8.1 to 8.4 2012


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8.1 to 8.4 2012

  1. 1. Energy Power and Climate change 8.1 – 8.4
  2. 2. Energy types Kinetic Potential Thermal Sound Light (Electromagnetic) Electrical Magnetic Nuclear Chemical
  3. 3. Energy degradation Every time energy is converted from one form to another thermal energy will be lost Conversion of energy into work is a cyclical process Energy transferred to surroundings is no longer able to do useful work
  4. 4. 8.1 Energy degradation andpower generation 1. Hot gas will cause the piston to move 2.But one stroke of the piston does not provide much energy 3.The process needs to be cyclical
  5. 5. Cyclical processesThe continuous production of energy can beobtained from a cyclical process Not all of the heat can be converted to work Some is transferred to the surroundings
  6. 6. Efficiency of heat engines Equation is not on the syllabusNo heat engine can transfer all of it’s energy towork.Some is always lost as heat to the surroundings.
  7. 7. Sankey diagrams 25%100%
  8. 8. Sankey diagrams A Sankey diagram show energy transfers in a scale diagram Arrowheads are in proportion to value You need to be able to draw these from data
  9. 9. Sankey diagrams For fossil fuel power stations
  10. 10. Sankey diagrams-nuclear
  11. 11. Sankey diagrams- solar
  12. 12. Sankey diagrams- hydroelectric
  13. 13. Sankey diagrams- wind
  14. 14. Sankey diagrams- wave
  15. 15. Production of electrical power1. Heat source2. Steam generation3. Turbines4. Generator5. Transmission lines
  16. 16. World Energy Sources 8.2
  17. 17. World energy SourcesIn 2006, about 18% of global final energy consumption came from renewables, 13% coming from traditional biomass, such as wood-burning. Hydroelectricity, providing 3% (15% of global electricity generation), solar hot water/heating, 1.3%.Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided some 0.8% of final energy consumption.Investment capital flowing into renewable energy climbed from $80 billion in 2005 to a record $100 billion in 2006.The World Institute of Economic Affairs reported that the replacement of current technology with renewable energy could help reduce CO2 emissions by 50% by 2050.
  18. 18. World energy SourcesWho uses the most of the total 15 TW? Industrial users (agriculture, mining, manufacturing, and construction) consume about 37%. Personal and commercial transportation consumes 20% residential heating, lighting, and appliances use 11% commercial uses (lighting, and provision of water etc) amount to 5% of the total. The other 27% of the worlds energy is lost in energy transmission and generation.In 2005, global electricity consumption averaged 2 TW. The energy rate used to generate 2 TW of electricity is approximately 5 TW, as the efficiency of a typical existing power plant is around 38%. The new generation of gas- fired plants reaches a substantially higher efficiency of 55%. Coal is the most common fuel for the worlds electricity plants.
  19. 19. World energy Sources Does it matter where you are geographically?
  20. 20. Do we know what is out there? Undiscovered Identified Economical ReservesDecreasing cost of extraction Other Not economical resources Decreasing certainty Known Existence
  21. 21. Nuclear power 6% Hydropower, geothermal, solar, wind 7% Natural Gas 12% Biomass 11%Coal21% Oil 32% World
  22. 22. Nuclear power 8% Hydropower geothermal solar, wind Natural 4% Gas 23%Coal22% Biomass Oil 39% 4% United States
  23. 23. Carbon dioxide emissions Carbon dioxide is one of the main contributors to greenhouse effect. It contributes 9-26% to the greenhouse effect. The image shows the increasing density of carbon dioxide in the atmosphere contributed by human activity
  24. 24. Carbon dioxide emissionsThe seven sources of CO2 from fossil fuel combustion are (with percentage contributions for 2000–2004): Solid fuels (e.g. coal): 35% Liquid fuels (e.g. gasoline): 36% Gaseous fuels (e.g. natural gas): 20% Flaring gas industrially and at wells: <1% Cement production: 3% Non-fuel hydrocarbons: <1% The "international bunkers" of shipping and air transport not included in national inventories: 4%
  25. 25. What is renewable? Reusable Bountiful Short time to regenerate Cheap Life time to regenerate Something else?
  26. 26. Energy density of fuel Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass J/kg Need to be able to do calculations
  27. 27. World consumption
  28. 28. Energy conversion of typical fuelsFirewood 16 MJ/kgBrown coal 9 MJ/kgBlack coal (low quality) 13-20 MJ/kgBlack coal 24-30 MJ/kgNatural Gas 39 MJ/m3Crude Oil 45-46 MJ/kgUranium* - in light water reactor 500,000 MJ/kg
  29. 29. Increasing heat and carbon content Increasing moisture content Peat Lignite Bituminous Coal Anthracite (not a coal) (brown coal) (soft coal) (hard coal) Heat Heat Heat Pressure Pressure PressurePartially decayed Low heat content; Extensively used Highly desirable fuelplant matter in swamps low sulfur content; as a fuel because because of its highand bogs; low heat limited supplies in of its high heat content heat content andcontent most areas and large supplies; low sulfur content; normally has a supplies are limited high sulfur content in most areas
  30. 30. Advantage Disadvantage Oil widely accepted in manufacturing , CO2 emission, greenhouse effect. relatively cheap and high efficiency Gas high efficiency expensive to transport and store, CH4 contributes to greenhouse effect. Coal widely accepted in manufacturing, low efficiency, air pollution, CO2 and CO cheapest among the three non- emission, greenhouse effect. renewable energy source Solar easy to get sun light, renewable energy expensive to use solar panel and grid, unstable source in modern due to the changeable weather Wind easy to get wind, renewable energy noise, spoil scenery, expensive maintaining fees source Biofuel clean, renewable energy source expensive in refining processGeothermal stable, renewable energy source expensive to build, the technology has not been very mature yetHydropower functional. very useful to avoid flooding very expensive to build, expensive to maintain, in some countries, renewable drought, harm the river eco-system energy source
  31. 31. 35 14.9 (kilometers per liter, or kpl) Average fuel efficiency(miles per gallon, or mpg) 30 12.8Average fuel economy Passenger cars 25 10.7 Total fleet 20 8.5 Pickups, vans, and sport utility vehicles 15 6.4 1980 1985 1990 1995 2000 2005 Year
  32. 32. 2.2 2.0Dollars per gallon (in 1993 dollars) 1.8 1.6 1.4 1.2 1.0 0.8 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year
  33. 33. A Combustion engine B Fuel tank C Electric motor D Battery bankB E Regulator D F Transmission E F A CFuelElectricity
  34. 34. H2 Hydrogen gas1 Cell splits H2 into protons 3 and electrons. Protons flow 1 across catalyst membrane.2 React with oxygen (O2). O2 23 Produce electrical energy (flow of electrons) to power car. 4 H2O4 Emits water (H2O) vapor.
  35. 35. A Fuel cell stack B Fuel tank C Turbo compressor B D Traction inverter D E Electric motor / C transaxle E AFuelElectricity
  36. 36. History of fossil fuelpower production Industrialisation Higher energy consumption Industry near to fossil fuel deposits
  37. 37. 3,500 Oil 3,000Oil equivalent (millions of metric tons) 2,500 Coal 2,000 1,500 1,000 Natural gas 500 0 1950 1960 1970 1980 1990 2000 2010 Year
  38. 38. 375 300Gigawatts of electricity 225 150 75 0 1960 1970 1980 1990 2000 2010 Year
  39. 39. 35 30 25Number of new reactors 20 15 10 5 0 1960 1970 1980 1990 2000 2010 Year
  40. 40. 60 History Projections OilEnergy consumption (quadrillion Btus) 50 Natural gas 40 Coal 30 Nuclear Nonhydro 20 renewable Renewable 10 hydro 1970 1980 1990 2000 2010 2020 Year
  41. 41. 100 Wood 80 CoalContribution to total energyconsumption (percent) 60 Natural gas Oil 40 Hydrogen Solar 20 Nuclear 0 1800 1875 1950 2025 2100 Year
  42. 42. Space HeatingPassive solar 5.8Natural gas 4.9Oil 4.5Active solar 1.9Coal gasification 1.5 Electric resistance heating (coal-fired plant) 0.4 Electric resistance heating 0.4 (natural-gas-fired plant) Electric resistance heating (nuclear plant) 0.3
  43. 43. TransportationNatural gas 4.9 Gasoline (refined crude oil) 4.1Biofuel (ethyl alcohol) 1.9Coal liquefaction 1.4Oil shale 1.2
  44. 44. Gases Gasoline Aviation fuel Heating oil Heated crude oil Diesel oil Naphtha GreaseFurnace and wax Asphalt
  45. 45. 60 History ProjectionsConsumption (million barrels per day) 50 40 30 20 10 0 1970 1980 1990 2000 2010 2020 Year
  46. 46. 70 60 50 OilOil price per barrel 40 30 20 (1997 dollars) 10 0 1950 1960 1970 1980 1990 2000 2010 Year
  47. 47. 60 HistoryHistory Projections Projections 50Oil (million barrels per day) 40 30 20 10 0 1970 1980 1990 2000 2010 2020 Year
  48. 48. 40 2,000 x 109 barrels total 30(x 109 barrels per year)Annual production 20 10 0 1900 1925 1950 1975 2000 2025 2050 2075 2100 Year World
  49. 49. 4 200 x 109 1975 barrels total 3 Undiscovered: 32 x 109(x 109 barrels per year) barrelsAnnual production Proven 2 reserves: 34 x 109 barrels 1 0 1900 1920 1940 1960 2080 2000 2020 2040 Year United States
  50. 50. Coal
  51. 51. Flue gasesCoal Limestone Steam Fluidized bed Water Air nozzles Air Calcium sulfate and ash
  52. 52. CoalPower is generated via a power plant in the following way: Coal and lmestone is injected into a bed furnace. The ash from the coal is removed from the plant and then disposed of. This furnace is used to heat a large container of water. this water then is turned into steam and then pushed at high speed through a turbine. The turbine turns a Generator. This generates a huge amount of electricity and is then carried off by the substandard power grid that is often shut off so that victoria still has its power The steam is then filtered in a number particulate controllers and any remaining ash is then removed. A fan then blows the steam out into the atmosphere.
  53. 53. Coal-emissions Carbon Dioxide Coal is the largest of the Carbon Dioxide Contribution Methane Most harmful of the Greenhouse Gasses Ashes Sludge Flue Gas Mercury Uranium Arsenic Thorium Assorted Heavy Metals
  54. 54. Coal-costs Economic – Coal – Plants – Labor – Transport Social – Health  Cancers caused – Environmental  Smog  Waste Products  Mining
  55. 55. Advantages DisadvantagesModerate existing High costssupplies Low net energyLarge potential yieldsuppliesEasily transported Large amount ofwithin and water needed tobetween processcountries Severe landEfficient disruption fromdistribution surface miningsystem in place Water pollution from mining residues Air pollution when burned CO2 emissions when burned
  56. 56. Oil
  57. 57. OilHow Oil Fuelled Power Station Works: The combustion of heavy oil turns the water in the boiler into steam This is then collected in the boiler drum. The steam is then returned to the boiler where it is superheated, dried, and directed towards the turbines. As it expands, the steam spins the turbine which drives the generator. After leaving the turbines, the steam passes through condensers which return it to a liquid state The water is pumped back into the boiler. This cycle is repeated.
  58. 58. Oil-emissions Carbon Dioxide Methane Most harmful of the Greenhouse Gasses Ashes Sludge Flue Gas Mercury Uranium Arsenic Thorium Assorted Heavy Metals
  59. 59. Oil-costsEconomic Oil Plants Labour TransportSocial Health – Cancers caused Environmental – Smog – Waste Products – Mining
  60. 60. Advantages Disadvantages Ample supply for Need to find 42–93 years substitute within 50 years Low cost (with huge subsidies) Artificially low price encourages waste and High net discourages energy yield search for alternatives Easily transported within and between countries Air pollution when burnedLow land use Releases CO2 when burnedEfficient distribu-tion system Moderate water pollution
  61. 61. Gas
  62. 62. Gas The combustion of natural gas turns the water in the boiler into steam This is then collected in the boiler drum. The steam is then returned to the boiler where it is superheated, dried, and directed towards the turbines. As it expands, the steam spins the turbine which drives the generator. After leaving the turbines, the steam passes through condensers which return it to a liquid state The water is pumped back into the boiler. This cycle is repeated.
  63. 63. Gas The combustion of natural gas turns the water in the boiler into steam This is then collected in the boiler drum. The steam is then returned to the boiler where it is superheated, dried, and directed towards the turbines. As it expands, the steam spins the turbine which drives the generator. After leaving the turbines, the steam passes through condensers which return it to a liquid state The water is pumped back into the boiler. This cycle is repeated.
  64. 64. Gas-emissions Carbon Dioxide Methane Most harmful of the Greenhouse Gasses Ashes Sludge Flue Gas Mercury Uranium Arsenic Thorium Assorted Heavy Metals
  65. 65. Gas-costs Economic – Oil – Plants – Labour – Transport Social – Health  Cancers caused – Environmental  Smog  Waste Products  Mining
  66. 66. Fossil fuel usage Why is fossil fuel use widespread? What is the energy density of each fossil fuel? What are the advantages of fossil fuel use? What are the disadvantages of fossil fuel use? What is the efficiency of fossil fuel power stations? What are the environmental concerns?
  67. 67. Nuclear Nuclear power is term used to describe the process that harness the energy produced in nuclear reactions. In nuclear reactions, the atomic energy within atomic nuclei is transformed into other forms of energy, mainly thermal energy. This is commonly done through the process of nuclear fission however nuclear reactions can also be done through the process of nuclear fusion and radioactive decay.
  68. 68. Nuclear Nuclear power has many applications for current and future uses. This is because of the large amounts of energy if transformed in these reactions in comparison to other sources of energy per unit mass. This makes it ideal for nuclear marine propulsion, to generate electricity for humanitys energy needs or even to fuel nuclear weapons.
  69. 69. Distinguish between controllednuclear fission (power production)and uncontrolled nuclear fission(nuclear weapons).Students should be aware of the moral and ethicalissues associated with nuclear weapons.
  70. 70. Nuclear Fission Nuclear Fission is a nuclear reaction where the nucleus of an atom is split into smaller particles producing lighter elements. The reaction is only energetically possible (i.e. the reaction is exothermic) if the binding energy per nucleon for the reactants is greater than the binding energy per nucleon for the products (Elements greater than Iron-56 are energetically possible). The reaction is initiated by bombarding the nuclei with neutrons. This type of nuclear reaction is used in nuclear power plants which harness the energy to produce electricity.
  71. 71. Small amounts of radioactive gasesUranium fuel input(reactor core) Containment shell Waste heat Electrical power Emergency core cooling system Steam Control rods Useful energy Turbine Generator Heat 25 to 30% exchanger Hot coolant Hot water output Condenser Pump Pump Coolant Cool water input Black Pump Waste Moderator heat Water Coolant passage Pressure vessel Waste Water source heat Shielding (river, lake, ocean) Periodic removal Periodic removal and storage of and storage of radioactive wastes radioactive liquid wastes and spent fuel assemblies
  72. 72. NuclearKey components Moderator Energy transfer Control rods Heat exchangers
  73. 73. NuclearRetractable Control Rods These are used to absorb free neutrons and prevent further fission events. Control rods, placed between the fissile uranium are retractable to expose more uranium and speed up the reaction or they can be injected to cover the uranium fuel rods and slow down the reaction.
  74. 74. NuclearModerator A moderator is a liquid medium, usually light or heavy water, that surrounds the uranium fuel rods in order to slow down the free neutrons so that they can be absorbed into uranium atoms more easily inducing fission, speeding up the reaction. If the moderator is at a higher temperature then usual, then the liquid becomes less dense, thus slowing down less neutrons.
  75. 75. NuclearEnergy transferApproximately 70% of the energy released from the reaction is wasted leaving only 30% transformed into electricity, however the energy content is far superior to conventional sources such as coal for an equivalent mass on the order of 10^7 times greater. Each fission event releases about two hundred million eV of energy
  76. 76. Energy transformations in areactor Fission fragments have EK This heats the fuel rod The coolant (gas) takes the heat from the rod The hot gas goes to the heat exchanger The hot gas turns the water to steam The steam drives the turbines The turbines drive the generator
  77. 77. NuclearEnrichment of uranium occurs so that the percentage of uranium-235 is increased to 2 or 3%. This allows the reaction to keep its ‘critical mass’ (the mass required to keep the chain reaction going). The method used to enrich the uranium relies on the different masses of the isotopes. This takes many stages and is very costly.
  78. 78. Enrichment U3O8 is then enriched by – Turning it to a gas – Gas placed in room with tiny hole at high up at one end – Lighter 235U has higher probability of diffusing through hole than 238U  Perhaps 1% higher – Repeated through many (100 +) rooms – Concentration now high enough to use
  79. 79. Production of plutonium Fissionable plutonium-239 can be produced from non-fissionable uranium-238 by the reaction illustrated. The bombardment of uranium-238 with neutrons triggers two successive beta decays with the production of plutonium.
  80. 80. NuclearFuel U238 Pu239 The speed of the neutrons – fast moving neutrons as less likely to become absorbed into the nuclei and thus unable to induce reactions. The mass or the number of nuclei – the more nuclei there are, the greater the chance that a neutron will get absorbed inducing further reactions. If the mass is too small then there is a high chance that neutrons will be lost of the surface of the ‘block’. Critical mass refers to the minimum mass required for a chain reaction to occur.
  81. 81. NuclearSafety rods are also placed into the reactor so that the reactor can be shut down if necessary in a matter of seconds. They are triggered automatically if the coolant pressure falls because of a pipe failure for example.
  82. 82. Advantages DisadvantagesLarge fuel High cost (evensupply with large subsidies)Lowenvironmental Low netimpact (without energy yieldaccidents) HighEmits 1/6 as environmentalmuch CO2 as coal impact (with major accidents)Moderate landdisruption and Catastrophicwater pollution accidents can(without happenaccidents) (Chernobyl)Moderate land use No acceptable solution for long-term storage Low risk of of radioactive accidents because wastes and of multiple safety decommissioning systems (except worn-out plants in 35 poorly designed and run reactors in former Spreads Soviet Union and knowledge and Eastern Europe) technology for building nuclear weapons
  83. 83. Nuclear Fusion Nuclear Fusion is a nuclear reaction where nuclei are join together or fuse producing heavier elements. The reaction is only energetically possible (i.e. the reaction is exothermic) if the binding energy per nucleon for the reactants is less than the binding energy per nucleon for the products (Elements less than Iron-56 are energetically possible). This type of reaction is continuously occurring in the stars.
  84. 84. Solar Solar heaters use solar collectors to harness solar radiation and convert to heat energy. Water is pumped through thin copper piping embedded in a blackened copper plate with rear insulation. On top of this is a glass plate. Water is piped through and heated by the infrared radiation. Examples – parabolic dish, solar furnace
  85. 85. Solar Panels Solar panels (arrays of photovoltaic cells) make use of renewable energy from the sun, and are a clean and environmentally sound means of collecting solar energy. Solar panels are made by semiconductor such as silicon. Normally, electricity cant get through semiconductors, but when the semiconductor is heated i.e by the sun, electricity can go through. When the sun shines on solar panels, the electrons are excited and start to move along a conducting wire, this flow of electrons generates electricity.
  86. 86. Heat to house (radiators or forced air duct)Heavy Pumpinsulation Hot water Super- tank window Heat exchanger ACTIVE
  87. 87. Solar Photovoltaic cells
  88. 88. PV Cell A photovoltaic cell (PV cell) is a semiconductor diode that converts visible light into direct current (DC) (electricity). Some PV cells can also convert infrared (IR) or ultraviolet (UV) radiation into DC electricity. These cells are what convert the energy from the sun into electricity creating this solar power energy source. PV cells are what make up solar panels as solar panels are many PV cells connected together.
  89. 89. Semiconductor Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. A semiconductor is a solid material that has electrical conductivity between that of an insulator and a conductor. When light shines on the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely. This free flow of electrons is what creates electricity.
  90. 90. SemiconductorTwo types of semiconductor p-type n-typeDoping silicon with a group 3 element results in an electron deficient layer (p-type), with a group 5 element results in an electron rich layer (n-type).
  91. 91. Single Solar CellBoron-enriched SunlightsiliconJunction CellPhosphorus-enriched silicon DC electricity
  92. 92. Semiconductorn-typeElectron rich therefore electron can move aroundp-typeElectron moves from hole to holeThis produces a potential difference
  93. 93. Solar Power Tower
  94. 94. Solar Thermal Plant
  95. 95. Nonimaging Optical Solar Concentrator
  96. 96. Advantages DisadvantagesModerate net Low efficiencyenergy High costsModerateenvironmental Needs backup orimpact storage systemNo CO2 emissions Need access to sun most ofFast construction the time(1-2 years) High land useCosts reducedwith natural gas May disturbturbine backup desert areas
  97. 97. Roof Options Panels ofSolar Cells Solar Cells
  98. 98. Advantages DisadvantagesFairly high net Need accessenergy to sunWork on cloudy Low efficiencydays Need electricityQuick installation storage system or backupEasily expandedor moved High land use (solar cell powerNo CO2 emissions plants) could disrupt desertLow areasenvironmentalimpact High costsLast 20-40 years (but should be competitive inLow land use 5-15 years)(if on roof or builtinto walls or DC current mustwindows) be converted to ACReducedependence onfossil fuels
  99. 99. SolarSeasonal/regional variation is due to: Solar constant Earth’s distance from Sun Altitude of Sun in sky Length of night/day
  100. 100. Hydroelectric
  101. 101. HydroelectricWater Storage in Lakes: The first, and probably most common method of storing water is to damn an existing river in order to increase its height and thus the potential for energy to be created.
  102. 102. HydroelectricTidal Water Storage This is very similar to wave storage in the Tapered wave form of storage. This system uses the kinetic energy of the wave to raise it up and store it so it can subsequently be ran past turbines and generate electricity.
  103. 103. HydroelectricPump Storage Electric energy is used to pump water up to reservoirs so it can then be run past turbines. pump storage is only effective as long as the energy output of the power plant is less than is consumed to pump the water up to the reservoir.
  104. 104. Advantages DisadvantagesModerate to high High constructionnet energy costsHigh efficiency High environmental(80%) impactLow-cost electricity High CO2 emissions fromLong life span biomass decay inNo CO2 emissions shallow tropical reservoirsduring operation Floods naturalMay provide flood areascontrol below dam Converts landProvides water habitat to lakefor year-round habitatirrigation of cropland Danger of collapseReservoir is useful Uproots peoplefor fishing andrecreation Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam
  105. 105. Question How much water must fall per second to produce 1,400 MW of electricity, if it falls through a height of 200m? Assume the turbine is 60% efficient.
  106. 106. Wind Rotor blades - The blades are what captures the energy of the wind and act like sails do on boats. When the wind forces the blades to move, it has transferred some of its energy to the rotor.
  107. 107. Wind Shaft - The wind-turbine shaft is connected to the center of the rotor. When the rotor spins, the shaft spins as well. In this way, the rotor transfers its mechanical, rotational energy to the shaft, which enters an electrical generator on the other end.
  108. 108. Wind Generator -The generator uses the properties of electromagnetic induction to produce electrical voltage. A simple generator consists of magnets and a conductor. The conductor is typically a coiled wire. Inside the generator, the shaft connects to an assembly of permanent magnets that surrounds the coil of wire. In electromagnetic induction, if you have a conductor surrounded by magnets, and one of those parts is rotating relative to the other, it induces voltage in the conductor. When the rotor spins the shaft, the shaft spins the assembly of magnets, generating voltage in the coil of wire. That voltage drives electrical current (typically alternating current, or AC power) out through power lines for distribution.
  109. 109. Wind At 33 mph, most large turbines generate their rated power capacity, and at 45 mph (20 meters per second), most large turbines shut down. There are a number of safety systems that can turn off a turbine if wind speeds threaten the structure, including a remarkably simple vibration sensor used in some turbines that basically consists of a metal ball attached to a chain, poised on a tiny pedestal. Probably the most commonly activated safety system in a turbine is the "braking" system, which is triggered by above-threshold wind speeds.
  110. 110. The wind blows the propeller round, which turns a generator to Wind power produce electricity •Wind Power is renewable •Doesnt cause pollution, doesnt need fuel •Need a lot of generators to get a sensible amount of power •Need to put them where winds are reliableEnergy = ½ mv2 The wind does not stop afterMass per sec = ρx volume = ρx Area x speed = ρπr2v passing through the turbine, therefore not all the energy can beEnergy = ½ ρπr2v x v2 = ½ ρπr2v3 harnessed (max = 59%)
  111. 111. Normal winds Moderate windsExisting projects Good windsPlanned projects Excellent winds
  112. 112. Gearbox Electrical generatorPower cableWind Turbine
  113. 113. Advantages DisadvantagesModerate to high Steady windsnet energy neededHigh efficiency Backup systems when neededModerate winds are lowcapital cost High land useLow electricity for wind farmcost (and falling) Visual pollutionVery low environ-mental impact Noise when located nearNo CO2 emissions populated areasQuick construction May interfere in flights of migratoryEasily expanded birds and kill birds of preyLand below turb-ines can be usedto grow crops orgraze livestock
  114. 114. Questions A wind generator is designed to work in winds of 10km/hr with a blade length of 3m. How much power can it produce? What would be the power output at 20km/hr? What would be the power output if the blade length were increased to 6m? ρair = 1.3Kgm-3
  115. 115. Wave
  116. 116. WaveFixed: Oscillating column Tapered Channel Wave RollerFloating: Pelamis Salter Duck WaveDragon PowerBuoy
  117. 117. WaveOscillating Water Column The water column used forced air to turn a turbine and produce electricity, as opposed to the actual water itself. As the wave enters the water column they force the air in the column out past the turbine and turn it, similarly, the negative pressure created as the wave retreats causes air to return in the opposite direction and also to turn the turbine. Irrespective of the direction of the air flow, due to the nature of the turbine it will always turn in the same direction
  118. 118. WaveWater column technology is perfect for conditions where there are strong tidal actions such coastal defences and other coastal situated instalments. The maximum output of a working water column is 500kW.There is an example of such a system installed in Scotland, where its power is used to fuel an electric bus, as well as supplying excess to the national grid of Scotland. This specific model of generator is easy to install and has a low profile so it does not intrude on coastal landscapes
  119. 119. Maths L a λVolume of water in red area = a x λ/2 x L Mass = Volume x density(ρ)Loss of GPE of the wave = mgh = (a x λ/2 x L x ρ) x g x aNumber of waves per sec = Frequency = v/λPower = loss of GPE per sec = a2 x λ/2 x L x ρ x g x v/λPower per unit length = ½ a2ρgv
  120. 120. Wave-TAPCHANThe Tapered Channel system uses a tapered channel which flows into a reservoir. The tapering of the channel increases the amplitude of the waves in order to raise its height. When the water overflows into the reservoir it is then stored. The water is subsequently fed past a turbine as it unleashes the potential energy gained from a greater height as kinetic energy, and the turbine then generates power.
  121. 121. Wave-WaveRollerThe WaveRoller system is a solid plate device anchored to the bottom of the sea which oscillates back and forth caused by the movements of bottom waves. The kinetic energy generated by the moving of the plate is harnessed through the use of a piston pump.The benefits of the WaveRoller system is that it is modular in form and can be installed in modules. The company that is developing the WaveRoller, claim that the modules are also easily maintained and electricity production can continue during unit maintenance.
  122. 122. Wave-SalterDuckThe Salter Duck rotates with a nodding motion as the wave passes. This pumps hydraulic fluid that drives a hydraulic motor, which in turn, drives an electrical generator. The Salter Duck is able to produce energy exceedingly efficiently, but its progress was set back as this calculation was found to be out by a power of 10.
  123. 123. OWC question Waves of amplitude 2m reach the beach every 15 seconds. The wavelength of the wave is 80m. Calculate The speed of the wave. The power per metre of the waves along the shore. The power available from a 3km beach.
  124. 124. Are there any other options?
  125. 125. Solid Biomass FuelsWood logs and pelletsCharcoalAgricultural waste (stalks and other plantdebris)Timbering wastes (branches, treetops, andwood chips)Animal wastes (dung)Aquatic plants (kelp and water hyacinths)Urban wastes (paper, cardboard, and othercombustible materials)Direct Conversionburning to gaseous and liquid biofuels Gaseous Biofuels Liquid Synthetic natural Biofuels gas(biogas) Ethanol Wood gas Methanol Gasohol
  126. 126. Advantages DisadvantagesLarge potential Nonrenewable ifSupply in some harvestedareas unsustainablyModerate costs Moderate to high environmentalNo net CO 2 impactincrease ifharvested and CO emissions 2burned if harvestedsustainably and burned unsustainablyPlantation can belocated on Lowsemiarid land photosyntheticnot needed for efficiencycrops
  127. 127. Advantages DisadvantagesCan be produced Not foundfrom water in natureLow environmental Energy is neededimpact to produce fuelNo CO2 emissions Negative net energyGood substitutefor oil Nonrenewable if generated byCompetitive price fossil fuelsif environmental or nuclear powerand social costsare included in High costs (butcost comparisons expected to come down)
  128. 128. Electric power Generator Cooling tower Condenser SteamSeparator Turbine Hot Warm brine Cooled water brineSteam and hot water Impermeable Pump rock Production Injection well well Permeable rock Cooled brine
  129. 129. Advantages DisadvantagesVery high Scarcity ofefficiency suitable sitesModerate net Depleted if usedenergy at too rapidlyaccessible sites CO2 emissionsLower CO2emissions than Moderate to highfossil fuels local air pollutionLow cost at Noise and odorfavorable sites (H2S)Low land use Cost too high except at the mostLow land concentrated anddisturbance accessible sourceModerateenvironmentalimpact
  130. 130. Central power plants Transmission and distribution systemResidential Commercial Industrial
  131. 131. Wind farm Small solar cell Bioenergy power plants power plants Fuel cells Rooftop solar Solar cell cell arrays rooftop systems Transmission and distribution system Small wind CommercialFuel cells turbine Residential Microturbines Industrial
  132. 132. Small modular unitsFast factory productionFast installation (hours to days)Can add or removemodules as neededHigh energy efficiency (60–80%)Low or no CO2 emissionsLow air pollution emissionsReliable
  133. 133. Improve Energy Efficiency More Renewable Energy Increase renewable energy toIncrease fuel-efficiency 20% by 2020 and 50% by 2050standards for vehicles,buildings, and appliances Provide large subsidies and tax credits for renewable energy Mandate government Use full-cost accounting and purchases of efficient least-cost analysis for com- vehicles and other devices paring all energy alternatives Encourage government purchase of renewable energyProvide large tax credits for devicesbuying efficient cars,houses, and appliances Greatly increase renewable energy research and developmentOffer large tax credits forinvestments in efficiency Reduce Pollution and Health RiskReward utilities forreducing demand Cut coal use 50% by 2020 Phase out coal subsidiesEncourage independent Levy taxes on coal and oil usepower producers Phase out nuclear power or putGreatly increase efficiency it on hold until 2020research and development Phase out nuclear power subsidies