2. Energy Systems & Sustainability Freshman Seminar 2013 Mayda M. Velasco Oct. 1, 2013

3. Few comments about... Nuclear Fusion

4. Introduction “Every time you look up at the sky, every one of those points of light is a reminder that fusion power is extractable from hydrogen and other light elements” -Carl Sagan, 1991

5. Our Sun

6. Fusion Advantages Abundant fuel, available to all nations – Deuterium and lithium easily available for thousands of years Environmental Advantages – No carbon emissions, short-lived radioactivity Modest land usage – Compact relative to solar, wind and biomass Can’t blow up – Resistant to terrorist attack – Less than 5 minutes of fuel in the chamber Not subject to daily, seasonal or regional weather variation – No large-scale energy storage nor long-distance transmission Can produce electricity and hydrogen – Compliments other nearer-term energy sources

7. Fusion Disadvantages Huge research and development costs Radioactivity

8. Background Fusion Basics

9. Energy-Releasing Reactions ChemicalFissionFusion Sample Reaction C + O 2  CO 2 n + 235 U  143 Ba + 91 Kr + 2 n 2 H + 3 H  4 He + n Typical Inputs (to Power Plant) Bituminous CoalUO 2 (3% 235 U+ 97% 238 U)Deuterium & Lithium Typical Reaction Temp. (K) 700100010 8 Energy Released per kg of Fuel (J/kg) 3.3 x 10 7 2.1 x 10 12 3.4 x 10 14

10. What is an atom?

11. Nuclear Power Nuclear fission – Where heavy atoms, such as uranium, are split apart releasing energy that holds the atom together Nuclear fusion – Where light atoms, such as hydrogen, are joined together to release energy

12. Fusion process

13. Stability Band – Lifetime  Radioactive waste

14. Nuclear Binding Energy Fusion favored Fission favored

15. States of Matter Plasma is sometimes referred to as the fourth state of matter

16. Plasma makes up the sun and the stars

17. Plasma Atoms In plasma the electrons are stripped away from the nucleus Like charges repel – Examples of plasma on earth: Fluorescent lights Lightning Neon signs

18. Other Typical Plasmas Interstellar Solar Corona Thermonuclear Laser

19. Characteristics of Typical Plasmas

20. Basic Characteristics Particles are charged Conducts electricity Can be constrained magnetically

21. Fusion Fuel Tritium Deuterium

22. The fuel of fusion

23. Inexhaustible Energy Supply Deuterium – Constitutes a small percentage of the hydrogen in water Separated by electrolysis 1 barrel (42 gallons) water  ¾ oz. Tritium – n + Li T + He – Lithium is plentiful Earth’s crust Oceans – Savannah, Georgia – Canada, Europe, Japan

24. Fusion Fuel: Deuterium

25. Other Possible Fusion Fuels: Helium-3 Nuclear Fusion Proton NeutronProton

26. Where is Helium-3? Helium-3 comes to us from the sun on the solar wind It cannot penetrate the magnetic field around the earth, so it eventually lands on the moon One shuttle load- 25 tons- would supply the U.S. with enough fuel for one year

27. HOW FUSION REACTIONS WORK?

28. Two Main Types of Fusion Reactions: #1 = Proton-Proton "P-P": Solar Fusion Chain

29. Two Main Types of Fusion Reactions: #2 = D-T D + T  4 He + n

30. More on Fusion Reactions

32. An enormous payoff The fraction of “lost” mass when H fuses into He is 38 parts out of 10,000 This lost mass is converted into energy The energy released from 1 gram of DT = the energy from about 2400 gallons of oil

34. The result Inexhaustible fuel source – Seawater & Lithium The MOST “bang for your buck” Inexpensive to produce Widely distributed fuel source – No wars No pollution – Helium is not polluting Fuel that is non-radioactive – Residue Helium-4 is non-radioactive Waste reduction

35. More of Fusion Radioactivity Stray Tritium – Relatively benign Doesn’t emit strong radioactivity when it decays – So only dangerous when ingested or inhaled Shows up in one’s body as water – Easily and frequently flushed out Half-life of 12 years – No long-term waste problem – Won’t decay while in one’s body – Less than natural exposure to radon, cosmic rays and much less than man-made x-rays

36. More on Fusion Radioactivity Reactor Structure – Development of special “low-activation” structural materials Vanadium Silicon-carbide – Wait ten to fifteen years after shutdown The reactor will be less radioactive than some natural materials (particularly uranium ores) Recycle into a new fusion reactor

37. Waste Reduction Power Source Total Waste (m3) High-Level RAD Waste Coal 10,000 (ashes) 0 Fission 440 120 Fusion: Today’s Materials 2000 30 Advanced Materials 2000 0

38. So why aren’t fusion plants already in operation? How fusion works and the obstacles in the way

39. The Problems Harnessing the Energy Achieving & sustaining high temperatures – The reaction takes place at a temperature hotter than the surface of the sun – 0.1 seconds Containing the fuel & the reaction Money for research and development

40. Harnessing the Energy

41. Achieving ignition temperatures 45