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Energy Security and Conservation A Major Part of the Solution to Energy Generation and Environmental Degradation Dr. Mukesh Rana Assitant Professor, SSNC.

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Presentation on theme: "Energy Security and Conservation A Major Part of the Solution to Energy Generation and Environmental Degradation Dr. Mukesh Rana Assitant Professor, SSNC."— Presentation transcript:

1 Energy Security and Conservation A Major Part of the Solution to Energy Generation and Environmental Degradation Dr. Mukesh Rana Assitant Professor, SSNC Email: 8 December 2015

2 ENERGY SECURITY Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 December 2015

3 Scientists in Energy James Joule First Law of Thermodynamics Sadi Carnot Second Law of Thermodynamics Carnot Cycle Thomas Edison Light Bulb, etc. Alexander Graham Bell Telephone 8 December 2015

4 Scientists in Energy Albert Einstein E=mc² Enrico Fermi First Nuclear Reactor William Shockley Transistor Bill Gates Computers 8 December 2015

5 Topics Energy Sources and Uses Fossil Fuels Nuclear Power Energy Conservation Solar Energy Fuel Cells Biomass Energy From the Earth’s Forces What’s Our Energy Future? 8 December 2015

6 PART 1: ENERGY SOURCES AND USES Work is the application of force through a distance. Energy is the capacity to do work. Power is the rate of flow of energy, or the rate at which work is done. –A small calorie is the metric measure of energy necessary to heat 1 gram of water 1 o C, whereas a British Thermal Unit (BTU) is the energy needed to heat 1 pound of water 1 o F –A joule is the amount of work done by a force needed to accelerate 1 kilogram 1 meter per second per second. Another definition for joule is the force of an electrical current of 1 amp/second through a resistance of 1 ohm. 8 December 2015

7 Measurements 8 December 2015

8 Worldwide Commercial Energy Production 8 December 2015

9 How We Use Energy What are the commercial uses of energy? –Industry uses 38%; –Residential and commercial buildings use 36%; and, –Transportation uses 26%. Half of all energy in primary fuels is lost during conversion to more useful forms while being shipped or during use. –Nearly two-thirds of energy in coal being burned to generate electricity is lost during thermal conversion in the power plant. Another 10% is lost during transmission and stepping down to household voltages. Natural gas is the most efficient fuel. –Only 10% of its energy content is lost during shipping and processing. Ordinary gas-burning furnaces are about 75% efficient. High-economy furnaces can be 95% efficient. 8 December 2015

10 Energy Use Trends A general trend is for higher energy use to correlate with a higher standard of living In an average year, each person in the U.S. and Canada consumes more than 300 times the amount of energy consumed by a person in one of the poorest countries of the world; however, Several European countries have higher living standards than the U.S., yet they use about half as much energy. Per Capita Energy Use & GDP 8 December 2015

11 E NERGY RESOURCE AVAILABILITY IN I NDIA SourceCapital cost (crores/MW) Emissions (t CO2-eq/Mwh) ReservesLongevity Coal4-51.110 5820 MT70 years Oil2.50.621200 MT~ 10 years Gas3.50.471.5 TCM~ 20 years Hydro6- 20 (Site and size dependant) 0148.7 GWNA Nuclear8-13070,000 tonnes of Uranium ~ 200 tonnes of Pu 40 years with Uranium Source : BP statistical review report, NHPC,NTPC 8 December 2015

12 I NDIA ' S ENERGY ASPIRATIONS Annual GDP growth projection : 8 – 9% Elasticity of electricity : GDP ~ 0.95 Net electricity generation required in 2020 : 1850 billion units – per capita electricity consumption in 2020 : ~ 1200 kWh – Still, well below world average of 2800 kWh India has announced intent to reduce CO2 intensity: GDP by 20-25% from 2005 levels by 2020 Multiple objectives for Indian energy policy – Access for all – Reliability – Low cost – Low carbon – Energy Security 8 December 2015

13 I NDIA ’ S PRIMARY ENERGY CONSUMPTION : A SNAPSHOT Source : BP statistical review of world energy, 2011; CSTEP In 2010 alone, India’s primary energy consumption grew by 9.2% 8 December 2015


15 E LECTRIC P OWER Current Capacity : 173,855 MW (utility) – 5th largest in the world Low per capita electricity consumption – India717 kWh – US14,000 kWh – China2500 kWh – World2800 kWh Peak shortage~ 15% 800,000 MW in 2030 – 40 – ~ 25,000 MW per year Environmental concerns – India 3rd largest emitter of CO2 behind China and US – 38% of emissions from power sector Energy security concerns – 67% power from coal-based thermal plants - need to depend on imports – Prototype breeder reactors to exploit thorium reserves 8 December 2015

16 SOURCE: CEA 8 December 2015




20 E NERGY SECURITY CONCERNS Source : Telegraph, FT 8 December 2015

21 P ROJECTED FUEL MIX IN 2020 Required capacity in 2020 assuming 8% growth = 387,280 MW in BAU scenario Source : Interim report, Planning commission 2011 8 December 2015

22 How do we grow to ~ 2,000 billion kWh by 2020 How do we get 3,00 billion kWh of low-carbon power? What fuel options & technologies? Wind Nuclear, Solar Hydro Bio-fuels Carbon Sequestration Hydrogen & fuel cells Hybrid cars Investments, research, policies? H OW TO G ROW AND BE S USTAINABLE ? 8 December 2015

23 W IND POWER Power proportional to V 3 Cost of generation reasonable: ~ Rs 3 per kWh – Economics sensitive to wind speeds World total installed 194,000 MW India: – Potential: 50,000 MW based on hub height of 50 m and 2% land usage – Recent studies offer reassessed potential at 80m 6-7% land usage Onshore - 676, 000 MW Offshore - 214,000 MW – Intermittent; grid stability is a concern China44, 733 MW US40,180 MW Germany27,215 MW Spain20,676 MW India13,000 MW India - 5th in wind capacity 8 December 2015

24 SOLAR POWER JNNSM launched in 2010 targets 22,000 MW by 2022 – Phase 1 ( until March 2013) Target of 1300 MW : 800 MW PV and 500 MW CSP 25 years of guaranteed feed in tariff – Off-grid PV Target of 2000 MW by 2022 Rural applications where grid is unviable or unreachable – Challenges High nominal cost of generation : ~ Rs 15 per kWh Water scarcity issues for CSP Requirement of skilled personnel 8 December 2015

25 N UCLEAR P OWER Installed Capacity4780 MW Generation~ 23 Billion kWh (2.5 % of total) Domestic Uranium reserves~ 61,000 Tons – Poor quality ore(0.01% - 0.05% Uranium) Large Thorium deposits – But, Thorium is fertile and has to be converted to fissile U233 in a reactor Phase Nuclear Program – Phase IBuild Pressurized Heavy Water Reactors using domestic Uranium – Phase IIReprocess spent fuel from Phase I to get Plutonium for Breeder Reactors – Phase IIIUse U233 (obtained from Thorium) and use it with Plutonium Domestic Uranium reserves can sustain 10,000 MW PHWR for 40 years – Low capacity factors due to Uranium mining constraints 8 December 2015

26 I NDIAN NUCLEAR POWER PROGRAM TypeOperatingProjections (2020) Projections (2030) Heavy Water Reactors 4,460 MW 10,000 MW Light Water Reactors 320 MW 9,300 MW22,000 MW Fast Breeder Reactors - 1,500 MW Total4780 MW 20,800 MW33,500 MW Nuclear capacity presently under construction : 5300 MW 8 December 2015


28 POTENTIAL R&D DOMAINS New and affordable materials for photovoltaic Clean coal technologies; carbon capture and sequestration Low-speed wind power Cellulosic ethanol Efficient and affordable hybrids, electric vehicles Energy storage – efficient batteries and condensers Demand side management of power Trained human resource 8 December 2015

29 Conservation of Energy 8 December 2015

30 PART 4: ENERGY CONSERVATION Hybrid gas-electric automobile 8 December 2015

31 ENERGY CONSERVATION – Most potential energy in fuel is lost as waste heat. – In response to 1970’s oil prices, average US automobile gas- mileage increased from 13 mpg in 1975 to 28.8 mpg in 1988. Falling fuel prices of the 1980’s, however, discouraged further conservation. Energy Conversion Efficiencies Energy Efficiency is a measure of energy produced compared to energy consumed. –Household energy losses can be reduced by one-half to three- fourths by using better insulation, glass, protective covers, and general sealing procedures. Energy gains can be made by orienting homes to gain passive solar energy in the winter. 8 December 2015


33 Definition Conservation of energy refers to efforts made to reduce energy consumption and to increase efficiency of energy use. 8 December 2015

34 Conservation of Energy P.E  K.E.  P.E.  K.E. … Is energy lost? No! Energy is converted! 8 December 2015

35  Conserve Electricity  Conserve Natural Gas  Conserve Water So On ………... What does conserve energy mean? What does conserve energy mean? 8 December 2015

36 Energy Conservation Consider safety first Saving energy is important, but avoid measures that have negative impacts on people and communities  All existing and potential health and safety issues should be evaluated prior to implementing any conservation measures Safety First! 8 December 2015

37 Law of Conservation of Energy Energy can be neither created nor destroyed. The total energy in a “closed” system is always the same. The energy may be in different forms, but the amount will be equal. 8 December 2015

38 Conservation of Energy Thermal Energy produced by friction is not useful energy-Why? It IS NOT used to do work. 8 December 2015


40 Perpetual Motion A machine that would run forever without the addition of energy. Some energy is wasted due to the thermal energy produced, so perpetual motion is not possible. So how does the “drinking bird” work? 8 December 2015

41 Technically, the Drinking Bird is a type of "Heat Engine". But thankfully you won't need a degree in physics or thermodynamics to understand the basics of how it works! The body of the bird comprises 2 glass "bulbs", one for the head and The glass tube which interconnects the two bulbs dips deep into a special liquid (usually coloured methylene chloride) in the body. ANATOMY OF A HAPPY DRINKING BIRD - HOW IT WORKS - The techie stuff. An important fact is that the bird will "drink" providing the head bulb is slightly cooler than the body bulb (i.e. there is a "temperature differential"). 8 December 2015

42 ANATOMY OF A HAPPY DRINKING BIRD - HOW IT WORKS - The techie stuff. Technically, the Drinking Bird is a type of "Heat Engine". But thankfully you won't need a degree in physics or thermodynamics to understand the basics of how it works! The body of the bird comprises 2 glass "bulbs", one for the head and The glass tube which interconnects the two bulbs dips deep into a special liquid (usually coloured methylene chloride) in the body. one for the lower body. An important fact is that the bird will "drink" providing the head bulb is slightly cooler than the body bulb (i.e. there is a "temperature differential"). The head is usually coated in a red felt-like material which absorbs water when the bird "drinks". Evaporation of water from the head causes the head to become cooler than the body. By lucky coincidence, the swaying motion of the bird assists the evaporation. Although the head and upper part of the glass tube appear to be "empty", they are actually full of invisible vapour from the methylene chloride. Methylene chloride is good for this because it doesn't take much heat energy to turn it into a vapour (It has a "low latent heat of evaporation"). Because the head is cooler than the body, some of this vapour condenses inside the head, like steam when it touches a cold window. As this vapour "shrinks" into minute droplets of fluid, it takes up a lot less space. This makes the pressure inside the head slightly lower than the body, causing the liquid to be sucked up the tube. You could also think of it as the "hot" fluid in the body making "steam" above itself, which blows the liquid up the tube (vapour pressure); it's all relative. The main thing is, the body is always warmer than the head. It's not the same a thermometer, though, because it does not rely on expansion of the liquid itself, which is insignificant. It's the pressure of the vapour that does the work. As the liquid rises up the tube, it gradually changes the centre of gravity of the bird. This makes it tip over more and more until eventually it tilts into the water. If everything is adjusted just right, then as it tilts over, the end of the tube inside the body comes out of contact with the liquid. Instead of pushing the liquid up the tube, the vapour above the liquid in the body can now quickly rush up the tube, equalising the pressures in head and body. As this happens, the liquid which has moved up towards the head now gurgles back down into the body. This rapidly moves the centre of gravity back to the lower body, and the bird swings back away from the glass. When you understand how the bird works, you will see how you can even "trick" it to "dip" with no water at all: If you shine a lamp towards only the bottom part of the bird, this slightly warms it (compared to the head), so there is the necessary "temperature differential" and it should "dip". If you have just shown your friends how the bird works (with water), then you may perhaps puzzle them again by removing the glass, and watching it continue to drink long even though the head has become dry, secretly using the warmth from a lamp nearby (which may have been on before). Take care, though, because excessive heat will burst the glass and make a terrible mess! (Thanks to Jan at "Arabesk" for this interesting trick 8 December 2015

43 “Zero energy” new homes 8 December 2015


45 Lighting Compact Fluorescents or Long Fluorescents using plasma discharges use only 1/3 of the energy and heat of incandescent lights, which derive their light from heating filaments hot enough to emit visible light. If every home changed their five most used lights, they would save $60 per year in costs. This would also be equal to 21 power plants. The fluorescents also last up to 10 times as long. Replacing one bulb means 1,000 pounds less CO2 emitted over the compact fluorescent’s lifetime. Traffic signal LEDs use 90% less energy and last 10 years rather than 2 years. 8 December 2015

46 Additional Advantages of Energy Conservation (Moralizing) Less need to secure oil overseas with attendant military and civilian casualties while costing hundreds of billions of dollars Fewer power plants and liquid natural gas ports are needed Less air pollution Less drilling for oil in Alaska and near national parks Less global warming and attendant environmental destruction 8 December 2015

47 Conclusions on Energy Conservation Energy conservation has saved the need for many power plants and fuel imports. It has also avoided CO2 and environmental pollution. Regulations on efficiency work, but voluntary efforts lag far behind. Much has been done, but much more can be done In this new era of global warming and high energy costs and energy shortages, the public must be informed and politicians sought who are sensitive to these issues. 8 December 2015

48 PART 6: FUEL CELLS Fuel cells use ongoing electrochemical reactions to produce electrical current Fuel cells provide direct-current electricity as long as supplied with hydrogen and oxygen. Hydrogen is supplied as pure gas, or a reformer can be used to strip hydrogen from other fuels. Fuel cells run on pure oxygen and hydrogen produce only drinkable water and radiant heat. Reformer releases some pollutants, but far below conventional fuel levels. Fuel cell efficiency is 40-45%. Positive electrode (cathode) and negative electrode (anode) separated by electrolyte which allows charged atoms to pass, but is impermeable to electrons. Electrons pass through external circuit, and generate electrical current. 8 December 2015

49 PART 7: BIOMASS 8 December 2015

50 Fuelwood Crisis Currently, about half of worldwide annual wood harvest is used as fuel. – Eighty-five percent of fuelwood is harvested in developing countries. By 2025, worldwide demand for fuelwood is expected to be twice current harvest rates while supplies will have remained relatively static. About 40% of world population depends on firewood and charcoal as their primary energy source. – Of these, three-quarters do not have an adequate supply. Problem intensifies as less developed countries continue to grow. – For urban dwellers, the opportunity to scavenge wood is generally nonexistent. 8 December 2015

51 Fuelwood Crisis in Less-Developed Countries About 40% of the world’s population depends on firewood and charcoal as their primary energy source. Supplies diminishing Half of all wood harvested worldwide is used as fuel. 8 December 2015

52 Using Dung as Fuel Where other fuel is in short supply, people often dry and burn animal dung. When burned in open fires, 90% of potential heat and most of the nutrients are lost. Using dung as fuel deprives fields of nutrients and reduces crop production. When cow dung is burned in open fires, 90% of the potential heat and most of the nutrients are lost. 8 December 2015

53 Using Methane As a Fuel 8 December 2015

54 Alcohol from Biomass Ethanol (grain alcohol) production could be a solution to grain surpluses but thermodynamic considerations question it being practical on a sustainable basis. Gasohol (a mixture of gasoline and alcohol) reduces CO emissions when burned in cars. Ethanol raises octane ratings, and helps reduce carbon monoxide emissions in automobile exhaust. Methanol (wood alcohol) Both methanol and ethanol make good fuel for fuel cells. 8 December 2015

55 PART 8: ENERGY FROM EARTH'S FORCES Water power produces 25% of the world’s electricity and it is clean, renewable energy. Dams cause social and ecological damage. Wind Geothermal Tidal Wave Hydropower 8 December 2015

56 Hydropower – By 1925, falling water generated 40% of world’s electric power. Hydroelectric production capacity has grown 15-fold, but fossil fuel use has risen so rapidly that now hydroelectric only supplies one-quarter of electrical generation. Total world hydropower potential estimated about 3 million MW. – Currently use about 10% of potential supply. Energy derived from hydropower in 1994 was equivalent to 500 million tons of oil. Much of recent hydropower development is in very large dams. Drawbacks to dams include: – Human Displacement – Ecosystem Destruction – Wildlife Losses – Large-Scale Flooding Due to Dam Failures – Sedimentation – Herbicide Contamination – Evaporative Losses – Nutrient Flow Retardation 8 December 2015

57 Wind Energy Wind power - advantages and disadvantages Wind farms - potential exists in Great Plains, along seacoasts and Eastern Washington 8 December 2015

58 This energy source involves the use of high-pressure, high- temperature steam fields that exist below the earth’s surface. Geothermal Energy 8 December 2015

59 Tidal & Wave Energy Ocean tides and waves contain enormous amounts of energy that can be harnessed. –Tidal Station - Tide flows through turbines, creating electricity. It requires a high tide/low- tide differential of several meters. –Main worries are saltwater flooding behind the dam and heavy siltation. –Stormy coasts with strongest waves are often far from major population centers. 8 December 2015

60 Part 9:An Alternative Energy Future? 8 December 2015

61 Why is renewable energy important? Renewable energy is important because of the benefits it provides. The key benefits are: Energy for our next … generation :Renewable energy will not run out ever.Other sources of energy are finite and will some day be depleted. Clean Energy sources : Renewable energy such as wind, solar, water etc. does not cause carbon dioxide emissions, and therefore does not contribute to climate change, like burning fossil fuels does. Jobs and the economy : Most renewable energy investments are spent on materials and workmanship to build and maintain the facilities, rather than on costly energy imports. Renewable energy investments are usually spent within the country, frequently in the same state, and often in the same town. This means energy need at home would create jobs and fuel local economies, rather than going overseas. Meanwhile, renewable energy technologies developed and built in the country are being sold overseas, providing a boost to the trade deficit. Energy security : After the oil supply disruptions of the early 1970s, our nation has increased its dependence on foreign oil supplies instead of decreasing it. This increased dependence impacts more than just our national energy policy. The use of renewable energy provide energy security for us. Renewable energy technologies are clean sources of energy that have a much lower environmental impact than conventional energy technologies. Wind, water, solar, geothermal are all resources capable of sustaining humankind for all the energy we need.

62 Choice of Energy Resources.

63 Taking this idea further… Vehicle Heat Trapping using Thermocouple But again…What really is Entropy?

64 Taking this idea further… Vehicle speed induced wind Trapping using windmills Today waste crisis and the continuing emphasis on energy efficiency (conservation of fuel resources) has led to a complete overhaul of the way in which power systems are analyzed and improved thermodynamically. The laws of physics himself do not offer any solution but can provide with an importance guidelines, insight and inspiration to direct our effort towards economic and ecological use of energy resources. The integration of these thermodynamic laws into energy resources hinges on a limits of environmental impacts. The entropy is almost related to waste or energy and a good choice of energy resource help in minimizing entropy change. It is renewable resources which produces low waste by maintaining low entropy change and reuse within system. These resources help in maintaining thermodynamical equilibrium and also provide energy security for us.

65 Taking this idea further… Vehicle mass impact Trapping using piezoelectricity But again…What really is Entropy? Recent globalization of Indian market loaded with a heavy dose of traffic and have caused and credited speedy transport of heavy vehicles on the highways that is spread across our whole country/land. This high speed of heavy vehicle necessarily exerts intense vibrations over and inside of highway surface. The energy radiated from these vibrations goes dissipated or wasted into surroundings and may be a cause of environmental pollution(apparent or hidden) wasted. In those pips we initiated to lip and harvest this energy of vibrations and wish to identify and scrutinize and derive ways so that a methodology could be developed.

66 8 December 2015

67 THANK YOU 8 December 2015


69 D EMAND - SIDE MEASURES : SMART GRIDS Indian Institute of Science & CSTEP – “Smart grid” test bed in IISc campus – Consortium of technology provider companies Ministry of Power (under R-APDRP) 8 December 2015

70 B IOFUEL P OTENTIAL India’s total land area328 million hectares (mha) – Cultivated142 mha – Cultivable wasteland30 mha – Rice40 mha – Wheat 26 mha Hazardous to divert agricultural area for bio-fuels. If entire wasteland used for growing bio-fuels, – Produce about 30 million tons of bio-oil – 10% of oil demand by 2031. Advisable to cultivate on such a large area? 8 December 2015

71 E THANOL O PPORTUNITIES Increase yield of sugarcane using drip irrigation & fertigation – Present average yield~ 80 tons per ha – Using drip irrigation & fertigation150 tons per ha Sweet sorghum: – Less water intensive than sugarcane – Two crops a year Cellulosic ethanol from agro-forest residues such as bagasse, rice husk, wood chips, crop residues. – Technology needs to be developed 8 December 2015

72 W HAT CAN 1 H ECTARE D O ? Bio-Fuels indirectly use solar energy Why not do it directly? Solar Option 1 Sugarcane Option 2 Corn Ethanol Option 3 Jatropha Option 4 Sweet Sorghum Option 5 Solar Sugarcane: 80 tons No Sugar Cane juice used to make ethanol. Ethanol: 6000 Liter per hectare Corn Yield: 7500 Kg per hectare Ethanol: 0.37 Liter per kg 2800 Liter per hectare 2000 to 3000 Trees per hectare Seed yield: 1 to 2 Kg per tree Oil Yield: 1 to 1.5 Ton per hectare Stalk yield: 35 – 50 tons per hectare Juice Extraction 45 – 50% Ethanol: 2500 to 3500 Liters per hectare Average daily radiation: 5- 6 kWh/m2 250 days of sunshine 50% area covered by PV panels 10% Efficiency of solar cells 8 December 2015

73 L AND REQUIRED ( HA /1000 MW) Source : NPCIL & CSTEP 8 December 2015

74 PART 2: FOSSIL FUELS Fossil fuels are organic chemicals created by living organisms that were buried in sediments millions of years ago and transformed to energy-rich compounds. Because fossil fuels take so long to form, they are essentially nonrenewable resources.  Coal  Oil  Natural Gas 8 December 2015

75 Oil Coal Natural Gas 8 December 2015

76 Coal Extraction and Use Mining is dangerous to humans and the environment Coal burning releases large amounts of air pollution, and is the largest single source of acid rain in many areas. Economic damages are billions of rupees Billions of tons of coal are burned the world over for electric power generation. As a result, multiple pollutants are released such as: –Sodium Dioxide (18 million metric tons) –Nitrogen Oxides ( over 5 million metric tons) –Particulates (over 4 million metric tons) –Hydrocarbons (over 600,000 metric tons) –Carbon Dioxide (over 1 trillion metric tons) 8 December 2015

77 Oil Extraction and Use The countries of the Middle East control two-thirds of all proven-in-place oil reserves. Saudi Arabia has the most. The U.S. has already used up about 40% of its original recoverable petroleum resource. Oil combustion creates substantial air pollution. Drilling causes soil and water pollution. Often oil contains a high sulfur level. Sulfur is corrosive, thus the sulfur is stripped out before oil is shipped to market. Oil is primarily used for transportation providing > 90% of transportation energy. Resources and proven reserves for the year 2000 are 650 billion barrels (bbl). 800 bbl remain to be discovered or are currently not recoverable. 8 December 2015

78 Natural Gas Consumption Proven world reserves and resources of natural gas equal 3,200 trillion cubic feet. This equals a 60 year supply at present usage rates. Natural gas produces only half as much CO 2 as an equivalent amount of coal. Problems: difficult to ship across oceans, to store in large quantities, and much waste from flaring off. World’s third largest commercial fuel (23% of global energy used). Produces half as much CO 2 as equivalent amount of coal. Most rapidly growing used energy source. 8 December 2015

79 PART 3: NUCLEAR POWER President Dwight Eisenhower, 1953, “Atoms for Peace” speech. –Eisenhower predicted that nuclear-powered electrical generators would provide power “too cheap to meter.” –Between 1970-1974, American utilities ordered 140 new reactors, but 100 were subsequently canceled. Nuclear power now produces only 7% of the U.S. energy supply. Construction costs and safety concerns have made nuclear power much less attractive than was originally expected. –Electricity from nuclear power plants was about half the price of coal in 1970, but twice as much in 1990. 8 December 2015

80 How Do Nuclear Reactors Work The common fuel for nuclear reactors is U 235 that occurs naturally (0.7%) as a radioactive isotope of uranium. U 235 is enriched to 3% concentration as it is processed into cylindrical pellets (1.5 cm long). The pellets are stacked in hollow metal rods (4 m long). 100 rods are bundled together into a fuel assembly. Thousands of these fuel assemblies are bundled in the reactor core. When struck by neutrons, radioactive uranium atoms undergo nuclear fission, releasing energy and more neutrons.This result triggers a nuclear chain reaction. This reaction is moderated in a power plant by neutron- absorbing solution (Moderator). Control Rods composed of neutron-absorbing material are inserted into spaces between fuel assemblies to control reaction rate. Water or other coolant is circulated between the fuel rods to remove excess heat. 8 December 2015

81 Nuclear fission occurs in the core of a nuclear reactor 8 December 2015

82 Kinds of Reactors 70% of nuclear power plants are pressurized water reactors (PWRs). Water is circulated through the core to absorb heat from fuel rods. The heated water is then pumped to a steam generator where it heats a secondary loop. Steam from the secondary loop drives a high-speed turbine making electricity. Both reactor vessel and steam generator are housed in a special containment building. This prevents radiation from escaping and provides extra security in case of accidents. Under normal operations, a PWR releases little radioactivity. 8 December 2015

83 Reactor Design 8 December 2015

84 Radioactive Waste Management Production of 1,000 tons of uranium fuel typically generates 100,000 tons of tailings and 3.5 million liters of liquid waste. –Now approximately 200 million tons of radioactive waste exists in piles around mines and processing plants in the U.S. About 100,000 tons of low-level waste (clothing) and about 15,000 tons of high-level (spent-fuel) waste in the US. –For past 20 years, spent fuel assemblies have been stored in deep water-filled pools at the power plants. (designed to be temporary). –Many internal pools are now filled, and a number plants are storing nuclear waste in metal dry casks outside. A big problem associated with nuclear power is the disposal of wastes produced during mining, fuel production, and reactor operation. –U.S. Department of Energy announced plans to build a high-level waste repository near Yucca Mountain Nevada in 1987. –Cost is $10-35 billion, and earliest opening date is 2010. –This allows the government to monitor & retrieve stored uranium. 8 December 2015

85 PART 5: SOLAR ENERGY Photosynthesis Passive solar heat is using absorptive structures with no moving parts to gather and hold heat. Greenhouse design Active solar heat is when a system pumps a heat- absorbing medium through a collector, rather than passively collecting heat in a stationary object. Water heating consumes 15% of US domestic energy budget. Mean solar energy striking the upper atmosphere is 1,330 watts per square meter. The amount reaching the earth’s surface is 10,000 times > all commercial energy used annually. Until recently, this energy source has been too diffuse and low intensity to capitalize for electricity production. 8 December 2015

86 High-Temperature Solar Energy Parabolic mirrors (left) are curved reflective surfaces that collect light and focus it onto a concentrated point. It involves two techniques: –Long curved mirrors focus on a central tube containing a heat-absorbing fluid. –Small mirrors arranged in concentric rings around a tall central tower track the sun and focus light on a heat absorber on top of the tower where molten salt is heated to drive a steam-turbine electric generator. 8 December 2015

87 Photovoltaic Solar Energy During the past 25 years, efficiency of energy capture by photovoltaic cells has increased from less than 1% of incident light to more than 10% in field conditions, and 75% in laboratory conditions. –Invention of amorphous silicon collectors has allowed production of lightweight, cheaper cells. Photovoltaic cells capture solar energy and convert it directly to electrical current by separating electrons from parent atoms and accelerating them across a one-way electrostatic barrier. –Bell Laboratories - 1954 1958 - $2,000 / watt 1970 - $100 / watt 2002 - $5 / watt 8 December 2015

88 Photovoltaic energy - solar energy converted directly to electrical current 8 December 2015

89 Transporting & Storing Electrical Energy Electrical energy storage is difficult and expensive. –Lead-acid batteries are heavy and have low energy density. Typical lead-acid battery sufficient to store electricity for an average home would cost $5,000 and weigh 3-4 tons. –Pumped-Hydro Storage –Flywheels 8 December 2015

90 Distributional Surcharges –Small charge levied on all utility customers to help finance research and development. Renewable Portfolio –Mandate minimum percentage of energy from renewable sources. Green Pricing –Allow utilities to profit from conservation programs and charge premium prices for energy from renewable sources. Promoting Renewable Energy 8 December 2015

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