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Passenger transportation: towards carbon neutrality

13.09.2022 — Dan Kreibich on behalf of SQUAKE

Dan Kreibich
The Sustainable Quake
7 min readSep 13, 2022

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Introduction

Decarbonizing transportation is necessary if climate change is to be halted. 23% of the energy-related CO2 that contributes to global warming is emitted by transportation. If nothing is done right away, by 2030, its percentage might rise to 40%. Over the past 50 years, transportation emissions have increased more quickly than other industries, and demand is expected to continue increasing in the coming decades to reach a 60% rise in emissions by 2050. And since 92% of the energy used in transportation comes from oil, decarbonizing the sector is particularly challenging.

Passenger transportation is responsible for a substantial amount of greenhouse gas emissions. In 2020, the industry produced around 7.3 billion tonnes of CO2 worldwide (Tiseo, 2021). About one-fifth of the world’s carbon dioxide (CO2) emissions are related to transportation. The need for transportation is anticipated to expand globally over the next several decades as the world’s population and income levels rise and more people are able to purchase automobiles, trains, and aircraft. The International Energy Agency (IEA) forecasts that by 2070, demand for passenger and freight aircraft will quadruple, vehicle ownership rates will rise by 60%, and global transport will have doubled. These elements working together would cause a significant rise in transportation emissions. However, significant technical advancements can help counteract this increase. The development of electric cars presents a workable solution to cut emissions from passenger vehicles as the globe moves toward lower-carbon electrical sources.

(Tiseo, 2021)

Emissions per passenger-kilometer (pax-km): focus on France

To illustrate the transport-related emissions through this article, we have decided to focus on France. Let alone one of the biggest countries in Europe, France is also leading the sustainability topic thanks to one the most detailed framework developed by their Ministry of Ecological Transition.

31% of the transport infrastructure of France is decarbonized, which is quite an achievement for such a growing sector. France is one of the largest markets for electric vehicles among major European economies, accounting for about 15% of car sales in 2021. Even ahead of the EU’s policy, the French government has decided to ban the sale of new petrol and diesel vehicles from 2035.

Globally, some of the smallest emission shares of passenger transportation come from rail (3%), buses (7%), and light commercial vehicles (5%) (Tiseo, 2021). According to data collected by the French Ministry of Ecological Transition (Ecologie FR), journeys made within the French public transport network using diesel (specifically by buses) emit between 149 and 177 grams of CO2 equivalent per passenger km. Meanwhile, electric buses, metros, trams, and cable railways release more than 20 times less carbon into the air. This shows that public transport can be far more sustainable when using electric vehicles. These emissions depend somewhat on where you are within France; emission per passenger km values for electric vehicles are higher in urban and peri-urban areas with over 250,000 people than in areas with under 250,000 people. The opposite was true for combustion engine buses.

(The environmental impact, 2021)

The transport sector is known to be one of the main generators of carbon dioxide globally, though most research work done focused on road transport and, to a lesser extent, on air transport. Rail transport-related data on the other hand remained quite fragmented in France until 2005 and was reduced to promotional information. For example, the SNCF (the main French railway operator) allows their customers to evaluate the environmental impact of their trip via an eco-comparator made available on their website, which is an encouraging first step to help raise awareness and change behaviors. It appears though that the tool delivers very generic calculations solely based on the length of a journey when so many additional factors are influencing the way a train journey emits CO2. Even though SNCF is being fully transparent on their methodology here (“a weighted average of emissions from each type of service according to their distribution: 85% TGV, 10% TRN and 5% TER”) it is not really allowing private consumers to get the level of information required to change their consuming behaviors towards carbon-heavy means of transport.

SNCF could start by providing more nuance in the emissions across its various train lines and power types:

  • Local express trains powered by diesel emit around 79.25 gCO2e/pax-km
  • Local express trains produce around 8.10 grams of CO2e/pax-km
  • Mainline trains are producing 5.11 grams of CO2e/pax-km
  • And finally, French TGV (high-speed trains), ranked number one, with only around 3.37 grams of CO2e/pax-km.

This further demonstrates the value of implementing electric passenger transportation to reduce emissions.

The most infamous mean of transportation when it comes to passenger transport is most probably air travel. The French Ministry of Ecological Transition has also reported on the CO2e/pass/km for this very sector and here is what was shown: emissions are dependent on the distance traveled and the capacity of a flight. On average, flights with fewer seats tend to emit more; A flight with under 50 seats emits around 238 grams of CO2e/pax-km while a flight with more than 250 seats emits only 93.5 grams of CO2e/pax-km.

Additionally, flights that travel shorter distances tend to emit more per passenger kilometer than long-haul flights. The average CO2 emissions per passenger kilometer for a flight with more than 250 seats that travels between 1000 and 2000 kilometers is 123 grams of CO2 equivalent per passenger kilometer. The average for a flight with the same number of seats that travels more than 11,000 kilometers is 94 grams of CO2 per passenger kilometer. This shows that long-haul flights with larger capacities are more efficient than short flights with smaller capacities.

(Ritchie, 2020)

Another mode of transportation that might not come first to mind, even though really trending in both rural and urban areas, is motorcycles and motorized vehicles. Data published by the French Ministry of Ecological Transition allow, here again, to grasp the scope of emissions related to using such vehicles. And the nuance comes from the type of piston displacement:

  • greater than or equal to 750 cubic centimeters (which use unleaded petrol) emit around 403 grams of CO2 per kilometer.
  • less than 750 cubic centimeters (which use unleaded petrol) emit around 336 grams of CO2 equivalent/km.

To bring another layer of perspective, a study published in the United States by Hollingsworth et al. (2019) also found that electric scooters there emit around 126 grams of CO2 equivalent per passenger kilometer, which is less than half the amount that petrol motorcycles and scooters use (Kazmaler et al., 2020).

While the French Ministry of Ecological Transition has collected valuable and insightful data for the emissions of numerous modes of passenger transportation, it is not the only source with such a database. Chalmers University has collected data on the emissions of multiple modes of transportation in Scandinavian countries while Department for Environment, Food, and Rural Affairs (DEFRA) has collected transportation data for the United Kingdom. The data obtained on the emissions in these different countries varies which shows that certain countries have been more successful in making transportation more sustainable. It requires it all, and as much and as diverse data sources as possible, to progress towards a deep understanding of transport relation emission to help regulators and consumers shape the future of decarbonized travel and transport.

Conclusion

Thanks to the data made available by the French Ministry of Ecological Transition, we now have science-backed proof that:

  • Electric modes of transportation (including motorcycles, cars, buses, trains, trams, and scooters) are more efficient as they emit less CO2 than petrol and diesel vehicles;
  • Emissions generated by public transport vary depending on the area;
  • Air travel-related emissions are highly dependent on the distance traveled and the capacity of an airplane. Long-haul flights and high-capacity planes have lower emissions than shorter flights and low-capacity planes.

I would like to thank Yury Erofeev, Victoire Ferrari, Sophie Beier, our partners, and the remaining team at SQUAKE for the performed research and analysis.

Bibliography

Transportation
Passengers
Carbon Emissions
Carbon Neutrality
Research

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Dan Kreibich
The Sustainable Quake

Written by Dan Kreibich

11 Followers

Decarbonizing travel & logistics. CPO at SQUAKE.

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