Energy Resources

1. Energy Resources Energy is used for domestic purpose, agricultural purpose, production of industrial goods and for the transportation purpose. In fact per capita energy consumption indicates the development of any country.

2. Growing energy demand: The demand for the energy resources are increasing due to increasing population and increased pace of development in developing country especially India and China. Between 1950 and 1990, the world’s energy need increases four folds. Rate of world energy uses in terra watts. Year (1965-2005)

3. Source of energy: • A source of energy is one which provide adequate amount of energy in a usable form over a long period of time. It is divided into two major type: • Renewable resource: it can be regenerated continuously in nature and are inexhaustible: examples: wood, solar, wind, tidal, hydropower, biomass energy, bio-fuel, geothermal energy and hydrogen. • Non-renewable resource: it include resources which accumulation in nature take place over a long span of time and once exhausted cannot be quickly replenished. Examples: coal, petroleum, natural gas, and fuels like uranium and thorium. • Renewable Energy resource: • a) Solar energy: The source of solar energy is the nuclear fusion reaction taking place in the sun where lighter hydrogen atom combine to form heavier helium atom. The luminosity of the Sun is about 3.86 x 1026 watts. This is the total power radiated out into space by the Sun. Most of this radiation is in the visible and infrared part of the electromagnetic spectrum, with less than 1 % emitted in the radio, UV and X-ray spectral bands. The power of the sun at the earth, per square metre is called the solar constant and is approximately 1370 watts per square metre (W m-2).

4. The energy of sun is harnessed from long time especially for drying purpose like seeds, clothes etc, however recently special instruments are use to harness the solar energy. Some of such instruments are: 1) Solar cell: also known as photovoltaic cells or PV cells are made up of semi-conductor material like silicon and gallium. This material is dope with Boron or Phosphorous to generate N and P region to create an electric field. As the solar light absorbed in the cell and electron get released which then follow the electric field and generate the electricity. It is pollution free electricity generation process, however due to the high cost of raw material and variability of sun intensity it is not much popular yet. Mainly used in calculator, electronic Watches, street light, traffic signal, water pumps etc.

5. Solar cooker: mainly used for the cooking food and boiling water. It is mainly of three design: heat-trap boxes, curved concentrators (parabolics) and panel cookers. Food cooks best in dark, shallow, thin metal pots with dark, tight-fitting lids to hold in heat and moisture. Solar power plant: Solar energy is harnessed on large scale by using concave reflector which cause boiling of water to produce steam. The steam turbine drives a generator to produce electricity .Example: 50K Watt capacity solar power plant has been installed at Gurgaon.

6. Solar water heater: Solar heat is used to warm water by conversion of light into heat energy. Solar furnace:A solar furnace is a structure used to harness the rays of the sun in order to produce high temperatures. This is achieved by using a curved mirror (or an array of mirrors) acting as a parabolic reflector to concentrate light (Insolation) on to a focal point. The temperature at the focal point may reach up to 3,000 degrees Celsius, and this heat can be used to generate electricity, melt steel or make hydrogen fuel.

7. Wind energy: Utilized Kinetic energy of wind to generate electricity. The energy is harnessed by making wind mill. A large number of wind mill installed in cluster called wind farm. The wind energy potential of our country is estimated to be about 20,000 MW , while at present we are generating about 1020 MW. The largest wind farm of our country is near Kanyakumari in Tamil Nadu generating 380 MW electricity.

8. Advantage of Wind power: • Pollution free source of energy. According to EPA estimates, running a 1 MW wind turbine for one year eliminates the following pollutants from entering the atmosphere: 1500 tons of carbon dioxide, 6.5 tons of sulfur dioxide, 3.2 tons of nitrogen oxides, and 60 pounds of mercury. • Required little maintenance cost after the installation. • Limitation of wind power: • The power produced by a turbine is proportional to the wind velocity cubed.  This means, at low wind speeds (i.e. 4 m/s), there is a significant drop-off in the power produced versus moderate wind speeds (i.e. 7 m/s). • T he power produced is proportional to the swept area that mean it is proportional to the blade length squared. • The wind farms are the source of noise pollution and also results into bird deaths due to bird strike on rotating wind mill blade. • Mainly useful in the costal areas with high wind speed. • High cost of per unit electricity compare to electricity generated from fossil fuels.

9. Hydropower energy: A hydraulic turbine converts the energy of flowing water into mechanical energy. A hydroelectric generator converts this mechanical energy into electricity. The operation of a generator is based on the principles discovered by Faraday. The present installed capacity of Hydropower as on 30-06-2011 is approximately 37,367.4 MW which is 21.53% of total Electricity generation in India.

10. Advantages to hydroelectric power: • Fuel is not burned so there is minimal pollution. It plays a major role in reducing greenhouse gas emission. • Relatively low operation and maintenance cost for hydropower. • It's renewable - rainfall renews the water in the reservoir, so the fuel is almost always there. • Disadvantages to hydroelectric power: • disadvantage of hydropower is related to the construction of Dams which resulted into inundation of land and wild life habitat. • Power supply depend upon the Hydrology (precipitation) so variation in rainfall event will affect the power generation. • Dam construction affects the quality of reservoir and stream water. • Displacement of local population.

11. Tidal energy: Ocean tides produced due to gravitational pool of sun and moon on earth surface. The energy is harnessed by using the difference in high tide (high water level) and low tide (low water level) in ocean. This energy is harnessed by constructing tidal barrage in costal areas such as bay and estuary. During high tide ocean water enter into the barrage reservoir and turn the turbine attached to produce electricity. In case of low tide, sea level is lower so water stored in the reservoir move out to ocean and again turn the turbine. High tide Low tide

12. Advantage of Tidal energy: • Environmental friendly method of energy generation with no pollution emission. • Tides are more predictable and can be predicted years in advance so reliable source of energy. • Barrage construction help in protection against floods in costal area and also help in the transportation. Disadvantage of tidal energy: 1) Only few suitable sites are present in world for harnessing the tidal energy. In India, two sites Gulf of Camby and Gulf of Kutch are producing tidal energy. 2) High capital cost and intermittent power generation takes place. 3) Change in the estuary ecosystem due to construction of barrage. 4) Accumulation of silt in the barrage which may accumulate pollutant.

13. Ocean Thermal Energy (OTE): The surface ocean layer is more warmer than the deeper ocean layer in the tropics and this temperature difference is used to generate electricity in Ocean thermal energy conversion power plant (OTEC). Minimum temperature difference should we 20°C or more for the OTEC power plant to work. OTEC system works as a heat engine with a low boiling point working fluid such as ammonia, which work between two temperature of deep and surface water. The working fluid circulate in the closed system taking heat from warm surface water and evaporated to run turbine and generate electricity and discharging heat to the cold water by help of heat exchanger. So it is a continuous electricity generation process.

14. Geothermal energy: The term geothermal comes from the Greek geo, meaning earth, and therme, meaning heat, thus geothermal energy is energy derived from the natural heat of the earth.The source of heat can be due to the fission of natural radioactive material present in rocks or molten lava come into contact of water reservoir. High temperature and high pressure stream fields are present below earth surface in many parts. In some part this high temperature streams come out naturally over the surface through cracks in the form of natural geysers such as Manikaran, Kullu and Sohna Haryana. Some time pipe has to drill through rock to bring this hot water on surface which in turn run turbine to produce electricity.

15. Biomass energy: Biomass is the organic matter produced by plant and animal in the form of wood, crop residue, cattle dung, manure, sewage etc. Biomass energy is of the following type: • Energy plantation: Solar energy is trapped by green plants through photosynthesis and converted into biomass energy which can be trapped either by burning directly or by getting converted into burnable gas or fuel by processing. Example: Plantation of cottonwood, leucaena etc. • Petro-crops: latex containing plants such as euphorbias and oil palms are rich in hydrocarbon and can yield fuel oil at high temperature and pressure. • Agricultural and urban waste: Such as crop residue, animal excreta is used to generate Biogas. It is a mixture of methane, carbon dioxide hydrogen and hydrogen sulphide produced due to anaerobic decomposition of animal and plant waste. It is a non-polluting, clean and low cost fuel especially used in rural areas. The sludge left over after decomposition of waste acts as fertilizer for agricultural land. Biogas are produced in the Biogas plant which are of two type depending upon their design: • Floating gas holder type • Fixed dome type.

16. BIOFUELS: Biomass can be fermented to produce ethanol and methanol which can be used as fuel. Plants such as sugarcane, sugar beet, corn etc are planted to produce ethanol. Ethanol is non polluting fuel however its calorific value is lower than the petrol. • Gasohol: It is a mixture of Gasoline and ethanol, commonly use in transportation sector. Its use is prevalent in Brazil and Zimbabwe. • Methanol: Burn at lower temperature than gasoline or diesel and also it is non-polluting fuel. • Hydrogen as a Fuel: Hydrogen have a high calorific value(150 kilojoules/gram) so it can serve as important fuel, however it is highly inflammable and explosive in nature so it use require safe handling. As present it is used in the spaceship as liquid hydrogen. Hydrogen can be produced by: • Thermal dissociation of water(3000°k) to produce H2. • electrolytic dissociation of water by flowing current through it. • photolysis of water in presence of sunlight.

17. Non-renewable source of energy: This group include fossil fuels like coal, petroleum, natural gas and nuclear energy. The original source of energy for fossil fuels are solar energy and their formation takes much longer time. 1) Coal : coal fired thermal power plant support 40% of total electricity generation of world. In case of India it support 69% of electricity generation. Thermal power plant uses Rankine cycle for power generation. Coal is used as fuel to produce steam from water which in turn run the turbine and produce electricity.

18. There are three type of coal based on their carbon content, anthracite(90%), bituminus(80%) and lignite(70%). India has about 5% of world coal but coal quality is not good in term of heat capacity. The major coal states of India are Jharkhand, Orissa, West Bengal, Madhya Pradesh, Andhra Pradesh and Maharashtra. Burning of coal is one of the major cause of air pollution.

19. Petroleum: It is the life line of global economy. There are 13 countries in the world which have 67% of total petroleum reserve together form the OPEC( organization of petroleum exporting country). The crude petroleum is a complex mixture of alkane hydrocarbon which is purified and refined by the process of fractional distillation to give various products like petroleum gas, kerosene, petrol, diesel, fuel oil, lubricating oil, paraffin wax, asphalt, plastic etc. Petroleum is cleaner fuel compared to coal as it leave no residue after burning. In India oil fields are located at Digboi(Assam), Gujarat plains and Bombay High, Offshore areas in deltaic coast of Godavari, Krishna, Cauvery and Mahanadi. Liquefied Petroleum Gas (LPG): The petroleum gas mainly contain butane, propane and ethane and can easily converted to liquid form under high pressure. LPG gas is mainly used in domestic cooking purpose is odourless gas often added with ethyl mercaptan ( a foul smelling gas) to detect the leakage of gas. Environment problem associated with Petroleum: 1) Air Pollution: Oil-powered vehicle emit carbon dioxide, sulphur dioxide, nitrous oxide, carbon monoxide and Particulate matter. Use of leaded petrol has severe affects on human health including neurological damage. Use of unleaded petrol reduces this effect however it contain benzene and butadiene which are carcinogenic compound.

20. 2) Accident at Oil drill sites: Accident either caused by human error or natural calamity results into large discharge of crude oil in offshore region. Example: April 2010 accident in BP owned oil drill site in Gulf of Mexico results into spillage of 5 million barrels of crude oil in the offshore ecosystem which seriously damage the coastal ecosystem. 3) Oil Slick: Mainly results due to spillage from the offshore oil well, cleaning of oil tankers and shipwrecks. When oil spill take place it form a floating layer of oil on the surface of ocean due to lower density of oil is know as oil Slick, it reduces the penetration of sunlight thereby reducing the primary productivity of the area. Natural Gas: It is mainly composed of methane(95%) with small amount of propane and ethane. It is the cleanest fossil fuel with high calorific value( 50Kj/g). Russia has maximum reserve(40%) followed by Iran(14%) and USA(7%). In India gas fields are present in Tripura, Jaisalmer, Off-shore area of Mumbai and the Krishna-Godavari Delta. Compressed natural gas (CNG) is used as substitute of petrol and Diesel in vehicle. Public transport system in Delhi completely switch to CNG for fuel requirement leading to improve air quality of the city. Synthetic natural gas (SNG) is produced from low grade coal through gasification process followed catalytic conversion to methane.

21. Nuclear Energy: Nuclear energy is harnessed by the process nuclear fission in naturally occurring radioactive element Uranium 235 and Thorium 232. U235 is most commonly used material in nuclear power plant, where energy released due to fission of radioactive material is used to heat the steam for turbine rotation. The energy released form 1kg of U235 is equivalent to that produced by burning 3,000 t of coal.

22. There are now 439 nuclear reactors in operation around the world in over 30 countries, providing almost 16% of the world’s electricity. India has 19 nuclear power plants in, which generates 4,560 MW (2.9% of total installed base) and 4 such power plants are in the pipeline and would be generating around 2,720 MW. Advantage of Nuclear energy: 1) Clean fuel: Electricity generation not release green house gases. 2) It is more economical due to high energy value and low fuel requirement compare to fossils fuels. Disadvantage of Nuclear energy: 1) Nuclear accident: Accident in the nuclear plant either due to human error( Chernobyl, Russia) or due to natural calamity( Fukushima, Japan) results into release of radionuclide in the environment which has long term effect such as death, cancer and genetic deformities. The affect is not only limited to the accident site but spread to large area with prevalent wind or ocean current. Example: Chernobyl Nuclear Power Plant in Ukraine suffer melting of reactor core in 26 April 1986, caused the largest uncontrolled radioactive release into the environment for about 10 days. Causing death of 28 people and displacement of 220,000 people from the vicinity of nuclear reactor. Other example is Three Mile Island, USA.

23. Disposal of radioactive waste material: The management, storage and disposal of radio active wastes resulting from nuclear power generation are the biggest expenses of the nuclear power industry. The waste varies in term of left over radioactivity in low level waste (medical or industrial waste) or high level ( Spent rod from nuclear plant). The waste disposal practice include burial into "Deep borehole disposal, ocean disposal, sub sea level disposal practices.