Let us discuss both the sources with suitable examples.
(A) Conventional Energy Sources:
The energy sources which cannot be compensated, once these are used (after their exploitation) are termed as conventional energy sources.
Some important conventional energy sources are discussed below:
Coal is a major conventional energy sources. It was formed from the remains of the trees and ferns grew in swamps around 500 millions year ago. The bacterial and chemical decomposition of such plant debris (which remained buried under water or clay) produced an intermediate product known as peat which is mainly cellulose (C6H10O5)n. Due to progressive decomposition by heat and pressure, the cellulose lost moisture H2 and Oz and got converted in to coal as per the given equation
The average formula of coal is (C3/H4/)n. Out of the 6000 billion tons coal stocks under earth crust, 200 tons have been exploited the present society. The coal reserves are found in the states like Jharkhand, Orissa, West Bengal, M.P. and A.P. Some important coal fields are : Talcher, Raniganj, Jharia, Bokaro, Panch Konkam, Signoulli, Chanda etc.
2. Petroleum and natural gases:
Petroleum is a complex mixture of hydrocarbons, mostly alkanes and cycloalkanes. It occurs below the earth crust entrapped under rocky strata. In its crude form, the viscous black liquid is known as petroleum and a gas in contact with petroleum layer which flows naturally from oil wells is termed as natural gases. The composition of natural gas is a mixture of mainly methane, (95.0%), small amounts of ethane, propane and butane (3.6%) and traces of CO2 (0.48%) and N2 (1.92%).
A liquid mixture of propane and butane can be obtained from natural gas or refinery gases at room temperature under a pressure of 3-5 atmosphere. This is stored and distributed in 40-100 litre capacity steel cylinders.
The crude petroleum after being refined and purified, are available as petrol, diesel, kerosene, lubricating oil, plastic etc. for commercial and domestic use. In India, the oil deposits, are found at Ganga-Brahmaputra Valley, Bombay high, plains of Gujarat, Thar desert of Rajasthan and area around Andaman Nicobar islands.
On the world basis, petroleum deposits are found at Saudi Arab, Iraq, Iran, Kuwait, USA, Mexico, Russia etc. As per the current survey, it is found that world petroleum deposits are diminishing at a very faster rate. If preventive steps are not taken, the existing petroleum will be available maximum up to 40 years.
3. Fuel woods:
The rural peoples require fuel wood or fire Wood for their day to day cooking which are obtained from natural forests and plantations. Due to rapid deforestation, the availability of fire wood or fuel wood becomes difficult. This problem can be avoided by massive afforestation (plantation) on degraded forest land, culturable waste land, barren land grazing land etc.
Energy obtainable from water flow or water falling from a higher potential to lower potential, is known is hydro- power. It is a conventional and renewable form of energy which can be transmitted to long distance through cables and wires.
In India, hydroelectric power is generated by a number of multipurpose river valley projects e.g. Hydro-power project Hirakud, Bhakra Mangal project, Narmada valley project, Nagarjun Sagar project, Sardar Sarovar project etc.
5. Nuclear energy:
A small amount of radioactive substance (U235) can produce a lot of energy through the process of nuclear fission. For example, one ton of uranium can provide energy which is much higher than three million tons of coal or 12 million barrels of oil. In order to obtain nuclear energy, nuclear reactors are required. There are around 300 nuclear reactors all over the world. India has only four nuclear power stations (reactors).
The nuclear energy can be used in production of electrical energy, as a fuel for marine vessel and space crafts and for the generation of heat in chemical processing plants. In India, Uranium deposits are found at different parts of Rajasthan and Singhbum of Jharkhand.
Thorium is recovered from monazite sand found in the state of Kerala. Due to the higher energy releasing tendency of these radioactive substances, these can be used in nuclear reactors to release energy crisis. But the radioactive substances are exhaustible and can be used to develop nuclear weapons of mass destruction. In addition, dumping or radioactive wastes cause serious environmental hazards.
(B) Non conventional energy sources:
The conventional energy sources discussed above are exhaustible and in some cases, installation of plants to get energy is highly expensive. In order to meet the energy demand of increased population, the scientists developed alternate nonconventional natural Resources sources of energy which should be renewable and provide a pollution free environment.
Some nonconventional, renewable and inexpensive energy sources are described below:
1. Solar energy:
Solar energy, a primary energy source, is non-polluting and inexhaustible.
There are three methods to harness solar energy:
(i) Converting solar energy directly into electrical energy in solar power stations using photo cells or photovoltaic cells or silicon solar cell.
(ii) Using photosynthetic and biological process for energy trapping. In the process of photosynthesis, green plants absorb solar energy and convert it into chemical energy, stored in the form of carbohydrate.
(iii) Converting solar energy in to thermal energy by suitable devices which may be subsequently converted into mechanical, chemical or electrical energy.
Since solar energy is non-ending and its conversion to some other energy form is nonpolluting, attention should be paid for the maximum utilization of solar energy.
2. Wind energy:
Wind is air in motion. The movement of air takes place due to the convection current set out in the atmosphere which is again due to heating of earth’s surface by solar radiation, rotation of earth etc. The movement of air occurs both horizontally and vertically.
The average annual wind density is 3 kW/m2/day along costal lines of Gujarat, western ghat central parts of India which may show a seasonal variation (i.e., in winter it may go up to 10kW/m2/day).]
Since wind has a tremendous amount of energy, its energy can be converted into mechanical or electrical energy using suitable devices, now days, wind energy s converted in to electrical energy which is subsequently used for pumping water, grinding of corns etc. As per available data dearly 20,000 mW of electricity can be generated from wind. In Puri, wind farms are set up which can generate 550 kW of electricity.
3. Tidal energy:
The energy associated with the tides of the Ocean can be converted in to electrical energy. France constructed the first tidal power plant in 1966. India could take up Ocean thermal energy conversion (OTEC) and by the process it will be capable of generating 50,000 mW of electricity, to meet the power requirements of remote oceanic islands and coastal towns. The Netherlands is famous for windmills. In India, Gujarat and Tamil nadu have windmills. The largest wind farm has been set at Kanyakumari which generates 380 mW of electricity.
4. Geothermal energy:
The geothermal energy may be defined as the heat energy obtainable from hot rocks present inside the earth crust. At the deeper region of earth crust, the solid rock gets melted in to magma, due to very high temperature. The magma layer is pushed up due to some geological changes and get concentrated below the earth crust. The places of hot magma concentration at fairly less depth are known as hot spots.
These hot spots are known as sources of geothermal energy. Now a days, efforts are being made to use this energy for generating power and creating refrigeration etc. There are a quite few number of methods of harnessing geothermal energy. Different sites of geothermal energy generation are Puga (Ladakh), Tattapani (Suraguja, M.P.), Cambay Basin (Alkananda Valley, Uttaranchal).
5. Bio-mass based energy:
The organic matters originated from living organisms (plants and animals) like wood, cattle dung, sewage, agricultural wastes etc. are called as biomass. These substances can be burnt to produce heat energy which can be used in the generation of electricity. Thus, the energy produced from the biomass is known as biomass energy.
There are three forms of biomass:
(i) Biomass in traditional form:
Energy is released by direct burning of biomass (e.g. wood, agricultural residue etc.)
(ii) Biomass in nontraditional form:
The biomass may be converted in to some other form of fuel which can release energy. For example carbohydrate can be converted into methanol or ethanol which may be used as a liquid fuel.
(iii) Biomass for domestic use:
When organic matters like cow dung, agricultural wastes, human excreta etc. subjected to bacterial decomposition in presence of water in absence of air, a mixture of CH4, C02, H2, H2S etc. is produced. These gases together is known as biogas. The residue left after the removal of biogas is a good source of manure and biogas is used as a good source of non-polluting fuel.
Biogas is an important source of energy to meet energy, requirements of rural area. As per given data, around 22,420-million m3 of gas can be produced from the large amount of cow dungs obtained in rural areas in a year. The gas is generated by the action of bacteria on cow dung in absence of air (oxygen). There are two types of biogas plants namely. Fixed done type and floating gas holder type (Fig.4.3 & 4.4).
These plants are commonly known as Gobar gas plants because the usual raw material is cow dung (Gobar). The methodology involves in the process is to prepare a slurry of cow dung with water. Sometimes form waters can also be added to the slurry.
The slurry is subjected to bacterial decomposition at 35 .C. There are about 330, 00 biogas plants in India. All India dung production is about 11.30 kg per cattle and 11.60 kg per buffalo with about 67.10 m3 of gas per ton of wet dung.
7. Petro plants:
In order to release the pressure on mineral oils (a nonrenewable resource), the scientists have discovered some potential plant species from which liquid hydrocarbons can be extracted. The liquid hydrocarbons present in such plants can be converted in to petroleum.
Such plants are known as petro plants which belong to families Apocynaceae, Ascalepiadaceae, Euphrobiaceae; Convolvulaceae and Spontaceae. Still research is on to increase the biomass of the petro plants and effective method of converting their hydrocarbons in petroleum.
8. Dendrothermal energy (Energy plantation):
Due to rapid deforestation and overgrazing, a number of denuded wastelands are formed. On these wastelands, fast growing trees and shrubs may be planted which will provide fuel wood, charcoal, fodder, etc. Through gasification, these plants can produce a lot of energy-
9. Baggasse-based plants:
Bagggasse is generated as a waste product in sugar mills. This can be utilised to produce electrical energy. As per available data, the sugar mills in India can generate about 2000 mW surplus electricity during crushing season.
10. Energy from urban waste:
Sewage and solid municipal wastes can also generate energy on their suitable treatments.