Fossil Fuels and Renewable Energy

Fossil Fuels

• Petroleum (crude oil) consists of hydrocarbons
• Fractional distillation separates crude oil components by boiling points.
  • Oil is heated in a vessel and compounds vaporize as temperature increases.
  • Smaller molecules rise higher in the fractionation tower.
• Gasoline octane rating measures resistance to engine knocking.
• E85 fuel gets lower mileage than pure gasoline due to the ethanol content.
• Natural gas burns cleanly and completely and produces little to no sulfur dioxide.
• Coal burning plants release sulfur oxides and carbon dioxide.
• "Clean coal" technologies include:
  • Coal washing to remove impurities.
  • Gasification to reduce nitrogen oxide generation.
  • Wet scrubbing to remove SO₂.
  • Carbon sequestration (not yet widely implemented).

Renewable Energy

• Wind energy is the fastest growing renewable in the last decade.
  • Wind energy represents kinetic energy.
  • Offshore locations provide faster/more uniform winds and proximity to coastal populations.
• Solar energy uses photovoltaic cells to convert sunlight directly to electricity.
  • Solar energy requires batteries for storage when sunlight is unavailable.
  • Solar energy is not yet practical for powering vehicle fleets.
  • A solar array the size of New Jersey would be needed to power the entire US.
• Biofuels include:
  • Biodiesel, which is made from renewable resources, is nontoxic, biodegradable, and usable in diesel engines.
  • Ethanol, which is produced from biomass like corn.
• Renewable sources currently represent about 18% of global energy consumption.

Electrochemistry

• Batteries generate electricity through redox reactions.
  • Oxidation occurs at the anode.
  • Reduction occurs at the cathode.
  • Voltage depends primarily on the nature of the materials in the reaction.
  • To be rechargeable, the electrochemical reaction must be reversible.
  • Mercury batteries have been replaced due to toxicity and disposal issues.
  • Supercapacitors have lower energy densities than batteries.
• Fuel cells:
  • Reduction takes place at the cathode.
  • Fuel cells don't run down because reactants flow in as needed.
  • Components of fuel cells: anode, cathode, electrolyte (no timer).
  • PEM fuel cells are cleaner than gasoline engines but have limited driving range.
  • Enable electricity generation in new locations.

Nuclear Energy

• Nuclear fission splits large nuclei to form smaller, more stable nuclei.
• Nuclear fission provides approximately 20% of US electricity.
• Nuclear radiation types (from highest to lowest mass): alpha, beta, gamma.
  • Gamma radiation is also electromagnetic radiation.
• Nuclear waste must be stored indefinitely.

Thermodynamics

• First law of thermodynamics: energy is neither created nor destroyed.
• Combustion: fuel combines with oxygen to release energy.
• Exothermic reactions release energy.
• Endothermic processes include photosynthesis.

Alternative Technologies

• Hybrid vehicles combine gasoline engines and electric motors with rechargeable batteries.
• MTBE (oxygenated gasoline additive) has been discontinued in some states due to health risks.
• Alternative energy research focuses on renewable sources, coal conversion, and biomass utilization.