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Energy from Fossil Fuels

Energy from Fossil Fuels. Energy from Chemistry. Question What is “chemical” energy? A form of potential energy Potential energy is stored in the (valence) electrons of atoms and molecules Lecture Questions What are exothermic and endothermic chemical reactions?

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Energy from Fossil Fuels

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  1. Energy from Fossil Fuels

  2. Energy from Chemistry • Question • What is “chemical” energy? • A form of potential energy • Potential energy is stored in the (valence) electrons of atoms and molecules • Lecture Questions • What are exothermic and endothermic chemical reactions? • Exothermic reaction: produces energy, usually as heat or light • Endothermic reaction: consumes energy as it proceeds • Why do some reactions produce energy (and some consume it)? • Chemical reactions • Consists of breaking and forming bonds • The formation of bonds always yields energy • The breaking of bonds always requires energy • The balance between these two processes determines the net energy yield/requirement of a chemical reaction

  3. The Fossil Fuels • What are the main fossil fuels? • Coal, oil (petroleum), natural gas • How are they mostly used? • Coal: electricity • Oil: transportation, heating • Natural gas: heating, electricity, cooking OECD Global

  4. Use of Coal

  5. Use of Natural Gas

  6. Use of Oil

  7. King Coal • Lecture Questions • What is coal? • A solid mixture consisting largely (about 85%) of carbon • Representative formula is C135H96O9NS • Plenty of other impurities • Toxic metals like Pb, Hg, As • Radioactive isotopes of various types • Three broad grades of coal • Anthracite (hard coal). Highest carbon content and heat value. • Bituminous coal (soft coal) • Lignite (brown coal). Lowest carbon content and heat value. • How is coal formed? • Originated as plant matter in hot, muggy regions • Most current coal formed 200-350 million years ago • Plant matter decays under conditions of low oxygen, high heat and pressure • First converted to peat

  8. Natural Gas • What is natural gas? • Gaseous mixture of hydrocarbons • Mostly methane, CH4 (60-80%) • Others: C2 HCs (5-9%), C3 HCs (3-18%), C4 HCs(2-14%) • How is it formed? • Decomposition of plant and animal remains that had been buried • Again: lack of oxygen, high heat and pressure • Methane is produced by anaerobic respiration • Plenty produced in sediments and landfills • Often accompanies coal and oil deposits

  9. Oil • What is oil (petroleum)? • A very complicated liquid mixture of hydrocarbons • Liquid HCs start at C4-C5 • Almost always contains dissolved natural gas as well • How is it formed? • Again, decomposition of biological matter • Most probably originated from ocean-dwelling microorganisms

  10. Oil Recovery

  11. Primary Recovery of Oil

  12. Secondary Recovery of Oil

  13. Oil Recovery

  14. Oil Distillation

  15. Oil Distillate Refinement • Gasoline Formation • Conversion of other oil fractions to gasoline • Cracking • Breaking apart larger molecules into smaller ones • Thermal cracking • Catalytic cracking • Gasoline enhancement • Purpose • Make it burn better of cleaner • Example: antiknock agents • Tetraethyl lead (TEL) • MTBE • Oxygenated Gasoline • Reduce CO emissions • MTBE, ethanol, methanol • Reformulated Gasoline (RFG) • Oxygenated gasolines with fewer volatile hydrocarbons • Reduce CO emissions • Reduced smog • May have reduced impact on groundwater (lower BTEX)

  16. Environmental Impacts of Fossil Fuels • What are the environmental impacts of using fossil fuels as energy sources? • Extraction • Coal mining • Oil and gas drilling • Storage and Transport • Leaks, spills • Combustion • Contributes to global warming, acid rain, smog, PM, eutrophication, toxic metals, exposure to radioactivity • All contribute to global warming, nitrate PM, eutrophication, and acidification due to HNO3 • Coal is the main culprit for SO2, metal and radionuclide emissions. It is also the worst of the three for PM.

  17. The Future of Fossil Fuels • Nonrenewable resources • They will eventually be exhausted and need to be replaced • Global warming may accelerate the replacement (or not) • Reserves and Resources

  18. Peak Oil • When will we run out of oil (and natural gas)? • Most important question is maybe: when will production begin to decline? (ie, “when will peak oil production occur?”) • In March 1998, two retired petroleum geologists (Campbell and Laherre) claimed that oil would peak in the first decade of the 21st century

  19. Peak Oil: Other Estimates

  20. Peak Oil • Unconventional Sources of Oil • Potentially a very large resource • Oil shales, tar sands, heavy oil • Extends peak production by 2-3 decades • Problems • More energy intensive (thus more expensive); more environmentally damaging

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