LESSON 7 NATURAL RESOURCES: ENERGY RESOURCES
INTRODUCTION
e term Energy was coined by Thomas Young (1737-1829), eighty years after Newton and applied it to what is now called kinetic energy. The term Energy can be defined as the “ability/capacity to do work”. The two laws of thermodynamics describe the behaviour of energy. The first law states that Energy can neither be created nor destroyed however; it can be transferred from one form to another. The second law states that some energy is always dissipated into an unavailable form i.e. heat energy. There is no spontaneous transformation of energy from one form to another (in the context of protoplasm) that is 100 per cent efficient. Energy is required by all living organisms and vegetation for the biochemical reactions of their cells. In fact, all living beings operate using energy. Energy moves the universe. About 99.8 per cent of our energy comes from solar radiation. It is the solar energy that plants use to make food which gets stored in plants as biomass. The consumption of energy is indicative of its development. It is because almost all developmental activities require energy either directly or indirectly. Also, there exists a wide range of disparities in terms of per capita consumption of energy among developed and developing nations.
GROWING ENERGY NEEDS
The development and growth process of a country requires generation as well as consumption of energy. Thus, growing energy needs is an index of national development. Energy is derived from both conventional and non-conventional resources. Furthermore, it is expected that global energy needs will rise steadily in the next two and a half decades. If governments stick with current policies then according to the World Energy Outlook’s Reference Scenario - the energy needs of the world would be 50% higher in 2030 than today with an average annual growth rate of 1.6%. India is among the fastest-growing markets in the world and is expected to be the second-largest contributor to the increase in global energy demand by 2035, accounting for 18% of the rise in global energy consumption. With limited fossil fuel reserves, the country has planned to increase its renewable and nuclear power industries. Fossil fuels to date continue to dominate energy supplies and are expected to remain the same in the coming years. Fossil fuels (coal, petroleum, natural gas etc.) are expected to cater for more than 80% of the projected increase in primary energy demand in this scenario. Natural gas demand is also growing at a very fast rate, which is driven mainly by power generation. Coal has been the largest energy source, especially in China and India.
Reasons for the increase in worldwide energy demands: We feel handicapped without the supply of energy. Can you think of life without electricity? Because of these rising demands and limited energy resources, these are under heavy stress. Attempts are continuously being made to develop alternate sources of energy. We meet our energy requirements to perform several activities every day from food, fuel and electricity. For a long, we have been exploiting fossil fuels on a large scale for this purpose. a) Globalization: Transportation is one of the largest consumers of energy in the world, accounting for more than 50% of liquid fuel consumption in countries. The energy required for transportation has inevitably increased with increased globalization. b) Industrialization, especially in emerging markets: There is a large-scale requirement for energy in businesses and factories in the form of both electricity and petroleum-based fuels in order to operate. The energy demand is increased as soon as economies industrialize. In other words, Industrialization and Urbanization have multiplied the demand for energy resources several-fold. c) Increasing wealth, especially in emerging markets: With the growth of the economy, energy also grows. This leads to increased energy demand and consumption. d) The rapid growth of the human population is putting heavy stress on all resources of energy.
SOURCES OF ENERGY
The source of energy can be defined as the one which can make available a sufficient quantity of energy in a usable form for a longer duration. Any energy source which provides an alternative to fossil fuel is called an alternate source of energy. All conventional mineralbased energy resources, such as fossil fuels, are exhaustible. It is estimated that if we continue to use coal at the present rate, the available coal reserve will exhaust in the present century itself. India produces petroleum which fulfils only half of our requirements and the remaining half is met by importing from other countries
RENEWABLE AND NON-RENEWABLE SOURCES OF ENERGY
In almost every part of the world, industrialization and agricultural development have increased the requirement for energy on a larger scale and the same can be directly related to the expansion of possible energy sources. These developments and expansions particularly in the field of industries as well as agriculture have caused a fall in their supply. Besides, traditional sources of energy have serious environmental concerns as these cause environmental pollution. Renewable energy sources/ Non-conventional energy sources: The increasing energy demands have compelled countries all over the world to think of a policy on energy and look into the possibility of having an energy system with no or very limited environmental impacts. The deposits of coal and oil will exhaust one day. The energy crisis has shown that for sustainable development in the energy sector, we must replace them with non-polluting renewable sources and conserve them. Efforts are being made to develop new sources of energy. These are called renewable sources of energy and include solar energy, wind energy, ocean energy, geothermal energy, urban waste, agricultural waste, energy plantations etc. These are non-polluting, environmentally clean and socially relevant. Moreover, no nation can afford to depend on only one form of energy there has to be a mix of various forms of energy. Non-renewable energy sources/ Conventional energy sources: The resources which have accumulated in nature over a long span of time and cannot be quickly replenished when exhausted are known as Non-renewable energy sources e.g. Coal, Petroleum, Natural gas, and nuclear fuels like uranium and thorium. Advantages of Renewable sources of Energy: 1. Renewable energy is available in abundant quantity and is free to use. 2. Renewable energy has low or zero carbon emissions, therefore they are considered green and eco-friendly. 3. Renewable energy develops self-reliance and minimizes the reliance on any third country for the supply of energy. 4. Renewable sources can cost less than consuming the local electricity supply. 5. Renewable sources of energy help in economic simulations and creating job opportunities, through building such types of equipment, instruments or plants that provide jobs to many people. Disadvantages of Renewable sources of Energy: Though renewable energy has many benefits and advantages it also has certain limitations, such as 1. High cost of initial investment to set up the plant. 2. Non-availability (Solar light only when days are sunny) 3. Loss of biodiversity and forest along with modification of local environment (Dam for hydroelectric energy). Advantages of Non-renewable sources of Energy: 1. Non-renewable sources of energy are cheaper and easy to use. 2. Non-renewable sources release a great amount of energy from the small amount of resource use (uranium). Disadvantages of Non-renewable sources of Energy: 1. Non-renewable sources of energy are limited and will end one day. Thus, their prices will keep rising and will not be accessible and available for everyone. 2. Their use is not eco-friendly as they release toxic gases that are creating serious environmental changes.
1. Solar Energy
The Sun is considered to be the ultimate source of energy for all other forms of energy either directly or indirectly. The phenomenon occurring inside the sun releasing a tremendous 1. Solar Energy The Sun is considered to be the ultimate source of energy for all other forms of energy either directly or indirectly. The phenomenon occurring inside the sun releasing a tremendous
amount of energy in the form of heat and light is nuclear fusion. The earth's space receives nearly 1.4 KJ/sec/m2 of solar energy. Advantages: 1. The energy produced by the sun is a renewable source of energy. The power source of the sun is absolutely free. 2. It produces electricity which doesn’t cause pollution of the environment. 3. It can be used in remote and isolated areas where there is no power supply. 4. Most solar energy systems have a lifespan of about 30 to 40 years. 5. In the majority of solar energy systems, there is hardly any requirement for maintenance during their lifetime, indicating that one need not put additional money into them. 6. Solar energy systems are now being considered and designed to satisfy particular needs. For example, outdoor lighting can be converted to solar. 7. Solar energy has various other applications apart from producing Photovoltaic energy viz. Solar cookers, Solar water heating systems, passive solar heating of homes etc. Disadvantages: 1. Solar energy can be harnessed only during the daytime or when it is a sunny day. Cloudy skies reduce its effectiveness. 2. Solar energy can be unreliable at times. 3. The amount of sunlight reaching the Earth’s surface varies with location, time of day, time of year and other weather conditions. 4. Transmission remains a barrier that has to be breached. 5. Installation cost is high as: a. Solar panels, solar cells as well as collectors are comparatively expensive to manufacture. b. It uses a special grade of Silicon which is expensive. c. Since silver is used for connecting the cells together it is more expensive. d. The current produced is DC and converting it to AC increases the cost. 6. Solar power stations are also very expensive to be built and also, and they fail to match the power output similar to sized conventional power stations. 7. The large-scale requirement of areas of land in order to capture solar energy.
8. In order to meet the requirement of energy during the night, batteries are charged during the day from solar energy. As a result, large storage space is required for these large and heavy batteries which need to be replaced at regular intervals
. 2. Wind Energy
The high-speed moving winds due as a result of their motion possess a lot of energy in them in the form of kinetic energy. Sun is the main driving force for the wind. Wind energy can be captured by making use of windmills. The force of the striking wind is the main driving force that helps the blades of the windmill to rotate continuously. The revolving blades can be utilised to drive a number of machines like electric generators, flour mills and water pumps. Nowadays a large number of windmills are being installed in clusters known as wind farms that feed power to the utility grid by producing a large amount of electricity. The prominent areas where the winds are strong and steady comprise the coats, hilly regions mountain passes and ridges in particular, open grasslands are utilised for wind farms. The minimum wind speed that can rotate the blades of a wind generator for satisfactory working is 15 km/hr. The largest wind farm in our country is near Kanyakumari in Tamil Nadu generating 380MW of electricity. Wind energy is considered to be the second fastest-growing source of energy since 1990 and probably the cheapest source. Advantages: 1. The wind is free of cost and can be captured efficiently with the help of modern technology. 2. Wind energy could also be used to produce hydrogen by electrolysis of water. 3. It can be used in remote and isolated areas where there is no power supply. 4. It is utilized for par generation, pumping water and other domestic purposes such as threshing, winnowing, cutting wooden logs etc.
5. Wind energy can also be used for battery charging to run generators. 6. It is a decent method of supplying energy to remote areas. 7. The wind farm can be used to generate revenue as they can be tourist attractions. 8. The land beneath the wind turbines can still be used for farming, especially in agricultural areas as wind turbines can be very tall and each turbine takes up only a small plot of land. 9. The recurring cost is less. Disadvantages: 1. The main disadvantage of wind power is down to the wind's unreliability factor. 2. A minimum wind speed of 15 km/hr i.e. 4.2 m/s is required to rotate the wind turbine. 3. The installer has to face nature’s problems because the wind doesn’t blow all the time i.e. it is not always predictable, therefore, electricity needs to be stored until it is used. There is also the requirement for backup systems. 4. There is a large-scale requirement for multiple wind turbines to produce a sufficient amount of electricity as a single wind turbine produces much less electricity than the average fossil fuelled power station. 5. The blades of the wind turbine may interfere with television reception or with microwave communication used by various telephone companies. 6. There is a large-scale requirement for land for installation. 7. The blades of the turbine can kill birds and migrate flocks thereby causing a loss of biodiversity. 8. The wind generators are few and give an unattractive outlook to the landscapes and are extremely noisy: This disturbs the residents of the area. 9. Optimum areas for wind farms are often the open plains, and the coast, where the land is expensive. 3. Hydroelectric Energy Hydropower is defined as “The electricity that is generated from the energy of falling water and running water that can be utilised for various useful purposes. Hydropower has been used in our country since ancient times for various purposes such as irrigation and the operation of various mechanical devices, such as watermills, sawmills, textile mills, dock cranes, domestic lifts, powerhouses and paint making. Hydroelectricity is considered to be the most widely used and accounts for nearly 16 % of global electricity generation. The first hydropower station in India was a small hydropower station of 130 KW commissioned in 1897 at
Sidrapong near Darjeeling in West Bengal. With the advancement in technologies and increasing requirements for electricity, emphasis was shifted to large-sized hydropower stations. Large hydropower projects in India are developed by the Ministry of power, the Government of India. Small and mini hydel projects have the potential to provide energy to remote and hilly areas where the extension of the grid system is uneconomical. The construction of mini/micro hydel plants with generation capacities between 3 MW and 15 MW is most suitable and avoids the socio-economic and environmental problems as occur during the construction of big dams. Applications: Generating Electricity, Flood risk management and Enabling Irrigation. Advantages: 1. Hydroelectricity is a clean source of energy. 2. The water can also be utilised for irrigation purposes. 3. The water can also be utilised as a source of drinking water provides drinking water to people living, particularly in the desert of Rajasthan and Gujarat. 4. It is absolutely non-polluting, has a long life, and has very low operating and maintenance costs, unaffected by inflation. 5. Help in controlling floods and making water available during non-rainy seasons for irrigation and other uses. 6. Once the dam is constructed, it produces electricity at a constant rate. 7. The gates can be opened and closed depending on the need for electricity. Also, the water saved during the closure of the gates can be utilised when the demand for electricity is high. 8. Dams and reservoirs are constructed to contribute to the production of electricity for many years and decades. 9. The build-up of water in the lake means that energy can be stored until needed when the water is released to produce electricity. 10. The production of electricity by dam systems doesn’t result in the production of greenhouse gases thereby it does not pollute the environment. Disadvantages: 1. The construction of Dams requires a huge investment of money and they need to be constructed to a very high standard. 2. The natural environment gets destroyed as a result of large-scale flooding.
3. The dam sites are especially the forest and agricultural areas and get submerged during construction. 4. It causes water logging and siltation. 5. It causes a loss of biodiversity and the fish population and other aquatic organisms are adversely affected. 6. Displace local people and create environmental problems of rehabilitation and related socio-economic problems. 7. Increases seismicity due to large volume of water impounded. 8. Loss of prime agricultural land (flood plain area). The area beneath the river is the most fertile which gets lost as a result of the construction of dams. 9. The natural water table is altered as a result of the construction of a large dam. 10. The buildings of large dams can cause serious geological damage. 4. Hydrogen Energy As hydrogen burns in the air, it combines with oxygen to form water with liberation of the enormous quantity of energy which is 150 kilojoules per gram. Hydrogen possesses the highest calorific value and therefore can serve as an excellent fuel. Hydrogen is a clean fuel and energy storage medium for various applications. The production of hydrogen is occurred by thermal dissociation, photolysis or electrolysis of water. Various organic effluents like a distillery, starch etc. can also produce Hydrogen by biological conversions. Advantages: 1. At present, in the form of liquid hydrogen, it is used as a fuel in spaceships. 2. H2 can be used in the fuel cell to generate electricity. In a fuel cell, hydrogen is burnt in air or oxygen under the pressure of an electrolyte to produce electricity. 3. Being very light, it would have to be stored in bulk. Disadvantages: 1. Hydrogen is highly explosive and inflammable and explosive. Therefore, in order to be used as fuel, it requires safe handling. 2. There is also great difficulty in storing as well as transporting hydrogen. 5. Ocean Energy More than 70% of the earth's surface is occupied thereby making it the world’s largest solar collector. The ocean forms a vital source of energy. Ocean Tides, produced by the gravitational force of the sun and moon, possess a tremendous amount of energy
Tidal Energy
The rise and fall of water in the oceans are referred to as high tide and low tide. In order to rotate the turbine, there is a requirement of several meters difference between the high and low tide. This difference in the tides can be exploited to harness tidal energy by constructing a tidal barrage. The seawater will flow into the reservoir of the barrage during the high tide turning the turbine and producing electricity by rotating the generators. When the sea level is low during the low tide sea water which was stored in the barrage reservoir flows out into the sea turning the turbine and producing electricity by rotating the generators. The potential of tidal power in India is estimated to be about 15,000 MW. In India, the Gulf of Cambay, Gulf of Kutch (1000 MW) and the Sunderban deltas (100 MW), Andaman and Nicobar Islands, Lakshadweep Islands, the coasts of Odisha, Kerala, Tamil Nadu, Karnataka and Maharashtra are the potential tidal power sites. The tidal power sites for harnessing tidal energy in the world are few. The Bay of Funday, Canada possess a potential of 5,000 MW of power generation with 17-18 m high tides. One of the first modern tidal power mills is located in La Rance, France. Ocean Wave Energy: The power of ocean waves, which operates on the principle of the oscillating water column, has not been exploited to its full potential except as power supplies for navigational aids. India has initiated a wave energy project at Vizhinijam Fishery Harbour near Trivandrum in Kerala as an indigenous effort. It was expected that on its completion, the project would be able to derive an energy output of 4.45 lakh units per year. The project resulted in a strict reality in 1991 when it started the generation of electricity to be fed to the grid of the Kerala State Electricity Board. Ocean Thermal Energy: As sunlight falls onto the surface of the ocean, the upper surface gets warmer while the lower layers have a relatively lesser temperature. This temperature difference between the upper and the subsequent lower layers of the ocean can be exploited to generate electricity through Ocean Thermal Energy conversion power plants. In order to produce electricity through the OTEC power plant, the minimum temperature difference between the surface and deeper levels is 20o C. Advantages: 1. Ocean wave energy and tidal energy is a free and clean source of energy.
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