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Energy Systems & Climate Change

Energy Systems & Climate Change. Thus. 12 Nov. 2009 Finish Ch.7: Nuclear Dr. E.J. Zita (& Cheri Lucas Jennings) zita@evergreen.edu. http://academic.evergreen.edu/curricular/energy/0910/home.htm. What’s happening today:. Questions? Announcements? Zita: finish Nuclear

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Energy Systems & Climate Change

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  1. Energy Systems & Climate Change Thus. 12 Nov. 2009 Finish Ch.7: Nuclear Dr. E.J. Zita (& Cheri Lucas Jennings) zita@evergreen.edu http://academic.evergreen.edu/curricular/energy/0910/home.htm

  2. What’s happening today: • Questions? Announcements? • Zita: finish Nuclear • Answer questions about Nuclear & Coal • 2:30 - Brief Reports • 3:15 - Seminar

  3. Ch.7 HW due NEXT week? Questions: 3, 4 Exercises: 8 Research problems: one per team (your choice)

  4. Isotopes Same number of protons = same chemistry Solve for m2

  5. Fusion: 4H  He + Dm

  6. Atomic mass Ex.7.5 showed that using a 5 kW electric dryer (powered by a 33% efficient nuclear plant) for an hour produces N=1.2x1018 nuclei of 239Pu (plutonium). Mass per nucleon = mn = 1.67 x 10-27 kg The mass of each 239Pu nucleus = m = 239 mn = _____ Total 239Pu mass produced = M = N m = ______

  7. C14 from cosmic rays Cosmic rays excite N14→ decays to C14 Solar max: magnetic solar wind sweeps away cosmic rays → less *N14→ less C14 http://www.nuclearonline.org/newsletter/Oct05.htm

  8. How can we use atomic isotopes to tell whether fossil fuel exhaust (e.g. old Carbon) is actually responsible for recent rise in Greenhouse Gases?

  9. Lower recent C14 /C12 from fossil fuel burning Little Ice Age: low solar magnetic activity  more cosmic rays and C14 Evidence of anthropogenic source for greenhouse gases

  10. Q

  11. Radioactive decay: l=decay rate

  12. Half-life = T1/2

  13. Half-life Solve for n and then t…

  14. Break? thendiscuss more of your questions on Nuclear and Coal

  15. Nuclear questions - Is there a safe way to propose nuclear disarmament alongside civilian nuclear power generation? - Does a greater temperature difference in a nuclear reactor also translate to higher efficiency? For example, does a reactor work more efficiently in the winter? Courtesy of Ben and Skunkworks

  16. How do nuclear weapons work? Nuclear bomb: fission of U (Hiroshima) or Pu (Nagasaki) by chemical explosions H-bomb: fusion of H excited by explosion of outer shell of fissioning U – much more powerful Image courtesy of FastFission

  17. How does IGCC work?

  18. How does IGCC work? A [coal] gasifier converts hydrocarbon feedstock into gaseous components by applying heat under pressure in the presence of steam. A gasifier differs from a combustor in that the amount of air or oxygen available inside the gasifier is carefully controlled so that only a relatively small portion of the fuel burns completely. This "partial oxidation" process provides the heat. Rather than burning, most of the carbon-containing feedstock is chemically broken apart by the gasifier's heat and pressure, setting into motion chemical reactions that produce "syngas." Syngas is primarily hydrogen and carbon monoxide, but can include other gaseous constituents; the composition of which can vary depending upon the conditions in the gasifier and the type of feedstock. DOE website: http://www.fossil.energy.gov/programs/powersystems/gasification/howgasificationworks.html

  19. How does IGCC work? In Integrated Gasification Combined-Cycle (IGCC) systems, the syngas is cleaned of its hydrogen sulfide, ammonia and particulate matter and is burned as fuel in a combustion turbine (much like natural gas is burned in a turbine). The combustion turbine drives an electric generator. Exhaust heat from the combustion turbine is recovered and used to boil water, creating steam for a steam turbine-generator. The use of these two types of turbines - a combustion turbine and a steam turbine - in combination, known as a "combined cycle," is one reason why gasification-based power systems can achieve high power generation efficiencies. Currently, commercially available gasification-based systems can operate at around 40% efficiencies… Another advantage of gasification-based energy systems is that when oxygen is used in the gasifier (rather than air), the carbon dioxide produced by the process is in a concentrated gas stream, making it easier and less expensive to separate and capture. [Then,} it can be sequestered - that is, prevented from escaping to the atmosphere, where it could otherwise potentially contribute to the "greenhouse effect." DOE website: http://www.fossil.energy.gov/programs/powersystems/gasification/howgasificationworks.html

  20. More coal or nuclear questions? Brief reports: Responses:

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