Fossil Fuels
For many years, burning fossil fuels has generated most of the energy required to propel our cars, power our businesses, and keep the lights on in our homes.
Even at present, oil, coal, and gas provide for about 80 percent of our energy needs.
How fossil fuels are formed?
Coal, crude oil, and natural gas are regarded as fossil fuels because they were formed from the fossilized, buried remains of plants and animals that lived millions of years ago. They were decomposed by microorganisms that led to the formation of fossil fuels. Fossil fuels have a high carbon content.
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Fossil Fuels Examples
Oil
Crude oil or petroleum is a Latin word meaning, ‘rock oil.’ It is a liquid fossil fuel that is formed of hydrocarbon compounds that can be found in underground reservoirs, in the cracks, crevices, sedimentary rocks, or in the tar sands near the earth’s surface.
Oil is obtained by drilling, on land or at sea, or by strip mining in the case of tar sands oil and oil shale.
Once the oil is extracted, it is channelized to refineries through supertanker, train, truck, or pipeline for a metamorphosis of it into usable fuels such as gasoline, propane, kerosene, and jet fuel, and in products such as plastics and paint.
Fact: Petroleum products supply about 37 percent of the energy needs of the U.S.
Coal
Coal is a hard carbon-heavy rock that can be burned as a solid fossil fuel. It is mostly carbon; however, it also contains hydrogen, sulfur, oxygen, and nitrogen.
It comes in four main varieties differentiated largely by carbon content, namely,
Lignite
Sub-bituminous
Bituminous
Anthracite
Coal is obtained by two methods:
Underground Mining: We use heavy machinery to cut coal from deep underground deposits.
Surface Mining: It is strip mining, it removes entire layers of soil and rock to access coal deposits buried deep.
Fact: Strip mining accounts for about two-thirds of coal sourced in the United States.
Natural Gas
Natural gas is also called fossil gas. It is a naturally occurring hydrocarbon gas mixture that is mainly composed of methane. It also includes varying higher amounts of alkanes, and sometimes it contains a percentage of nitrogen, carbon dioxide, hydrogen sulfide, or helium.
It can be either conventional or non-conventional based upon the place where they are found underground.
Conventional Natural Gas: This gas is located in porous rock beds that can be accessed via standard drilling.
Unconventional Natural Gas: It isn’t easy to extract this gas through a regular drilling process. A special technique named fracking is used for its extraction.
Effects of Fossil Fuels
The harmful effects of fossil fuels are outlined below:
Land Degradation
During the process of extraction of fossil fuels, processes like unearthing, processing moving underground oil, gas, and coal deposits takes an enormous toll on our landscapes and ecosystems.
The fossil fuels dispose the waste disposal into the wells, on the land, because of this, the wildlife habitat that relies on the land for breeding gets destroyed.
Air Pollution
Burning coal releases unsafe compounds like sulfur oxide. During the combustion of car engines and power plants, gases are released into the atmosphere because of which the depletion of the ozone layer occurs, and UV-rays reach directly to the earth possessing damage to the living beings.
Water Pollution
Industries disposing waste into the water have high amounts of mercury, which pollutes the drinking water and jeopardizes the freshwater ecosystem.
Global Warming
Burning of fossil fuels emits a lot of greenhouse gases like carbon dioxide into the atmosphere, causing an increase in the temperature of the atmosphere. Global warming leads to the melting of glaciers causing rising sea levels.
Thermal Power Plant
A fossil fuel power plant is a thermal power plant that burns fossil fuels such as coal, petroleum, or natural gas to produce electricity.
They are designed on a large scale for continuous operations, and in many countries, the plant provides most of the electrical energy.
Working of Thermal Power Plant
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Thermal power plants work on the principle of the Rankine cycle.
From, Process 1-3: In a boiler, the coal is burned to produce the heat.
Process 3-4: A high-pressure and high-temperature steam is passed through the pipe to the inlet of the turbine.
This steam hits the turbine blades and makes the turbine rotate. Here, the conversion of heat energy into mechanical energy takes place.
Process 4-5: The steam escapes from the outlet of the turbine to enter the condenser, which is just below the turbine.
The steam in the condenser converts into the water with the help of the coolest indirect heat exchange. A major amount of energy loss occurs here.
Process 5-1: In the condenser, the bottom water is collected. This water is again pumped in a boiler with the help of a heavy pump called a boiler feed pump.
Apart from the Diagram
There are two high-pressure turbines joined one after the other followed by a low-pressure turbine that starts rotating, and sets the generator into motion. The high-pressure turbine is about 170 bar and temperature of about 353°C, while a low-pressure turbine with ~ 0.1 bar pressure and temperature as low as 40°C. This converts mechanical energy into electrical energy.
FAQs on Conventional Sources of Energy - Fossil Fuels
1. What are conventional sources of energy, and why are fossil fuels a primary example?
Conventional sources of energy are traditional, non-renewable energy sources that have been used extensively for many years. Fossil fuels, such as coal, petroleum, and natural gas, are primary examples because they were formed from the fossilised remains of ancient plants and animals millions of years ago and are consumed much faster than they can be naturally replenished.
2. What are the main types of fossil fuels?
The three main types of fossil fuels are:
- Coal: A solid, carbon-rich rock that is primarily burned in thermal power plants to generate electricity.
- Petroleum (Crude Oil): A liquid fossil fuel found in underground reservoirs, which is refined to produce gasoline, diesel, and jet fuel.
- Natural Gas: A gaseous fuel composed mainly of methane, often found alongside petroleum deposits and considered the cleanest-burning fossil fuel.
3. How are fossil fuels like coal and petroleum formed?
Fossil fuels are formed through the anaerobic decomposition of buried organic matter over millions of years. Coal originates from the remains of dense forests and plants in ancient swamps. Over time, layers of sediment created immense heat and pressure, transforming this plant matter into coal. Similarly, petroleum and natural gas were formed from the remains of tiny marine organisms that were buried under layers of sand and rock on the ocean floor.
4. What is the main difference between conventional and non-conventional sources of energy?
The key difference lies in their renewability and history of use. Conventional sources like fossil fuels are non-renewable and have been the traditional backbone of global energy for over a century. In contrast, non-conventional sources, such as solar, wind, and geothermal energy, are renewable, meaning they replenish naturally and represent more modern, sustainable energy technologies.
5. How does a thermal power plant use fossil fuels to generate electricity?
A thermal power plant generates electricity by converting the chemical energy in fossil fuels into electrical energy. The process involves several key steps:
- Combustion: A fossil fuel like coal is burned in a boiler to produce immense heat.
- Steam Generation: This heat is used to boil water, creating high-pressure steam.
- Turbine Rotation: The high-pressure steam is directed at the blades of a turbine, causing it to spin rapidly. This converts heat energy into mechanical energy.
- Electricity Generation: The spinning turbine is connected to a generator, which converts the mechanical energy into electrical energy.
6. What are the major environmental impacts of using fossil fuels?
The extensive use of fossil fuels leads to significant environmental damage, including:
- Air Pollution: Burning fossil fuels releases pollutants like sulphur dioxide and nitrogen oxides, causing acid rain and smog.
- Global Warming: It is the largest source of carbon dioxide (CO₂) emissions, a greenhouse gas that traps heat in the atmosphere and drives climate change.
- Land Degradation: Extraction methods such as strip mining and drilling can destroy ecosystems and natural landscapes.
- Water Pollution: Oil spills during transportation and waste from industrial processes can contaminate rivers and oceans, harming aquatic life.
7. Among coal, petroleum, and natural gas, which is considered the 'cleanest' fossil fuel and why?
Natural gas is widely considered the cleanest-burning fossil fuel. This is because, per unit of energy produced, it releases significantly less carbon dioxide than oil or coal. It also emits negligible amounts of sulphur dioxide and nitrogen oxides, which are major contributors to air pollution and acid rain. While still a non-renewable resource, its combustion is more efficient and less polluting than other fossil fuels.
8. If fossil fuels are so harmful, why are they still the dominant source of energy worldwide?
Despite their environmental drawbacks, fossil fuels remain dominant due to their high energy density, meaning a small amount of fuel produces a large amount of energy. Furthermore, the global infrastructure for extracting, transporting, and using these fuels has been developed over more than a century, making them a highly reliable and relatively inexpensive source for continuous, on-demand power. Transitioning to renewable energy on a similar scale requires massive investment and solving challenges related to energy storage and grid stability.
