1. Physics 362 – week 9 Modern Physics Seminars

2. The energy challenge

3. HDI: longevity (life expectancy), educational attainment, and standard of living (gross domestic product per capita)

4. How to produce electricity? Conversion of mechanical energy into electricity (dynamo) Conversion of chemical energy into electricity Conversion of nuclear energy into electricity Conversion of photon energy into electricity

5. Energy sources Oil, Natural Gas, and Coal Nuclear Renewable energy source Solar Cells Water Power plants Windmills Biomass Hydrogen

6. Energy sources

7. Cost of energy production Photovoltaic cells: $0.2-0.3 per kW h Wind turbines: $0.04-0.05 per kW h Gas: ~ $0.02 per kW h

8. Carbon reduction

9. Carbon Reduction

10. World and U.S. reserves

11. Nuclear Energy Production E = m c 2 ?

12. Chronology 1905 E=mc 2 – Einstein 1939 First nuclear fission – Hahn and Strassmann 1942 First nuclear reactor – Fermi 1951 First reactor to generate electricity

13. Nuclear Forces  The nucleus is stable if the nuclear attraction dominates over the EM repulsion EM repulsion between protons Nuclear attraction

14. Binding Energy BE > 0 Higher Binding energy means more stable nuclei ~ 8 MeV/nucleon BE/A ~ constant for A>20

15. Energy production If BE/A initial < BE/A final  E initial =  M j c 2 =  (Z j m p +N j m n )c 2 -BE j /A j ·A j ] E final =  M i c 2 =  (Z i m p +N i m n )c 2 -BE i /A i ·A i ]  E final - E initial =  BE i /A i ·A i -  BE j /A j ·A j > 0

16. Energy production fissionfusion

17. Uranium Isotopes IsotopePercentHalf-life (years) 238 U99.2844.46 billions 235 U0.711704 millions 234 U0.0055245,000 239 Pu93/5724,110

18. Nuclear Fission Heavy nucleus is bombarded with neutrons  It decays into two smaller nuclei + neutrons

19. Uranium Fission

21. Chain reaction

22. Self sustained chain reaction K = Reproduction Constant K < 1  The reactor is sub-critical  it dies out K = 1  The reactor is critical  self sustained chain K>>1  The reactor becomes unstable

23. Energy Production K ~ 1 Neutron leakage  area/volume ratio Neutron Energy Neutron capture by non-fission elements Control of power level Safety

24. Nuclear Reactor

25. Nuclear Power Plants

26. Generation I reactors Fuel: 235 U 238 U/ 239 Pu 232 Th/ 233 U Oxides Carbides Metal alloys

27. Generation I reactors Fuel: 235 U 238 U/ 239 Pu 232 Th/ 233 U Oxides Carbides Metal alloys Coolants: Light water Gases Heavy water Organic liquid Liquid metal Molten salts System configuration: Pressurized water Boiling water

28. Pressurized Water Reactor

29. Next Generation

30. Solar cells

32. Satellites

33. Solar Cells

34. Water Power plants

35. Windmills Up to 72 m in rotor diameter Estimated 3-22 Q of energy

36. Biomass Wood burning Fermentation and distillation to produce ethanol Steam-powered generators

37. Hydrogen fuel cells Gemini and Apollo spacecrafts 2H 2 +O 2  2H 2 O+electricity+heat