#sreeshanphysics

Ch:- 7

Fossil fuels are natural energy sources formed from the remains of ancient plants and animals that were buried and subjected to heat and pressure over millions of years. They are non-renewable resources and are primarily used for energy generation. The three main types are coal, oil, and natural gas.

1. Formation

• Fossil fuels form over millions of years under layers of sediment.

• Organic material, such as dead plants and marine organisms, decomposes and becomes buried.

• Heat, pressure, and time transform this material into coal, oil, or natural gas, depending on the conditions.

2. Types of Fossil Fuels

1. Coal:

   • Formed from plant remains.

   • Found in sedimentary rock layers.

   • Used primarily for electricity generation and steel production.

2. Oil (Petroleum):

   • Derived from marine organisms.

   • Found in underground reservoirs or oil sands.

   • Used for fuels like gasoline, diesel, and jet fuel, and as a base for plastics.

3. Natural Gas:

   • Mainly composed of methane.

   • Found in pockets within the earth or alongside oil reservoirs.

   • Used for heating, electricity, and as a cleaner-burning alternative to coal and oil.

3. Energy Production

• Fossil fuels are burned to release energy in the form of heat.

• This heat is used to produce steam, which drives turbines connected to generators to create electricity.

• In engines, fossil fuels release energy through combustion to power vehicles or machinery.

4. Advantages

• High energy density (provides a lot of energy per unit).

• Reliable and widely available.

• Well-established infrastructure for extraction, transport, and use.

5. Disadvantages

• Non-renewable (finite supply).

• Major contributor to greenhouse gas emissions, causing global warming.

• Air pollution (e.g., sulfur dioxide and nitrogen oxides contribute to acid rain).

• Environmental damage during extraction (e.g., oil spills, mining).