Pollution
Pollution is the damaging and undesirable change in the physical or biological features of environment (air, land or water), than can adversely affect all aspects of human life or other desirable species. In other words, pollution is the unfavourable alteration of the environment due to damaging addition of any materials or energy in it.
Pollution is the most cCHAPritical ecological crisis for today’s world. There is pollution of air, water, land by different material pollutants. Addition of damaging amounts of energy to the environment is called non-material pollutions such as radiations pollution and noise pollution.
Air Pollution
When concentration of harmful substances gases or particulate matter increases in the air beyond their normal amounts the air is said to be polluted. Air pollution is the most common type of pollution, particularly in industrial urban areas. Air pollution is basically caused by burning of fossil fuels such as coal, petrol and natural gas. Some air pollution is also produced by industrial and agricultural activity etc. Particular pollutants include carbon particles, lead, asbestos particles, mineral dust, pollen grains, resins etc. The common gaseous pollutants are Carbon monoxide, CO₂, SO₂ oxides of nitrogen, chlorine etc. Air pollution has both pathological as well as effect on climate.
1. Pathalogical Effects of Air Pollution
Air pollution is the cause of many respiratory diseases like bronchits, cough, asthma, sorc throats, eye irritation, lung cancer and many nervous disorders. Carbonmonoxide (CO), is a poisonous gas and reduces the oxygen carrying capacity of the blood. In low quantities it causes nausea, head aches and sluggishness. Large levels of CO in blood may result in death. SO₂ irritates lining of respiratory tract, causing cough, bronchitis, asthma, lung cancer etc. Lead is added to air from automobile exhausts and is absorbed by the blood. It causes lead poisoning, which produces anaemia, stomach pains, kidney failure. It may also damage the nervous system and cause many nervous disorders. Asbestos particles are the main cause of lung cancer in the workers.
2. Environmental Effects of Air Pollution on Climate
Air pollution considerably affects the local as well as global weather and climate. Following are some of the major effects of air pollution on the environment
i. Photochemical Smog
In simple terms, smog is the mixture of air and smoke. Burning of fossil fuels at high temperature by vehicles and industry, releases nitrogen oxides (NO₂). With the energy supplied by the sunligh, the NO₂ combines with hydrocarbons (methane, ethane etc) to form secondary pollutants called photochemical oxidants. Presence of those pollutants scatter the light and a hazy milky smog is formed. Which is called the photochemical smog. It is very harmful for human health causes irritation of respiratory tract and lungs, head aches and breathing difficulties, which may even prove fatal.
ii. Acid Rains
Burning of fossil fuel by transport vehicles and industries produce pollutants such as SO₂, NO₂, CO₂. In this atmosphere these gases mix with the moisture of the air and gradually from dilute acids, which fall to the ground with rain. Such rains are called acid rains. Acid rains cause many respiratory diseases in humans. Acid rains also increase the acidity of the soil and water thus damaging crops and aquatic life. Corrosive action of H₂SO4 damages the buildings, statues and structures of historical and cultural importance.
iii. Green House Efect (Global Warming)
CO₂ plays an important role in regulating the earth’s surface temperature. Layer of CO₂ in upper atmosphere allows the sun rays to pass through atmosphere and reach the earth as short wave electromagnetic radiation. However, it partially prevents the long wave infra red heat radiation from escaping to outer space. Thus the globe is kept warm. Due to excessive burning of fossil fuels, the amount of CO₂ in atmosphere has become abnormally high. It holds back the increasing quantities of the heat waves and therefore the atmosphere gets over heated. This phenomenon is called green house effect. The possible effects of global warming are
There is a protective layer of Ozone in the upper layers of the atmosphere. It acts as a shield and reduces the penetration of harmful ultraviolet rays of the sun. This ozone layer can be broken by release of chlorine atoms at high altitude. The main source of chlorine atoms is a group of industrially produced compounds called Chlorofluorocarbon (CFC). These chemicals are used as refrigerator and also in pressurised acrosol cans CFCs get accomodated in greater amounts at high altitudes (stratosphere). Under normal conditions these compounds are inert, but at high altitudes they release chlorine atoms due to action of intense short wave ultraviolet radiation from the sun. Chlorine atoms then react with Ozone molecules and convert them to oxygen. (Each atom of chlorine reacts with about 1,00,000 molecules of ozone). Reduction in Ozone layer allows greater ultraviolet radiation to reach the earth. It is thought that this intensified radiation can cause significant increase in skin cancer and other adverse effects associated with ultraviolet radiaiton.
Water Pollution
Any contamination of fresh water or marine is called water pollution. Major sources of water pollution are
1. Domestic Waste or Sewerage
2. Industrial Waste
3. Agricultural Waste
1. Pollution of Water by Sewerage
Sewerage may include faccal matter, dissolved organic matter such as carbohydrates, urea etc, inorganic substances like nitrates, phosphates, detergents , insecticides etc. Both surface and soil water can be polluted by the sewage. Most of the components of sewage are biodegradable and are decomposed by natural processes, but when their intake exceeds the decomposing capacity of the environment, water becomes polluted. Some of the ill effects of sewage pollution are
Most of the streams and lakes are polluted by industrial wastes which include metals like lead, copper, mercury acids, alkalis, cyanides, arsenic, chlorine and many other toxic materials. These pollutants cause death to aquatic life and are also harmful for humans when they drink polluted water. These toxic substances cause various diseases of kidney, liver and nervous system. Some of which may prove fatal.
3. Pollution of Water by Agricultural Waste
Fertilisers, insecticides and pesticides and poultry feed contain many harmful components such as chlorine, nitrates etc, which contaminate soil and surface water. In rivers and streams they kill the aquatic life. Chlorine reduces the reproductive rate of aquatic animals. High nitrite concentration in drinking water converts haemoglobin in the blood to methemoglobin, which reduces blood’s oxygen carrying capacity.
Pollution by Oil
Oil is the main pollutant of marine water. Leakage from oil tankers and off shore oil wells kills many marine animals and plants.
Entrophication Or Algal Bloom
Natural lakes are divided into two types on the basis of production of organic matter. Entrophic lakes are shallow and contain high amount of nutrients. As a result phytoplankton growth is very high. This leads to increased number of heterotrophs which consume oxygen for respiration. Therefore, oxygen content of such lakes is reduced. The olgatrophic lakes are deeper and contain fewer amounts of nutrients. Therefore phytoplankton growth is poor and lesser number of heterotrophs are present and the oxygen content is high. Addition of agriculture waste, sewage, factory waste, increases the inorganic nutrients of the lakes. This over-enrichment is called entrophication. It causes algal bloom or explosive growth of small photosynthetic organisms such as algae. As the algae die, the activity of decomposers increase and they consume more and more oxygen. Deficiency of oxygen results in massive death of useful organisms such as fishes.
Land Pollution
The land can be polluted by deposition of solid waste and by harmful chemicals and hazardous waste.
1. Deposition of Solid Waste
Increase in population and rapid urbanisation has resulted in creation of enormous amounts of solid waste. It includes house hold garbage, hospital waste usually contaminated with various germs, agricultural, animal and industrial waste, dead animals and plants and host of other substances. If this refuse is dumped in open places without any pre-treatment, it pollutes the land. Wastes from hospitals carry germs of many dangerous diseases and the organic matter in the refuse provide favourable conditions for their growth and multiplication. These dumping sites also provide favourable breeding grounds for flies, rats and other vectors for pathogenic organisms. All these factors together pose a grave threat to the health of the population. Huge amounts of solid waste pose economic problems also because their proper disposal is very costly.
Harmful Chemicals and Hazardous Wastes
The land is also polluted by many harmful chemicals such as fertilisers, pesticides, insecticides which contain poisonous components. Most of the these pollutants are bio-nondegradable and stay in the soil for long periods. Solid wastes which cause human illness and death are called hazardous wastes. They include substances like mercury, cadmium, lead, nuclear wastes. They can ultimately end up in human body through food, water and radiation and cause dangerous disorders including cancer. These substance also interfere with biochemical cycles, thus decreasing the fertility of the soil.
Non-Material Pollution
Non-material pollution is the addition of damaging amount of energy to the environment. It includes radiation pollution, noise pollution, thermal pollution.
1. Radiation Pollution
Radiation, in the sense of pollution, comes from radio-active isotopes of such substances as Uranium, Radium, Thorium, Plutonium etc., which are used in nuclear reactors, atomic explosions, x-ray plants and other such devices. These radiation can penetrate tissues and organs of man and accumulate there. They may cause diseases like Leukaemia, bone tumour, cancer of many organs. Radiations also increases the mutation rate in the germ cells, which can produce genetic abnormalities in future generations.
2. Noise Pollution
Noise is the unwanted sound which the recipient does not like and which can adversely affect a person mentally, physically or aesthetically. Noises above 80 decibels are considered loud, uncomfortable and is harmful for human health. Noise is produced by motor vehicles, aeroplanes, machines, radio, TV, loud speakers. Loud noise is the serious threat to man’s physical and mental health. It affects mental peace, distracts the concentration and thus affects the quality and work output. Calm and quiet environment is a must for any creative and scholarly work. Loud noise is responsible for many disorders of cardrovascular and nervous system. People having continuously in environment of loud sound show symptoms of nervous stress, such as irritation, high blood pressure, headaches, sleeplessness, fatigue and depression. Persistent noise damages the internal car and may lead to impairment of hearing or even permanent deafness.
Energy
Like other natural resources, the energy resources can also be classified into renewable resources and non-renewable resources. The renewable energy sources are those which are almost inexhaustible. These include solar energy, energy of falling water (hydro energy), wind energy, wave and tidal energy, plant materials etc. Non-renewable energy sources are those which are found in fixed quantity and cannot be replaced and are therefore exhaustible. For example fossil fuels like petroleum, natural gas, caol, nuclear fuels like uranium etc are non-renewable energy resources.
1. Fossil Fuels
Coal, petroleum and natural gas are collectively called the fossil fuels. These fuels are derived mostly from plant material that got buried and fossilized in deeper layers of earth hundreds of million of years ago. Thus their energy remained separated from energy of the biosphere for a very long period.
Coal is derived from oxidized carbon of plant tissues. The supplies of coal are about 10 times the combined supply of petroleum and natural gas. Petroleum and natural gas are materials of organic origin derived from partial decomposition of plant tissues, particularly the marine plants.
Fossil fuels supply about 95% of energy requirement of the world. Major gas and oil fields in Pakistan are located in Sui region of Balochistan, Potohar region of Punjab and Badin in Sindh.
2. Nuclear Energy
Splitting of atoms of radio-active elements (heavy elements) is called fission. It releases tremendous amount of energy from a very small mass. In an atomic reactors, the fission is controlled and the energy is produced gradually. Here 1 kg of fuel is fissioned in 7 hours and releases $30,00,000 kilowatts energy. In order to get the same amount of energy 3 million kg of coal would be required.
Use of nuclear fuel poses environmental hazards and health problems. Large amount of radio active waste is produced. If released on land or in water it continuous to emit radio-active material which can cause dreadful diseases like cancer and mutations of genes. Safe disposal of radio-active waste is very costly. Accidental leakage from nuclear power plants can cause tremendous loss of human life.
3. Hydro-Electric Power
The falling water has a great amount of energy which can be used to generate electricity called hydro-electric power. It can be produced economically in mountainous regions, where river and stream make natural falls. To ensure constant flow of water, storage sites such as lakes and dams are built. This ensures generation of the power through out the year. Many countries of the world has potential sites for building Hydro-electric power houses. (The world capacity of generating hydroelectric power is estimated to be around 2900 million kilowatts, but only 250 million kilowatts has been developed)
Hydro electric power is cheap, clean, pollution free and renewable source of energy, but dams built at the site for storage of water destroy natural ecosystem and have limited life to silting.
In Pakistan there are large hydro-electric power plants at Tarbela, Mangla, Warsak, Dargai. At present maximum power generation from all the major hydro-electric power units is 4300 Megawatts.
4. Solar Energy
The energy of sun will last for billions of years and thus can be regarded as inexhaustible. Earth receives a maximum of 1400 watts per square meter when the sun is at the top. Solar energy can be used in two ways. One way is to directly capture the sunlight and use it for heating the water, buildings etc. The second method is to use solar energy to generate electricity. This method is costly and is not economical for large scale use. Another disadvantage of solar energy is its non availability during night and cloudy weather because no reliable method of storing the solar energy is available presently.
5. Geothermal Energy
Heat produced deep beneath the surface of earth due to natural decay of radio-active material, is known as the geothermal energy. This energy comes to the surface as heat in the form volcanic activity, hot water springs, steam and geysers. At present the use of geothermal energy is very limited due to high cost involved in its exploration. Only about 0.1% of world’s requirement is met by geothermal energy.
6. Solid wastes
Solid wastes includes all the domestic and municipal trash, paper and its products, animals dung, agricultural and industrial waste, plastic materials, wood material and host of such items. Millions of tons of solid waste is generated every year and can be converted into energy. Certain type of solid waste, such as animals dung and plant litter can be converted into hot gases known as biogas which can be used as a fuel.
7. Ocean Thermal Gradient
The difference of temperature between the surface water and deeper water of a ocean is called the ocean thermal gradient. This gradient is very large in tropics, where surface temperature is about 25⁰C and at few hundred meter depth the temperature is about 5⁰C. Thus the heat is conducted from regions of higher temperature to regions of lower temperature. This gradient is used to derive ammonia turbine for production of energy. This technology is still in its infancy.
8. Tidal Power
The high tide derives the water towards the land and the low tide moves the water away from the land. The difference in height of the water and low tides is made use of in tidal power stations to generate electricity. A tidal power station consists of a long barrier called a tidal barrage. The flow of water across the barrage turns its turbines, which in turn derive the generators for production of electricity. It is estimated that the total energy flow due to tides in shallow seas is about 1.1 billion kilowatts of which 13 million kilowatts can be harnessed presently with existing technology.
Energy Conservation
The energy sources of earth are limited and are fast declining. It is therefore necessary to use the energy in a balanced and planned way. Some of the ways of energy conservation are
Pollution is the damaging and undesirable change in the physical or biological features of environment (air, land or water), than can adversely affect all aspects of human life or other desirable species. In other words, pollution is the unfavourable alteration of the environment due to damaging addition of any materials or energy in it.
Pollution is the most cCHAPritical ecological crisis for today’s world. There is pollution of air, water, land by different material pollutants. Addition of damaging amounts of energy to the environment is called non-material pollutions such as radiations pollution and noise pollution.
Air Pollution
When concentration of harmful substances gases or particulate matter increases in the air beyond their normal amounts the air is said to be polluted. Air pollution is the most common type of pollution, particularly in industrial urban areas. Air pollution is basically caused by burning of fossil fuels such as coal, petrol and natural gas. Some air pollution is also produced by industrial and agricultural activity etc. Particular pollutants include carbon particles, lead, asbestos particles, mineral dust, pollen grains, resins etc. The common gaseous pollutants are Carbon monoxide, CO₂, SO₂ oxides of nitrogen, chlorine etc. Air pollution has both pathological as well as effect on climate.
1. Pathalogical Effects of Air Pollution
Air pollution is the cause of many respiratory diseases like bronchits, cough, asthma, sorc throats, eye irritation, lung cancer and many nervous disorders. Carbonmonoxide (CO), is a poisonous gas and reduces the oxygen carrying capacity of the blood. In low quantities it causes nausea, head aches and sluggishness. Large levels of CO in blood may result in death. SO₂ irritates lining of respiratory tract, causing cough, bronchitis, asthma, lung cancer etc. Lead is added to air from automobile exhausts and is absorbed by the blood. It causes lead poisoning, which produces anaemia, stomach pains, kidney failure. It may also damage the nervous system and cause many nervous disorders. Asbestos particles are the main cause of lung cancer in the workers.
2. Environmental Effects of Air Pollution on Climate
Air pollution considerably affects the local as well as global weather and climate. Following are some of the major effects of air pollution on the environment
i. Photochemical Smog
In simple terms, smog is the mixture of air and smoke. Burning of fossil fuels at high temperature by vehicles and industry, releases nitrogen oxides (NO₂). With the energy supplied by the sunligh, the NO₂ combines with hydrocarbons (methane, ethane etc) to form secondary pollutants called photochemical oxidants. Presence of those pollutants scatter the light and a hazy milky smog is formed. Which is called the photochemical smog. It is very harmful for human health causes irritation of respiratory tract and lungs, head aches and breathing difficulties, which may even prove fatal.
ii. Acid Rains
Burning of fossil fuel by transport vehicles and industries produce pollutants such as SO₂, NO₂, CO₂. In this atmosphere these gases mix with the moisture of the air and gradually from dilute acids, which fall to the ground with rain. Such rains are called acid rains. Acid rains cause many respiratory diseases in humans. Acid rains also increase the acidity of the soil and water thus damaging crops and aquatic life. Corrosive action of H₂SO4 damages the buildings, statues and structures of historical and cultural importance.
iii. Green House Efect (Global Warming)
CO₂ plays an important role in regulating the earth’s surface temperature. Layer of CO₂ in upper atmosphere allows the sun rays to pass through atmosphere and reach the earth as short wave electromagnetic radiation. However, it partially prevents the long wave infra red heat radiation from escaping to outer space. Thus the globe is kept warm. Due to excessive burning of fossil fuels, the amount of CO₂ in atmosphere has become abnormally high. It holds back the increasing quantities of the heat waves and therefore the atmosphere gets over heated. This phenomenon is called green house effect. The possible effects of global warming are
- Melting of the polar ice which in turn would raise the sea level flooding vast coastal areas.
- Early melting of shows in the mountains would flood large areas of farmland.
- Warming of atmosphere can cause heavy rains and strong hurricanes and storms.
There is a protective layer of Ozone in the upper layers of the atmosphere. It acts as a shield and reduces the penetration of harmful ultraviolet rays of the sun. This ozone layer can be broken by release of chlorine atoms at high altitude. The main source of chlorine atoms is a group of industrially produced compounds called Chlorofluorocarbon (CFC). These chemicals are used as refrigerator and also in pressurised acrosol cans CFCs get accomodated in greater amounts at high altitudes (stratosphere). Under normal conditions these compounds are inert, but at high altitudes they release chlorine atoms due to action of intense short wave ultraviolet radiation from the sun. Chlorine atoms then react with Ozone molecules and convert them to oxygen. (Each atom of chlorine reacts with about 1,00,000 molecules of ozone). Reduction in Ozone layer allows greater ultraviolet radiation to reach the earth. It is thought that this intensified radiation can cause significant increase in skin cancer and other adverse effects associated with ultraviolet radiaiton.
Water Pollution
Any contamination of fresh water or marine is called water pollution. Major sources of water pollution are
1. Domestic Waste or Sewerage
2. Industrial Waste
3. Agricultural Waste
1. Pollution of Water by Sewerage
Sewerage may include faccal matter, dissolved organic matter such as carbohydrates, urea etc, inorganic substances like nitrates, phosphates, detergents , insecticides etc. Both surface and soil water can be polluted by the sewage. Most of the components of sewage are biodegradable and are decomposed by natural processes, but when their intake exceeds the decomposing capacity of the environment, water becomes polluted. Some of the ill effects of sewage pollution are
- It is responsible for water borne diseases like Typhoid, Amoebic dysentary, hepatitis, cholera etc. Harmful chemicals present in sewage also damage the tissues of the body can cause several diseases.
- Organic pollutants in sewage provide favourable medium for bacterial growth, which consume the oxygen of water. As a result fishes and other useful animals are killed for lack of oxygen.
- Anaerobic conditions also produce bad smelling compounds such as H₂S₂ which make the water unfit for human consumption.
Most of the streams and lakes are polluted by industrial wastes which include metals like lead, copper, mercury acids, alkalis, cyanides, arsenic, chlorine and many other toxic materials. These pollutants cause death to aquatic life and are also harmful for humans when they drink polluted water. These toxic substances cause various diseases of kidney, liver and nervous system. Some of which may prove fatal.
3. Pollution of Water by Agricultural Waste
Fertilisers, insecticides and pesticides and poultry feed contain many harmful components such as chlorine, nitrates etc, which contaminate soil and surface water. In rivers and streams they kill the aquatic life. Chlorine reduces the reproductive rate of aquatic animals. High nitrite concentration in drinking water converts haemoglobin in the blood to methemoglobin, which reduces blood’s oxygen carrying capacity.
Pollution by Oil
Oil is the main pollutant of marine water. Leakage from oil tankers and off shore oil wells kills many marine animals and plants.
Entrophication Or Algal Bloom
Natural lakes are divided into two types on the basis of production of organic matter. Entrophic lakes are shallow and contain high amount of nutrients. As a result phytoplankton growth is very high. This leads to increased number of heterotrophs which consume oxygen for respiration. Therefore, oxygen content of such lakes is reduced. The olgatrophic lakes are deeper and contain fewer amounts of nutrients. Therefore phytoplankton growth is poor and lesser number of heterotrophs are present and the oxygen content is high. Addition of agriculture waste, sewage, factory waste, increases the inorganic nutrients of the lakes. This over-enrichment is called entrophication. It causes algal bloom or explosive growth of small photosynthetic organisms such as algae. As the algae die, the activity of decomposers increase and they consume more and more oxygen. Deficiency of oxygen results in massive death of useful organisms such as fishes.
Land Pollution
The land can be polluted by deposition of solid waste and by harmful chemicals and hazardous waste.
1. Deposition of Solid Waste
Increase in population and rapid urbanisation has resulted in creation of enormous amounts of solid waste. It includes house hold garbage, hospital waste usually contaminated with various germs, agricultural, animal and industrial waste, dead animals and plants and host of other substances. If this refuse is dumped in open places without any pre-treatment, it pollutes the land. Wastes from hospitals carry germs of many dangerous diseases and the organic matter in the refuse provide favourable conditions for their growth and multiplication. These dumping sites also provide favourable breeding grounds for flies, rats and other vectors for pathogenic organisms. All these factors together pose a grave threat to the health of the population. Huge amounts of solid waste pose economic problems also because their proper disposal is very costly.
Harmful Chemicals and Hazardous Wastes
The land is also polluted by many harmful chemicals such as fertilisers, pesticides, insecticides which contain poisonous components. Most of the these pollutants are bio-nondegradable and stay in the soil for long periods. Solid wastes which cause human illness and death are called hazardous wastes. They include substances like mercury, cadmium, lead, nuclear wastes. They can ultimately end up in human body through food, water and radiation and cause dangerous disorders including cancer. These substance also interfere with biochemical cycles, thus decreasing the fertility of the soil.
Non-Material Pollution
Non-material pollution is the addition of damaging amount of energy to the environment. It includes radiation pollution, noise pollution, thermal pollution.
1. Radiation Pollution
Radiation, in the sense of pollution, comes from radio-active isotopes of such substances as Uranium, Radium, Thorium, Plutonium etc., which are used in nuclear reactors, atomic explosions, x-ray plants and other such devices. These radiation can penetrate tissues and organs of man and accumulate there. They may cause diseases like Leukaemia, bone tumour, cancer of many organs. Radiations also increases the mutation rate in the germ cells, which can produce genetic abnormalities in future generations.
2. Noise Pollution
Noise is the unwanted sound which the recipient does not like and which can adversely affect a person mentally, physically or aesthetically. Noises above 80 decibels are considered loud, uncomfortable and is harmful for human health. Noise is produced by motor vehicles, aeroplanes, machines, radio, TV, loud speakers. Loud noise is the serious threat to man’s physical and mental health. It affects mental peace, distracts the concentration and thus affects the quality and work output. Calm and quiet environment is a must for any creative and scholarly work. Loud noise is responsible for many disorders of cardrovascular and nervous system. People having continuously in environment of loud sound show symptoms of nervous stress, such as irritation, high blood pressure, headaches, sleeplessness, fatigue and depression. Persistent noise damages the internal car and may lead to impairment of hearing or even permanent deafness.
Energy
Like other natural resources, the energy resources can also be classified into renewable resources and non-renewable resources. The renewable energy sources are those which are almost inexhaustible. These include solar energy, energy of falling water (hydro energy), wind energy, wave and tidal energy, plant materials etc. Non-renewable energy sources are those which are found in fixed quantity and cannot be replaced and are therefore exhaustible. For example fossil fuels like petroleum, natural gas, caol, nuclear fuels like uranium etc are non-renewable energy resources.
1. Fossil Fuels
Coal, petroleum and natural gas are collectively called the fossil fuels. These fuels are derived mostly from plant material that got buried and fossilized in deeper layers of earth hundreds of million of years ago. Thus their energy remained separated from energy of the biosphere for a very long period.
Coal is derived from oxidized carbon of plant tissues. The supplies of coal are about 10 times the combined supply of petroleum and natural gas. Petroleum and natural gas are materials of organic origin derived from partial decomposition of plant tissues, particularly the marine plants.
Fossil fuels supply about 95% of energy requirement of the world. Major gas and oil fields in Pakistan are located in Sui region of Balochistan, Potohar region of Punjab and Badin in Sindh.
2. Nuclear Energy
Splitting of atoms of radio-active elements (heavy elements) is called fission. It releases tremendous amount of energy from a very small mass. In an atomic reactors, the fission is controlled and the energy is produced gradually. Here 1 kg of fuel is fissioned in 7 hours and releases $30,00,000 kilowatts energy. In order to get the same amount of energy 3 million kg of coal would be required.
Use of nuclear fuel poses environmental hazards and health problems. Large amount of radio active waste is produced. If released on land or in water it continuous to emit radio-active material which can cause dreadful diseases like cancer and mutations of genes. Safe disposal of radio-active waste is very costly. Accidental leakage from nuclear power plants can cause tremendous loss of human life.
3. Hydro-Electric Power
The falling water has a great amount of energy which can be used to generate electricity called hydro-electric power. It can be produced economically in mountainous regions, where river and stream make natural falls. To ensure constant flow of water, storage sites such as lakes and dams are built. This ensures generation of the power through out the year. Many countries of the world has potential sites for building Hydro-electric power houses. (The world capacity of generating hydroelectric power is estimated to be around 2900 million kilowatts, but only 250 million kilowatts has been developed)
Hydro electric power is cheap, clean, pollution free and renewable source of energy, but dams built at the site for storage of water destroy natural ecosystem and have limited life to silting.
In Pakistan there are large hydro-electric power plants at Tarbela, Mangla, Warsak, Dargai. At present maximum power generation from all the major hydro-electric power units is 4300 Megawatts.
4. Solar Energy
The energy of sun will last for billions of years and thus can be regarded as inexhaustible. Earth receives a maximum of 1400 watts per square meter when the sun is at the top. Solar energy can be used in two ways. One way is to directly capture the sunlight and use it for heating the water, buildings etc. The second method is to use solar energy to generate electricity. This method is costly and is not economical for large scale use. Another disadvantage of solar energy is its non availability during night and cloudy weather because no reliable method of storing the solar energy is available presently.
5. Geothermal Energy
Heat produced deep beneath the surface of earth due to natural decay of radio-active material, is known as the geothermal energy. This energy comes to the surface as heat in the form volcanic activity, hot water springs, steam and geysers. At present the use of geothermal energy is very limited due to high cost involved in its exploration. Only about 0.1% of world’s requirement is met by geothermal energy.
6. Solid wastes
Solid wastes includes all the domestic and municipal trash, paper and its products, animals dung, agricultural and industrial waste, plastic materials, wood material and host of such items. Millions of tons of solid waste is generated every year and can be converted into energy. Certain type of solid waste, such as animals dung and plant litter can be converted into hot gases known as biogas which can be used as a fuel.
7. Ocean Thermal Gradient
The difference of temperature between the surface water and deeper water of a ocean is called the ocean thermal gradient. This gradient is very large in tropics, where surface temperature is about 25⁰C and at few hundred meter depth the temperature is about 5⁰C. Thus the heat is conducted from regions of higher temperature to regions of lower temperature. This gradient is used to derive ammonia turbine for production of energy. This technology is still in its infancy.
8. Tidal Power
The high tide derives the water towards the land and the low tide moves the water away from the land. The difference in height of the water and low tides is made use of in tidal power stations to generate electricity. A tidal power station consists of a long barrier called a tidal barrage. The flow of water across the barrage turns its turbines, which in turn derive the generators for production of electricity. It is estimated that the total energy flow due to tides in shallow seas is about 1.1 billion kilowatts of which 13 million kilowatts can be harnessed presently with existing technology.
Energy Conservation
The energy sources of earth are limited and are fast declining. It is therefore necessary to use the energy in a balanced and planned way. Some of the ways of energy conservation are
- Use of energy efficient machines, engines and manufacturing processes. It has been estimated that 75% of electricity produced is wasted due to use of inefficient machines and appliances.
- Reduce wastage by recycling the energy.
- Reduce the number of transport vehicles by encouraging mass transit systems in urban areas.
- Minimizing use of air conditioning and artificial light. Increasing use of energy efficient bulbs and encouraging use of natural light.
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