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Lecture notes on renewable energy sources, covering topics such as commercial and non-commercial energy, conventional and non-conventional energy, global primary energy reserves, nuclear and hydro power supply, final energy consumption, and sector-wise energy consumption in India. The document also includes a disclaimer stating that it cannot be used as a substitute for prescribed textbooks and that the committee members are not accountable for any issues arising out of use of this document.
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7th Semester, B.Tech. (Electrical Engineering & EEE)
This document does not claim any originality and cannot be used as a substitute for
prescribed textbooks. The information presented here is merely a collection by the committee
members for their respective teaching assignments. Various sources as mentioned at the end
of the document as well as freely available material from internet were consulted for
preparing this document. The ownership of the information lies with the respective authors
or institutions. Further, this document is not intended to be used for commercial purpose and
the committee members are not accountable for any issues, legal or otherwise, arising out of
use of this document. The committee members make no representations or warranties with
respect to the accuracy or completeness of the contents of this document and specifically
disclaim any implied warranties of merchantability or fitness for a particular purpose. The
committee members shall be liable for any loss of profit or any other commercial damages,
including but not limited to special, incidental, consequential, or other damages.
Any physical activity in this world, whether carried out by human beings or by nature, is cause due to flow of energy in one form or the other. The word ‘energy’ itself is derived from the Greek word ‘en-ergon’, which means ‘in-work’ or ‘work content’. The work output depends on the energy input.
Energy is one of the major inputs for the economic development of any country. In the case of the developing countries, the energy sector assumes a critical importance in view of the ever- increasing energy needs requiring huge investments to meet them.
Energy can be classified into several types based on the following criteria:
Primary energy sources are those that are either found or stored in nature. Common primary
energy sources are coal, oil, natural gas, and biomass (such as wood). Other primary energy
Fig1.1. Major Primary and Secondary sources
sources available include nuclear energy from radioactive substances, thermal energy stored in
earth's interior, and potential energy due to earth's gravity. The major primary and secondary
energy sources are shown in Figure 1.
Primary energy sources are costly converted in industrial utilities into secondary energy sources;
for example coal, oil or gas converted into steam and electricity. Primary energy can also be
used directly. Some energy sources have non energy uses, for example coal or natural gas can be
used as a feedstock in fertilizer plants.
Commercial Energy
The energy sources that are available in the market for a definite price are known as commercial energy. By far the most important forms of commercial energy are electricity, coal and refined petroleum products. Commercial energy forms the basis of industrial, agricultural, transport and commercial development in the modern world. In the industrialized countries, commercialized fuels are predominant source not only for economic production, but also for many household tasks of general population.
Examples: Electricity, lignite, coal, oil, natural gas etc.
Non-Commercial Energy
The energy sources that are not available in the commercial market for a price are classified as non-commercial energy. Non-commercial energy sources include fuels such as firewood, cattle dung and agricultural wastes, which are traditionally gathered, and not bought at a price used especially in rural households. These are also called traditional fuels. Non-commercial energy is often ignored in energy accounting.
Example: Firewood, agro waste in rural areas; solar energy for water heating, electricity generation, for drying grain, fish and fruits; animal power for transport, threshing, lifting water for irrigation, crushing sugarcane; wind energy for lifting water and electricity generation.
Consumption of a large amount of energy in a country indicates increased activities in these sectors. This may imply better comforts at home due to use of various appliances, better transport facilities and more agricultural and industrial production. All of this amount to a better quality of life. Therefore, the per capita energy consumption of a country is an index of the standard of living or prosperity (i.e. income) of the people of the country.
1.5 Global Primary Energy Reserves*
Coal
The proven global coal reserve was estimated to be 9,84,453 million tonnes by end of 2003. The USA had the largest share of the global reserve (25.4%) followed by Russia (15.9%), China (11.6%). India
was 4th in the list with 8.6%.
Oil
The global proven oil reserve was estimated to be 1147 billion barrels by the end of 2003. Saudi
Arabia had the largest share of the reserve with almost 23%. (One barrel of oil is approximately
160 liters)
Gas
The global proven gas reserve was estimated to be 176 trillion cubic metres by the end of 2003. The Russian Federation had the largest share of the reserve with almost 27%. (*Source: BP Statistical Review of World Energy, June 2004)
Global Primary Energy Consumption
The global primary energy consumption at the end of 2003 was equivalent to 9741 million tons of
oil equivalent (MTones). The Figure 1.3 shows in what proportions the sources mentioned above
contributed to this global figure.
Energy distribution between developed and developing Countries
Although 80 percent of the world's population lies in the developing countries (a four- fold population increase in the past 25 years), their energy consumption amounts to only 40 percent of the world total energy consumption. The high standards of living in the developed countries are attributable to high energy consumption levels.
Also the rapid population growth in the developing countries has kept the per capita energy
consumption low compared with that of highly industrialized developed countries. The world
average energy consumption per person is equivalent to 2.2 tones of coal. In industrialized
countries, people use four to five times more than the world average and nine times more than the
average for the developing countries. An American uses 32 times more commercial energy than an
Indian.
Coal dominates the energy mix in India, contributing to 55% of the total primary energy pro- duction. Over the years, there has been a marked increase in the share of natural gas in prima- ry energy production from 10% in 1994 to 13% in 1999. There has been a decline in the share of oil in primary energy production from 20% to 17% during the same period.
Energy Supply
Coal Supply
India has huge coal reserves, at least 84,396 million tones of proven recoverable reserves (at the end of 2003). These amounts to almost 8.6% of the world reserves and it may last for about 230 years at the current Reserve to Production (R/P) ratio. In contrast, the world's proven coal reserves are expected to last only for 192 years at the current R/P ratio.
Reserves/Production (R/P) ratio - If the reserves remaining at the end of the year are divided by the production in that year, the result is the length of time that the remaining reserves would last if production were to continue at that level.
Fig. 1.4: Energy Distribution Between Developed and Developing Countries
Nuclear Power Supply
Nuclear Power contributes to about 2.4 per cent of electricity generated in India. India has
ten nuclear power reactors at five nuclear power stations producing electricity. More nuclear
reactors have also been approved for construction.
Hydro Power Supply
India is endowed with a vast and viable hydro potential for power generation of which only
15% has been harnessed so far. The share of hydropower in the country's total generated units
has steadily decreased and it presently stands at 25% as on 31st May 2004. It is assessed that
exploitable potential at 60% load factor is 84,000 MW.
Final Energy Consumption
Final energy consumption is the actual energy demand at the user end. This is the difference
between primary energy consumption and the losses that takes place in transport, transmission
& distribution and refinement. The actual final energy consumption (past and projected) is
given in Table1.2.
TABLE 1.2 DEMAND FOR COMMERCIAL ENERGY FOR FINAL CONSUMPTION (BAU SCENARIO) Source Units 1994-95 2001-02 2006-07 2011- Electricity Billion Units 289.36 480.08 712.67 1067. Coal Million Tonnes 76.67 109.01 134.99 173. Lignite Million Tonnes 4.85 11.69 16.02 19. Natural Gas Million Cubic 9880 15730 18291 20853 Oil Million Tonnes 63.55 99.89 139.95 196. Source: Planning Commission _BAU:Business As Usual
Sector Wise Energy Consumption in India
The major commercial energy consuming sectors in the country are classified as shown in the Figure 1.5. As seen from the figure, industry remains the biggest consumer of commercial energy and its share in the overall consumption is 49%. (Reference year: 1999/2000)
Figure 1.5 Sector Wise Energy Consumption (1999-2000)
Economic growth is desirable for developing countries, and energy is essential for economic
growth. However, the relationship between economic growth and increased energy demand is not
always a straightforward linear one. For example, under present conditions, 6% increase in India's
Gross Domestic Product (GDP) would impose an increased demand of 9 % on its energy sector.
In this context, the ratio of energy demand to GDP is a useful indicator. A high ratio reflects
energy dependence and a strong influence of energy on GDP growth. The developed countries,
by focusing on energy efficiency and lower energy-intensive routes, maintain their energy to
GDP ratios at values of less than 1. The ratios for developing countries are much higher.
India's Energy Needs
The plan outlay vis-à-vis share of energy is given in Figure 1.6. As seen from the Figure, 18.0%
of the total five-year plan outlay is spent on the energy sector.
Figure 1.6 Expenditure Towards Energy Sector
has consistently declined from 60% in the 50s to 30% currently. Same is expected to go down to 8% by 2020. As shown in the figure 1.8, around 92% of India's total oil demand by 2020 has to be met by imports.
Natural Gas
India's natural gas production is likely to rise from 86.56 million cmpd in 2002-03 to 103.08 million cmpd in 2006-07. It is mainly based on the strength of a more than doubling of production by private operators to 38.25 mm cmpd.
Electricity
India currently has a peak demand shortage of around 14% and an energy deficit of 8.4%.
Keeping this in view and to maintain a GDP (gross domestic product) growth of 8% to 10%, the
Government of India has very prudently set a target of 215,804 MW power generation
capacity by March 2012 from the level of 100,010 MW as on March 2001, that is a capacity addition
of 115,794 MW in the next 11 years. In the area of nuclear power the objective is to achieve 20,
MW of nuclear generation capacity by the year 2020.
TABLE 1.3 INDIA'S PERSPECTIVE PLAN FOR POWER FOR ZERO DEFICIT POWER BY 2011/12 (SOURCE TENTH AND ELEVENTH FIVE-YEAR PLAN PROJECTIONS)
Thermal
(Coal) (MW)
Gas / LNG / Diesel (MW)
Nuclear
(MW)
Hydro
(MW)
Total(MW)
Installed capacity as on
March 2001 61,
Gas: 10,
Diesel: 864 2720 25,116^ 100, Additional capacity
(2001-2012)
53,333 20,408 9380 32,673 115,
Total capacity as on
March 2012
114, (53.0%)
31, (14.6%)
12, (5.6%)
57, (26.8%)
215,
Price of energy does not reflect true cost to society. The basic assumption underlying efficiency of market place does not hold in our economy, since energy prices are undervalued and energy wastages are not taken seriously. Pricing practices in India like many other developing countries are influenced by political, social and economic compulsions at the state and central level. More often than not, this has been the foundation for energy sector policies in India. The Indian energy sector offers many examples of cross subsidies e.g., diesel, LPG and kerosene being subsidized by petrol, petroleum products for industrial usage and industrial, and commercial consumers of electricity subsidizing the agricultural and domestic consumers.
Coal
Grade wise basic price of coal at the pithead excluding statutory levies for run-of-mine (ROM) coal are fixed by Coal India Ltd from time to time. The pithead price of coal in India compares favorably with price of imported coal. In spite of this, industries still import coal due its higher calorific value and low ash content.
Oil
As part of the energy sector reforms, the government has attempted to bring prices for many of the petroleum products (naphtha, furnace oil, LSHS, LDO and bitumen) in line with international prices. The most important achievement has been the linking of diesel prices to international prices and a reduction in subsidy. However, LPG and kerosene, consumed mainly by domestic sectors, continue to be heavily subsidized. Subsidies and cross-subsidies have resulted in serious distortions in prices, as they do not reflect economic costs in many cases
Natural Gas
The government has been the sole authority for fixing the price of natural gas in the country. It has also been taking decisions on the allocation of gas to various competing consumers. The gas prices varies from Rs 5 to Rs.15 per cubic meter.
Electricity
Electricity tariffs in India are structured in a relatively simple manner. While high tension consumers are charged based on both demand (kVA) and energy (kWh), the low-tension (LT) consumer pays only for the energy consumed (kWh) as per tariff system in most of the electricity boards. The price per kWh varies significantly across States as well as customer segments with- in a State. Tariffs in India have been modified to consider the time of usage and voltage level of supply. In addition to the base tariffs, some State Electricity Boards have additional recovery from customers in form of fuel surcharges, electricity duties and taxes. For example, for an industrial consumer the demand charges may vary from Rs. 150 to Rs. 300 per kVA, whereas the energy charges may vary anywhere between Rs. 2 to Rs. 5 per kWh. As for the tariff adjustment mechanism, even when some States have regulatory commissions for tariff review, the decisions to effect changes are still political and there is no automatic adjustment mechanism, which can ensure recovery of costs for the electricity boards.
In addition, photochemical reactions resulting from the action of sunlight on NO 2 and VOCs from vehicles leads to the formation of ozone, a secondary long-range pollutant, which impacts in rural areas often far from the original emission site. Acid rain is another long-range pollutant influenced by vehicle NOx emissions.
Industrial and domestic pollutant sources, together with their impact on air quality, tend to be steady- state or improving over time. However, traffic pollution problems are worsening world-wide. The problem may be particularly severe in developing countries with dramatically increasing vehicle population, infrastructural limitations, poor engine/emission control technologies and limited provision for maintenance or vehicle regulation.
The principle pollutants produced by industrial, domestic and traffic sources are sulphur dioxide, nitrogen oxides, particulate matter, carbon monoxide, ozone, hydrocarbons, benzene, 1,3- butadiene, toxic organic micro pollutants, lead and heavy metals.
Brief introduction to the principal pollutants are as follows:
Sulphur dioxide is a corrosive acid gas, which combines with water vapour in the atmosphere to produce acid rain. Both wet and dry deposition have been implicated in the damage and destruction of vegetation and in the degradation of soils, building materials and watercourses. SO 2 in ambient air is also associated with asthma and chronic bronchitis. The principal source of this gas is power stations and industries burning fossil fuels, which contain sulphur.
Nitrogen oxides are formed during high temperature combustion processes from the oxidation of nitrogen in the air or fuel. The principal source of nitrogen oxides - nitric oxide (NO) and nitrogen dioxide (NO 2 ), collectively known as NOx is road traffic. NO and NO 2 concentrations are greatest in urban areas where traffic is heaviest. Other important sources are power stations and industrial processes.
Nitrogen oxides are released into the atmosphere mainly in the form of NO, which is then readily oxidized to NO 2 by reaction with ozone.
Elevated levels of NOx occur in urban environments under stable meteorological conditions,
when the air mass is unable to disperse.
Nitrogen dioxide has a variety of environmental and health impacts. It irritates the respiratory system and may worsen asthma and increase susceptibility to infections. In the presence of sunlight, it reacts with hydrocarbons to produce photochemical pollutants such as ozone.
Nitrogen oxides combine with water vapour to form nitric acid. This nitric acid is in turn removed from the atmosphere by direct deposition to the ground, or transfer to aqueous droplets (e.g. cloud or rainwater), thereby contributing to acid deposition.
Acidification from SO 2 and NOx
Acidification of water bodies and soils, and the consequent impact on agriculture, forestry and fisheries are the result of the re-deposition of acidifying compounds resulting principally from the oxidation of primary SO 2 and NO 2 emissions from fossil fuel combustion. Deposition may be by either wet or dry processes, and acid deposition studies often need to examine both of these acidification routes.
Airborne particulate matter varies widely in its physical and chemical composition, source and particle size. PM 10 particles (the fraction of particulates in air of very small size (<10 μm)) are of major current concern, as they are small enough to penetrate deep into the lungs and so potentially pose significant health risks. In addition, they may carry surface-absorbed carcinogenic compounds into the lungs. Larger particles, combustion, where transport of hot exhaust vapour into a cooler exhaust pipe can lead to spontaneous nucleation of "carbon" particles before emission. Secondary particles are typically formed when low volatility products are generated in the atmosphere, for example the oxidation of sulphur dioxide to sulphuric acid. The atmospheric lifetime of particulate matter is strongly related to particle size, but may be as long as 10 days for particles of about 1mm in diameter.
Concern about the potential health impacts of PM 10 has increased very rapidly over recent years. Increasingly, attention has been turning towards monitoring of the smaller particle fraction PM2. capable of penetrating deepest into the lungs, or to even smaller size fractions or total particle numbers.
Carbon monoxide (CO) is a toxic gas, which is emitted into the atmosphere as a result of combustion processes, and from oxidation of hydrocarbons and other organic compounds. In urban areas, CO is produced almost entirely (90%) from road traffic emissions. CO at levels found in ambient air may reduce the oxygen-carrying capacity of the blood. It survives in the atmosphere for a period of approximately 1 month and finally gets oxidized to carbon dioxide (CO 2 ).
Ground-level ozone (O 3 ), unlike other primary pollutants mentioned above, is not emitted directly into the atmosphere, but is a secondary pollutant produced by reaction between nitrogen dioxide (NO 2 ), hydrocarbons and sunlight. Ozone can irritate the eyes and air passages causing breathing difficulties and may increase susceptibility to infection. It is a highly reactive chemical, capable of attacking surfaces, fabrics and rubber materials. Ozone is also toxic to some crops, vegetation and trees.
Whereas nitrogen dioxide (NO 2 ) participates in the formation of ozone, nitrogen oxide (NO) destroys ozone to form oxygen (O 2 ) and nitrogen dioxide (NO 2 ). For this reason, ozone levels are not as high in urban areas (where high levels of NO are emitted from vehicles) as in rural areas. As the nitrogen oxides and hydrocarbons are transported out of urban areas, the ozone-destroying NO is oxidized to NO 2 , which participates in ozone formation.
of industrial applications. Its single largest industrial use worldwide is in the manufacture of batteries and it is also used in paints, glazes, alloys, radiation shielding, tank lining and piping.
As tetraethyl lead, it has been used for many years as an additive in petrol; with the increasing use of unleaded petrol, however, emissions and concentrations in air have reduced steadily in recent years.
Climatic Change
Human activities, particularly the combustion of fossil fuels, have made the blanket of green- house gases (water vapour, carbon dioxide, methane, ozone etc.) around the earth thicker. The resulting increase in global temperature is altering the complex web of systems that allow life to thrive on earth such as rainfall, wind patterns, ocean currents and distribution of plant and animal species.
Greenhouse Effect and the Carbon Cycle
Fig 1.11 The green house effect
Life on earth is made possible by energy from the sun, which arrives mainly in the form of visible light. About 30 percent of the sunlight is scattered back into space by outer atmosphere and the balance 70 percent reaches the earth's surface, which reflects it in form of infrared radiation. The escape of slow moving infrared radiation is delayed by the green house gases. A thicker blanket of greenhouse gases traps more infrared radiation and increase the earth's temperature (Refer Figure 1.11).
Greenhouse gases makeup only 1 percent of the atmosphere, but they act as a blanket around the earth, or like a glass roof of a greenhouse and keep the earth 30 degrees warmer than it would be otherwise - without greenhouse gases, earth would be too cold to live. Human activities that are responsible for making the greenhouse layer thicker are emissions of carbon dioxide from the combustion of coal, oil and natural gas; by additional methane and nitrous oxide from farming activities and changes in land use; and by several man made gases that have a long life in the atmosphere.
The increase in greenhouse gases is happening at an alarming rate. If greenhouse gases emissions continue to grow at current rates, it is almost certain that the atmospheric levels of carbon dioxide will increase twice or thrice from pre-industrial levels during the 21st century.
Even a small increase in earth's temperature will be accompanied by changes in climate- such as cloud cover, precipitation, wind patterns and duration of seasons. In an already highly crowded and stressed earth, millions of people depend on weather patterns, such as monsoon rains, to continue as they have in the past. Even minimum changes will be disruptive and difficult.
Carbon dioxide is responsible for 60 percent of the "enhanced greenhouse effect". Humans are
burning coal, oil and natural gas at a rate that is much faster than the rate at which these fossil fuels were created. This is releasing the carbon stored in the fuels into the atmosphere and
upsetting the carbon cycle (a precise balanced system by which carbon is exchanged between
the air, the oceans and land vegetation taking place over millions of years). Currently, carbon
dioxide levels in the atmospheric are rising by over 10 percent every 20 years.
Current Evidence of Climatic Change
Cyclones, storm, hurricanes are occurring more frequently and floods and draughts are more intense than before. This increase in extreme weather events cannot be explained away as random events.
This trend toward more powerful storms and hotter, longer dry periods is predicted by computer models. Warmer temperatures mean greater evaporation, and a warmer atmosphere is able to hold more moisture and hence there is more water aloft that can fall as precipitation. Similarly, dry regions are prone to lose still more moisture if the weather is hotter and hence this leads to more severe droughts and desertification.
Future Effects
Even the minimum predicted shifts in climate for the 21st century are likely to be significant and disruptive. Predictions of future climatic changes are wide-ranging. The global temperature may climb from 1.4 to 5.8 degrees C; the sea level may rise from 9 to 88 cm. Thus, increases in sea level this century are expected to range from significant to catastrophic. This uncertainty reflects the complexity, interrelatedness, and sensitivity of the natural systems that make up the climate.
