CBSE Notes Class 8 Science Chapter 3 - Coal and Petroleum

Coal and petroleum are important energy sources that have powered human progress for centuries. Both are fossil fuels, formed from the remains of plants and animals over millions of years. While they have fueled industrial growth and technology, their use also harms the environment.

1.0What is Coal and Petroleum?

Natural resources are materials or substances found in nature, such as air, water, minerals, forests, and wildlife, that are used by humans for survival and economic activity.

Natural resources can be classified into two types:

1. Inexhaustible Resources: These are available in unlimited quantities and cannot be depleted by human activities, such as sunlight and air.
2. Exhaustible Resources: These are limited in nature and can be depleted due to human use, including forests, wildlife, minerals, coal, petroleum, and natural gas.

Coal and petroleum are essential fossil fuels used for industries, transportation, and electricity. However, growing concerns about environmental damage and climate change are driving a shift towards renewable energy alternatives.

2.0Formation of Coal and Petroleum

Both coal and petroleum are formed through natural processes that take millions of years.

• Coal Formation: Coal is formed from plant material that accumulated in swamps and peat bogs millions of years ago. Over time, the plant material was buried under layers of sediment, where it was subjected to high heat and pressure, transforming it into coal. Here is an image that shows the process of coal formation: plant material in a swamp is buried and, under heat and pressure over time, turns into peat, then lignite, and finally coal.

• Petroleum Formation: Petroleum is formed from the remains of marine organisms, primarily plankton, that settle at the bottom of oceans and seas. These remains were covered by layers of sediment and subjected to heat and pressure over millions of years, resulting in the formation of petroleum.

3.0Types of Coal

Coal is classified into different types based on its carbon content and energy-producing capability:

4.0Types of Petroleum Products

Petroleum, also known as crude oil, is refined into various products through a process called fractional distillation. Some of the key petroleum products include:

1. Gasoline (Petrol): A fuel used primarily in automobiles.
2. Diesel: Another important fuel used in heavy vehicles, industrial machinery, and generators.
3. Kerosene: Commonly used for heating, lighting, and aviation fuel.
4. Liquefied Petroleum Gas (LPG): Used for cooking, heating, and as fuel in some vehicles.

5.0Uses of Coal and Petroleum

Coal and petroleum are integral to modern life due to their extensive applications across various industries.

6.0Natural Gas 

• Natural Gas is an important fossil fuel, easily transported via pipes and stored as compressed natural gas (CNG).
• CNG is used for power generation, as a cleaner fuel for vehicles, and in homes and factories through pipelines.
• India has vast natural gas reserves, found in places like Tripura, Rajasthan, Maharashtra, and the Krishna Godavari delta.
• Natural gas is also a key raw material for producing chemicals and fertilizers.

7.0Limited Natural Resources

Some natural resources, like fossil fuels (coal and petroleum), forests, and minerals, are exhaustible. Fossil fuels take millions of years to form, but their known reserves may last only a few hundred years. Additionally, burning these fuels causes air pollution and contributes to global warming. Therefore, it is essential to use them sparingly to protect the environment and ensure their availability for the future.

In India, the Petroleum Conservation Research Association (PCRA) offers tips to save fuel:

• Drive at a constant, moderate speed.
• Switch off the engine at stops.
• Maintain correct tyre pressure.
• Regularly service your vehicle.