By
Grace Smoot

Fossil fuels (coal, oil, and natural gas) have been and still are the world’s primary energy source. But they are also responsible for emitting billions of tons of carbon dioxide (CO₂) emissions into our atmosphere every year. So, we had to ask: What is fossil fuel energy really, and how does it contribute to climate change?

Fossil fuels consist of coal, oil, and gas that were formed from natural remains millions of years ago. They have some of the highest carbon footprints (820, 970, and 490 gCO₂), directly contribute to climate change, have various negative environmental effects, and are considered dirty energies.

Keep reading to find out all about what fossil fuel energy is, its global capacity, its carbon footprint, its environmental benefits and drawbacks, and how it can combat climate change.

The Big Picture of Fossil Fuel Energy

Fossil fuels consist of coal, oil, and NG which release stored energy when combusted.

How Is Fossil Fuel Energy Defined

Fossil fuels consist of coal, oil, and natural gas (NG), all of which were formed millions of years ago when the carbon-rich remains of animals and plants were decompressed and heated deep underground.

“Fossil fuel: fuels, such as gas, coal, and oil, that were formed underground from plant and animal remains millions of years ago”

Cambridge Dictionary

Over time, plant and animal remains gradually built up on the earth’s surface and the ocean floor, mixing with sand, silt, and calcium carbonate. Under immense heat and pressure, some of these remains were converted into coal, some into oil, and some into NG depending on the combination of organic matter present, how long it was buried, and their pressure conditions. 

What Are the Different Types of Fossil Fuel Energy 

There are 3 main types of fossil fuels: coal, oil, and natural gas (NG).

• Coal energy is produced via the combustion of black or brownish-black sedimentary rock. Coal is one of the most important primary fossil fuels used for domestic energy generation and overseas transport and is one of the cheapest for its energy content. 

“Coal: a combustible black or dark brown rock consisting mainly of carbonized plant matter, found mainly in underground deposits and widely used as fuel.”

Cambridge Dictionary

• Oil energy is produced via the refinement and processing of crude oil. Petroleum products made from crude oil include gasoline, distillates (diesel fuel and heating oil), jet fuel, waxes, lubricating oils, and asphalt. 

“Oil: petroleum (= the black oil obtained from under the earth’s surface from which gasoline comes)”

Cambridge Dictionary

• NG energy is produced via conventional drilling or by hydraulic fracturing. NG is used primarily for heating and generating electricity but can also be used as a raw material (feedstock) in the production of chemicals, fertilizer, and hydrogen, and as lease and plant fuel. 

“Natural Gas: flammable gas, consisting largely of methane and other hydrocarbons, occurring naturally underground (often in association with petroleum) and used as fuel”

Oxford Dictionary

These 3 types of fossil fuel energy contribute directly to climate change, so let’s have a closer look at them next.

What fossil fuel energy is	Fossil fuels consist of coal, oil, and natural gas which were formed underground from plant and animal remains millions of years ago.
What the different types fossil fuel energy are	There are 3 main types of fossil fuels: coal, oil, and natural gas.
How fossil fuel energy works	Fossil fuel energy works by combusting coal, oil, and NG. This generates heat which turns water into steam, rotates turbines, and drives generators to produce electricity.
The global capacity of fossil fuel energy	Fossil fuels are a finite resource, and if we continue to use them at our current rate we can expect to run out of coal in approximately 100 years, oil in 50 years, and NG in 50 years.
The carbon footprint of fossil fuel energy	On a life-cycle basis, the carbon footprint of fossil fuel energy ranges anywhere from 490 to 970 grams of CO2 equivalent per kWh (gCO2/KWh) of electricity produced.
The environmental benefits of fossil fuel energy	Although fossil fuels do not benefit the environment, there are various methods to possibly mitigate their environmental impact.
The environmental drawbacks of fossil fuel energy	Burning fossil fuels adds to the total level of CO2 in our atmosphere and expedites global warming. Fossil fuels also cause air pollution, oil spills, and fragmentation of wildlife.
Fossil fuel energy and climate change	Fossil fuels contribute to climate change by exacerbating temperature rise, sea-level rise, ice melting, and ocean acidification.

How Does Fossil Fuel Energy Work

In general, fossil fuel energy works by combusting coal, oil, and NG in fossil fuel power plants. 

Fossil fuel power plants operate in the following way:

• The fossil fuel enters the combustion chamber of a boiler, where it is incinerated. 
• The hot gasses and heat energy convert water into steam. 
• The steam is then passed into a turbine where it rotates the blades at a high speed. 
• The blades then turn a generator which generates the electricity. 
• Once the steam passes through the turbine it is condensed back into water and returned to the boiler chamber to be reheated.

How Does Fossil Fuel Energy Actually Produce Energy

More specifically, each fossil fuel is acquired and generated via different methods:

• Coal is first mined before being transported to a coal-fired power plant. The 4 main types, or ranks, of coal (anthracite, lignite, subbituminous, and bituminous) depend on the type and amount of carbon the coal contains and the amount of heat energy the coal can produce. Coal energy is then blown into the combustion chamber of a boiler, where it is incinerated to generate energy. 

• Crude oil must first be extracted before going through the refinement process (distilling, cracking, reforming, and treating). After refinement, the oil is transported to a power plant (an oil-fired plant) or directly to consumers by tanker, truck, or railroad tank car. Oil energy is generated when crude oil is combusted.

• NG is acquired in one of two ways, either by conventional (vertical) drilling or by hydraulic fracturing. It is then processed before being transported from well sites to power plants by pipeline or by ship. NG energy is generated when NG, a flammable gas composed of mostly methane (CH₄), some hydrocarbon gas liquids (HGLs), and non hydrocarbon gasses (CO₂ and water vapor) is combusted. 

What Is the Global Capacity of Fossil Fuel Energy

Fossil fuel consumption began with the Industrial Revolution, and consumption has increased exponentially over the past 70 years. The type of fuel we consume has shifted from solely coal, to coal and oil, and lastly to coal, oil, and NG. 

When breaking it down into the 3 categories of fossil fuels, the US is the top producer of both oil and NG while China produces the most coal. 

The top 6 fossil fuel producing countries in the world are:

1. US
2. Russia
3. Iran
4. Canada
5. Qatar
6. China

The COVID-19 pandemic caused a temporary decrease in fossil fuel production globally. Coal production decreased 4%, oil by 7%, and NG by 3%. However, although global CO₂ emissions decreased by 5.8%, they quickly rebounded in 2021 and increased 4.8%, indicating that global fossil fuel production also rebounded. 

While coal consumption has decreased in the US and European Union (EU), consumption continues to increase in some Asian countries such as China and India.

The top 10 largest oil producers in the world account for 72% (67 million barrels per day (mb/d)) of global oil global production, which is approximately 94 mb/d total.

Since 2010, 80% of NG growth has been concentrated within the US, China, and the Middle East. 

Although the exact date at which we will run out of fossil fuels is unknown, if we continue to use them at our current rate we can expect to run out of coal in approximately 100 years, oil in 50 years, and NG in 50 years. These resources are finite, and finding substitute energy sources will be necessary to sustain the global economy in the future. 

What Is the Carbon Footprint of Fossil Fuel Energy

The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the greenhouse gas (GHG) emissions associated with consumption, but also includes other emissions such as CH₄, nitrous oxide, and chlorofluorocarbons.

“Carbon footprint: the amount of greenhouse gasses and specifically carbon dioxide emitted by something (such as a person’s activities or a product’s manufacture and transport) during a given period”

Merriam Webster

Basically, it is the amount of carbon emitted by an activity or an organization. This includes GHG emissions from fuel that we burn directly (e.g., heating a home, driving a car) and GHG emissions from manufacturing the products that we use (e.g., power plants, factories, and landfills). 

On a life-cycle basis, the carbon footprint of fossil fuel energy ranges anywhere from 490 to 970 grams of CO₂ equivalent per kWh (gCO₂/KWh) of electricity produced. 

Type of Fossil Fuel	Carbon Footprint
Coal	820 gCO2/KWh
Oil	970 gCO2/KWh
Natural Gas (NG)	490 gCO2/KWh

Have a look at the illustration below to see the average life-cycle CO₂ equivalent emissions of fossil fuels (the three energy sources with the highest carbon footprint) and how they compare to the other energy types.

When discussing the carbon footprint of fossil fuel energy, we must take into account carbon emissions across the energy’s building, operating, and building back phases.

The life-cycle stages of fossil fuel energy	Each stage’s carbon footprint
Building of fossil fuel energy	Coal: Mining, construction, and transportation of coal to power plants Oil: Oil extraction and refinement, construction of oil-fired plants, and transportation of oil to refineries and plants NG: Extracting and processing NG, transportation of NG through pipes and on ships, construction of NG power plants
Operating of fossil fuel energy	Coal: Operation of the coal power plant  Oil: Oil combustion and operation of mechanical equipment at plants NG: NG combustion, operation of equipment at NG power plants, and leakage of CH4 from in-service wells
Building back of fossil fuel energy	Coal: Shutdown, decommissioning, remediation, and redevelopment Oil: Plugging wells and decommissioning power plants; CH4 seepage from unplugged wells NG: Plugging wells and decommissioning power plants; CH4 seepage from unplugged wells

The world collectively emitted 13.98 billion tons (bt) of CO₂ from coal, 11.07 bt from oil, and 7.40 bt from NG in 2020. 

Burning coal, oil, and NG emits 214.3-228.6, 139-161, or 117 lbs of CO₂ per million Btu, respectively. Although the CO₂ emissions from the combustion of NG are about 50%-60% less than those from coal and oil, the primary component of NG, CH₄, is 34 times stronger at trapping heat than CO₂ over 100 years. This means that a little CH₄ can go a long way when contributing to global warming.

Because fossil fuel consumption makes up the majority of our electricity generation, it is important to understand what their carbon footprints are and how their carbon emissions affect the global climate change process.

How Environmentally Friendly are Fossil Fuels

Fossil fuels are our primary energy source, but their combustion produces over 33 bt of CO₂ emissions annually which contributes significantly to global climate change.

“Environmentally friendly: (of products) not harming the environment.”

Cambridge Dictionary

Coal, oil, and NG are considered dirty fuel sources because of their high rate of CO₂ emissions, toxic heavy metals, and other chemicals that contribute to global climate change. Because of this, the environmental benefits are scarce, and the environmental drawbacks are abundant. 

What Are Environmental Benefits of Fossil Fuels

Although fossil fuels do not benefit the environment, there are ways to possibly mitigate their environmental impact. Various methods to do so include:

1. Coal: Ways to possibly mitigate its environmental impact include desulfurization, carbon capture, and re-use and recycling. For desulfurization, scrubbers are installed in smokestacks to remove sulfur dioxide (SO₂) emissions before they enter the atmosphere. For carbon capture, CO₂ from coal emissions is separated and recovered in a concentrated stream for later injection underground (sequestration). For reuse, land used for coal mining is reclaimed and repurposed as airports, landfills, and golf courses. For recycling, waste emissions can be used to produce cement and synthetic gypsum for wallboard.

2. Oil: To minimize environmental impacts, technological advances in drilling, production, and transportation of oil as well as strict safety and environmental laws and regulations must be enforced. For example, satellites, GPS, and remote sensing technology can detect oil reserves underground which negates the need to drill many exploratory wells. Also, horizontal and directional drilling allows a single well to produce oil from a much larger area, reducing the overall number of wells needed.

3. NG: This is considered the cleanest fossil fuel because it has lower levels of CO₂, CO, nitrogen oxides, and SO₂ than both coal and oil. However, these emissions and methane still contribute directly to global climate change. The best way to mitigate its environmental impact is to detect, fix, and repair methane leaks from well-pads, processing plants, compressor stations, and large distribution facilities. Doing this can reduce methane output by 1.70-1.80 million metric tons per year.

What Are Environmental Drawbacks of Fossil Fuels

Overall, burning fossil fuels adds to the total level of CO₂ in our atmosphere and expedites global warming. 

• Atmospheric CO₂: Levels of CO₂ in our atmosphere have increased as a result of human emissions since the beginning of the Industrial Revolution in 1750. Emissions increased steadily to 5 bt per year in the mid-20th century before increasing exponentially to more than 35 bt per year at the end of the 20th century. The global average amount of CO₂ in the atmosphere was about 280 parts per million (ppm) in 1750 but today registers at over 400 ppm. By the end of the 21st century, this number is expected to exceed 900 ppm. Burning fossil fuels adds to this total, which in turn amplifies the greenhouse effect and causes global warming. 

• Global warming: This phenomenon occurs when CO₂ and other air pollutants absorb sunlight and solar radiation in the atmosphere, trapping the heat and acting as an insulator for the planet. Since the Industrial Revolution, Earth’s temperature has risen a little more than 1 degree Celsius (C), or 2 degrees Fahrenheit (F). Between 1880-1980 the global temperature rose by 0.07C every 10 years. This rate has more than doubled since 1981, with a current global annual temperature rise of 0.18C, or 0.32F, for every 10 years. Experts claim that to avoid a future plagued by rising sea levels, acidified oceans, loss of biodiversity, more frequent and severe weather events, and other environmental disasters brought on by the hotter temperatures, we must limit global warming to 1.5C by 2040. 

Each of the 3 fossil fuels also has specific environmental drawbacks:

1. Coal: The combustion of coal produces over 14 bt of CO₂ emissions every year which contributes significantly to global climate change. Air pollution can cause numerous health problems including asthma, breathing difficulties, brain damage, heart problems, and cancer. Leftover coal ash residue and toxic heavy metals can leach into surface (ponds, lakes) and groundwater ponds, lakes, landfills, and other sites which could eventually lead to the contamination of waterways and drinking water supplies. Methods to burn coal without adding to atmospheric CO₂ levels are often expensive and difficult to successfully implement.

2. Oil: Oil spills cause serious environmental harm by contaminating water and soil, causing explosions and fires, and harming wildlife. Oil combustion also releases CO₂ and other particulates which can cause respiratory problems. In the case of fracking, large amounts of water and potentially hazardous chemicals are required, which can decrease water availability for people and aquatic life and can result in leaks and spills of fracking fluids. Fracking produces large amounts of wastewater which require treatment before disposal, and injecting it back underground can cause earthquakes that are large enough to be felt.

3. NG: Drilling for NG can disturb vegetation and soil and may require clearing and leveling the area around a well pad. Drilling also produces air pollution and may contaminate water sources via erosion, fracking fluids, equipment runoff, and sedimentation. Erosion and fragmentation of wildlife habitat and migration patterns have also been documented. When NG is burned at well sites, it releases CO₂, carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen oxides into the atmosphere. Burning NG instead of releasing it directly into the atmosphere produces lower levels of GHG emissions because CO₂ is not as potent as methane, but it still contributes to the overall level of CO₂ in our atmosphere. 

The easiest way to mitigate the environmental impact of fossil fuels is to simply not rely on them in the first place. Fossil fuel combustion releases toxic chemicals, heavy metals, CO₂, and contributes directly to global warming. 

How Does Fossil Fuel Energy Contribute to Climate Change

Fossil fuels have powered our businesses, cars, and lights for over a century, today providing over 80% of our energy. But when burned they release large amounts of carbon and other greenhouse gas emissions, which directly contribute to climate change.

Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 33 bt of CO₂ are emitted from burning fossil fuels. 44% (14.5 bt) of this comes from coal, 34% (11.2 bt) from oil, and 21% (6.9 bt) from NG. The carbon found in fossil fuels reacts with oxygen in the air to produce CO₂. This warms the earth by acting as a heating blanket, and a warmer earth comes with a host of negative side effects. 

CO₂ emissions contribute to climate change in the following ways:

• Increasing temperatures: Earth’s atmosphere has warmed 1.5℃ since 1880. This may not seem like a lot, but these degrees create regional and seasonal temperature extremes, reduce sea ice, intensify rainfall and drought severity, and change habitat ranges for plants and animals.

• Rising sea levels: Global sea levels have increased approximately 8-9 inches since 1880, displacing people living along coastlines and destroying coastal habitats. Roads, bridges, subways, water supplies, oil and gas wells, power plants, sewage treatment plants, and landfills remain at risk if sea level rise goes unchecked. 

• Melting of sea ice: Since 1979 arctic sea ice has declined by 30%. Sea ice plays a major role in regulating the earth’s climate by reflecting sunlight into space and providing habitat for animal species. If all of the glaciers on Earth melted, sea levels would rise by approximately 70 feet, effectively flooding out every coastal city on the planet. 

• Changing precipitation patterns: Extreme weather events (e.g., hurricanes, floods, droughts) are becoming more common and more intense. Storm-affected areas will experience increased precipitation and flooding whereas areas located further from storm tracks will experience decreased precipitation and droughts.

• Ocean acidification: The ocean absorbs 30% of the CO₂ released into the atmosphere, which decreases the pH (increases the acidity) of the ocean. In the past 200 years, the pH of oceans has decreased by 0.1 pH units, which translates to a 30% increase in acidity. Aquatic life unable to adjust to this rapid acidification will die off. A prime example of this is coral bleaching, where coral expel the algae (zooxanthellae) living in their tissues as a result of changes in temperature, light, or nutrients. 

The more we reduce CO₂ emissions, the more we slow the rate of temperature rise, sea-level rise, ice melting, and ocean acidification. When these rates are slowed, the earth’s biodiversity does not have to struggle to adapt to temperature and pH changes. People will not be displaced due to the flooding of coastal areas. And icebergs will continue to provide climate regulation. 

Final Thoughts

Fossil fuels have been the world’s primary energy source for decades. But coal, oil, and NG have high carbon footprints across their building, operating, and building back phases. Oil has the highest CO₂ emissions per kWh followed closely by coal and lastly NG. Although NG is touted as a cleaner fossil fuel, it still contributes more CO₂ emissions annually than alternative energy sources like solar, wind, and hydropower.

Fossil fuels cause significant environmental degradation and contribute heavily to global warming. In addition, air pollution, oil spills, and fragmentation of wildlife pose serious risks. The easiest way to mitigate the environmental impact of fossil fuels is to simply not rely on them in the first place.

Stay impactful,

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