How to Calculate Long-haul Air Freight CO₂ Emissions

This knowledge base document describes how to calculate Carbon Dioxide (CO₂) emissions for long-haul air cargo transport, and provides an example that can be used for similar calculations.

For any type of transport, CO₂ emissions are a matter of weight, distance and mode of transportation.

For example, depending on year and model, your car emits about 160 g CO₂ per kilometer 1. For a 140 kilometer round trip that totals to 22.4 kg CO₂. (Imp: 87 miles driving emitting 50 lb CO₂).

We are going to calculate the amount of emissions caused by long-haul air freight.

Air Freight

Because take-off and landing cause seriously higher emissions than cruising speed flight, long-haul flights have lower emissions averages per km than short-haul flights. For any calculation, long-haul and short-haul air freight are different modes of transportation, using different emissions figures.

Air Freight CO₂ Calculation

Long-haul air freight CO₂ emissions are about 500 g CO₂ per 1,000 kg cargo per 1 km 2. This is for long-haul above 5,000 km, with a large cargo plane using modern engines. Our example uses such a plane on an intercontinental long-haul.

We have 3.9 kg cargo travelling between Miami and Bangkok. It's 15,611 km by air freight.  (Imp: 8.6 lb cargo air freighting 9,700 miles).

How much CO₂ does this emit? Again, specifically for long-haul:

Air freight 1,000 kg cargo for 1 km: 500 g CO₂.
Air freight 1 kg cargo for 1 km is: 500/1,000 = 0.5 g CO₂

Air freight 1 kg cargo for 15,611 km is: 0.5 x 15,611 = 7.81 kg CO₂
Air freight 3.9 kg cargo for 15,611 km is 7.81 x 3.9 = 30.46 kg CO₂

The 3.9 kg air shipment going 15,611 kilometers emits 30.46 kg CO₂ emissions.

Actually, you can do this type of weight calculation yourself now. For different transportation modes find the appropriate CO₂/km averages. You'll see that slower types of transport have notably lower CO₂ emissions.

One way to counter CO₂ emissions is to plant trees. An average tree absorbs approximately 22 kg CO₂ per year. JEDI has planted over 1,500 trees on own ground, with villagers planting another 1,000 trees on their own and public ground, for a total of about 55,000 kg (55 tonnes) of annual CO₂ absorption.

CO₂ Price

While the planet very likely knows what trees do, it has no relation to human material value labels like "carbon emissions cost", price, allowance, or tax. Any monetary valuation of CO₂ emissions should therefore be taken with three grains of salt.

On 24 August 2018 the official European Emission Allowance "price" for CO₂ was 23.93 USD per tonne(20.55 Euro) 3. This is equivalent to 0.02 ¢ per kilogram. It is significantly up from about 5.82 USD per tonne (5.00 Euro) a year earlier, and before that. Note that these allowances are priced artificially based on governments creating papers 4 with text like "Carbon Emission 1 tonne" and allowing "free" markets to decide their value. Initially too many of these papers were issued, they were unpopular, there was some talk of fraud, so their price dropped so low that your friendly neighborhood café was better off buying these allowances for its soda maker than getting the real thing. See here > current CO₂ price.

In 2015 the US government calculated the social cost of carbon emissions at 37.00 USD per tonne, while Stanford University, taking wider economic effects into account, estimated 220.00 USD per tonne 5.

CO₂ and CO₂e

CO₂ stands for Carbon Dioxide, a colorless gas containing one carbon atom double bonded to two oxygen atoms. It exists naturally as a trace gas, and as a man made gas mainly through burning fossil fuels. It acts as a greenhouse gas, responsible for heating up earth's surface and lower atmosphere.

CO₂e stands for Equivalent Carbon Dioxide. It shows the "global warming potential" (GWP) of any other greenhouse gas in terms of what it would be when expressed as CO₂. So, CO₂ itself has a global warming potential of 1. The greenhouse gas methane is 25 times stronger in global warming potential than CO₂, so its GWP is 25.

Those other "e" gases have clout.

SwitchGear

The most destructive of these other "e" gases is named SF6, Sulphur hexafluoride. It is widely used in the electrical industry's switchgears to prevent short circuits and accidents. Its use is on the rise due to the higher degree of electrification in the transition to cleaner energy.

SF6 with a global warming potential of 23,000. It is banned in the EU, except for use in the electrical industry, because there appeared to be no viable alternative. But now there is, and its high time electrical manufacturers make a switch to those alternatives. You can help, insist on SF6-free switchgear.

Refrigerants

Freon

Among the other "e" gases there's also manufactured refrigerant gases used in air conditioners and refrigerators, such as the conventionally used Freon 6, 7 gases. These are fluorocarbon (CFC, HCFC, HFC) gases that 1) deplete the earth's ozone layer and 2) have global warming potentials of thousands to tens of thousands greater than CO₂. An early example was Freon CFC-12 /R-12, highly destructive to the ozone layer, with a global warming potential about 10,000 times greater than CO₂. Some improvements have been made, reducing the ozone depletion effect, while current Freon variants have global warming potentials of about 1,300 to 4,000 times greater than CO₂ 8.

Edit July 2018: After initial stabilization of the Ozone hole, it has grown gain, with additional effect on global warming. Apparently manufacturers in China have been widely using old, banned CFC-11 / R-11 as a cheap foaming agent to produce cheap home insulation 9.

"New" Freon

Newest Freon variants are hydrofluoroolefins (HFOs). They have zero effect on the ozone layer, and a lower global warming potential, yet still still hundreds of times greater than CO₂. The newest version for automobiles goes by the name HFO-1234yf / R-1234yf. Its technical advantage is its use as so-called "drop-in" replacement of the conventional R-134a refrigerant (edit: but finally it requires a number of aircon system modifications). Its monetary advantage is that it is patented by those same Freon manufacturers, Honeywell & Dupont, allowing for continued shareholder profit 10  (at the cost of continued global warming).

Low carbon natural refrigerants

Best to go back to the natural refrigerants 11. These were in widespread use before pernicious Freon became a household term. The natural refrigerants are carbon dioxide (CO₂) itself, ammonia, and hydrocarbon refrigerants, specifically propane, iso-butane and propylene. Many large industrial refrigeration facilities never abandoned their natural refrigerants, since they are patent-free, widely available, inexpensive, and have very low to zero global warming potential. They do require specifically designed cooling hardware, but that's about it.

Not in the future - but right now

Most European automobile brands (BMW, Daimler, Volkswagen/Audi, Porsche) have already redesigned their new vehicle air conditioners to use natural refrigerant CO₂ 12, also known as R-744, at low cost. Good for the environment with global warming potential GWP = 1.

In Thailand and many other countries, most Japanese car brands still use the bad old, conventional R-134a for their new 2022 models, including new hybrid vehicles. Most probably because Thailand (among others) is on a later implementation schedule for conversion to low CO₂ refrigerants. But why? In all cases, it won't hurt to actively request cooling with a low CO₂ refrigerant, even if you cannot get it (yet).

It may very well be possible for you to improve your own environmental footprint by converting, or switching to an air conditioner with refrigerant that has low or no atmospheric impact 13.

Related

Hydrogen fuel breaks down to water and oxygen when burned; no greenhouse gases. The engine was invented in 1801/1842. The first hydrogen vehicle was a tractor in 1959. The first mass produced passenger vehicle was made in 2013/2015 > by guess who? Others soon followed. The main bottleneck remains a wide availability of Green Hydrogen, which is made by green electricity.

Back to air transport: Green Hydrogen can become a replacement for fossil fuels in jet engines. It's just a matter of time, and let's speed it up: https://www.bbc.com/future/article/20210401-the-worlds-first-commercial-hydrogen-plane.

Airbus reveals new zero-emission concept aircraft - 2020-09-21      https://www.airbus.com/newsroom/press-releases/en/2020/09/airbus-reveals-new-zeroemission-concept-aircraft.html.  This requires hydrogen to be created by clean energy. JEDI's recommendation: Hurry up and get it done now.

Norway's plan for a fleet of electric planes - 2018-08-22
http://www.bbc.com/future/story/20180814-norways-plan-for-a-fleet-of-electric-planes

THAI's phad kaprao causes most greenhouse gas - 2015-03-23 https://www.bangkokpost.com/thailand/general/505551/thai-phad-kaprao-causes-most-gas. From five selected dishes available on Thai Airways, the preparation of khao phad kaprao khai dao produces the highest greenhouse gases at 1.32 kg per meal. But it remains on the menu as a Thai signature dish, while at 50,000 meals a year, it does create a footprint. Still, that pales when compared to steak, the meat alone is > 27 kg CO₂e.

Footnotes

1. https://www.eea.europa.eu/data-and-maps/daviz/average-emissions-for-new… or  https://carfueldata.vehicle-certification-agency.gov.uk/search-new-or-u…
2. https://timeforchange.org/co2-emissions-shipping-goods