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Challenges & Achievements of 21st Century

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1 Challenges & Achievements of 21st Century
Prof. R. P. Tandon Materials Laboratory at University of Delhi (MatsLab, DU) Department of Physics and Astrophysics University of Delhi, Delhi , India Home page:

2 Scheme of talk Nanotechnology Metamaterials Other Advance Materials
Challenges: Environmental and Pollution Energy: Renewable Sources Harvesting of Energy

3 Nanotechnology

4 Introduction One of the most fascinating field of the present day material science is Nanotechnology. The movement from bulk to the atomic scale has revolutionized the present day science. Nanotechnology research has been tremendously accelerated and is still emerging field.

5 Introduction Nanoscience, that is the observation, understanding and manipulation of matter at the nanometer scale is expected to have a strong impact on tomorrow’s products. Various areas benefit from these developments, such as materials science, medicine and information technology. Information and communication technologies (ICT) have already derived much benefit from the downsizing of components.

6 Nanotechnology One nanometer is the amount a man's beard grows in the time it takes him to lift a razor to his face. “Nano” – From the Greek word for “dwarf” and means 10-9, or one billionth. 10-9 meters = 1 nanometer (nm). 1 nanometer is about 3 atoms long. “Nanotechnology” – Manufacturing materials, devices and machines at the nanometer, or atomic/molecular, scale.

7 How small is a nanometer? (and other small sizes)
1 cm Start with a centimeter. Now divide it into 10 equal parts. Now divide that into 10 equal parts. Now divide that into 100 equal parts. Finally divide that into 100 equal parts. A centimeter is about the size of a bean. Each part is a millimeter long. About the size of a flea. Each part is 100 micrometers long. About the size (width) of a human hair. Each part is a micrometer long. About the size of a bacterium. Each part is a 100 nanometers long. About the size of a virus. Each part is a nanometer. About the size of a few atoms or a small molecule. 1 mm 100 mm 1 mm 100 nm 1 nm

8 What is really Nanotechnology all about?
Tailoring the bulk property of any material Interesting results at nano scale range Size effect Enhancement in sensitivity Enhanced storage capacity

9 Standard it can address
Nanotechnology Idea Standard it can address The idea of “Nano” – being small Structure of Atoms Nanomaterials have a high surface area (nanosensors for toxins) Structure and properties of matter, Personal and Community Health Synthesis of nanomaterials and support chemistry (space propulsion) Chemical Reactions Shape Memory Alloys Motion and Forces, Abilities of technological design, Understanding about science and technology Nanocrystalline Solar Cells Conservation of Energy and increase in disorder (entropy), Interactions of energy and matter, Natural Resources Nanocoatings resistive to bacteria and pollution Personal and Community Health, Population Growth, Environmental Quality, Natural and human-induced hazards i

10 "Imagine a technology so powerful nano revolution that allow such feats as desktop manufacturing, cellular repair, artificial intelligence, inexpensive space travel, clean and abundant energy, and environmental restoration; a technology so portable that everyone can reap its benefits; a technology so fundamental that it will radically change our economic and political systems; a technology so imminent that most of us will see its impact within our lifetimes. Such is the promise of Nanotechnology." - Kai Wu, Institute of Nanotechnology. How It Started The central premise of the nanotechnology revolution is that any stable chemical structure that can be described can be built. This possibility was first advanced by Richard Feynman in 1959 when he said: "The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom." His talk entitled "There Is Plenty Room At the Bottom" has become a classic milestone.

11 Why small is good? Faster Lighter Can get into small spaces Cheaper
More energy efficient Different properties at very small scale

12 The color of gold changes as the particle size changes at the nanometer scale.
Chad Mirkin, Northwestern University, in NYTimes article by K. Chang

13 The melting point of gold decreases rapidly as the particle dimension reaches the nanometer scale.
Melting point of gold as a function of gold particle diameter m.p. bulk 1000 Tmelting (oC) 500 Particle Diameter (nm) Reference: Buffat and Borel, Phys. Rev. A, vol. 13, p. 2287,1976.

14 Effect of size on properties
Optically speaking, as the size of the particle decreases, the wavelengths of absorption and emission decrease CdSe Quantum dots

15 Examples of Nanotechnology Applications
Supercomputer in your palm, perhaps made from silicon nanowires, carbon nanotubes, or organic materials such as DNA Very tiny motors, pumps, gyroscopes, and accelerometers; helicopters the size of flies or smaller Tiny bio- and chemical-sensors; nanoparticles that track and destroy cancer cells; artificial body parts and implantable drug delivery systems Nano-composite materials and embedded nano-particles for stain and wrinkle resistant clothes, for transparent zinc oxide sunscreen, and for photo ink that never fades

16 Iron nanoparticles to clean poisons from water
Gold nanoparticles, some coated with antibodies, that fluoresce and heat up can track and destroy cancer cells (University of Illinois, Georgia Tech, Rice, U. Texas, and UCSF) Iron nanoparticles to clean poisons from water Carbon nanotube transistor for future computer chips

17 Much of the motivating force and technology for nanotechnology came from integrated circuit industry. Intel’s transistors As with the fabrication of integrated circuits, nanotechnology is based on building structures and systems at very small sizes.

18 How do you build something so small?
Tools are needed to image, analyze, and manipulate very small features - Scanning Probe Microscopy, including the Atomic Force Microscope (AFM) laser sample surface piezoelectric stage cantilever probe probe tip photo detector AFM tip, used to manipulate, image and measure atomic scale features.

19 Relative size of clean room contaminants
How do you build something so small? Requires very clean environment: “clean room” Relative size of clean room contaminants Magnified image of contaminant on wafer surface, which can cause defects and failures in nanostructures A lab user

20 AFM image of mineral surface showing atomic structure.
AFM image of CD surface. Quesant AFM image of mineral surface showing atomic structure. Positioning single atoms with scanning tunneling microscope (Xe on Ni). Eigler, IBM, 1990. Other scanning probe microscopes measure other properties, such as electrical and magnetic.

21 Current Applications Utilizing the Optical Properties of QD’s
Light-emitting diodes Fluorescence Tags Lasers Advantages: Nanocrystals (QDs) have very narrow emission spectrum. Using nanocrystals you can get much purer color emissions. The color of light emitted can be tuned simply by manipulating the size of the nanocrystal used rather than using a completely different molecule.

22 Nanotechnology- in future
Nano-motor Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube, nanomotors, a molecular actuator, An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at Cornell University in They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage.

23 Metamaterials

24 Metamaterials What are metamaterials?
-Artificial materials that exhibit electromagnetic responses generally not found in nature. Double negative (DNG, i.e. ε<0 and μ<0). Negative Refractive Index (NRI, i.e. n<0). Left-Handed (E-field, H-field, and wave vector don’t obey right-hand rule.) Back-ward wave (Energy flow and wave vector are anti-parallel.) There are also single-negative materials (SNG), i.e. either ε<0 or μ<0.

25 Metamaterials Overview Meta: Greek prefix meaning “Beyond”
Metamaterial = “Meta” + “Material” Meta: Greek prefix meaning “Beyond” “Metamaterials” are synthetic structures that possess electromagnetic properties “beyond” conventional materials They gain electromagnetic properties from their structure as opposed to their intrinsic material property The goal is to give a structure an “effective” permittivity and permeability by providing electric and magnetic responses using artificial metallic inclusions. These effective parameters are the result of averaging the spatial fields across the material.

26 What happens to Snell’s law when n is negative?
It is still true and just wave bends so that the refracted wave remains in the same side of the normal as the incident wave.

27 How do metamaterials make something appear invisible?
Duke University's David R. Smith suggests this: Imagine a fabric woven of thread. In this fabric, light is only allowed to flow over the threads (meaning it can't travel into the nooks and crannies between the threads). If you punch a hole in the fabric with a pin, light will go around the hole and resume its original course of travel, since light can only travel over the thread. So to the light waves, the hole doesn't exist. If you put an object in the hole, the light waves would go around the object too, effectively rendering the object invisible

28 Theory of Metamaterials
They guide light around an object, rather than reflect or refract the light. So to the light waves -- and the human eye that perceives them -- the object might as well not even be there! If the light waves can be guided by the metamaterials around the object and back to its original course, the object wouldn't cast a shadow, either. This is another goal of using metamaterials to create cloaking devices.

29 Fundamental Property of metamaterials is the ability to produce negative refraction.

30 Other Advanced Materials

31 Solid Metal Organic (plastics) Inorganic Single crystal Ceramics Glass
Functional Functional (Technical) Optical

32 SENSOR MATRIALS Sensor Materials System are non-living systems that integrate the functions of sensing, actuation, logic and control to respond to changes in their conditions or the environment to which they are exposed, in a useful & repetitive manner. Ceramics Shape memory alloys Optical fiber Conductive polymers


34 Popular Ceramic Materials
Stimulus Type Materials Thermal NTC Thermistor Transistion metal spinels, PTC heater barium titanate Chemical Gas Cubic ZrO2, TiO2, SnO2, Humidity Al2O3, MgCr2O4 Mechanical Piezoelectric PZT ceramics Optical glass fibres Electrical Varistor ZnO Phosphor YAG, Y2O3 Optical Laser YAG:Nd, Filter Photochromic glass Magnetic Memory Ferrites, YIG

35 Ferroelectrics Ferroelectrics are characterized by the presence of spontaneous polarization Ps which may be reoriented between two or more equivalent directions by the application of a large electric field. There are in total 32 crystal classes 21: Non centrosymmetric 20: P/E  Piezoelectric 10: possess unique polar axis: Pyroelectrics Temperature dependence of spontaneous polarization It is only those pyroelectric crystals which possesses 2 or more equivalent axis, between which the polarization may be switched that are defined as “Ferroelectrics” In a large number of ferroelectrics, equivalent orientation sttes may be obtained by rotation about two or four fold axis. Switching of S. P. by electric field is called “Polarization reversal”

36 + l l + + l + l l + + l + l + l + l + + l l l + + + l l + + + l l l +
Poling axis + l

37 where stress T causes strain S, Y is elastic modules
Direct P/E Effect T=YS where stress T causes strain S, Y is elastic modules D (charge per unit area)= Q/A=DT “d” constant is C/N Converse Effect Applied Field E produces strain S, Expansion or Contraction Depending on Ploarity S=dE (d is expressed as m/V) d=D/T=S/E g constant; g=d/έ Coupling constant: Electrical energy into mechanical energy Total Electrical energy

38 Perovskite Structure (BaTiO3)
Similar Perovskites Pb (Zr, Ti) O3 - (PZT) Barium Oxygen Titanium

39 Application of ferroelectrics / P-E
High voltage generator - gas igniters Ultrasound MEDICAL IMAGING Eye – Ear of Navy – SONAR hydrophones Harnessing of Ocean Sensors and Actuators Ultrasonic flaw detection New memories Dielectric resonator

40 SMART SYSTEM Composites Ceramics SMART SENSORS (EYE) Polymers
Crystals SMART SENSORS (EYE) ELECTRONICS (BRAIN) LOGICAL DECISION 3. ACTUATOR (ARM) : Electromechanical Electrostrictive e.g. (i) Drung Delivery: Insulin (ii) Adjustable Wings: Aircraft (iii) Collision Avoidance: Smart Highways (iv) Artificial Muscles (v) Self Repairing Bridges/ Building


42 SENSOR Gather information, of, mech,. biological, chemical, Magnetic
SENSOR Gather information, of, mech, biological, chemical, Magnetic processes. ELECTRONICS Process information through sensors and through some decision making processes direct the actuators to respond. ACTUATOR Moving, positioning, regulating, there by controlling the environment.


44 Sound Channel - SOFAR Channel
1.0 KM Sound Channel - SOFAR Channel

45 Velocity (m/s) 1550 1500 1510 1520 1530 1540 500 1000 2000 2500 3000 3500 I II III Depth (m)




49 Ferroelectric Memories
Semiconducting type Static Random Access Memory (SRAM) Dynamic Random Access Memory (DRAM) Read Only Memory (ROM, and EEPROM) Magnetic Memories Magnetic Bubble. Permalloy Films etc. Essential Features: Capacity Read access and write access times Operating and storage temperature For Non-Volatile Memories Retention Endurance

50 Polarization Ps Pr VR is read voltage VW(0)=write 0 VW(1)=-VR=write 1
dP(I) Vc VR Pr Ps Problem areas: Leakage Current Dielectric Breakdown Reliability Aging Fatique Candidate Materials: PZT 6-25 microC/cm2 PLT microC/cm2 PLZT 5-17 microC/cm2

51 C storage=  oA / d I-T DRAM: Features Small memory area
Reduction in Cost per Bit Uses Less Power Reliable C storage=  oA / d To optimize: d , A, o d: reduce thickness of the film A: Increase area o :Look for alternative materials like Y2O3, Ta2O5 etc. Charge storage density Qc= C(V) Improvent Factor=K*Em(alt. Diel.) /(K*Em(SiO2) Em is maximum sustainable electric field. This shows 7 times in charge storage needed for 256 Mbit DRAM (1~m m2)

52 Photonic Crystal Artificial structures with the optical equivalent of the energy gap is semiconductors promise a wealth of new devices that could satisfy the demand for ever-faster computers and optical communications. MOORE’S LAW 4K 1M 1GHz 16K 256K 16M 64M 16GHz Min. Dim. (mm) 1976 80 84 88 92 96 2000 2004

53 Home control system

54 NASA’s Morphing Program
Future Air-Car NASA’s Morphing Program


56 Global Warming

57 GLOBAL WARMING Hurricane Wilma hit Florida’s southern west coast on 24 October 2005.

58 Climate Change and Global Warming
“Climate change" refers to a change in the state of the climate that can be identified by changes in the mean and/or variability of its properties, and that persists for extended periods, typically decades or longer. The climate change referred to may be due to natural causes or the result of human activity. “Global warming” is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Green-House Effect contributes for Global Warming where heat is trapped inside earth’s atmosphere.

59 Today main reason attributed to climate change is Global Warming
Today main reason attributed to climate change is Global Warming. The effects, or impacts, of climate change may be physical, ecological, social or economic. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the Northern Hemisphere. According to Intergovernmental Penal on Climate Change (IPCC), "[most] of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in [human greenhouse gas] concentrations". It is predicted that future climate changes will include further global warming (i.e., an upward trend in global mean temperature), sea level rise, and a probable increase in the frequency of some extreme weather events.

60 Schematic of the natural greenhouse effect.

61 Greenhouse Gases THE GREENHOUSE gases are those gases in the atmosphere which, by absorbing thermal radiation emitted by the Earth’s surface, have a blanketing effect upon it. The most important of the greenhouse gases is water vapour, but its amount in the atmosphere is not changing directly because of human activities. The important greenhouse gases that are directly influenced by human activities are carbon dioxide, methane, nitrous oxide, the chlorofluorocarbons (CFCs) and ozone .

62 Rice paddy fields have an adverse environmental impact because of the large quantities of methane gas they generate. World methane production due to paddy fields has been estimated to be in the range of 30 to 90 million tonnes per year.

63 What causes global warming?
Carbon dioxide and other air pollution that is collecting in the atmosphere like a thickening blanket, trapping the sun's heat and causing the planet to warm up. Coal-burning power plants are the largest U.S. source of carbon dioxide pollution -- they produce 2.5 billion tons every year. Automobiles, the second largest source, create nearly 1.5 billion tons of CO2 annually. Good news: technologies exist today to make cars that run cleaner and burn less gas, modernize power plants and generate electricity from nonpolluting sources, and cut our electricity use through energy efficiency. The challenge is to be sure these solutions are put to use.

64 Is the earth really getting hotter?
Yes. Although local temperatures fluctuate naturally, over the past 50 years the average global temperature has increased at the fastest rate in recorded history. And experts think the trend is accelerating: the 10 hottest years on record have all occurred since Scientists say that unless we curb global warming emissions, average U.S. temperatures could be 3 to 9 degrees higher by the end of the century.

65 Which country is the largest source of global warming pollution?
The United States. Though Americans make up just 4 percent of the world's population, they produce 25 percent of the carbon dioxide pollution from fossil-fuel burning -- by far the largest share of any country. In fact, the United States emits more carbon dioxide than China, India and Japan, combined. Clearly America ought to take a leadership role in solving the problem. And as the world's top developer of new technologies, they are well positioned to do so -- they already have the know-how.


67 Global warming-Climate Change: Consequences
Agriculture: Health: Floods and Weather Disaster: Heat and Cold Waves: Diseases

68 Effect on Weather Regional effects of global warming vary in nature. Some are the result of a generalised global change, such as rising temperature, resulting in local effects, such as melting ice. In other cases, a change may be related to a change in a particular ocean current or weather system. In such cases, the regional effect may be disproportionate and will not necessarily follow the global trend. South Atlantic hurricane, "Catarina", which hit Brazil in March 2004

69 Effect on Oceans Oceans serve as sinks for carbon dioxide, taking up much that would otherwise remain in the atmosphere, but increased levels of CO2 have led to ocean acidification and thus decreasing ocean pH. As the temperature of the oceans increases, they become less able to absorb excess CO2. Oxygen depletion: The amount of oxygen dissolved in the oceans may decline, with adverse consequences for ocean life

70 Effect on Agriculture Climate change will impact agriculture and food production around the world due to: the effects of elevated CO2 in the atmosphere, higher temperatures, altered precipitation and transpiration regimes, increased frequency of extreme events, and modified weed, pest, and pathogen pressure.

71 Possible Effect of Higher Concentration of CO2 on agriculture
Higher CO2 levels lead to reduced plant uptake of nitrogen resulting in crops with lower nutritional value. This would primarily impact on populations in poorer countries less able to compensate by eating more food, more varied diets, or possibly taking supplements. Reduced nitrogen content in grazing plants has also been shown to reduce animal productivity in sheep, which depend on microbes in their gut to digest plants, which in turn depend on nitrogen intake.

72 In the long run, the climatic change could affect agriculture in several ways :
productivity, in terms of quantity and quality of crops agricultural practices, through changes of water use (irrigation) and agricultural inputs such as herbicides, insecticides and fertilizers environmental effects, in particular in relation of frequency and intensity of soil drainage (leading to nitrogen leaching), soil erosion, reduction of crop diversity rural space, through the loss and gain of cultivated lands, land speculation, land renunciation, and hydraulic amenities. adaptation, organisms may become more or less competitive, as well as humans may develop urgency to develop more competitive organisms, such as flood resistant or salt resistant varieties of rice.

73 Conifer forest showing trees damaged by ‘acid rain’
Conifer forest showing trees damaged by ‘acid rain’. An important factor that will influence the future concentrations of sulphate particles is ‘acid rain’ pollution, caused mainly by the sulphur dioxide emissions. This leads to the degradation of forests and fish stocks in lakes, especially in regions downwind of major industrial areas.

74 Heat and Cold Waves Hot days, hot nights and heat-waves have become more frequent. In August 2003, a heat-wave in Europe resulted in excess mortality in the range of 35,000 total deaths. Cold-waves continue to be a problem in northern latitudes, where very low temperatures can be reached in a few hours and extend over long periods. Reductions in cold-deaths due to climate change are projected to be greater than increases in heat-related deaths in the UK.

75 Global Warming and Implications for INDIA
The effects of global warming on the Indian subcontinent vary from the submergence of low-lying islands and coastal lands to the melting of glaciers in the Indian Himalayas, threatening the volumetric flow rate of many of the most important rivers of India And South Asia. In India, such effects are projected to impact millions of lives. As a result of ongoing climate change, the climate of India has become increasingly volatile over the past several decades; this trend is expected to continue.

76 Dominating Aspects of Global Warming and Climate Change in INDIA
Economic Social Pollution

77 Effect of Global Warming and Climate Change on Indian Economy
The Indira Gandhi Institute of Development Research has reported that, if the predictions relating to global warming made by the Intergovernmental Panel on Climate Change come to fruition, climate-related factors could cause India's GDP to decline by up to 9%; contributing to this would be shifting growing seasons for major crops such as rice, production of which could fall by 40%. Around seven million people are projected to be displaced due to, among other factors, submersion of parts of Mumbai and Chennai, if global temperatures were to rise by a mere 2 °C. Villagers in India's North Eastern state of Meghalaya are also concerned that rising sea levels will submerge neighboring low-lying Bangladesh, resulting in an influx of refugees into Meghalaya which has few resources to handle such a situation.

78 Lakshdweep faces danger of submergence.
If severe climate changes occur, Bangladesh will lose land along the coast line. This will be highly damaging to Bangalies especially because nearly two-thirds of Bangladeshis are employed in the agriculture sector, with rice as the single-most-important product. The economy has grown 5-6% over the past few years despite inefficient state-owned enterprises, delays in exploiting natural gas resources insufficient power supplies, and slow implementation of economic reforms. However, Bangladesh remains a poor, overpopulated, and inefficiently-governed nation. If no further steps are taken to improve the current conditions global warming will affect the economy severely worsening the present issues further. Lakshdweep faces danger of submergence.

79 Effect of Global Warming on Social Scenario in India
Climate Change in India will have a disproportionate impact on the more than 400 million that make up India's poor. This is because so many depend on natural resources for their food, shelter and income. More than 56% of people in India work in agriculture, while many others earn their living in coastal areas. For majority of these peoples for whom climate change will mean hunger, food insecurity, and destruction of livelihoods

80 What can I do to help fight global warming?
Make conserving energy a part of your daily routine. DRIVE SMARTER CARS Choose an efficient vehicle: High-mileage cars such as hybrids and plug-in hybrids use less gas and save money. Over its lifetime, a 40-mpg car will save roughly $3,000 in fuel costs compared with a 20-mpg car. Compare fuel economy performance before you buy. Drive smart. If all Americans kept their tires properly inflated, gasoline use nationwide would come down 2 percent. A tune-up could boost your miles per gallon anywhere from 4 to 40 percent, and a new air filter could get you 10 percent more miles per gallon. GREEN HOMES AND BUILDINGS Weatherize your home or apartment. Heating and cooling consume about 40 percent of energy in the home. Sealing drafts and making sure that your home has adequate insulation are two easy ways to become more energy-efficient. Buy energy-efficient appliances. Look for the Energy Star label, which identifies the most efficient appliances. Replace your light bulbs with compact fluorescent bulbs. Compact fluorescent bulbs (CFLs) last 10 times longer than incandescent bulbs. What's more, CFLs lower your energy bills and keep a half-ton of carbon dioxide out of the air. BETTER COMMUNITIES AND TRANSPORTATION Drive less. Choose alternatives to driving such as public transit, biking, walking and carpooling, and bundle your errands to make fewer trips. Choosing to live in a walkable "smart growth" community near a transportation hub will mean less time driving, less money spent on gas and less pollution in the air.


82 Energy In physics, energy is often understood as the ability a physical system to do work on the other physical systems.

83 Did you know… ...that the incandescent light bulb has an energy efficiency of only 5%, and the rest of the energy is used to generate heat rather than light? ... that methane has 25 times the impact of carbon dioxide as a greenhouse gas. … that 1 unit saved at end use is equivalent to 2 units generated in the power plant. …that if motor rewinding is not done properly , the efficiency will reduce by 5 to 8%. …that every time you open the refrigerator door, up to 30 percent of the cold air can escape. …glass produced from recycled glass instead of raw materials reduces related air pollution by 20%, and water pollution by 50% ...that in 2004, the worldwide energy consumption of the human race was 15 TW (= 1.5 x 1013 W) with 86.5% from burning fossil fuel. ...that recycling aluminium saves 95% of the energy cost of processing new aluminium.


85 Currently, there are five viable sources of renewable energy that we as humans can take advantage of

86 Wind Energy Wind Energy is generated by harnessing the kinetic energy of atmospheric air. Wind Energy has had been in use for centuries for several other purposes such as sailing, irrigation and for grinding grain. Wind power systems transform kinetic energy of the wind into useful sources of power. During ancient times, wind power systems were used for both milling and irrigation. It was during the early years of the 20th century that wind power was started to be harnessed for generation of electricity. Windmills have also been used in several countries to pump water. Wind turbines work by transforming the Wind Energy into mechanical power that can be used for conversion to electricity or for other mechanical purposes like grinding. Wind turbines are used either as stand-alone units or in groups known as Wind Farms. Small-sized wind turbines, known as aero generators are used for charging large-sized batteries. More than 80% of the global Wind Energy capacity is installed in 5 countries with India at the 5th position. Wind power is the fastest growing source of renewable energy globally with an established capacity in excess of 14,000 MW.

87 Wind turbines

88 Wind Energy Advantages
Wind Energy is a free source of energy that is available in plenty. However, it has to be harnessed at places that have wind blowing regularly all the time. Wind power is eco-friendly because it doesn’t produce any pollution and there is no release of any toxic gases. In addition, more and more people are increasingly using wind power due to increase in awareness of this never-ending, renewable source of energy. While Wind Energy is cheaper, it doesn’t take millions of years to form, which is the case with fossil fuels. The following points establish the advantages of using Wind Energy. A smaller area is required to setup wind turbines for the generation of wind power, compared to the area required for setting up power stations. In addition, the land used for generating wind power can be used for cattle grazing and agricultural purposes. New developments in Wind Energy can offer solution to the issue of increase in the price of fossil fuels like petroleum and gas, and also to the issue of green house effect. With the increase in population, wind power is turning into an extra source of energy as an increasing number of people turning to this cheaper source of energy. It is also the type of energy that can be accessed by remote areas where it is expensive and difficult to run electrical lines. Wind Energy is also increasingly being considered for large scale production. As per experts, if maximum wind power is harnessed, it can help generate 10 times the energy that is being used at present. When used optimally in the future, Wind Energy can help all the countries to become independent in their energy requirements.


90 Solar Energy Solar is the Latin word for sun—a powerful source of energy that can be used to heat, cool, and light our homes and businesses. That's because more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. A variety of technologies convert sunlight to usable energy for buildings. The most commonly used solar technologies for homes and businesses are solar water heating, passive solar design for space heating and cooling, and solar photovoltaics for electricity. Businesses and industry also use these technologies to diversify their energy sources, improve efficiency, and save money. Solar photovoltaic and concentrating solar power technologies are also being used by developers and utilities to produce electricity on a massive scale to power cities and small towns.

91 A concentrating solar power (CSP) system for electricity generation, that consists of a solar thermal array of a number of dish-shaped mirrors each focusing radiation on a receiver attached to a Stirling engine (see bottom left) that converts heat into electricity.


93 Geothermal Energy Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma. Almost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water. In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii.


95 Bio - Mass Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, raw material from the forest, major parts of household waste and wood. Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment or power plants that are now burning fossil fuels. Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas.

96 The difference between biomass and fossil fuels
The vital difference between biomass and fossil fuels is one of time scale. Biomass takes carbon out of the atmosphere while it is growing, and returns it as it is burned.  If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. This is either during woodland or arboricultural management or coppicing or as part of a continuous programme of replanting with the new growth taking up CO2 from the atmosphere at the same time as it is released by combustion of the previous harvest.  This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels.


98 Tidal Power The world’s first commercial-scale tidal turbine, developed by British tidal energy company, Marine Current Turbines, has delivered electricity onto the grid for the first time. In principle, SeaGen works much like an “underwater windmill” with the rotors driven by the power of the tidal currents rather than the wind. Conservative estimates suggest there is at least five gigawatts of power in tidal flows in Britain, but there could be as much as 15GW. The tidal current turbine, known as SeaGen, has briefly generated 150kW of power onto the grid as part of its commissioning work, ahead of it achieving full capacity a few weeks from now. SeaGen’s power is being intentionally constrained to 300kW during the commissioning phase, but once fully operational, it will generate 1.2MW of clean, renewable energy to the equivalent of 1000 homes. The chosen site for the installation, Strangford Lough in Northern Ireland has a very powerful (and very regular) tidal pull and is recognized as one of the main tidal “hotspots” in UK and Irish waters.

99 A tidal stream turbine

100 Energy Conservation Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources.



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