What Is the Carbon Footprint of Fossil Fuels? A Life-Cycle Assessment

What Is the Carbon Footprint of Fossil Fuels? A Life-Cycle Assessment

Grace Smoot

Read Time:14 Minutes

this site

follow follow

Impactful Ninja is reader-supported. When you buy through links on our site, we may earn an affiliate commission. For example, as Amazon Associates, we earn from qualifying purchases. Learn more Learn more .

Affiliate Disclosure

Hey fellow impactful ninja 👋

You may have noticed that Impactful Ninja is all about providing helpful information to make a positive impact on the world and society. And that we love to link back to where we found all the information for each of our posts.

  • Most of these links are informational-based for you to check out their primary sources with one click.

  • But some of these links are so-called "affiliate links" to products that we recommend.

Why do we add these product links?

First and foremost, because we believe that they add value to you. For example, when we wrote a post about the environmental impact of long showers, we came across an EPA recommendation to use WaterSense showerheads. So we linked to where you can find them. Or, for many of our posts, we also link to our favorite books on that topic so that you can get a much more holistic overview than one single blog post could provide.

And when there is an affiliate program for these products, we sign up for it. For example, as Amazon Associates, we earn from qualifying purchases.

What do these affiliate links mean for you?
  1. First, and most importantly, we still only recommend products that we believe add value for you.

  2. When you buy something through one of our affiliate links, we may earn a small commission - but at no additional costs to you.

  3. And when you buy something through a link that is not an affiliate link, we won’t receive any commission but we’ll still be happy to have helped you.

What do these affiliate links mean for us?
  1. When we find products that we believe add value to you and the seller has an affiliate program, we sign up for it.

  2. When you buy something through one of our affiliate links, we may earn a small commission (at no extra costs to you).

  3. And at this point in time, all money is reinvested in sharing the most helpful content with you. This includes all operating costs for running this site and the content creation itself.

What does this mean for me personally?

You may have noticed by the way Impactful Ninja is operated that money is not the driving factor behind it. It is a passion project of mine and I love to share helpful information with you to make a positive impact on the world and society. However, it's a project in that I invest a lot of time and also quite some money.

Eventually, my dream is to one day turn this passion project into my full-time job and provide even more helpful information. But that's still a long time to go.

Stay impactful,

Fossil fuels (coal, oil, and natural gas) are the world’s primary energy source. But they are also responsible for emitting billions of tons of CO2 emissions into our atmosphere every year. So, we had to ask: What is the carbon footprint of fossil fuels? 

Fossil fuels have some of the highest carbon footprints. Per kWh produced, coal emits 820, oil 970, and natural gas 490 grams of carbon dioxide on a life-cycle basis. They directly contribute to climate change, have various negative environmental effects, and are considered dirty energies.

Keep reading to learn about the overall carbon footprint of fossil fuels and their carbon footprint throughout their life cycles. 

How Are Fossil Fuels Defined 

Fossil fuels have powered our businesses, cars, and lights for over a century, today providing for over 80% of our energy. They consist of coal, oil, and natural gas (NG), all of which were formed millions of years ago. 

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 pressure conditions. 

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

Cambridge Dictionary
Tip: You can click here to directly jump to the carbon footprint summary section for all types of green energy.

There are three main types of fossil fuels:

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
  • Coal: A black or brownish-black sedimentary rock that is one of the most important primary fossil fuels used for domestic energy generation and overseas transport. The 4 main types, or ranks, of coal (anthracite, lignite, subbituminous, bituminous) depend on the type and amount of carbon the coal contains and the amount of heat energy the coal can produce.
Related: Check out the full article about coal energy here: What Is the Carbon Footprint of Coal Energy? A Life-Cycle Assessment

In 2020, 477 million tonnes (432.7 million tons)  of coal were consumed in the United States (US) alone. This represents around 10% of total US energy consumption.

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

Cambridge Dictionary
  • Oil: Referred to as crude oil when it is first extracted and then petroleum products after it has been refined and processed. Petroleum products made from crude oil include gasoline, distillates (diesel fuel and heating oil), jet fuel, waxes, lubricating oils, and asphalt. Oil is the world’s primary fuel source for transportation.
Related: Check out the full article about oil energy here: What Is the Carbon Footprint of Oil Energy? A Life-Cycle Assessment

In 2020, 18.12 million barrels per day (b/d) of oil were consumed in the US alone, this represents around 24% of total energy consumption. In terms of total petroleum consumption, gasoline represented 44%, distillates 21%, hydrocarbon gas liquids (HGLs) 18%, and jet fuel 6%. 

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
  • NG: Composed of mostly methane (CH4) and some HGLs and nonhydrocarbon gases (CO2 and water vapor). It 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. 
Related: Check out the full article about natural gas (NG) here: What Is the Carbon Footprint of Natural Gas? A Life-Cycle Assessment

In 2020, 30.5 trillion cubic feet (Tcf) of NG were consumed in the US alone. This represents around 34% of total US energy consumption.

What is the Carbon Footprint of Fossil Fuels

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 methane (CH4), nitrous oxide, and chlorofluorocarbons.

Carbon footprint: the amount of greenhouse gases 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). 

What Is the Overall Carbon Footprint of Fossil Fuels

Fossil fuels are considered dirty energy because of their carbon footprint. On a life-cycle basis, coal emits 820 grams of carbon dioxide (CO2) equivalent per kWh of electricity produced, which is the highest out of all of the fuel types. Oil emits 970 grams of CO2 equivalent per kWh. And NG emits 490 grams of CO2 equivalent per kWh, the third-highest life cycle out of all of the fuel types, but the lowest out of the three fossil fuels. 

Illustration of CO2 equivalent per energy source
World Nuclear Association: Average life-cycle CO2 equivalent emissions

The world collectively emitted 14.36 billion tons (bt) of CO2 from coal, 12.36 bt from oil, and 7.62 bt from NG in 2019. 

Illustration of CO2 emisions by fuel line
Our World in Data: CO₂ emissions by fuel type, World

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. 

Illustration of global fossil fuel consumption
Our World in Data: Global Fossil Fuel Consumption

When breaking it down into the three 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

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.

To understand the carbon footprint of fossil fuels, we must assess its life cycle and each stage’s carbon footprint. This life-cycle assessment (LCA) is a method to evaluate the environmental impacts of products and materials. Over the years, companies have strategically used LCA to research and create more sustainable products. So, let’s have a look at the LCA of fossil fuels!

The life-cycle stages of fossil fuelsEach stage’s carbon footprint
Building of fossil fuelsCoal, Oil, NG: Mining (or drilling), construction of the power plant, transporting material from mines to the power plant
Operating of fossil fuelsCoal, Oil, NG: Operation of the power plants, combustion of the fossil fuel
Building back of fossil fuelsCoal and NG: Shutdown, decommissioning, remediation, and redevelopment of the power plantsOil: Little to no carbon footprint at this stage 

The total carbon footprint of fossil fuels would equal the carbon footprint from building + the carbon footprint from operating + the carbon footprint from building back.  

What Is the Carbon Footprint of Building Fossil Fuels

Building fossil fuel energy includes mining the material, constructing the power plant, and transporting the material from the mines to the power plant. 

  • Mining and Drilling: The mining industry generates between 1.9 and 5.1 bt of CO2 annually, with an additional 400 million tons coming from power consumption. 
  • Construction: Fossil fuel power plants have many components, and building these components requires machinery that emits CO2. Boiler rooms, smokestacks, cooling towers, generators, and turbines are all components with a carbon footprint. 
  • Transportation: Coal, oil, and NG are typically transported from mines to power plants by rail, river barge, or truck, all of which run on diesel fuel. Burning one gallon of diesel fuel produces 22.38 pounds of CO2

What Is the Carbon Footprint of Operating Fossil Fuels

Fossil fuel power plants burn coal, oil, or NG. The heat turns water into steam which rotates turbines and drives generators to produce electricity. 

  1. Coal: CO2 emissions at this stage occur upon combustion of coal and are also associated with the operation of the mechanical equipment (e.g., turbines and generators) at the power plant. Burning coal emits anywhere from 214-228 lbs of CO2 per million British Thermal Units (Btu). This number varies based on the type of coal that is being burned. In 2019, the US burned 48% bituminous, 44.1% subbituminous, and 7.5% lignite coal, all of which have different carbon ratios and therefore will produce different amounts of CO2 per ton burned. 
  1. Oil: Emissions at this stage occur upon combustion and refinement of oil and are also associated with the operation of the mechanical equipment (e.g., turbines and generators) at the power plant. Burning oil emits anywhere from 139-161 lbs of CO2 per million Btu depending on whether it is propane, gasoline, or diesel fuel.
  1. NG: Emissions at this stage occur upon combustion of NG, are associated with the operation of the mechanical equipment (e.g., turbines and generators) at the power plant, and are released when oil and NG wells, storage tanks, pipelines, or processing plants leak methane into the atmosphere. Burning NG emits 117 lbs of CO2 per million Btu. 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, methane, is 34 times stronger at trapping heat than CO2 over 100 years. This means that a little methane can go a long way when contributing to global warming.

What Is the Carbon Footprint of Building Back Fossil Fuels

Building back fossil fuels is a similar process for both coal and NG but differs for oil.

  1. Coal: Coal power plant decommissioning is only loosely regulated. The four main stages of decommissioning are shutdown, decommissioning, remediation, and redevelopment. The time for physical decommissioning varies and can overlap with remediation and development. Coal plants have had a historical life expectancy of 46 years, but they can remain in operation from anywhere between 50 and 60 years. CO2 emissions at this stage occur when utilizing construction equipment to demolish the buildings and construct new buildings in the old power plant’s place. 
  1. Oil: Oil wells can produce for anywhere from 20-40 years, and they are plugged when they are no longer used. The area surrounding the well can be restored. In offshore drilling, the program “Rigs-to-Reefs” topples old oil wells and leaves them on the seafloor, establishing an artificial reef that attracts barnacles, coral, clams, sponges, and other marine life. This method has virtually no carbon footprint because the existing well is not demolished. 
  1. NG: NG plants have an average age of 22 years in the US. CO2 emissions at this stage occur when utilizing construction equipment to demolish the buildings and construct new buildings in the old power plant’s place. 

What Role Do Fossil Fuels Play in Contributing To Climate Change

Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 36 bt of CO2 are emitted from burning fossil fuels. 44% (15.8 bt) of this comes from coal, 34% (12 bt) from oil, and 21% (7.5 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:

  • 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. 

How Environmentally Friendly are Fossil Fuels

Fossil fuels are our primary energy source, but their combustion produces over 36 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 re-use, 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.
  1. 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. 
  1. 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

Each of the main fossil fuels has its environmental drawbacks as well as collectively adding to atmospheric CO2 levels and contributing to global warming. 

  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.
  1. 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.   
  1. 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. 

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

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. 

The COVID-19 pandemic and increased interest in cleaner forms of energy such as solar, wind, and hydropower drove global demand for fossil fuels down in 2020.

  • Coal demand fell by approximately 7% (500 million tons) between 2018 and 2020. 
  • Oil demand will grow at an average annual rate of 950 thousand barrels per day (kb/d), a reduction from 1.5mb/d seen over the past decade. 
  • NG demand saw a 4% drop in 2020 but is expected to recover in 2021 and have a 1.5% average growth rate from 2021-2025.

Final Thoughts

Fossil fuels are the world’s primary energy source and have been for decades. But their high carbon footprint across the building, operating, and building back phases causes significant environmental degradation and contributes heavily to global warming. 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.

Demand for fossil fuels has fallen in the last decade due to increased interest in these alternative energy sources. Reducing fossil fuel consumption would benefit our health and our planet’s health.

Stay impactful,

Illustration of a signature for Grace


Did you know that the internet is a huge polluter of the environment? But fortunately not this site. This site is powered by renewable energy and all hosting-related CO2 emissions are offset by three times as many renewable energy certificates. Find out all about it here.

Three Related Posts

One Unrelated Post