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Describe the use, methods, and effects of fossil fuels in power generation.

Energy Generation from Fossil Fuels

A power plant with tall stacks, from which dark smoke is billowing against a cloudy sky. Superimposed on the smoke are blue circles containing chemical symbols for various pollutants such as lead (Pb), nickel (Ni), sulfur dioxide (SO2), iron (Fe), arsenic (As), and selenium (Se), indicating the types of pollutants that may be emitted from such facilities. — **Burning fossil fuels produces SPM and SO₂.**

The combustion of fossil fuels is a process that converts stored chemical energy in the fuels into thermal energy, which can be used for various purposes such as generating electricity, heating, or transportation. Fossil fuels are mainly composed of carbon and hydrogen atoms.

When fossil fuels are burned in the presence of oxygen, they react with the oxygen molecules and produce carbon dioxide and water as the main products, along with other pollutants such as sulfur dioxide (SO₂), nitrogen oxides (NO_x), and particulate matter (also known as suspended particulate matter or SPM), which are tiny particles left over from the burning process. The reaction releases a large amount of heat. The general equation for the combustion of a hydrocarbon fuel is:

Fuel + Oxygen \to Carbon dioxide + Water + Heat

For example, the combustion of methane, the main component of natural gas, can be written as:

$LaTeX: CH_4+2O_2\Longrightarrow CO_2+2H_2O+Heat$

Essential Knowledge

The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy.

Energy from fossil fuels is produced by a process called thermal power generation, which involves converting the chemical energy stored in the fuels into electrical energy.

The process of a coal-fired power plant. It includes labeled components such as a coal conveyer, boiler, turbine, generator, transformer, and cooling tower, all connected to show the flow from coal input to electricity and heat output. — **Thermal Power Generation involves burning fossil fuels to produce heat.**

When it comes to energy generation from fossil fuels, it's all about harnessing the power of burning these fuels to create heat. This heat is used to turn water into steam. The steam then spins a turbine, kind of like a giant fan, which in turn generates electricity. It's like a big, fiery chain reaction that ultimately lights up our homes and powers our devices.

Essential Knowledge

Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which generates electricity.

Fossil Fuel Extraction

Fossil fuels, such as coal, oil/petroleum, and natural gas, are essential sources of energy that power our daily lives. But have you ever wondered how these fuels are extracted from the earth? Explore the tabs below to learn more about how we extract each type of fossil fuel from the Earth:

Coal
Oil
Natural Gas

Coal Extraction

a large mining truck in motion at an active mining site. — **Mining removes large amounts of rock to expose coal deposits.**

Coal is typically mined through two main methods: surface mining and underground mining.

In surface mining, large machinery, such as bulldozers and excavators, are used to remove layers of soil and rock to expose the coal seams.

On the other hand, underground mining involves digging tunnels deep into the earth to access the coal deposits. Once the coal is extracted, it is transported to processing plants for cleaning and refining.

Surface mining accounts for around 70% of our coal mining and underground mining accounts for the remaining 30%. Once it has been extracted from the ground, coal is broken into smaller pieces, and shipped by train or truck to its ultimate destination. In the United States, about 88% of coal is used to heat water in power plants to produce electricity.

Refer back to the Mining Lesson in the Land and Water Use Module for more detailed information about mining.

Petroleum/Oil Extraction

an offshore oil drilling rig in calm waters under a clear blue sky — **Oil rigs bring oil to the surface and transport it via pipelines to refineries.**

The oil industry calls the process of withdrawing oil from an oil field production, but really it should be called extraction because they aren’t producing anything. Primary recovery of oil can only remove about 25% of the oil from an oil field. Secondary recovery can remove up to 50% of the oil from an oil field by manipulating pressure in the oil reservoir by injecting brine (very salty water) or steam. Enhanced recovery injects carbon dioxide and allows the oil to flow again, recovering even more oil. Each additional step in the recovery process, however, makes the extracted oil more expensive. Oil companies stop extracting oil once extracting the oil costs more than consumers are willing to pay for it. The more oil prices rise, the more additional steps in the recovery process make economic sense to the oil companies.

Once oil reaches the surface, it is transported by pipeline or tanker ship to a refinery where it is separated using a process known as fractional distillation. Tall distillation towers at the refinery separate the different-sized hydrocarbons in crude oil. The different sized hydrocarbons produce different fuels. The fuels ranked from shortest to longest are petroleum gases, gasoline, kerosene, fuel oil, lubricants, and residues.

Besides simply being burned, it was soon discovered that petroleum could be broken into a wide variety of products through fractional distillation, a process in which heat is used to separate the many carbon-based compounds found in oil. Gasoline, kerosene, diesel fuel, butane, and naphtha can all be distilled from crude oil.

Natural Gas Extraction

a graphical representation of fracking. A drilling rig is on the surface. Below the surface, various geological layers are depicted in different textures and colors, indicating diverse materials. Pipes extend from the rig, penetrating these layers to reach an underground reservoir that appears to be on fire, symbolizing the extraction process. — **Fracking extracts natural gas trapped in shale formations.**

Hydraulic fracturing, also known simply as fracking, is a fairly new technique used to collect natural gas.

A well is drilled vertically to the desired depth, then horizontally into the rock layer containing oil or gas.
A mixture of water, sand, and chemicals is injected at high pressure to create fractures in the rock, allowing the trapped gas to flow.
The released gas or oil flows back to the surface through the well.
The gas or oil is collected, treated, and then transported for use.

The process of fracking uses millions of gallons of water.

Essential Knowledge

Humans use a variety of methods to extract fossil fuels from the earth for energy generation.

Environmental Effects of Fossil Fuels

Using fossil fuels as the main source of energy in society has led to a number of significant environmental issues. There are many issues surrounding the production of fossil fuels.

The tabs below touch on some of the most important and wide-reaching issues associated with extraction, transportation, processing, and combustion of fossil fuels. Are there any impacts that you were unaware of? Which do you think is the most important? Why?

Extraction
Transportation
Processing
Combustion

Extraction

an oil pump jack, prominently colored in blue and red, operating in a field under a cloudy sky. — **Extracting fossil fuels disrupts the environment.**

Coal

Mining or drilling for fossil fuels can disturb or disrupt habitats on land and in the ocean. When these habitats are disrupted, the species that live in these environments can suffer. For example, mountaintop removal of coal completely destroys mountaintops. Extracting fossil fuels from the environment also negatively impacts the aesthetics (beauty) of the environment.

Coal production produces quite a bit of pollution. Coal is located in veins of rock that can be as wide as 30 meters. Coal is hazardous to mine and dirty to handle. Miners often get a disease from mining coal known as black lung, or coal workers’ pneumoconiosis (CWP), from inhaling coal dust. Surface mining accounts for 69% of our coal mining and underground mining accounts for the remaining 31%. Once it has been extracted from the ground, broken into smaller pieces, and shipped by train or truck to its ultimate destination.

Oil/Petroleum

When attempting to mine or drill for coal and petroleum, pockets of natural gas are exposed. The gas may be captured directly or simply flared (burned) off as a nuisance.

Natural Gas

Hydraulic fracturing (“fracking”) for natural gas uses a large amount of water. When the water is used in fracking, the quality of the water is degraded, which means the water can no longer be used.

The waste products of fracking must be disposed of in special wells deep in Earth’s crust, which has been implicated in causing earthquakes.

The number and distribution of earthquakes with a magnitude greater than 3 in the Central US from 1973 to 2020. The map shows the Central US with earthquakes represented by dots, concentrated mainly in Oklahoma. The bar graph illustrates a significant increase in earthquakes after 2008, with 867 earthquakes from 1973-2008 and 3804 from 2009-2020. — **Earthquakes in the Central United States have increased significantly since we have started fracking in those areas.**

In the central United States, where there has been a lot of fracking, earthquakes have significantly increased in frequency compared to historical activity. More research is being done into this process to try to lower the occurrence of fracking-related earthquakes.

an aerial view of a large ship, possibly a cargo or container ship, navigating through dark blue waters. An oil spill can be seen on the water’s surface around the ship. — **Transporting fossil fuels risks oil spills, which can be devastating.**

Transportation

Fossil fuels are typically extracted from one location then transported to another location for processing into usable fuel. Transporting fossil fuels requires fossil fuels, which means air pollution.

Transportation of various fossil fuels always carries with it the risk of accidental spills and contamination of land or aquatic environments.

After processing, fossil fuels must be transported again, but this time to distribution points such as gas stations and power plants.

Even pumping gasoline into a vehicle releases fossil fuel fumes into the atmosphere, thus contributing to tropospheric ozone formation, one of the six main air pollutants monitored by the EPA.

an industrial scene, likely a refinery or chemical plant, with numerous tall, metallic structures and pipes. — **Processing fossil fuels produces significant waste.**

Processing

Processing fossil fuels often requires burning fossil fuels, which means more air pollution (again).

Processing plants also produce a significant amount of waste, which must be disposed of securely.

Once the fossil fuels are processed, they must be transported to a power plant, gas station, or some other place where they can be used by the consumer (us), which results in even more air pollution.

Using the fossil fuels in power plants creates air pollution as well.

Are you noticing a trend, every step of fossil fuel usage produces air pollutants because every step involves burning fossil fuels. We will learn more about the pollutants produced during combustion in the next tab.

Combustion

a power plant with tall stacks, from which dark smoke is billowing against a cloudy sky. Superimposed on the smoke are blue circles containing chemical symbols for various pollutants such as lead (Pb), nickel (Ni), sulfur dioxide (SO2), iron (Fe), arsenic (As), and selenium (Se), indicating the types of pollutants that may be emitted from such facilities. — **Carbon dioxide isn't the only pollutant released when fossil fuels are burned.**

Air Pollution

Using the fossil fuels in power plants creates air pollution as well. Coal power plants release soot, hydrocarbons, and sulfur oxides, but the combustion of every type of fossil fuel has significant impacts on the environment and the climate.

Smoke and fumes from coal fires increase air pollution. A typical 1000-MW coal power plant burns 8,000 tons of coal per day. This releases 20,000 tons of carbon dioxide and 800 tons of SO₂, which is as much carbon dioxide as all of the cars and trucks in the United States.

Burning fossil fuels release many pollutants into the atmosphere, but the pollutants below are the most significant:

Carbon dioxide (CO₂) levels in the atmosphere have risen steadily during the same time period as the increase in fossil fuel use.
Sulfur dioxide (SO₂) results from the burning of coal that contains sulfur impurities and has been implicated in the production of acid rain.

the rear section of a yellow vehicle, likely a car, emitting a significant amount of dark smoke from its exhaust pipe. — **Exhaust from our vehicles contributes significantly to air pollution.**

Nitrogen oxides (NO_x) are formed any time a fuel is combusted at very high temperatures and have also been implicated in the production of acid rain.
Particulate matter (also known as suspended particulate matter or SPM) is tiny particles left over from the burning process that contribute to haze, smog, and lung impairment in humans.

By releasing carbon dioxide and other greenhouse gases into the atmosphere, combustion of fossil fuels enhances the greenhouse effect and contributes to global climate change. When the concentration of greenhouse gases increases beyond the natural level, it causes the Earth’s temperature to rise faster and more than the normal range, leading to various changes in the climate patterns and the ecosystems. According to the U.S. Environmental Protection Agency, fossil fuels accounted for 74 percent of the U.S. greenhouse gas emissions in 2019.

When coal is burned, it results in approximately 1600 tons of ash that must be removed and stored in special landfills.

Another issue to consider is that many of the pollutants from burning fossil fuels react in the atmosphere to become even more dangerous pollutants such as photochemical smog.

a serene natural landscape under a clear blue sky with a tall, dead tree with its bark stripped away, revealing the pale wood underneath. — **Acid rain can damage natural areas.**

Pollutants associated with both petroleum and coal combustion have resulted in more power plants using natural gas as their main form of heat-producing fuel. A benefit of natural gas is that it does not produce any of the hydrocarbons or sulfur dioxides that are produced when other fossil fuels are burned. It only produces carbon dioxide, a greenhouse gas, and water.

Health Effects

The combustion of fossil fuels also emits other pollutants that affect the air quality and the health of living organisms. For example, sulfur dioxide and nitrogen oxides can react with water and other substances in the atmosphere to form acid rain, which can damage buildings, crops, soil, and aquatic life.

Particulate matter, which consists of tiny solid or liquid particles suspended in the air, can reduce visibility and cause respiratory problems, cardiovascular diseases, and cancer.

Lead, which is sometimes added to gasoline as an anti-knock agent, can accumulate in the body and cause neurological disorders, especially in children.

Essential Knowledge

Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds.

Mitigating the Effects of Fossil Fuel Use

an illustrative diagram of an electrostatic precipitator. — **Electrostatic precipitators reduce air pollution from power plants, but they are expensive to install. These costs are eventually passed onto the consumer (us).**

To reduce the negative impacts of fossil fuel combustion, some possible solutions include improving the efficiency of energy use, developing alternative and renewable energy sources, implementing carbon capture and storage technologies, and promoting conservation and sustainability practices.

The EPA now requires significant amounts of air pollution control equipment on power plants, vehicles, and other users of fossil fuels.

For example, power plants are often required to install equipment like Cyclone Separators, Fabric Filters, Cartridge Filters, Electrostatic Precipitators (ESPs), High-Efficiency Particulate Air (HEPA) Filters, Venturi Scrubbers, and Fiber-Bed Mist-Eliminators. Additionally, for controlling nitrogen oxides, technologies such as Selective Non-Catalytic Reduction (SNCR) or Selective Catalytic Reduction (SCR) may be required.

The Clean Air Act 💨 mandates that vehicles have emission control systems, which include catalytic converters and evaporative emission control systems to reduce harmful emissions.

All this pollution-prevention equipment is expensive. Companies do not want to spend more than they have to when producing or burning fossil fuels because it either decreases their profits or forces them to increase prices for the consumers. And consumers do not want to spend more than they have to for fuel, so they do not want prices to increase either.

In either case, reducing pollution from burning fossil fuels increases the costs paid to use fossil fuels. The short story is that if we want a cleaner atmosphere, we need to be willing to pay a higher monetary cost for it.

Fossil fuels have helped shape society for several hundred years. The environmental and health costs associated with using them have led to more research and development of alternative energies. As we continue to use up the finite supply of fossil fuels on Earth, the move to renewable energies will accelerate.

AP Exam Tip

You should know the basics of how fossil fuels are extracted from the Earth.

You should know some mitigation strategies for reducing the environmental impacts of fossil fuels.

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