another.
Units of Different forms of Energy and their Relation
1. Mechanical Energy : Energy due to motion (kinetic energy) or inherent position of a body (potential energy) is called mechanical energy. The unit of mechanical energy is joule. One joule is defined as amount of energy required if power of one watt is used for one second.
2. Heat Energy: Internal energy in substance due to vibration and movement of atoms and molecules within the substance is called heat or thermal energy. Heat is considered as low quality energy because it is dispersed. The unit of heat energy is calorie. Amount of heat energy required to raise the temperature of one gram of water by 1°C is one calorie.
1 kilocalorie (kcal) = 1000cnlorie .
Nowadays joule is used as unit of heat energy and it is internationally accepted.
1cal = 4.187joule (joule 's constant) 1kilojoule = 1000 joules
3. Electrical Energy: Energy due to flow of electric current is called electrical energy. Electrical energy is a high quality form of energy because it can be transported by conductive wires, can be stored in batteries and is used to make other forms of energy.
Unit of Electrical Energy: You must be familiar with the unit of electrical energy as one kilowatt-hour (1 kWh), because you pay your electricity bill by the units (kilowatt-hours) you consume over a billing period of one month or two months.
1 kilowatt-hour (kWh) = 1000 watt-hours (Wh)
1 watt-hour (Wh) = 1 watt × 3600 seconds = 3600 joules (J)
1 kilowatt-hour (kWh) = 3, 600, 000 joules (J) = 3600 kilojoules (kJ)
Relation
1 joule (J) = 1 watt-second
or
1watt = 1 joule/second
1 kilo joule (kJ) = 1000 watt-seconds
1kWh = 36, 00, 000 joules
= 36,00,000/4.187 calorie
= 860 kilocalories (kcal)
1 kWh = 3600 kJ = 860 kcal
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