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ENERGY

ENERGY. Energy cannot be created or destroyed , it can only change its form of existence. Energy types. Chemical energy – stored in chemical bonds and can be released upon chemical reaction Heat energy – transferred between bodies by thermal interactions

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ENERGY

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  1. ENERGY Energycannotbecreatedordestroyed, itcanonlychangeitsformofexistence

  2. Energytypes • Chemicalenergy – storedinchemicalbonds and canbereleaseduponchemicalreaction • Heatenergy – transferredbetweenbodiesbythermalinteractions • Mass energy – equivalenceof mass and energydescribedas E = m c2 • Kineticenergy – energythatobjectposessesduetoitsmotion E = ½ m v2 • Potentialenergy – energythatobjectposessesduetoitsposition E = m g H • Electricenergy – E = q V • Magneticenergy • Nuclearenergy • Etc.

  3. Energyquality and exergy • Lawsofthermodynamics: 1. The heat, Q, added to a system equals the change in the internal energy, U, of the system plus the work, W, done by the system Q = U + W 2. It is impossible to remove thermal energy from a system at a single temperature and convert it to mechanical work without changing the system surroundings in some other way • Exergy - the useful work that can be extracted from a system which executes a loss-free process between its initial state and a dead state • Dead state – stateofequilibriumwiththesurroundings

  4. Energyconsumption

  5. Stateofthe art Image: http://ourfiniteworld.com/2012/03/12/world-energy-consumption-since-1820-in-charts/ Image: http://alfin2300.blogspot.com/2011/04/can-small-modular-nuclear-reactors-save.html

  6. Possiblefuturetrends Image: http://archive.transitiontowntotnes.org/content/future-scenarios-0

  7. Currentenergyconsumptionbyvarioussources Datasource: BritishPetroleum, 2013

  8. Scenariosforfutureenergysources Image: http://s01.static-shell.com/content/dam/shell-new/local/corporate/Scenarios/Downloads/Scenarios_newdoc.pdf Image: http://www.kuuvikriver.info/the-arctic-and-you.html

  9. Fossilfuelsasenergysource

  10. Oil • Estimatedtotaloil reserves: • 190 km3 (1.2 trilionbarrels) withoutoilsands • 595 km3 (3.74 trillion barrels) with oil sands • 1 oil barrel (bbl) = 42 US gallons = 158.987 L Image: http://ourfiniteworld.com/ Image: Wikipedia Image: Wikipedia

  11. Natural gas • Major proven resources (2013): world – 187.3 trillion m3 • Iran (33.6 trillion m3) • Russia (32.9 trillion m3) • Qatar (25.1 trillion m3) • Turkmenistan (17.5 trillion m3) • Saudi Arabia (8.2 trillion m3) • United Arab emirate (6.1 trillion m3) • Unconventionalgas, incl. shalegas: • 900 trillionsm3 • ca. 164 trillions m3are readily recoverable Image: Wikipedia

  12. Coal • Total reserve estimate: 948 billionsoftonnes • Coalcanundergocracking and gasificationtoproduceliquid and gaseousfuels (feasibility?) Image: Google Image: http://www.eia.gov/todayinenergy/detail.cfm?id=3350

  13. Oilshale • Worldwide: 7718 billionsoftonnes • GreenRiverformation (US): 52 % ofworldoilshale • Contains ca. 35 % organics (kerogen) • Escessivelystudied and dealtwithinEstonia • KnownEstonian reserves of2.23 billionsoftonnes • Estonian mining: • 12 to 13 millionsoftonnesp.a. • 9 totentonnesp.a. burned, rest – treatedtoproduceshaleoil and phenols Image: adoptedfromEnefit Image: Allix P. et al., Oilfield Review 22 (2010) 6

  14. Heatengines: fueltowork

  15. Heatenginedefinition • System thatperformsconversionofheatorthermalenergytomechanicalwork • MaximalefficiencylimitedbyCarnottheorem: • 3 % forproposedoceanthermalenergyconversion (OTEC) powerplants • 18-20 % forpetrolengines • 45 % forsupercriticalcoal-firedpowerplant • Over 80 % forheat and powerco-generationplants Image: Wikipedia

  16. Steamengine • Firstcuriosities – 1st century AD (HeroofAlexandria) • Rudimentaryengines – Taqial-Din (1551), Jerónimo de Ayanz y Beaumont (1606), Giovanni Branca (1629), Denis Papin (1679, 1690) • Commercialsteam-poweredwater pumps – Thomas Savery (1698), Thomas Newcomen (1712), Jacob Leupold (1720) • 1763-75 – James Watt • 1849 – George Henry Corliss • 1884 – sir Charles Parsons, steamturbine Image: http://science.howstuffworks.com/transport/engines-equipment/steam2.htm Image: Wikipedia Image: Wikipedia

  17. Petrolengine • Petrol (UK), gasoline (US) • Variousdevelopmentsfrom 5th centuryonwards • 1876 – Nicholaus Otto, four-strokeengine • 1929 – Felix Wankel • Pterolenginecouldintheoryusehydrogenforfuel Image: Wikipedia

  18. Dieselengine • 1892, Rudolf Diesel • Upto 45 % efficiency, moreeconomic • Fuelcheapertoobtain, no flammablevapours • Turbo-pressurisinglimitedonlybymotorcomponentsmechanicalstrenght • Less CO and NOxinexhaust , • Biodieseleasytosynthesize • Greatermechanicalstrength, moremassive and heaviermotors • Summer and winterdieselfuel

  19. Fossilfuel-operatingpowerplants

  20. Overview • Fossilfuelscombustion • Vapourproduction • Steamorgasturbinerotationgenerateselectricity • Excessheatremovedbycoolingtowers • Combinedcycleplants: gasturbine and steamturbine • 33-60 % efficiency, upto 70 % forcombinedcycle • Greenhousegasemissions Images: Wikipedia

  21. Example: modern coal-firedpowerplant 1 - cooling tower, 2 - cooling water pump, 3 - transmission line (3-phase), 4 - unit transformer (3-phase), 5 - electric generator (3-phase), 6 - low pressure turbine, 7 - condensate extraction pump, 8 – condenser, 9 - intermediate pressure turbine, 10 - steam governor valve, 11 - high pressure turbine, 12 – deaerator, 13 - feed heater, 14 - coal conveyor, 15 - coal hopper, 16 - pulverised fuel mill, 17 - boiler drum, 18 - ash hopper, 19 – superheater, 20 - forced draught fan, 21 – reheater, 22 - air intake, 23 – economiser, 24 - air preheater, 25 – precipitator, 26 - induced draught fan, 27 - chimney stack Image: Wikipedia

  22. Nuclearenergy

  23. Basics and overview • 1951 – ExperimentalBreederReactor 1, USA • 1954 – Obninsk, USSR: nuclearreactorgenerateselectricityforpowergrid • Smallfuelamounts, radioactiveelementsoftenfoundinmetallurgyslags, phosphogypsum, etc. • Smallwasteamount • Operating and wastehazards Image: http://visual.merriam-webster.com/science/chemistry/matter/nuclear-fission.php Image: Wikipedia Shutter UO2tablets Zr Spring

  24. Boilingwaterreactor • Startup neutron source: mixtureof241Am and 9Be • Controlrods: boricacidadsorbsneutrons(neutron poison) • 135I and 135Xe buildup: neutron poisonthat „burnsoff“ Image: Wikipedia

  25. Pressurisedwaterreactor Image: Wikipedia

  26. Breeder reactor Image: Wikipedia

  27. Renewableenergysources

  28. Renewableenergyusebysource Totalenergyconsumption – 8.6 % (Friday, 2013) Electricitygeneration – 25.6 % (BritishPetroleum, 2013)

  29. Biomass and biofuel • Biomass: whengrowth and harvesting are inbalance, plants are sort of „naturalbatteries“ storingSun’senergy • Otherprocesses’ residuescanbeused • Biofuels • Fermentationgivesbiogasorethanol • Biodiesel: usedvegetableoils, fats, recycledgreases • Biodieselisproducedbytranseterification: • Combustionin engines and powerplants

  30. Hydroelectricity (1) • USA – 7 %, Norway – 99 %, Brazil – 93 %, Canada – 58 %, Sweden – 50 % oftotalpowerproduction • Potentialenergyoffallingwateristransformedtoelectricalenergybyturbine • Pumped-storage: duringlowelectricitydemand (nighttime), mostwaterispumpedbackintoreservoir • Ecosystemdamage and loss oflandduetoreservoirs Images: http://ga.water.usgs.gov/edu/hyhowworks.html

  31. Hydroelectricity (2) • Run-of-the-river • Tidalenergy Image: Wikipedia Image: http://www.alternative-energy-news.info/technology/hydro/tidal-power/

  32. Windpower • Works on kineticenergyofwind • 1st century AD – HeroofAlexandria, windwheel • From 9th century – windmills • 1887 – James Blyth made firstwindturbineforelectricutyproduction • Over 2.5 % worldwidetotalpowersupply, 25 % inDenmark • Backingsupplyorpowerstorageneededduetotheintermittencyofwind • Increasedbird and batfatalitiesduetocollisionwith propeller blades – radars and microwavedetectorsappliedinsomeplacestopreventthat • Noiseissues, officiallyunsupported Images: Google

  33. Solarpower • Black dots on map – areaswhichuponbeingcoveredwithsolarcellscan serve asenergysupplyforthewholeworld • Photovoltaics (PV): Si, thin film • Concentratedsolarpower (CSP) Images: Wikipedia Graph: http://techon.nikkeibp.co.jp/article/HONSHI/20100326/181377/

  34. Photovoltaics: basics • n-typesemiconductor – excessofelectrons • p-typesemiconductor – excessofholes (lackofelectrons) • p-njunction: chargecarriersdiffuseintoborderingregionofoppositesemiconductor • Uponphotoexcitation, electronflowstartsfrompton side: electricalcurrent • Canpowerstandaloneinstruments, orbeconnectedtoelectricalgrid Image: http://www.solarcell.net.in/ Image: Wikipedia

  35. Photovoltaicpowerstation • Solarcellslinkedintogreatermodules • Solartrackerscanbeusedtomaximizeoutput • Producesdirectcurrent (DC), inverterstogetalternatingcurrent (AC) • Energystorageisneededforpowerdelivery at night Image: http://www.solarserver.com/solarmagazin/solar-report_0509_e_3.html Images: Wikipedia

  36. Solarthermalenergy • Solarenergyisusedfor heating upreceivingliquid • Temperaturescanreachfrom 45 C (waterheaters) to 3500 C (solarfurnace) • Heatstorageallowscontinuousenergyproduction • steam • moltensalt • graphite Images: Wikipedia

  37. Geothermalenergy • Oldestuses – hotsprings • Direct heating hotwatertemperature 150 C orless (incl. geothermalheat pumps) • Indirect: steamforturbines • AlthoughEarth’sheatcanbeconsideredrenewable, localdepletionispossible • Emissionofgreenhousegasesdrawnfromtherocks (CO2, NH3, H2S, etc.) isconsiderablysmallerthanincaseoffossilfuels Image: http://www.way2science.com/geothermal-power-plant/

  38. Oceanthermalenergyconversion (OTEC) • Usestemperature gradient betweensurface and deeperwaterlayers • Closecircuit: circulatingworkfluid (lowboilingtemperature) • Opencircuit: producesdesalinatedwateraswell • Carbondioxideemissionsduetotemperature and pressurechanges • Bringingnutrientsfromthedeepintoshallow part Image: http://nextbigfuture.com/2010/11/ocean-thermal-energy-conversion-otec.html Image: Wikipedia

  39. Fuelcells

  40. Basics • Fuelcell – electrochemicaldevicethatconvertschemicalenergyoffueldirectlyintoelectricalenergy („coldcombustion“) • 1838 – C. F. Schönbein, 1839 – W. Grove • Fuels: hydrogen, alcohols, ammonia, methane, petrol, etc. Image: Wikipedia 2 H2 – 4 e- 4 H+ O2 + 4 H+ + 4 e- 2 H2O

  41. Types and applications

  42. Heat pumps

  43. Workingprinciple • Firstartificial refrigeraator -1756, W. Cullen • Firstscientificallydescribedby W. Thomson, Lord Kelvin, asheatamplifier, 1852 • Basics: • Heatisneededforevaporation • Heatisreleaseduponcondensation • Boilingtemperaturedepends on pressure • Usedtooperate on freons, now – ammonia, butane, propane, carbondioxide • Refrigerators, conditioners, heating systems • Itispossibletobetupto ca. 2.5-5 kW h of heatenergywhenapplying 1 kW h ofelectricenergy Image: Wikipedia Image: http://progressivetimes.files.wordpress.com/2012/02/geothermal_heat_pump.jpg

  44. Energyconservation and passivebuildings

  45. Main principles • Minimizetheamountofescapingheat – superinsulation: inSweden, min 335 mm forwalls (0.1 W m-2 K-1) and 500 mm forroof (0.066 W m-2 K-1) • Decreasedprimaryenergyconsumption • Passivesolardesign: reducedsurfacearea, windowsorientedtowardsthesun • Airtightness: aircirculationprovidedbymechanicalventilationwithheatrecovery • Heatpumps (heatfromsurroundings and recuperatingheatfromexhaustair) • Heatrecuperationfrom major appliances • Excessiveuseofdaylighting • Solarpanels, wherepossible Images: Wikipedia

  46. Pinchtechnology: basics

  47. Simplecase: twostreams, heatresuperation • A – heatsuppliedbysteam • B – heattakenbycoolingwater • Consider 20 C minimalplausibletemperaturedifferenceforheatexchanger • X – amountofheatrecuperated Image: http://www.me.mtu.edu/~jwsuther/erdm/pinchtech.pdf

  48. Compositecurves: twohotstreams • Streamwithconstantheatcapacity (CP) – straightline Image: http://www.me.mtu.edu/~jwsuther/erdm/pinchtech.pdf

  49. Combinedcompositecurves • Whenminimaltemperaturedifferenceisset, compositecurvescanbeshifted • Wegetamountofrecuperativeheat, and minimalamountsofcooling and heating agents • Belowpinchpoint: heatsource • Abovepinchpoint: heat sink Image: http://www.me.mtu.edu/~jwsuther/erdm/pinchtech.pdf

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