Energy is the key to development. In fact, the amount of energy production and consumption is sometimes considered as an index of a country’s economic development.
Conventional (Non-Renewable) Energy Resources
Fossil fuels are found inside the earth’s crust where they have formed through heat and compression of forests, waste and other organic matter, which got buried due to earthquake, landslide, etc.
Classification of Fossil Fuels
(A) Solid (e.g. Coal)
Coal is the most abundantly found fossil fuel in the world. It contains carbon, water, sulphur and nitrogen. Coal meets 70 per cent of the total energy needs of the world found and 87.4 per cent of all commercial energy. In India about 58 per cent of commercial energy is obtained from coal and 38 per cent from petroleum along with natural gas.
Coal is used for cooking, heating, in industries and thermal power plants. Petroleum is useful for transportation; agricultural equipments and, some industries. Natural gas is used both in cooking and in industries.
Types of Coal or Coal Energy
The amount of fixed carbon and hydro carbons forms the basis of classification of coal into various types given as under:
• Anthracite is a hard and dense coal which is relatively free of iron compounds and moisture. The amount affixed carbon may be as high as 95 percent. It is jet black, lustrous and has a fine texture. It burns with a blue flame and gives no smoke.
• Bituminous coal is unusually black and highly lustrous. The moisture content is relatively low. The fixed carbon content ranges from about 50 to over 80% and that of volatile matter from 40 to 15 per cent.
• Lignite is also known as brown coal. The higher grades vary from dark brown to almost black. It is characterized by high moisture content, generally about 40%. The fixed carbon content is also about 40%. The structure is fibrous, and sometimes woody. It has the tendency to crumble into fine coal in shipment and in storage.
• Peat occurs in bogs, especially in areas of cool temperate climates.
Advantages of Coal
• Coal is present in large amount (Most abundant). So it can be used as an energy source.
Disadvantages of Coal
• Release of CO2 and SO2 gas in the atmosphere cause Green House Effect and Global Warming.
• In thermal power plants, burning of coal also generates large amount of flyash. Flyash is a toxic waste, contains toxic heavy metals.
• Workers in the coal mines suffer from following lung diseases: Black-lung disease, Asthma, Bronchitis, Lung cancer.
(B) Liquid (e.g. Petroleum)
Petroleum or Crude Oil
• The gaseous fuels are basically derived from petroleum. It is a natural, underground fossil energy resource. It is formed due to decomposition of micro plankton deposited upon the sea beds, lakes and rivers for millions of years. The decomposition takes place by the action of bacteria, under lack of oxygen and also by catalytic cracking. It is also called crude oil.
• The following are the various uses of petroleum:
a) For heating homes particularly in the cold regions.
b) As industrial power to drive/move engines and for heating furnaces and producing thermal electricity.
c) As transport power for driving railways, motor cars, ships and aeroplanes.
d) As lubricants of machines especially high speed machines.
e) As a raw material in various petro-chemical industries, such as synthetic rubber, synthetic fibres, fertilizers, medicines, etc.
• Advantages of Petroleum
a) Liquid fuel (Petroleum) is easy to transport.
b) Liquid fuel (Petroleum) is comparatively cleaner.
c) They have made possible the introduction and development of newer means of transport.
a) After extraction it causes contamination in the water when the leakage takes place.
b) It’s burning produces CO2 and enhances the green house effect.
c) All combustion processes produce the pollutants like NO, SO2, CO, NO2, CO2, Smog.
d) Petroleum contributes to acid rain and urban pollution.
(c) Gaseous (e.g. Natural Gas)
• Natural gas is a fossil fuel.
• It is eco-friendly fuel.
• It is a mixture, of hydrocarbon gases trapped under the earth’s surface. It is mainly consisting of methane (CH4), Propane (C3H8) and Butane (C4H10). After processing it is transported to supply filling stations. Natural gas can be used in two different forms.
1. LPG (Liquefied petroleum Gas)
It is the mixture of Propane, Butane and Ethane.
2. CNG (Compressed Natural Gas)
It is mainly Methane (CH4.).
The major uses of natural gas include:
• It is widely used as fuel in industries and in domestic cooking.
• Petro-chemical industries use natural gas as fuel and raw material.
• Chemical industries such as artificial rubber, plastics, fertilizers, ink, carbon, etc. use natural gas as raw material.
• Natural gas is sometimes used for artificial lighting.
• It is a clean fuel, requiring little processing.
• It can be readily transported.
• Smog formation is less in its use.
• It is cheaper than petroleum.
• It requires both high pressure and low temperature for compression.
• Thick walled tanks are required for storage as it is stored at a high pressure.
• Methane is a green house gas.
• Leakage, in any case, is a serious threat to the environment.
Shale gas refers to natural gas that is trapped within shale formations. Shales are fine-grained sedimentary rocks that can be rich resources of petroleum and natural gas. Sedimentary rocks are rocks formed by the accumulation of sediments at the Earth’s surface and within bodies of water. Common sedimentary rocks include sandstone, limestone, and shale.
• Unavoidable impacts are area consumption due to drilling pads, parking and manouvering areas for trucks, equipment, gas processing and transporting facilities as well as access roads.
• Major possible impacts are air emissions of pollutants, groundwater contamination due to uncontrolled gas or fluid flows due to blowouts or spills, leaking fracturing fluid, and uncontrolled waste water discharge.
• Fracturing fluids contain hazardous substances, and flow-back in addition contains heavy metals and radioactive materials from the deposit. Groundwater contamination by methane, in extreme cases leading to explosion of residential buildings, and potassium chloride leading to salinization of drinking water is reported in the vicinity of gas wells.
• The impacts add up as shale formations are developed with a high well density (up to six wells per km²).
Coal bed Methane
• Coal Bed Methane is methane (natural gas) trapped in coal seams underground.
• To extract the gas, after drilling into the seam, it is necessary to pump large amounts of water out of the coal seam to lower the pressure.
• It is often also necessary to frack the seam to extract the gas.
• There are a similar catalogue of negative environmental and social effects as with Shale Gas.
• This includes methane migration, toxic water contamination, air pollution, increased carbon emissions and a general industrialisation of the countryside. Impacts that are specific to CBM include depletion of the water table and potentially subsidence.
• It is a highly developed alternative for energy production in place of coal.
• Nuclear energy by can be derived by two processes: Nuclear Fission, Nuclear Fusion.
• Nuclear Fission (Chain-Reaction Mechanism)
a) The heavy nucleus on bombardment with neutron splits into lighter nuclei (Barium and Krypton) releases large amount of energy. One a.m.u. (Atomic Mass Unit) of uranium-235 yield energy equal to burning of 15 metric tons of coal.
b) Nuclear reactors are the devices need to liberate energy from nuclear fuels, under controlled conditions. The output of these reactors is in the form of a high temperature fluid. This can be used in the generation of electricity or as a direct source of heat for intensive industries.
• Advantages of Nuclear Energy
a) Large amount of energy is produced in nuclear fission reaction.
• Disadvantages of Nuclear Energy
a) High safety measures are required in the operations of Nuclear Reactors.
b) Highly equipped (knowledge + equipments) engineers are required for operating nuclear reactors.
c) Radioactive waste is released from Nuclear Power plants. It cannot be buried inside the earth and under the groundwater.
d) Due to high safety measures, nuclear reactors are located in isolated areas. To reduce the risks. Nuclear power plants are far distance away from the industries that require high energy in the areas of high population.
e) Due to uncontrolled nuclear fission reaction in the nuclear reactor, explosion Occurs. e.g. Chernobyl nuclear disaster in Chernobyl, 1986 and Fukushima nuclear disaster, 2011.
• Due to radioactive pollution of iodine-131; Cesium 134, Cesium 137, thousands of people died and suffered from variety of diseases biz. loss of hair, thyroid; blood cancers, nausea, anaemia and ulcerating skirt:
• Large social and economic loss occurred.
• Genetic Diseases: Sudden change in the genes is known as mutation, causes genetic diseases. Atom bomb explosion in Hiroshima Nagasaki, Japan also caused genetic diseases and large socio-economic loss.
Renewable Energy Resources
• Solar energy is available in very large amount, thus considered perpetual energy resource and is considered major future source of energy.
• Ultimate source of energy in an ecosystem is Sun.
• Solar energy influences earth’s climate. Wind energy, biomass and hydropower are the resultant of solar energy.
Applications of Solar energy
A. Photovoltaic: Conversion of Solar Energy of Electricity
• Semiconductors when irradiated with sunlight, electrons present in their ground state get energized to jump to an excited state i.e. flow of electrons occur and generates electricity. The phenomenon is known as Photovoltaic’s (PVs).
• Thus, Photovoltaic’s are the arrays of cells consisting of semiconductors that effectively converts solar radiation into electricity (Direct Current), used to power bulb or equipment or to recharge a battery. An inverter converts DC to AC for, grid connected power generation.
B. Solar Thermal
• Solar Thermal Power systems, also known as Concentrating Solar Power systems, use concentrated solar radiation as a high temperature energy source to produce electricity using thermal route.
C. Other Applications of Solar Energy
• Solar cooker
• Solar water heater
• Solar furnace
• Solar power plant
• Solar toys
• Solar air-conditioning
• Solar vehicles
• Solar chimney
• Space cooling and heating
• Day lighting (solar street lights and traffic lights)
• Solar desalination
Advantages of Solar Energy
(i) It is renewable energy resource.
(ii) Solar power is pollution free.
(iii) Solar powered instruments are easy to install and use e.g. solar panels, solar water heaters, solar lighting, solar Pumps, solar fountains.
(iv) Long life and low maintenance.
(v) Solar system based electricity is a cheaper source of energy as compared to energy obtained from conventional electric systems.
(vi) Solar Photovoltaics are used for the electricity generation in remote and isolated areas e.g. forest, hills, deserts. PV is frequently used in watches, pocket calculators and toys.
Disadvantages of Solar Energy
(i) Solar energy production is hampered when the Sun is not available (i.e. during nights, less sunny days and cloudy days).
(ii) Technology is to be kept advancing in such a way to efficiently capture the solar radiations over a larger area.
(iii) Initial cost of installation is high. In case of photovoltaic cell, price of silicon wafers makes it very costly.
(iv) Solar cooking is a long time taking process. The food kept in the container can be over-heated if not removed from solar-cooker timely.
(v) Solar cooker cannot work as a substitute of LPG chullas because all type of foods cannot be prepared in solar cooker, e.g., chapatti.
Potential available in India
• India is endowed with vast solar energy potential. About 5,000 trillion kWh per year energy is incident over India’s land area with most parts receiving 3-5 kWh per sq. m per day. Based upon the availability of land and solar radiation, the potential of solar power in the country has been assessed to be 750 GW.
Generation of electricity by using the force of falling water is called hydro electricity or hydel power. It is cheaper than thermal or nuclear power. Dams are built to store water at a higher level; which is made to fall to rotate turbines that generate electricity.
The basic principle behind hydropower energy is the damming of rivers to create artificial in waterfalls, sometimes natural waterfalls are also used. The falling water is used to turn the turbines that drive electrical generators.
(i) Clean source of energy (eco-friendly or non-polluting).
(ii) Cheaper than thermal power plants.
(iii) Other benefits e.g. fishing, beauty of land- area.
(i) Reservoir Induced Seismicity (RIS). The continuous pressure of water column on the earth core increases the probability of occurrences of earthquakes.
(ii) Water-borne and water induced diseases are caused.
(iii) Flood is caused if leakage occurs in the dam.
India is blessed with immense amount of hydro-electric potential and ranks 5th in terms of exploitable hydro-potential on global scenario. As per assessment made by CEA, India is endowed with economically exploitable hydro-power potential to the tune of 148700 MW of installed capacity.
Wind energy is the kinetic energy associated with the movement of atmospheric air. Wind energy systems convert this kinetic energy to more useful forms of power.
The Indian wind energy sector has an installed capacity of 23,439.26 MW (as on March 31, 2015). In terms of wind power installed capacity, India is ranked 5th in the World. Today India is a major player in the global wind energy market.
(i) Cost of production is not high, can be reduced by research.
(ii) Initial investment is moderate.
(iii) Operation and maintenance cost is not high.
(v) Available in large amount.
(vi) Produce more energy due to high efficiency.
(vi) Land below turbines can be used for growing crops and stock (animal) grazing.
(i) Availability depends on steady (continuous) winds or climate.
(ii) Unsteady winds affect power production.
(iii) Noise pollution (a) due to rotation of blades; (b) due to rotation of turbines.
(iv) Large open area is required for electricity production.
Geothermal Energy is the energy obtained from heat stored in the earth crust and used for various purposes like electricity generation or direct heating applications. Geothermal energy is basically stored in earth crust up to depth of 3 to 4 km.
Hot water and steam from deep underground can be piped up through underground wells and used to generate electricity in a power plant.
Benefits of Geothermal Energy
• It is a clean fuel as compared to fossil fuel such as oil, gas or coal. A geothermal field emits only 1/6th CO2 as compared to any clean natural gas fired power plant. Binary plants are further less polluter among all geothermal power plants.
• Ground Source Heat Pumps can be a good source of saving money for consumers by reducing electricity bill as it includes only capital cost and maintenance cost is very less.
• The capital cost of geothermal power plant is very high but average units produced per year is very high as compared to other renewable energy resources such as solar, hydro, wind, etc.
• Salts and dissolved minerals contained in geothermal fluids are usually re-injected with excess water back into the reservoir at a depth well below groundwater aquifers. This system prolongs the life of the reservoir as it recycles the treated waste water.
• Geothermal Energy (Other than Power) can also be applied in Cold Storage, Tourist Resorts and pools, Melting snow, Poultry & Fish Farming, Mushroom Farming, Horticulture, Greenhouses, Aquaculture, Industrial processes, Space heating, etc.
Geothermal Energy in India
In India, exploration and study of geothermal fields started in 1970. The GSI (Geological Survey of India) has identified 350 geothermal energy locations in the country. The most promising of these is in Puga valley of Ladakh. The estimated potential for geothermal energy in India is about 10000 MW.
The major sites for geothermal energy are:
• Himalayas: J&K, HP and Sikkim; PUGA hot spring in J&K and Manikaran in HP.
• Sohana: Haryana, Rajasthan.
• Son-Narmada-Tapi (SONATA): MP, Chhattisgarh and Jharkhand; Tattapani spring in Chhattisgarh.
• Cambay: Mainly Gujarat and some parts of Rajasthan
• Godavari: AP
• Mahanadi: Orissa, Taptapani Spring in Orissa.
Hydrogen as a source of energy
• Hydrogen energy is at present only at the Research, Development and Demonstration (RD&D) stage.
• Hydrogen is burned electrochemically with oxygen to produce electricity. Electrodes are clipped in electrolyte preferably Sodium Hydroxide.
• Hydrogen and oxygen is passed in the fuel cell and following chemical reaction generates electricity:
Advantages of Hydrogen
(i) Hydrogen has highest calorific value (150 kj/g). Thus it is an excellent fuel.
(ii) It is an eco-freindly source of energy.
(iii) Source of hydrogen (water) is present in large amount.
(iv) Simplest and lightest fuel in gaseous form.
Disadvantages of Hydrogen
(i) Hydrogen gas is highly explosive (inflammable).
(ii) High (safety measures) are required in storage an transportation saferty measure.
(iii) Production of hydrogen is costly.
Biogas is a combustible mixture of gases consists mainly of methane (CH4) and carbon dioxide (CO2) and is formed from the anaerobic bacterial decomposition of organic compounds, i.e. without oxygen. The gases formed are the waste products of the respiration of these decomposer microorganisms and the composition of the gases depends on the substance that is being decomposed.
The principal benefits of biogas include:
a) Conversion of natural organic waste into fertilizer: The conversion is carried out in a machine called the polythene bio gas digester. Cow dung slurry is put into the machine. The product is organic fertilizer of high quality. The fertilizer obtained is rich in nitrogen. It has been analyzed, that, fertilizer made by the polythene bio gas digester contains nitrogen content 3 times more than the product made by conventional processes. It is completely natural and free from harmful synthetic chemicals.
b) Eco friendly energy production: The calorific value of biogas is equal to that of half liter of diesel oil (6 kWh/m3). Methane is a key component of the gas. Biogas is fully capable of replacing other rural energy sources like wood, hard coal, kerosene, plant residues, and propane. Hard coal possesses a calorific value of 8.5kWh/kg per 0.7 kilograms. Larger biogas plants generate and feed electricity into mainstream power grids. Smaller biogas production units can support lighting and cooking requirements.
c) Considerable workload reduction in rural areas: This is particularly true for rural women engaged in day to day household work. Installing a biogas unit will relieve her of the tiring and tedious job of collecting and ferrying firewood. Since, biogas burns cleanly, the rural homes will not suffer from smoke and consequently rural denizens will suffer less from physical problems like bronchial complications. Cooking is also easier with a gas stove and takes less time.
d) Visible improvement in rural hygiene: Biogas contributes positively to rural health conditions. Biogas plants lower the incidence of respiratory diseases. Diseases like asthma, lung problems, and eye infections have considerably decreased in the same area when compared to the pre-biogas plant times. Biogas plants also kill pathogens like cholera, dysentery, typhoid, and paratyphoid.
e) Environmental benefits on a global scale: Biogas plants significantly lower the greenhouse effects on the earth’s atmosphere. The plants lower methane emissions by entrapping the harmful gas and using it as fuel.
f) Protects the earth’s natural resources: 1 biogas plant is computed to save 32 liters of kerosene and 4 tons of firewood every year. The organic chemical plant also contributes indirectly to the protection of soil.
Disadvantages of Biogas:
a) The process is not very attractive economically (as compared to other biofuels) on a large industrial scale.
b) It is very difficult to enhance the efficiency of biogas systems.
c) Biogas contains some gases as impurities, which are corrosive to the metal parts of internal combustion engines.
d) Not feasible to locate at all the locations.
• Biodiesel is an alternative fuel for diesel engines that is produced by chemically reacting a vegetable oil or animal fat with an alcohol such as methanol. The reaction requires a catalyst, usually a strong base, such as sodium or potassium hydroxide, and produces new chemical compounds called methyl esters. It is these esters are known as biodiesel.
• Biodiesel can be used in its pure form (B100) or blended with petroleum diesel. Common blends include B2 (2% biodiesel), B5, and B20.
• The following plant species are known to be good sources for the biodiesel
1. Jatropha curcas (Jatropha)
2. Pongamia pinnata (Karanj)
3. Azadirachta indica (Neem)
4. Madhuca indica (Mahua)Advantages of Bio Diesel
• Bio Diesel is the most valuable form of renewable energy that can be used directly in any existing, unmodified diesel engine.
• Producing more biofuels will save foreign exchange and reduce energy expenditures and allow developing countries to put more of their resources into health, education and other services for their neediest citizens.
• Biofuels burn more cleanly than gasoline and diesel. Using biofuels means producing fewer emissions of carbon monoxide, particulates, and toxic chemicals that cause smog, aggravate respiratory and heart disease, and contribute to thousands of premature deaths each year.
Marine Energy or Ocean Energy
a. Wave Energy
• Wave energy is generated by the movement of a device either floating on the surface of the ocean or moored to the ocean floor.
• Wave conversion devices that float on the surface have joints hinged together that bend with the waves. This kinetic energy pumps fluid through turbines and creates electric power.
a) Wave energy has this advantage over solar or wind energy that the energy has been naturally concentrated by accumulation over time and space and transported from the point at which it was originally present in the winds.
b) A much greater amount of power is concentrated in the waves than in the wind. If we compare the power concentrated in a good wind energy to the corresponding area having wave energy then we will find that wave energy is 100 times greater than wind energy.
c) It is a free and renewable energy source.
d) Wave power devices do not need huge land masses like solar energy wind energy.
e) These devices are almost pollution-free. After removing the energy from the waves waters are left in a placid state.
f) No wastes or greenhouse gases are produced in the process. In my opinion this is the most important advantage of wave energy.
a) The major demerit of wave energy, in comparison to wind, is that the energy is available in the ocean. So the equipment needed for the extraction of wave energy must operate in a marine environment. The transportation of energy is a great factor because the energy produced needed to be transferred to a great distance from the shore.
b) Wave energy converters must be capable of withstanding very severe peak stresses in storms.
c) Finding a proper site for the extraction of energy from the wave is pretty tough because wave energy is totally related to ocean!
d) Devices needed for the harnessing of the wave energy are very complicated.
e) Many economic factors are important in the installation of a wave energy based power plant. These factors are capital, maintenance cost, repair cost as well as replacement cost. For the power generation companies economic factors can play as the major disadvantage of wave energy.
b. Tidal Energy
• The tidal cycle occurs every 12 hours due to the gravitational force of the moon. The difference in water height from low tide and high tide is potential energy.
• Similar to traditional hydropower generated from dams, tidal water can be captured in a barrage across an estuary during high tide and forced through a hydro-turbine during low tide.
• To capture sufficient power from the tidal energy potential, the height of high tide must be at least five meters (16 feet) greater than low tide.
• There are only approximately 20 locations on earth with tides this high and India is one of them.
• The Gulf of Cambay and the Gulf of Kutch in Gujarat on the west coast have the maximum tidal range of 11m and 8m with average tidal range of 6.77m and 5.23m respectively.
Advantages of Tidal Energy:
a) It is an inexhaustible source of energy.
b) Tidal energy is environment friendly energy and doesn’t produce greenhouse gases.
c) As 71% of Earth’s surface is covered by water, there is scope to generate this energy on large scale.
d) We can predict the rise and fall of tides as they follow cyclic fashion.
e) Efficiency of tidal power is far greater as compared to coal, solar or wind energy. Its efficiency is around 80%.
f) Although cost of construction of tidal power is high but maintenance costs are relatively low.
g) Tidal Energy doesn’t require any kind of fuel to run.
h) The life of tidal energy power plant is very long.
i) The energy density of tidal energy is relatively higher than other renewable energy sources.
Disadvantages of Tidal Energy:
a) Cost of construction of tidal power plant is high.
b) There are very few ideal locations for construction of plant and they too are localized to coastal regions only.
c) Intensity of sea waves is unpredictable and there can be damage to power generation units.
d) Influences aquatic life adversely and can disrupt migration of fish.
e) The actual generation is for a short period of time. The tides only happen twice a day so electricity can be produced only for that time.
f) Frozen sea, low or weak tides, straight shorelines, low tidal rise or fall are some of the obstructions.
g) This technology is still not cost effective and more technological advancements are required to make it commercially viable.
h) Usually the places where tidal energy is produced are far away from the places where it is consumed. This transmission is expensive and difficult.
c. Ocean Thermal Energy Conversion (OTEC)
• Ocean Thermal Energy Conversion is a technology that converts solar radiation to electric power.
• OTEC systems use the ocean’s natural thermal gradient, consequently the temperature difference between the warm surface water and the cold deep water below 600 meters by about 20o C, an OTEC system can produce a significant amount of power. The oceans are thus a vast renewable resource, with the potential to help us produce billions of watts of electric power.
• OTEC has a potential installed capacity of 180,000 MW in India.
Advantages of OTEC:
a) OTEC uses clean, renewable, natural resources. Warm surface seawater and cold water from the ocean depths replace fossil fuels to produce electricity.
b) Suitably designed OTEC plants will produce little or no carbon dioxide or other polluting chemicals.
c) OTEC systems can produce fresh water as well as electricity. This is a significant advantage in island areas where fresh water is limited.
d) There is enough solar energy received and stored in the warm tropical ocean surface layer to provide most of present human energy needs.
e) The use of OTEC as a source of electricity will help reduce the state’s almost complete dependence on imported fossil fuels.
Disadvantages of OTEC:
a) OTEC produced electricity at present would cost more than electricity generated from fossil fuels at their current costs.
b) OTEC plants must be located where a difference of about 20º C occurs year round.
c) Ocean depths must be available fairly close to shore-based facilities for economic operation.
d) Construction of OTEC plants and lying of pipes in coastal waters may cause localised damage to reefs and near-shore marine ecosystems.
e) Discharging the cold water at the oceans’ surface could change local concentrations of nutrients and dissolved gases.