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

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

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Grace Smoot

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Propane is commonly used in cooking and heating applications, but did you know it can also be used as a transportation fuel? It has been dubbed a clean-burning fuel that can help combat climate change. So we had to ask: What is the carbon footprint of propane?

Propane has a lower carbon footprint than gasoline and petroleum diesel. One gallon of propane emits 12.61 pounds (5,719 grams) of CO2 when combusted, and driving one mile on average emits 351 grams of CO2. It combats climate change and has various environmental benefits. 

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

Here’s What the Carbon Footprint of Propane Is

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).

Propane, also known as liquified petroleum gas (LPG), is a gaseous, alternative, cleaner-burning fuel used in light-, medium-, and heavy-duty propane vehicles. Because of its availability, energy density, clean-burning qualities, and low cost, propane is the world’s third most common transportation fuel. It is surpassed only by gasoline and diesel fuel in terms of widespread usage.

Propane: a heavy flammable gaseous alkane C3H8 found in crude petroleum and natural gas and used especially as fuel and in chemical synthesis”

Merriam-Webster Dictionary

Propane is a by-product of natural gas (NG) processing and crude oil refining. Liquid components recovered during NG processing include ethane, methane, propane, and butane, and heavy hydrocarbons. Liquid components recovered during oil refining include propane, butane, and other gases.

Propane can only be used in propane-specific vehicles (shuttles, police vehicles, school buses) in the form of HD-5, which consists of at least 90% propane and no more than 5% propylene and 5% other gases (butane and butylene). It is stored inside vehicles in pressurized (100-200 psi) tanks, which causes the gas to condense into a liquid. Propane has a higher octane rating than gasoline, meaning it is more stable and resistant to engine knocking. But it also has a lower Btu rating, so it takes more fuel by volume to drive the same amount of miles. 

Unlike gasoline and diesel fuel which emit 19.59 and 22.44 pounds (lb) of CO2, respectively, per gallon upon combustion, propane emits only 12.61 lb per gallon. 

Burning of propane Carbon footprint
Burning one gallon 5,719 grams (g) of CO2 emitted
Driving one mile (on average) 351 g of CO2 emitted
Per million British thermal units (Btu) 138.63 lb of CO2 emitted

Oil (including gasoline and diesel fuel) is the world’s primary fuel source for transportation. But since the turn of the century, there has been a push towards cleaner-burning transportation fuels with fewer negative effects on the environment. This is one major reason the propane market is expected to increase from $126.5 billion (B) in 2020 to $146.7B, by 2027.

To understand the total carbon footprint of propane, 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 propane!

The life-cycle stages of propane Each stage’s carbon footprint
Building of propane “plant” CO2 emissions from construction of oil-fired plants and NG power plants 
Extracting of propane CO2 emissions from oil extraction/refinement and NG extraction/processing
Transportation of propane CO2 emissions from transporting propane by barges, tankers, pipelines, trucks, and railroads across distances
Building back of propane “plant” CO2 emissions from utilizing construction equipment to demolish the buildings and construct new buildings in the old oil-fired or NG plant 

The total carbon footprint of propane would equal the carbon footprint from building + the carbon footprint from extracting and refining + the carbon footprint from transportation + the carbon footprint from building back.  

What Is the Carbon Footprint of Building Propane “Plant”

Propane is a by-product of natural gas (NG) processing and crude oil refining. Oil wells extract crude oil and NG, which is then transported to petroleum refineries or NG power plants. Petroleum refineries and NG power plants 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 Propane

In order to extract propane you first need to extract the oil and NG from which it is derived. Oil and NG are often found within the same reservoir, so they are often extracted in the same manner. Drilling or fracking exposes oil and NG reservoirs for extraction.

Extracting oil and NG 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

Propane is then collected as a byproduct of oil refinement and NG processing.

Oil refinement 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: Because there is a demand for lighter distilled products like gasoline, refineries convert heavy liquids into lighter liquids via cracking. Cracking breaks up long hydrocarbon chains into smaller ones, converting heavy oil into gasoline. 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 gasoline. 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 motor fuels. Refineries can also mix additives such as octane enhancers, metal deactivators, anti-oxidants, anti-knock agents, rust inhibitors, or detergents. 

And processing NG typically involves four main steps:

  1. Oil and condensate removal
  2. Water removal
  3. Separation of natural gas liquids
  4. Sulfur and carbon dioxide removal

These two processes produce propane that can then be gathered and transported for commercial use. 

What Is the Carbon Footprint of Transportation of Propane

Crude oil and NG are transported from extraction wells to oil refineries and NG power plants via barges, tankers, pipelines, trucks, and railroads. After refinement and processing removes the propane, it is then stored underground as a liquid until it is needed. When it is needed, it is transported to a retail plant that a local propane supplier draws from for consumer consumption. But if the propane is not being consumed locally, it must be transported. And sometimes over very long distances. 

The top 5 propane-exporting countries (billions [B] of dollars) in 2019 were:

  1. United States – $12.5B 
  2. Qatar – $2.81B
  3. United Arab Emirates – $2.58B
  4. Canada – $1.8B
  5. Saudi Arabia – $1.56B

The top 5 propane-importing countries (billions [B] of dollars) in 2019 were:

  1. China – $6.09B 
  2. Japan – $4.62B
  3. India – $2.97B
  4. Mexico – $1.8B
  5. South Korea – $1.71B

Calculating the carbon footprint of propane transportation involves knowing where the propane is produced, where it is being consumed, and the distance between the two. For example, transporting propane from the United States to China is an approximately 7,252 mile (11,671 kilometer) transportation distance. Likewise, the transportation distance between Canada and South Korea is an approximately 5,344 mile (8,601 kilometer) transportation distance.

The carbon footprint of transportation for these instances would be high because of the long transportation distance multiple modes of transportation required. 

On the other hand, if gasoline 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 Propane

Propane is a by-product of natural gas (NG) processing and crude oil refining. Oil wells can produce for anywhere from 20-40 years, and NG plants have an average age of 22 years in the US. When an oil or NG well is done producing, it is plugged to stop the flow of methane to the surface.

However, over 3 million abandoned oil and NG 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 Propane Play in Combating Climate Change

Propane is considered a clean-burning fuel because the GHG emissions from propane combustion are much lower than that of gasoline and diesel fuel. Using propane can reduce GHG emissions by almost 13%, and using NG-derived propane can reduce petroleum use by 99%, which in turn helps combat climate change. 

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.

Reduced CO2 emissions from propane combat 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. 

Climate change results in global warming, when CO2 and other air pollutants absorb sunlight and solar radiation in the atmosphere, thereby 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 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 Propane

Propane comes with lower levels of GHG emissions compared to gasoline and petroleum diesel fuel. 

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

Cambridge Dictionary

When discussing the issue of climate change, both the environmental benefits and drawbacks of propane must be taken into consideration.

What Are Environmental Benefits of Propane

The environmental benefits of propane include:

  1. Mitigates climate change: propane can emit up to 26% fewer GHGs than gasoline and 38% fewer GHGs than oil in furnaces.
  1. Improves air quality: propane emits 60% less carbon monoxide (CO) than gasoline and 98% less particulate matter than petroleum diesel. It also releases no CH4 and little to no sulphur, soot, hydrogen/oxygen oxides, and air toxics (benzene, acetaldehyde). These pollutants can cause ground-level ozone formation, acid rain, cancer, and reproductive/birth defects. 
  1. Eliminates oil spills: In the event of an oil spill, propane quickly evaporates into the atmosphere. This means it will not leach into and contaminate the surrounding soil.
  1. Eliminates fugitive emission impacts: Because it is not a GHG, propane will not negatively harm the environment if it is released into the atmosphere prior to combustion. On the other hand, NG is composed mostly of CH4, which has a global warming potential 25 times that of CO2. If it is released into the atmosphere prior to combustion, NG will accelerate the global warming process. 

What Are Environmental Drawbacks of Propane

Although propane is a cleaner-burning fuel, it is still derived from fossil fuels. To extract propane you must first extract oil and NG, a process which comes with the following environmental drawbacks.

  • Drilling: This 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. 
  • Landscape alterations: Drilling for NG causes surface distribution from drill pads, roads, and pipelines that alter the landscape. Fragmentation of wildlife habitat and migration patterns have also been documented. 
  • Water pollution: Land clearing may cause dirt, minerals, and other pollutants to erode into nearby waterways. Drinking water may become contaminated with hazardous chemicals via drilling, fracturing, processing, and refining the gas, and wastewater disposal. 

Final Thoughts

Propane is an alternative fuel source with a lower carbon footprint across its building, extraction, transportation, and building back stages when compared to gasoline and diesel fuel. It is cleaner-burning and releases fewer amounts of GHG emissions upon combustion. However, because it is still derived from fossil fuels, the environmental drawbacks associated with oil and NG extraction must be taken into account.

Stay impactful,

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Grace Smoot

Grace loves to research and write about all things related to climate action and sustainability. She holds a Bachelor’s of Science degree in Environmental Biology and works as an Environmental Survey Technician. Outside of work, she loves to work out, play soccer, and take her dog for long walks.

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.

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