Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege

1. Engineering 10 Chp.6 FutureChallenges Bruce Mayer, PE Licensed Electrical & Mechanical EngineerBMayer@ChabotCollege.edu

2. FIRST and SECOND Laws ofTHERMODYNAMICS • Class Question: Can Anyone Describe Either of the FIRST or SECOND Laws of ThermoDynamics?

3. Laws of ThermoDyamics • In the Instructor’s Opinion The SECOND Law is the GREATEST of all the “Laws of Physics” • The ThermoDyamic Laws • Describe the Relationships & Connections Between Work↔Heat↔Energy • Describe and Quantify Reversibility and IRReversibilty • Explains What’s “The Best we can Do”

4. The “Laws”  What are they? • First Law of Thermodynamics • Energy can neither be CREATED nor DESTROYED • But Energy Can be Moved, or Changed to Other forms • Second Law of Thermodynamics • NATURALLY OCCURRING processes are Directional • Natural process can go ONE WAY, but NOT the OTHER

5. Reversibility • Reversibility is the ability to run a process back and forth (backwards and forwards) infinitely withOUT Losses • Money analogy: Currency Conversion • NO service fee (reversible): $100  113000₩, and one hour later at the same place, 113000₩ $100 • WITH service fees (IRreversible: $100  68€, and one hour later at the same place, 68€$90 (5% fee both ways)

6. Pressure Voltage MotorGenerator Turbine Pump Electric Current Fluid Flow Reversibility and Energy • If IRreversibilities were ELIMINATED, these systems would run FOREVER. • These Systems would then be Perpetual Motion Machines

7. Example: Popping at Ballon • A “reversible process” can go in either direction, but these processes are rare • Generally, the irreversibility shows up as waste heat X Not reversible unless energy is expended

8. Sources of Irreversibilities • Friction (force drops) • Voltage (electrical) drops • Pressure drops • Temperature drops • Concentration drops • Magnetic Hysteresis (H Drops)

9. Irreversibility Example • It’s EASY To Mix the Cream Into the Coffee • It’s extremely difficult to Unmix (separate) the Cream from the Mixxed Coffee • It takes a LOT of Effort, or WORK, to separate

10. First Law of ThermoDynamics • One form of work may be converted into Another, • Or, work may be converted to heat, • Or, heat may be converted to work, • But, ALWAYS FINAL energy = INITIAL energy

11. 2nd Law of Thermodynamics • We intuitively know that heat flows from higher to lower temperatures and NOT the other direction. • i.e., heat flows “DownHill”; just like water • WHY don’t we see Water flow UpHill, or Heat move Cold→Hot on Occasion? • Water and Heat Flow ONE-WAY Because These processes “down-flow-hill” are inherently Irreversible.

12. Heat↔WorkConverstions • Heat transfer is inherently irreversible. • This places LIMITS on the amount of work that can be produced from heat. • Heat can be converted to work using heat engines; e.g., • Jet engines (planes), • Steam engines (Old Locomotives) • Steam Turbines (electrical PowerPlants), • Internal combustion engines (automobiles)

13. W High-temperature Source, Thot Heat Engine Low-temperature Sink, Tcold Qcold Qhot (e.g. cooling pond) (e.g. flame) Heat into Work (Power Plant) • W = Mechanical Work • Q = Heat • A heat engine takes in an amount of heat, Qhot, and produces work, W, and waste heat Qcold Qhot = W + Qcold • Nicolas Sadi Carnot (karnō) derived the LIMITS of converting heat into work

14. Carnot Equation: Efficiency • Given the heat ENGINE on the previous slide, the maximumwork that can be produced is governed by: • where the temperatures are absolute (e.g. Kelvins) • Thus, as ThotTcold, Wmax 0 • This ratio is also called the Thermal Efficiency, η N.L.S. Carnot

15. Example: PowerPlant 1000 °F = 1460 °R • A PowerPlant Boiler Runs at about 1000 °F • The “Heat Sink” is the cold Pacific Ocean at 52 °F • What is ηmax ? 52 °F = 512 °R

16. W High-temperature Source, Thot Heat Engine Low-temperature Sink, Tcold Qcold Qhot (e.g. InSide AC) (e.g. OutSide Air) Moving Energy Cold→Hot • Not USING Heat, Just Moving it Around • Moving Heat UPhill requires WORK • The CoEfficient of Performance, CoP, informs about the effectiveness of AirConditioners and HeatPumps

17. Carnot Equation: CoP • Given the heat PUMP on the previous slide, the Minimum Work needed to move heat UpHill is governed by: • where the temperatures are absolute (e.g. Kelvins) • Thus, as ThotTcold, Wmin 0 • This ratio is also called the CoEfficient of Performance, CoP

18. Example: Air Conditioner 105 °F = 565 °R • It’s REALLY Hot Outside, 105 °F • A “Cold Blooded” person Keeps the house at 65 °F • What is CoPmax? 65 °F = 525 °R

19. Nicolas LéonardSadi Carnot • Founder of the Science of ThermoDynamics • BORN: Paris, France,June 1 1796 • DIED: Paris, France,August 24 1832

20. “Water Powered” Hydrogen Car • A “Hydrogen” car is the SAME THING as the traditional “Electric Car” • In BOTH Cases Electric Motors turn the Wheels • In an “Electric Car” The Energy is stored in traditional Batteries • In an H2 car the energy is stored in Hydrogen Tanks • Sometimes at 5,000 psi

21. “Water Powered” Car • It’s Easy • Just get some H2O, split it into H2 & O2 • Store the H2 in Tanks in your Car, • Run it thru a “Fuel Cell” to turn an Electric Motor • Could also burn it in a Heat Engine • Off you go

22. “Water Powered” Car – Not so Fast

23. Energy & Humans • James Watt and His Predecessors (e.g., Savery & Newcomen) FREED Human Kind From Muscle Power • The Heat Engine Was One of the Great Advances in Human History • Enabled the “Industrial Age” • The Generation & Application of Energy Multiplies The Capabilities of EVERY Person

24. Watt’s Engine Watt, James (1736-1819) Scottish inventor and mechanical engineer, renowned for his improvements of the steam engine. Watt was born on January 19, 1736, in Greenock, Scotland. He worked as a mathematical-instrument maker from the age of 19 and soon became interested in improving the steam engines, invented by the English engineers Thomas Savery and Thomas Newcomen, which were used at the time to pump water from mines.

25. Energy Sources • Let’s LIST Real And Potential Energy Sources OTHER Than Fossil Fuels • ? • ? • ? • ? • ? • ?

26. Energy Sources  Fact & Fancy • Wind Power • Wind Turbines Are VERY Attractive • Energy Input to Produce is Low • Incremental Added Capacity • NO Emissions of Any Kind • Limitations • Low Energy Density • Must Cover Large Areas to Produce Much Energy • Limited Viable Sites • Balance of System Costs • Need AC→AC Frequency Converter

27. Energy Sources  Fact & Fancy • Split Wood, Not Atoms → BioMass • Burning Garbage or Plant Matter is Attractive • Simultaneous Solution to Energy and Solid-Waste Problems • “Renewable” Resource • Low Energy Input to Produce • Limitation: Emission Stream is VERY Unpleasant • Scrubbing Wood-Smoke is MUCH Harder than Cleaning Gasoline Combustion ByProducts

28. Glen Canyon Dam – Page, AZ • Electrical Power Generation • River: Colorado River • Plant Type: Conventional • Powerhouse Type: Above Gnd • Turbine Type: Francis • Original Nameplate Capacity: 950,000 kW (950 MWe) • Installed Capacity:1,304 MWe • Year of Initial Operation:1964 • Net Generation (FY 2005): 3,208,591,407 kWh • Rated Head:510 feet

29. Glen Canyon DamAerial View Lawn Generators Visitor Center Bridge TransmissionTowers TransformerSwitchYard

30. Glen Canyon Dam – Page, AZ

31. Glen Canyon Dam – Power Gen 150 rpm48 Poles

32. Glen Canyon Dam – Power Gen

33. Glen Canyon Dam – Power Gen • Set-UP Transformers 13.8kV  230kVor 13.8kV  345kV

34. Francis Turbine Generator System

35. Energy Sources  Fact & Fancy • Hydroelectric Power • Fancy: Can Provide for Future Growth • Fact: Almost ALL Viable Hydro Sites Have Been USED • Damming More Rivers is a Political Issue • Ethanol as AutoMobile Fuel • Fancy: Ethanol Can Replace Oil As a Source for Automobile Fuel • Fact: Making Ethanol from Corn May Use MORE Energy than It Produces

36. Energy Sources  Fact & Fancy • Ethanol Continued • DISTILLATION of Ethanol from Fermented Corn Requires Large Amounts of Energy • Usually Provided by Burning Fossil Fuels at the Distillation Site, or at the Electrical Power Plant • Solar PhotoVoltaics Can Supply Future Needs • Photovoltaic Solar-Electric Cells Have Many Advantages (ref. Mr. Murphy) • Remote Siting, Incremental Expansion

37. Energy Sources  Fact & Fancy • Solar Cells Continued • BUT Making a Solar Cell Requires Large Amounts of Energy • Silicon Cells are Made by, in the Beginning, MELTING SAND • Production Processes Can be Energy Intensive as Well • Connecting to the Existing Electric Grid Includes a Great Deal of “Balance of System” Components • DC→AC “Inverters”, Special Electrical boxes

38. Energy Sources  Fact & Fancy Proton Exchange Membrane (PEM) FC http://fuelcells.si.edu/basics.htm • Solar Cells Continued • Solar Radiation has a Very Low “Energy Density” • Requires LARGE Areas to Collect Significant Amounts of Energy • Can Crowd-Out Other Uses: Solar-Farm vs. Tomato-Farm • Hydrogen Fuel Cells • Based on Chemical Reaction See also http://www.olympusmicro.com/primer/java/fuelcell/

39. Solar-Farm vs. Orange Orchard

40. Energy Sources  Fact & Fancy • Hydrogen Fuel Cells Continued • The Fuel Cell Reaction Looks Very Good • NO VOCs/HydroCarbon Emissions • NO NOx emission • NO Greenhouse Gases (CO2) • But WHERE Do We Get the HYDROGEN? • There are NO Hydrogen WELLS or MINES • The Viable Sources of Massive Amounts of Hydrogen themselves Require Large Energy or Carbon Inputs

41. Energy Sources  Fact & Fancy • In Apr04 Gov. Arnold Schwarzenegger has proposed an ambitious network of hydrogen filling stations by 2010 • See also http://www.hydrogenhighway.ca.gov/ • But How can we MAKE all the Hydrogen needed to Replace Gasoline? • There are 3 Viable Alternatives

42. Energy Sources  Fact & Fancy • Use WIND or NUCLEAR Power to generate Electricity which, in Turn, would be Used to Electrolize WATER • Electrolosis applies Electrical current to water and splits it into oxygen and hydrogen, which are then separated… • The Chemical Reaction • This is a Very Energy Intensive Process; about 75% efficient

43. Electric Cars: H2vsElectroChem Ulf Bossel, “Does a Hydrogen Economy Make Sense?”, Proceedings of the IEEE | Vol. 94, No. 10, October 2006, pp 1826-1837

44. Energy Sources  Fact & Fancy • Steam reforming of natural gas • If you take methane, the main component of natural gas, and expose it to steam, the final products are primarily carbon dioxide and hydrogen. Chemically • This is already a Large-Volume Industrial Process, but it produces a LOT of CO2 – a GreenHouse Gas • Natural Gas Supplies seem ample

45. Energy Sources  Fact & Fancy • Coal gasification • hydrogen could be produced at centralized plants, compressed and most likely transported in trucks. • Coal is mostly carbon & hydrogen, but also contains some sulfur. Exposed to water at high temperature and high pressure, it chemically reacts to yield carbon monoxide (CO) and hydrogen. • But CO is Poisonous to Humans

46. Energy Sources  Fact & Fancy • Coal gasification, cont. • Oxygen from additional water vapor turns carbon monoxide into carbon dioxide. So the end products are primarily carbon dioxide and hydrogen gas. Chemically • We have LOTS of Coal, but still need to clean up the CO2 and H2S

49. USA Primary Energy Production by Source http://www.eia.doe.gov/aer/overview.html * 2009