Rethinking transportation’s footprint: What most CO2 calculations miss

AeroTime is excited to welcome Dr. Klaus Radermacher as our columnist. With over 35 years in management, science, and consulting, Dr. Radermacher brings a wealth of experience in analyzing and assessing transportation systems. His innovative approach integrates infrastructure and movement processes into holistic CO2 and energy comparisons. Follow his LinkedIn newsletter “Think. Mobility. Differently.” for regular insights on mobility concepts and transportation systems. The views and opinions expressed in this column are solely those of the author and do not necessarily reflect the official policy or position of AeroTime.

Few other topics are currently being discussed as intensively and emotionally as the “ecological footprint” of various transportation systems, usually reduced to more or less correct figures on CO2 and NOx emissions. Such discussions often result in highly simplified statements such as “taking the train is environmentally friendly”, “driving a car is harmful to the environment” and “flying is even more harmful”.

The fact that an appropriate evaluation is much more complex and that it is not sufficient to measure only the exhaust gases at the tailpipe in order to take the environmental aspect adequately into account will be illustrated in this study. Previous approaches to assessing and comparing greenhouse gases (GHG) emissions in a broader context have primarily aimed to include not only short-term emissions but also their long-term climate impact. The approach described here aims to evaluate transport sector emissions holistically, including ALL necessary infrastructure components. Emissions that so far have been attributed to “industry” or “the construction sector” are now attributed to the specific transportation system and assigned to the respective transportation service provided, as long as they are directly related to the provision of that service. For example, large amounts of steel and aluminum are needed in the construction of trains, cars or airplanes, concrete and steel in the construction of roads, bridges, tunnels, runways. If the cause-effect relationship of each transportation system is appropriately taken into account, the energy consumption and pollutants produced by concrete and steel for highway bridges must be allocated to the energy and pollutant balance of the road transport mode; if the structures are railroad bridges or tunnels, they must be allocated accordingly to railway transportation, and the concrete for airport runways must be added to the balance of the aviation transport system. This approach is very complex, but even a few examples prove that it is not sufficient at all to measure only the direct exhaust gases at the tailpipe in order to take adequate account of the environmental aspect.

For the four major transport systems – road, railway, air and water – Table 1 shows which components the respective systems require to provide a transport service.

Table 1: The four basic transport systems and their respective necessary components

Each of these systems requires an actual means of transport, i.e., cars, trains, aircraft and ships. Likewise, all systems require their own specific infrastructure, which can be divided into a “node” infrastructure (train stations, airports, ports, parking lots, etc.), a “route” infrastructure (road network, railway network, waterways, etc.) and a “control” infrastructure (signal boxes, signal systems, traffic lights, traffic signs, air traffic control systems, lighthouses, buoys, etc.). Furthermore, the table lists the energy sources for the propulsion of the respective means of transport.

To be clear from the outset: Not all the figures that would be necessary to correctly determine the CO2 footprint of an individual airport or the entire railway or highway network that has already incurred in the construction are available or even known. Until a few decades ago, CO2 was considered a naturally occurring, non-toxic, invisible and odorless gas to which no real relevance was attached. It was only about 20 years ago that awareness of the greenhouse gas effect of CO2 was first raised.

However, this important and correct change in perception and assessment now even more needs to be adequately considered in current and future decisions on mobility and transportation systems.

In the industrial field, the largest energy consumers and CO2 emitters include the steel industry, aluminum and copper production, and the cement and concrete industries. To produce one ton (1,000 kg) of steel in a blast furnace, around twenty gigajoules (GJ) of energy are required, equivalent to around 5,600 MWh (megawatt hours). Since the energy for steel production comes primarily from (fossil) coke (coal), the production of one ton of crude steel generates more than 2 tons of CO2. This is only the energy and pollutant balance from the blast furnace and coke plant process; everything else that occurs in the rolling mill or during further refinement of the raw material steel must still be added in each case. The carbon footprint for aluminum or copper are even more negative than for steel; depending on the primary energy used, between eight and 12 metric tons of CO2 are emitted to produce one ton of pure aluminum, for copper it’s more than six tons on average, with a rather large span depending on the production method.

Contrary to widespread belief, rail travel is by no means environmentally friendly when viewed from a holistic system perspective. The tunnel- and bridge-intensive routes for high-speed trains in particular cause millions of tons of CO2 during construction, which is primarily due to the huge quantities of steel, concrete and copper required. One kilometer of track alone requires 120 tons of rail steel, for which 240 tons of CO2 have already been emitted in the blast furnace and coking plant process alone. For high-speed lines, the amount of CO2 per PKM is often in the three-digit gram range from the construction of the line alone!

Ultimately, it is always necessary to look at the total amount of CO2 produced, taking into account all infrastructure components and the transport volume provided over time. Transport volume is measured in PKM (person kilometer) or TKM (ton kilometer). Motorized Individual Traffic (MIT) in Germany amounts to around 967 billion PKM per year, that of rail transport to around 96 billion PKM; in other words, 10 times as many PKM result from car travel compared to train travel!

“Simple truths” such as those mentioned at the beginning of this text collapse like a house of cards in a draught when viewed holistically. When has it ever been pointed out that the CO2 emissions from the production of an average car alone account for 33 grams of CO2 for every PKM driven, which must be added to the average 85 grams of CO2 from the exhaust pipe? In the case of electric vehicles, the production-related CO2 impact is currently even higher, as battery production is still very CO2-intensive. The background to these enormous “hidden burdens” per PKM is above all the incredible inefficiency of motorized individual transport (MIT). With an average driving time of just one hour per day (the car is parked for 23 hours and requires parking space) and an average utilization of just 1.5 of the five available spaces, this results in a calculated utilization efficiency of 1.25%. If such poorly used cars with combustion engines are replaced by equally poorly used electric vehicles thanks to state subsidies of up to 9,000 euros, this may help the automotive industry, but it does nothing to reduce CO2 emissions.

The distortions in public perception become even more drastic when the construction of the infrastructure is taken into account. High-speed rail lines in particular, which are mainly made of concrete, steel and copper and often run through very long tunnels and over high valley bridges, cause millions of tons of CO2 during construction. The blanket statement that rail travel is environmentally and especially climate-friendly can therefore only be dismissed as a “spinach fallacy” of the 21st century, because a false statement does not become correct through constant repetition. (For decades in the 20th century, “experts” repeatedly claimed that spinach was a vegetable particularly rich in iron. This statement was based on a miscalculation or decimal point error in the first scientific analysis around 1890. After that, this false claim was only ever copied and quoted. It was not until 1981 that this myth was “debunked”.)

For the aviation transportation system, the table above shows another important finding: for the transportation systems of aviation, the ecological and economic costs of route infrastructure are zero. The air between two airports never needs to be built or maintained. This has a significant impact on the overall ecological balance of the transportation systems. (By the way, the same is true for shipping across the oceans.)

Looking at the table and all relevant systems components show, how important it is to have a system-oriented view when assessing, comparing and discussing ecological footprints of transport systems.

Mobility is complex. Mono-causal thinking does not provide any solutions.

It is definitely possible to save tens of millions of tons of CO2 every year in the mobility sector without anyone having to give up their usual level of mobility. The decisive lever for this is more efficient mobility, rather than simply ignoring CO2 emissions caused by the construction and maintenance of transport infrastructure in the calculation does not help anyone, let alone the climate.

Objectively speaking, it is neither justified nor helpful to demonize certain means of transport and hail others as the solution to all future problems. There is an urgent need to think holistically across the entire process chain, to keep an eye on all the necessary infrastructure components and to consider complex cause-and-effect relationships without ideological blinkers.

A non-ideological open-mindedness towards new findings, processes, methods and technologies is absolutely essential in order to avoid always being on “well-trodden paths” in the future. The discussion on the mobility concepts for the future must be consistently objectified across all boundaries and be based on scientific principles and what is technically feasible. Emotions and ideologies and the categorical adherence to what has proved successful in the past but is more of a hindrance in the future will not get us any further in this important debate.