1. Fossil Fuels

• Coal: One of the oldest energy sources, used extensively for electricity generation through coal-fired power plants. Coal is abundant but releases high levels of CO2 and pollutants when burned.

• Oil (Petroleum): Vital for transportation (gasoline, diesel), heating, and electricity generation. Crude oil is refined into various products, each with its environmental impact, primarily from CO2 emissions.

• Natural Gas: Often seen as cleaner compared to coal and oil due to lower CO2 emissions per energy unit. It's used for heating, cooking, and power generation. However, methane leakage during extraction and transport is problematic.
  
  ​2. Nuclear Power

• While not a fossil fuel, nuclear power is often included in discussions of traditional energy because it has been a significant source of electricity for many decades. It involves nuclear fission to generate heat, which produces steam to drive turbines.

• Pros: High energy density, low greenhouse gas emissions during operation.

• Cons: Nuclear waste management, potential for accidents (e.g., Chernobyl, Fukushima), high initial costs, and long construction times for new plants.
  
  3. Wood and Biomass

• Before the widespread use of fossil fuels, wood was the primary energy source for heating and cooking.

• Traditional Biomass: Includes wood, animal dung, and other organic material burned directly for energy. This is still prevalent in many developing regions but can lead to deforestation and indoor air pollution.
  
  4. Hydroelectric Power (Traditional Large Dams)

• While renewable, large hydro projects are often categorized with traditional methods due to their long history and established infrastructure.

• Benefits: Provides consistent electricity, can serve as storage for flood control, and has no direct emissions.

• Drawbacks: Environmental disruption (habitat destruction, altered water flow), social issues (displacement of communities), and high upfront costs.