By
Grace Smoot

Aviation is an approximate $471.8 billion industry, with roughly 2.9 million people flying per day. Although flying has greatly increased the ease at which we travel, aircraft fuel combustion also emits significant amounts of CO₂ into the atmosphere every year. So, we had to ask: What is the carbon footprint of aviation/jet fuel?

On a life-cycle basis, aviation/jet fuel has a high carbon footprint. Aviation gas emits 18.3 pounds (lb) and jet fuel 21.1 lb of CO₂ per gallon combusted, and flying one mile on average emits 53 pounds of CO₂. It directly contributes to climate change and has various negative environmental effects.

Keep reading to learn about the overall carbon footprint of aviation/jet fuel, its carbon footprint throughout its life-cycle, and how environmentally friendly it is.

Here’s What the Carbon Footprint of Aviation/Jet Fuel Is

The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the 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).

Aviation/jet fuel is a petroleum-based fuel used to power aircrafts.

”Jet fuel or aviation turbine fuel: a type of aviation fuel designed for use in aircraft powered by gas-turbine engines”

Wikipedia

Oil is referred to as crude oil when it is first extracted and then as 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: petroleum (= the black oil obtained from under the earth’s surface from which gasoline comes)”

Cambridge Dictionary

There are two main aviation/jet fuel types, aviation gasoline (AVGAS) and jet fuel.

1. AVGAS: This is used in piston-engine aircrafts which fly via rotation of the thrust-generating propellers. It contains some tetraethyl lead additive, which protects the engine but is also a toxic substance to humans if inhaled or absorbed into the bloodstream. It comes in two forms, AVGAS 100 and AVGAS 100LL. AVGAS 100 has a high lead content and is dyed blue. AVGAS 100LL has a low lead content and is dyed green.

2. Jet Fuel: This is used in turbine-jet engines which fly via the thrust of expelled air. It is a colorless, kerosene-based fuel that comes in two forms, Jet A and Jet A1. Jet A has a higher freezing point, does not typically include static dissipater additives (which aid in decreasing static charges that form when jet fuel moves), and is most commonly used in the United States (US). Jet A1 has a lower freezing point, contains static dissipater additives, and is the most common global jet fuel.

AVGAS is generally more expensive than jet fuel and takes longer to distill, reform, and combine. But it also has a higher sales volume and is used in more aircrafts around the world.

Jet fuel has a lower sales volume and is used in fewer aircrafts around the world. But is also generally cheaper than AVGAS and is easier to obtain, refine, and reform. 1 lb (0.45 kg) of jet fuel produces 6.97 lb (3.16 kg) of carbon dioxide (CO₂) upon combustion.

Burning of aviation/jet fuel	Carbon footprint
Burning one gallon	AVGAS: 8,309 gCO2 emitted Jet Fuel: 9,570 gCO2 emitted
Flying one mile (on average)	Jet Fuel: 53.3 pounds (lb) CO2 emitted
Per million British thermal units (Btu)	AVGAS: 152.46 lb CO2 emitted Jet Fuel: 159.25 lb CO2 emitted

Global aviation CO₂ emissions reached 1.04 billion tons in 2018 and has seen a 4-5% increase per year since the year 2010. 

Oil (including aviation/jet fuel) is the world’s primary fuel source for transportation. This is one major reason the market for aviation/jet fuel is expected to increase from $178.560 billion in 2019 to $253.261 billion in 2025. But aviation/jet fuel also accounts for 2.5% of total global CO₂ emissions, so it is important to understand what its carbon footprint is. And how its carbon emissions affect the global climate change process.

To understand the total carbon footprint of aviation/jet fuel, 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 jet fuel!

The life-cycle stages of aviation/jet fuel	Each stage’s carbon footprint
Building of petroleum refinery	CO2 emissions from building the components of the petroleum refinery
Extracting of aviation/jet fuel	CO2 emissions from drilling/fracking, reforming, treating, and blending crude oil
Transportation of aviation/jet fuel	CO2 emissions from transporting aviation/jet fuel by barges, tankers, pipelines, trucks, and railroads across distances
Building back of petroleum refinery	CO2 emissions from plugging wells and decommissioning power plantsCH4 seepage from unplugged wells

The total carbon footprint of aviation/jet fuel would equal the carbon footprint from building + the carbon footprint from extracting + the carbon footprint from transportation + the carbon footprint from building back.

What Is the Carbon Footprint of Building Petroleum Refineries

Oil wells extract crude oil, which is then transported to petroleum refineries to produce finished aviation/jet fuel. 

Aviation/jet fuel is one of many products manufactured in petroleum refineries. Refineries consist of machinery such as boilers, cooling towers, blowdown systems, compressor engines, and heaters, all of which must be manufactured and therefore also have a carbon footprint. Likewise, the construction equipment needed to physically construct the buildings emits CO₂.

What Is the Carbon Footprint of Extracting Aviation/Jet Fuel

Oil and natural gas (NG) are often found within the same reservoir, so they are often extracted in the same manner. Drilling or fracking exposes oil reservoirs for extraction. 

Extracting oil involves seven main steps:

1. Preparing the rig site
2. Drilling
3. Cementing and testing
4. Well completion
5. Fracking
6. Production and fracking fluid recycling
7. Well abandonment and land restoration

Once the oil is extracted and separated from the NG, it is transported via pipeline to petroleum refineries where it is broken down into various components and reconfigured into new products. One of these new products is aviation/jet fuel. 

Oil refinement to produce aviation/jet fuel occurs via the following steps:

• Distilling: Crude oil is heated until it becomes a vapor. The vapor is lifted upwards in a distilling column and collects at different levels in trays, separating the liquids. Lighter products (butane) rise to the top of the column whereas gasoline, naphtha, kerosene, diesel, and heavy gas oil collect in trays going from top to bottom in the column.

• Cracking: Cracking breaks up long hydrocarbon chains into smaller ones. Cat cracking, catalyst-driven cracking, is the most common form of cracking. 

• Reforming: Refineries again use a catalyst to increase the quality and volume of aviation/jet fuel. Reforming increases the octane number by rearranging the naphtha hydrocarbons to create gas molecules. A high octane number is more beneficial because it can withstand more compression before detonating. And the higher the octane number, the more stable the fuel. 

• Treating: Crude oil contains pollutants including sulfur, nitrogen, and heavy metals that must be removed. The treating process removes these pollutants either by binding them to hydrogen, absorbing them in columns, or adding acid to them.  

• Blending: Finished petroleum products are a blend of various streams of hydrocarbons that are then mixed into aviation/jet fuels. Refineries can also mix additives such as octane enhancers, metal deactivators, anti-oxidants, anti-knock agents, rust inhibitors, or detergents to meet specific storage or flight condition requirements.

What Is the Carbon Footprint of Transportation of Aviation/Jet Fuel

Crude oil is transported from extraction wells to petroleum refineries via barges, tankers, pipelines, trucks, and railroads. After refinement, the aviation/jet fuel is then transported to aircrafts by tanker, truck, or railroad tank car. If the refined aviation/jet fuel is not being consumed locally, it must be transported. Sometimes over very long distances. 

The top 5 jet fuel-producing countries (amount per day) in 2020 were:

1. US – 1407 thousand barrels per day (tb/d)
2. South Korea – 325 tb/d
3. Japan – 199 tb/d
4. India – 172 tb/d
5. Turkey – 105 tb/d

The top 5 jet fuel-consuming countries (amount per day) in 2020 were:

1. US – 1077 thousand barrels per day (tb/d)
2. Japan – 114 tb/d
3. United Kingdom – 107 tb/d
4. South Korea – 104 tb/d
5. Germany – 101 tb/d

Calculating the carbon footprint of aviation/jet fuel transportation involves knowing where it is produced, where it is being consumed, and the distance between the two. For example, transporting jet fuel from the US to Germany is an approximately  4,898 mile (7,882 kilometer) transportation distance. Likewise, transportation from the US to India is 8,446 miles (13,595 kilometers). The carbon footprint of transportation for these circumstances would be high because it is a long distance that would require multiple modes of transportation. 

On the other hand, if aviation/jet fuel is produced in the United States and is also being consumed in the United States, the transportation distance is much shorter and would require fewer modes of transportation, leading to a lower carbon footprint for this stage. 

Essentially, the longer the transportation distance, the higher the carbon footprint. And the higher the carbon footprint for this, the worse effect it has on the environment. 

What Is the Carbon Footprint of Building Back Petroleum Refineries

Oil wells can produce for anywhere from 20-40 years. When a well is done producing oil it is plugged to stop the flow of methane to the surface. However, over 3 million abandoned oil and gas wells are unplugged in the US alone, and these wells leak millions of metric tons of methane into our atmosphere every year. Simply plugging these wells could reduce methane emissions by 99%, which would help mitigate global warming. 

In some instances, 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.

What Role Does Aviation/Jet Fuel Play in Contributing to Climate Change

Aviation accounts for 1.9% of all greenhouse gas emissions, 81% of which come from passenger travel and 19% from freight travel. 60% of emissions from passenger travel are from international travel and 40% are from domestic travel.

“Climate Change: changes in the world’s weather, in particular the fact that it is believed to be getting warmer as a result of human activity increasing the level of carbon dioxide in the atmosphere”

Cambridge Dictionary

Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 36 billion tons (bt) of CO₂ are emitted from burning fossil fuels. The carbon found in fossil fuels reacts with oxygen in the air to produce CO₂ which warms the earth by acting as a heating blanket.

CO₂ emissions contribute to climate change in the following ways:

• Increasing temperatures: Earth’s atmosphere has warmed 1.5 degrees Celsius (C) 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. 

How Environmentally Friendly Is Aviation/Jet Fuel

Aviation/ jet fuel combustion produces a significant amount of CO₂ and other greenhouse gases. 

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

Cambridge Dictionary

Aviation/jet fuel is not environmentally friendly because it emits CO₂ and other chemicals that contribute to global climate change. Although there are ways to minimize its environmental impact, there are still many environmental drawbacks.

What Are Environmental Drawbacks of Aviation/Jet Fuel

Understanding aviation/jet fuel’s various environmental drawbacks is important to protect the environment. Because it is derived from crude oil, aviation/jet fuel comes with some of the same drawbacks as oil:

• Oil Spills: Small oil spills occur when refueling a ship, and large oil spills occur when pipelines break, oil tankers sink, or drilling operations go wrong. Oil spills, in general, cause serious environmental harm by contaminating water and soil, causing explosions and fires, harming wildlife, and contaminating seafood. When oil enters the environment it is difficult and expensive to remediate. 

• Fracking: Large amounts of water and potentially hazardous chemicals are required when fracking, which can decrease water availability for people and aquatic life and can result in leaks and spills of fracking fluids. Fracking also 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.

There is also a drawback unique to aviation/jet fuel:

• Contrail formations: 30% of jet fuel exhaust is water vapor. By itself, water vapor has a minimal impact on global warming, but its presence in the exhaust plume causes water to freeze into ice. The ice crystals draw water vapor from the atmosphere and expand to form contrail-induced cirrus clouds. The cirrus clouds trap infrared radiation, causing a warming impact 3x that of CO₂. The clouds themselves have a short lifespan, but the thousands of flights per day coupled with their warming influence make them a significant contributor to aviation-induced global warming. 

And there are environmental drawbacks associated with all petroleum-derived products:

1. Atmospheric CO₂: CO₂ accounts for approximately 70% of all aircraft emissions. CO₂ is such a potent greenhouse gas because after its emission, 30% of a given quantity of gas is removed from the atmosphere naturally over the course of 30 years and 50% of the remaining CO₂ disappears after a few hundred years. But the remaining 20% persists in our atmosphere for thousands of years.

2. 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 oil industry pollutes the air and water, adds to the total level of CO₂ in our atmosphere, and expedites global warming. Because aviation/jet fuel is derived from oil, the easiest way to mitigate the environmental impact of aviation/jet fuel is to simply not rely on it in the first place. Its combustion releases toxic chemicals, heavy metals, CO₂, and contributes directly to global warming. 

What Are Ways to Make Aviation/Jet Fuel Less Environmentally Detrimental 

To minimize the negative environmental impacts of aviation/jet fuel, technological advances in drilling, production, and transportation of oil as well as strict safety and environmental laws and regulations must be enforced.

• Improved technology: Satellites, GPS, and remote sensing technology can detect oil reserves underground which negate the need to drill multiple exploratory wells.

• Efficient drilling methods: Horizontal and directional drilling allows a single well to produce oil from a much larger area, reducing the overall number of wells needed. 

• Controlling CH₄ leaks: Detecting, fixing, and repairing CH₄ leaks from well-pads, processing plants, compressor stations, and large distribution facilities is crucial. 

• Recycle water and use efficient production practices: Recycling water and avoiding utilizing freshwater sources can reduce water requirements. Constructing wells properly and maintaining them after drilling is complete is crucial for efficiency. 

• Implement practices that reduce risk of induced seismicity: Avoiding water injection into active fault lines, limiting injection rates, installing seismic monitors, establishing a protocol for when seismic activity is induced, and abandoning wells with seismic activity are all ways to mitigate this threat. 

The best way to make aviation/jet fuel less environmentally detrimental is to use sustainable aviation fuel (SAF) instead of conventional jet fuel. SAF is a biofuel made from biomass, renewable organic material from plants and animals that can be used to produce a wide range of products including energy, everyday products that contain plastics, and fuel. SAF burns cleaner in aircrafts, has a smaller carbon footprint, and emits less toxic chemicals than jet fuel.

However, using biomass as a fuel source also comes with its drawbacks, the most serious of which is deforestation. In some parts of the world, large swaths of forests have been cleared and burned to plant vegetation needed to make biofuel. Our forests absorb 2.6 bt of CO₂ every year, but deforestation occurs at roughly 10 million hectares (~ 25 million acres) per year. The world has lost more than 1/3 of its forest since the last ice age, which occurred about 2.6 million years ago. 

Trees combat climate change, purify the air, provide housing for millions of plant and animal species, protect against floods and water pollution, and improve mental health. Chopping these trees to make space for crops has a devastating effect on the environment because it reduces the amount of trees that can capture our CO₂ emissions. Protecting forest habitats increases carbon sequestration and decreases the effects of global climate change. 

The best ways to avoid the environmental drawbacks associated with SAF are to use wet waste sources (manure and sewage sludge) and to keep the scale of SAF production low because the land needed to produce SAF is also needed for food and carbon storage.

Final Thoughts

Aircrafts have made our lives easier as far as fast transportation is concerned, but even more concerning is the high carbon footprint of aviation/jet fuel across its building, extracting, transportation, and building back stages. The CO₂ and other greenhouse gases emitted contribute heavily to global warming, and oil spills, air pollution, and fracking can cause environmental and public health degradation. Reducing aviation/jet fuel consumption and incorporating SAF into our energy mix would benefit our health and our planet’s health.

Stay impactful,

Sources

• Statista: Market size of the airline industry worldwide from 2018 to 2021
• Federal Aviation Administration: Air Traffic By The Numbers
• Britannica: Carbon Footprint
• United States Environmental Protection Agency: System of Registries
• Skybrary: Fuel
• US Energy Information Administration: Oil and Petroleum Products Explained
• IJet: The Different Types of Aviation Fuel or Jet Fuel
• Carbon Offset Guide: CO2 Emissions
• US Energy Information Administration: Carbon Dioxide Emissions Coefficients
• BlueSkyModel: 1 Air Mile
• Our World in Data: Climate change and flying: what share of global CO2 emissions come from aviation?
• Our World in Data: Global CO2 emissions from aviation
• Environmental and Energy Study Institute: Fossil Fuels
• GlobeNewswire: Worldwide Aviation Fuel Industry to 2025 – Key Drivers, Restraints and Opportunities
• Science Direct: Life-cycle assessment (LCA) 
• MIT SMR: Strategic Sustainability Uses of Life-Cycle Analysis
• American Petroleum Institute: Refinery Processes
• US Environmental Protection Agency: Petroleum Refining
• Coloradans for Responsible Energy Development: The seven steps of oil and natural gas extraction
• Library of Congress: Modes of Transportation – Oil and Gas Industry – A Research Guide
• US Energy Information Administration: Gasoline Explained – Octane in Depth
• Knoema: Refinery output of jet fuel
• The Global Economy: Jet fuel consumption – Country rankings
• DistanceFromTo: Distance from Germany to United States
• DistanceFromTo: Distance from India to United States
• Coloradans for Responsible Energy Development: How long does fracking last?
• Forbes: Plugging Abandoned Oil Wells Is One ‘Green New Deal’ Aspect Loved By Both Republicans And Democrats
• Bureau of Safety and Environmental Enforcement: Rigs-to-Reefs
• Our World in Data: Sector by sector – where do global greenhouse gas emissions come from?
• The National Wildlife Federation: Climate Change
• National Oceanic and Atmospheric Administration: Climate Change – Global Temperature
• National Oceanic and Atmospheric Administration: Climate Change – Global Sea Level
• United States Geological Survey: How would sea level change if all glaciers melted?
• National Aeronautics and Space Administration, U.S.A.: How does climate change affect precipitation?
• National Oceanic and Atmospheric Administration: Ocean Acidification
• National Ocean Service: What is coral bleaching?
• World Nuclear Association: Carbon Emissions from Electricity
• United Nations Framework Convention on Climate Change: The Paris Agreement
• National Resources Defense Council: Global Warming 101
• National Oceanic and Atmospheric Administration: Oil Spills
• Environmental and Energy Study Institute: Fact Sheet – The Growth in Greenhouse Gas Emissions from Commercial Aviation (2019)
• National Oceanic and Atmospheric Administration: Climate Change – Atmospheric Carbon Dioxide
• Union of Concerned Scientists: The Hidden Costs of Fossil Fuels
• Natural Resources Defense Council: Reducing Natural Gas Leakage to Protect the Environment Is Easy to Do, Saves Money, and Creates Jobs
• Business for Social Responsibility: Fuel Sustainability Brief – Natural Gas
• International Air Transport Association: What is SAF?
• Our World in Data: Deforestation and Forest Loss
• Food and Agricultural Organization of the United States: State of the World’s Forests 2020
• Woodland Trust: Why do we need trees?
• One Green Planet: How Saving Wildlife Benefits Humans – In Ways We Really Need
• ClientEarth: What is a Carbon Sink?
• Office of Energy Efficiency and Renewable Energy: Sustainable Aviation Fuels