Midterm Test 2 – Study Guide Chapters 5, 6, and 7

Chapter 5: Fossil Energy

• Fossil Fuels Contribution to Energy
  • Fossil fuels provide a significant percentage of the world’s primary energy.
• Conventional Fossil Fuels
  • Three types: coal, oil, natural gas.
• Origin of Energy in Fossil Fuels
  • Fossil fuels originate from ancient biological materials (plants and animals) subjected to heat and pressure over millions of years.
• Conditions for Formation
  • Essential conditions include high pressure, heat, and anaerobic environments.
• Formation of Coal
  • Coal forms from accumulated plant matter (peat) that undergoes anaerobic decomposition over time.
• Peat and Forms of Coal
  • Peat: accumulation of partially decayed organic matter.
  • Different forms include lignite (low-grade), sub-bituminous, bituminous, and anthracite (high quality).
• Formation of Oil & Natural Gas
  • Formed from the transformation of organic matter (kerogen) under heat and pressure.
• Anticlines and Hydrocarbons
  • Anticlines: geological formations where oil and gas can accumulate.
• Natural Gas and Crude Oil Composition
  • Natural gas primarily consists of methane; crude oil is a complex mixture of hydrocarbons.
• Refining Crude Oil
  • Main products include gasoline, diesel; refining process typically involves distillation.
• Chemical Composition Differences
  • Coal is solid, complex; oil and natural gas are liquid and gaseous hydrocarbons, respectively.
• Hydrocarbons
  • Gasoline contains alkanes like octane; natural gas consists mainly of methane.
• Combustion Products
  • CO2 and water vapor are two primary combustion products; CO2 is categorized as a greenhouse gas.
• Greenhouse Gases
  • Both CO2 and water vapor can contribute to climate change, with CO2 being the dominant greenhouse gas.
• Carbon Dioxide Emissions
  • Ranking: coal > oil > natural gas; differences in emissions arise from carbon content variations.
• Emission Prevention
  • Technology exists to reduce emissions but complete prevention is challenging.
• Fuel Efficiency
  • Only 15-20% of gasoline energy reaches wheels; hybrids improve this through regenerative braking.
• Regenerative Braking
  • Technique that converts kinetic energy back into stored energy during braking.
• Resource vs Reserve
  • Resources are estimated quantities; reserves are known, economically recoverable volumes.
• Coal Reserves
  • The country with the highest reserves is the United States.
• Coal Energy Content
  • Energy content varies significantly across coal grades.

Chapter 6: Environmental Impact of Fossil Fuels

• Pollutants vs Greenhouse Gases
  • Pollutants: substances that harm the environment; greenhouse gases trap heat.
• Fossil Fuel Combustion Products
  • Essential products include CO2, water vapor; avoiding CO2 emissions is virtually impossible during combustion.
• Regulations on CO2 Emissions
  • Regulations focus on limiting emissions to mitigate climate change impacts.
• Diesel vs Petrol
  • Diesel: higher energy density and efficiency but may produce more NOx and particulate matter.
• Contaminants in Coal & Petroleum
  • Include sulfur, mercury, particulate matter, and various organic compounds.
• Particulate Matter
  • Tiny particles from combustion affecting air quality and health.
• Emission Reduction Techniques
  • Techniques include filtration (e.g., filters, cyclones, electrostatic precipitators) to capture particulates.
• Filter Performance
  • Filters may fail in excessive dust or moisture; efficiency and maintenance are critical.
• Cyclones and Precipitators
  • Cyclones separate larger particles using centrifugal force, while electrostatic precipitators capture charged particles.
• Sulfur Emissions
  • Main sources are fossil fuels; sulfur levels vary by fuel type, and desulfurization is possible.
• Acid Rain
  • Rain with a pH < 5.6, caused by sulfur and nitrogen oxides, negatively affects ecosystems.
• Flue Gas Desulfurization
  • Process to remove sulfur from exhaust gases of fossil fuels.
• Carbon Monoxide
  • Produced from incomplete combustion; it is toxic and affects human health.
• Catalytic Converters
  • Devices in vehicles that convert harmful gases (like CO) into less harmful emissions.
• NOx Gases
  • Include nitrogen oxides; treatment can reduce NOx emissions.
• Photochemical Smog
  • Caused by reactions between sunlight and pollutants; often appears as brown haze.
• Inversion Conditions
  • Atmospheric conditions that trap pollutants near the surface, worsening air quality.
• Ozone Production
  • Formed from photochemical reactions involving NOx and VOCs; smog precursors include hydrocarbons and NOx.
• Mercury Pollution
  • Sources include coal combustion; accumulates in food chains, affecting human health.
• Radioactive Pollutants
  • Found in coal waste; coal plants emit more radiation than nuclear plants under regular conditions.
• Clean Air Act Definition
  • Defines clean air with six criteria pollutants including particulate matter, ozone, and lead.

Chapter 7: Nuclear Energy

• Contribution of Nuclear Energy
  • Nuclear energy constitutes about 10% of global primary energy and 20% of electricity generation.
• Leading Nuclear Power Countries
  • United States has the highest generation capacity, while France generates most of its electricity from nuclear.
• Atomic Nucleus Constituents
  • Composed of protons (charged) and neutrons (neutral).
• Atomic Number and Mass Number
  • Atomic number: number of protons; mass number: total number of protons and neutrons.
• Nuclide and Isotopes
  • Nuclide: a distinguishable atomic species; isotopes are variants of elements with different neutron counts.
• Forces in Nucleus
  • Strong nuclear force holds nucleons together; weak nuclear force is involved in beta decay.
• Binding Energy
  • Energy required to bind nucleons; high binding energy indicates stability.
• Nuclear Fission vs Fusion
  • Fission: splitting heavy atomic nuclei; fusion: combining light nuclei; fusion releases significantly more energy.
• Radioactivity and Decay
  • Three decay types: alpha (particle emission), beta (electron emission), gamma (high-energy electromagnetic radiation).
• Radiation Impact
  • Alpha is least penetrating, gamma is most penetrating; beta particles are harmful to tissues.
• Half-Life
  • Time taken for half of a radioactive substance to decay; unique to each isotope.
• Background Radiation Sources
  • Natural sources (cosmic rays, radon) and human-made (medical, nuclear power).
• Fission Processes
  • Spontaneous vs neutron-induced; neutron-induced can release energy quicker.
• Fissile Materials
  • Materials capable of sustaining fission (e.g., Uranium-235, Plutonium-239); Uranium-235 occurs naturally.
• Fission Process Requirements
  • Requires certain conditions (critical mass) for chain reactions; moderators slow neutrons for fission.
• Control Mechanisms in Reactors
  • Control rods absorb neutrons to regulate reactions; coolants remove heat to prevent overheating.
• Nuclear Fuel Cycle Steps
  • Includes mining, enrichment, utilization in reactors, and waste management.
• Uranium Enrichment
  • Process to increase U-235 concentration; military and civilian applications differ in enrichment levels.
• Spent Fuel Risks
  • Highly radioactive; needs careful handling and storage; more radioactive than fresh fuel.
• Fusion Reaction Conditions
  • Requires high temperatures and pressures; Lawson criteria and confinement techniques (inertial and magnetic) are key issues.
• Environmental Impact of Fusion
  • Generally less waste than fission; however, challenges remain in practical implementation.