What are fossil fuels?

Fossil fuels are organic materials found inside the earth's surface. They are mainly composed of dead remains of plants and animals. The primary component constituents of fossil fuels are carbon and hydrogen, which are usually burnt to produce energy. Fossil fuels are believed to be formed millions of years ago when dead remains of animals and plants were subjected to high heat and pressure.

Coal, petroleum, and natural gas are three of the most popular examples of fossil fuels. Coal is a solid material usually formed in sedimentary rock deposits. Dead remains of plants and animals remain piled up in layers to form coal. Many coal-fired power plants rely majorly on coal, as a raw source of fuel for the production of electricity. Coal was the primary fuel source in the 1700s, now near about one-third of the world's population relies on coal as a major source of energy.

Petroleum occurs between the layers of sedimentary rocks and it undergoes refining, to produce combustible fuels. Natural gas majorly occurs in the pockets above oil reserves and sometimes between the gaps of sedimentary rocks. Nearly, two-thirds of the world's population relies on natural gas for electricity generation and household cooking.

Fossil fuel as an energy source for power plants

Power plants are the units installed in large areas of land whose prime focus is for the generation of electricity. All the power plants make use of some sort of energy input, which is then converted into electrical energy via a generator. In the present era, the majority of power plants rely on fossil fuels and their by-products as an important energy input. Fossil fuels such as coal is one of the most popular sources of fuel used worldwide for energy production. Other by-products of fossil fuels, such as petroleum by-products like natural gas and diesel are the second most popularly used fuel for energy sources.

Every power plant makes use of several turbines and generators as the main components that form the powerhouse of power plants. The energy generated from the combustion of fossil fuels is transferred to the turbines, that is coupled to an electrical generator. The generator converts the energy of combustion into electricity, which is transmitted via electricity grids and transmission lines.

Environmental impacts on burning fossil fuels

Apart from meeting the huge energy demands of mankind through power generation, burning fossil fuels has led to a major contribution of environmental damage and climate change in the long term. Some of the major environmental impacts due to burning fossil fuels are discussed in this section.

Global warming

Carbon dioxide is known as the primary greenhouse gas. Methane, Nitrous oxide, and water vapor are other examples of greenhouse gases. The use of carbon-rich fuels such as petrol and diesel, which are the primary source of fuels for automobiles and transportation, is the main culprit of environmental damage. Combustion of such fuels emits carbon dioxide as the primary by-product which is a prime greenhouse gas. Extensive carbon emissions, including carbon dioxide, have formed a layer on the earth's atmosphere which restricts the escape of the sun's harmful ultraviolet radiation, resulting in heating of the earth's surface. This phenomenon of heating the earth's surface, due to trapping of the ultraviolet radiation, is known as global warming. It is due to global warming that many parts of the earth's surface are experiencing major climate change.

Acid rain

Acid rains are natural rains with toxins present in the earth's atmosphere. These toxins are heavily ejected into the earth's atmosphere by burning fossil fuels. Sulfur dioxide and nitrogen oxides are the two main compounds of acid rain. Nitrogen oxides are released into the atmosphere from power plants. These compounds react with water and oxygen present in the atmosphere to form nitric and sulfuric acid. These are corrosive acids that ruin natural water bodies along with plants and the environment.

Air and Water pollution

A majority of industries, that depend on fossil fuels as the main source of energy input, release harmful by-products into the air through exhausts and chimneys. Even these harmful substances are discharged into nearby water bodies, polluting and corrupting the water sources. Water pollution has resulted in major damage to the aquatic and marine life which directly impacted the marine ecosystem and damage to the coral reefs.

Air pollution has led to an increased percentage of carbon dioxide in the atmosphere which has a direct impact on public health. Public health issues due to air pollution include lung diseases and breathing issues.

Alternative to fossil fuels

As a measure to safeguard our environment, a major shift from fossil fuels towards non-conventional energy sources is necessary. It is the duty of the Environmental Protection Agency to initiate the use of non-conventional energy sources and put a strict ban on various coal mining procedures. Coal mining also has a direct relation to deforestation and oxygen depletion.

Environmental Protection Agency is a body that thrives for the protection of the environment by initiating clean procedures in energy generation.

Here, in this section, some of the alternatives to fossil fuels have been outlined which are well supported by the Environmental Protection Agency.

Natural gas for clean cooking

Natural gas is considered to be a clean energy source for cooking and other household purposes and it is an alternative to coal and petroleum products. The burning of natural gas results in low carbon emissions and harmful environmental by-products. Natural gas apart from cooking can also be used as a fuel source for automobiles as a replacement fuel of petrol and diesel, more precisely known as compressed natural gas (CNG).

Use of renewable energy sources

Renewable energy sources like solar energy, tidal energy, geothermal energy, and hydropower energy should be extensively used in place of fossil fuels. The use of such fuels accounts for zero carbon emissions and ultimately results in eco-friendly energy generation.

Context and Applications

This topic is extensively taught in various undergraduate and postgraduate degree courses of:

• Bachelors of Technology in Mechanical engineering
• Masters of Technology in Mechanical engineering
• Masters of Technology in Environmental Engineering
• Bachelors in Science in Physics
• Bachelors in Science in Chemistry

Practice Problems

1. Which of the following is termed as a renewable energy source?

1. Tar sands
2. Coal
3. Solar energy
4. Fossil fuels

Answer: Option c

Explanation: Solar energy is known as a renewable energy source.

2. Which of the following is a greenhouse gas?

1. Carbon dioxide
2. Sulfur dioxide
3. Nitrogen dioxide
4. Nitrous oxide

Answer: Option a

Explanation: Carbon dioxide is termed a major greenhouse gas.

3. Which of the following are the compounds of acid rain?

1. Carbon and hydrocarbon
2. Ground-level volatile compounds
3. Sulfur dioxide and nitrogen oxides
4. None of these

Answer: Option c

Explanation: Sulfur dioxide and nitrogen oxides are the major compounds of acid rain.

4. Which of the following is a conventional energy source?

1. Biomass
2. Petroleum
3. Tar sands
4. All of these

Answer: Option b

Explanation: Petroleum is a conventional energy source.

5. Which of the following is the natural reserve for coal?

1. Sedimentary rocks
2. Impoundments
3. Earth's mantel
4. Earth's core

Answer: Option a

Explanation: Coal can be found in between layers of sedimentary rocks.