Combustion, Fossil Fuels and Nuclear Power

Combustion and Power Generation

  • Types of Power Generation

    • Coal
    • Natural Gas (NG)
    • Nuclear Power
    • Process involves splitting atoms, releasing a substantial amount of heat

  • Coal Power Generation

    • Mining
    • Process: Pulverized coal must be broken into smaller pieces for feeding into boilers
    • Waste: Coal ash produced, requiring storage in ponds
      • Concern: History of pond failures
    • Environmental Concerns
    • Water Use: High amounts of water required for cooling
      • Issue: Contributes to thermal pollution
    • Pollution: Defined as material in the environment at levels detrimental to life
    • Emissions: Includes water vapor, CO₂, and sulfur (some captured using scrubbers)

  • Shift to Natural Gas for Power Generation

    • Reason: Natural gas generates less pollution (notably no sulfur)
    • Operational Flexibility: Power plants using natural gas can be stopped and started easily

Problems of Fossil Fuel Extraction

  • Coal Mining Issues

    • Habitat Destruction: Major impact on local ecosystems
    • Worker Safety Concerns
    • Coal Ash Ponds: Risk of failure which can lead to coal ash slurry contamination downstream

  • Petroleum Extraction Issues

    • Pumping Problems: Risks associated with pipeline breaks, oil spills from ships, and offshore oil rigs
    • Flaring: Burning of waste methane at oil rigs
    • Environmental Consideration: This process converts methane, a potent greenhouse gas, to CO₂, which is less harmful

Hydraulic Fracturing (Fracking)

  • General Overview
    • Concerns:
    • Habitat Impact: Environmental footprint is present but not extensive
    • Water Use: Concerns regarding groundwater contamination
    • Seismic Activity: Fracking has been associated with increased seismic events
    • Practical MCQ: Assesses knowledge of fracking implications and operations

Nuclear Power

  • Process of Nuclear Fission

    • Fuel: Utilizes Uranium-235 (U-235)
    • Mechanism: Enriched U-235 fuel rods are bombarded with neutrons leading to a chain reaction and heat generation

  • Use of Heat

    • Electricity Generation: The heat generated from nuclear fission is used to produce electricity

  • Pros and Cons of Nuclear Power

    • Pros:
    • No CO₂ emissions (no greenhouse gases)
    • Reliable electricity generation potential
    • Produces a small amount of waste material
    • Cons:
    • Not renewable
    • Radiation hazards including radioactive waste management
    • Risks of reactor meltdowns and explosions if not adequately cooled

  • Nuclear Waste Storage

    • Challenges: Management of spent U-235 nuclear waste
    • Storage Sites: Example includes Yucca Mountain
      • Local Opposition: Citizens of Nevada oppose this site

  • Transport Issues

    • Risk Factors: Transportation of waste (via trucks, trains) presents a risk for accidental radiation release

Nuclear Accidents

  • Key Incidents

    • Three Mile Island (1979): Water pump failure caused a lack of cooling leading to a partial meltdown
    • Chernobyl (1986): Significant meltdown and reactor explosion; resulted in an exclusion zone
    • Fukushima (2011): Tsunami-induced power failure led to the meltdown of three reactors

  • Half-Life

    • Concept: Time required for half of a radioactive substance to decay
    • Examples:
    • Carbon-14: 5,730 years
    • Cesium-137: 30 years
    • Plutonium-239: 20,000 years

  • Practical MCQs: Engages with potential exam questions pertaining to nuclear power, its implications, and safety concerns.