Decarbonisation Pathways for Transport

Abstract

An overview of the main drivers of the transport energy demand and the assumed socio-economic development (population and GDP) until 2050 for ten world regions are given. The countries in each world region are tabulated. Detailed documentation of projected shifts in transport modes for all world regions, including technological assumptions and energy intensities, by vehicle type is presented. This section contains the OECM 1.5 °C transport scenarios for aviation, shipping, road, and rail, each broken down into passenger and freight transport. The calculated energy demands and energy-related carbon emissions for all transport modes are provided.

1 Introduction

The transport sector consumed 28% of the final global energy demand in 2019, and its decarbonisation potential is therefore among the most important of all industries. Given its size and diversity, not only with regard to different transport modes and technologies but also regional differences, it is also one of the most challenging sectors. In 2019, transport consumed 65% of the total oil demand globally. Therefore, the transition from oil to electric drives and to synthetic fuels and biofuels is key to achieving the goals of the Paris Climate Agreement. A rapid uptake of electric mobility, combined with a renewable power supply, is the single most important measure to be taken to remain within the carbon budget of the 1.5 °C pathway.

The financial sector Transport spans civil aviation, shipping, and road transport, including passenger and freight transport, and all related services. For each transport mode, there are two main sub-sectors:

• 1. Design, manufacture, and sale of planes, ships, and road vehicles for the transportation of passengers and freight

• 2. Operation and maintenance of vehicles to provide transport services for passengers and freight

This section is based on multiple closely linked research projects: the One Earth Climate Model (OECM) developed in 2019 (Teske et al., 2019) and 2021 and the TUMI Transport Outlook 1.5 °C (Teske et al., 2021), which was developed within a multi-stakeholder dialogue, including two workshops organised by Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH (GIZ) and the University of Technology Sydney/Institute for Sustainable Futures (UTS/ISF) in June and September 2021. As a result, the OECM methodology described in Chap. 3 has been expanded to achieve higher levels of accuracy and resolution, in both the area of the transport demand projections and the calculation of the regional and global transport energy demands.

The demand projections are based on a bottom-up approach. The actual basis of the passenger transport demand is diverse (e.g. to get groceries, to commute for work, or for leisure and recreation), and the transport demand is expressed in kilometres per person per year. Therefore, the development of this transport demand is dependent upon a number of different factors, among the most important of which are the actual population development and economic situation of a region. Geography and lifestyle also play important roles.

In considering the transport of goods, it is important where the goods are produced, the resources required, and where they are located. Economies with high local production rates have lower transport demands than those with high import/export dependence. However, calculation of the actual transport demand is based on non-energy-related factors. A transport or travel demand does not necessarily lead to an energy demand if a non-energy transport mode, such as walking or cycling, is used—sufficient to satisfy the demand. However, most transport modes require energy, and the amount of energy per kilometre depends upon the energy intensity of the chosen vehicle.

The demand for transport energy does not inevitably lead to CO₂ emissions if the energy is generated from renewable electricity and/or renewable fuels. Therefore, a carbon-neutral global transport sector is possible, while regional and intercontinental travel and global trade are maintained.

The transport demand is dependent upon a huge number of factors—the most important of which are the population size and the economic situation. In general, more people and a higher economic standard entail a higher transport demand. The transport service structure—and therefore the transport mode—also depends on a variety of factors. The actual distance travelled, the travel time required, the availability of certain transport modes, and the costs, among other factors, define the chosen transport mode. Each transport mode includes a variety of vehicles with different energy intensities. The transport mode ‘road’, for example, has by far the largest number of different vehicle options: buses, a huge variety of car types with different drive trains, motorcycles, bicycles, and even walking.

A global scenario requires the simplification of the transport demand projections. A detailed analysis of the purpose of each of those transport demands in kilometres per day for the entire population is not possible. Therefore, the methodology focuses on the development of regional person–kilometres (pkm) and tonne–kilometres (tkm) per year. The main factors affecting demand changes are population and economic development.

Whereas the industry and service pathways (Chaps. 5 and 6) were developed with accumulated global gross domestic product (GDP) values and bottom-up product-based projections, such as the annual steel production (in million tonnes per year), the demand projections for the buildings and transport sectors have been developed on the basis of specific data from ten world regions, to capture the significant regional differences. The geographic breakdown is based on IEA’s ten world regions used in the World Energy Outlook series (see Table 8.1).

Table 8.1 World regions used for the 1.5 °C OECM transport scenario

2 Socio-economic Assumptions

The assumed development of regional populations is based on the projections of the United Nations Department of Economic and Social Affairs, whereas the regional GDP developments are based on World Bank projections. The global values for population and GDP are identical throughout the entire analysis, across all sectors. The regional values are used for the buildings and transport sectors, whereas for all other sectors, the resulting (summed) global values are used (Table 8.2).

Table 8.2 Assumed population and GDP developments by region in 2020–2050

3 Transport Demand

3.1 Global and Regional Transport Demands

The global pandemic began in early 2020 and led to significant travel restrictions across the world. At the time of writing (December 2021), travel restrictions in many countries are still in place.

The global oil demand accounted for 11.5 Gt of energy-related CO₂ in 2019 (IEA, 2020a). The transport sector consumes 65% of total oil demand, which included oil for international bunkers (10.4% of the total oil demand). Road transport consumed more than 40% of the total oil demand in 2019. The sector’s growth has been responsible for over half the growth in the total oil demand since 2000 (BloombergNEF, 2020). As a result of the restricted mobility imposed to stop spread of the COVID-19 virus, the global pandemic led to a significant reduction in the oil demand, especially for road transport and aviation, which are responsible for nearly 60% of oil use (IEA, 2020a). The global oil demand is estimated to have dropped by 8% in 2020. At the time of writing, the global pandemic is still ongoing, although travel restrictions have been relaxed in many countries, increasing in the transport demand relative to that in 2020. In our transport demand projections, we assume that the demand will continue to increase to pre-pandemic levels by 2025.

The pandemic had a dramatic impact on public transport. Fear of being infected with COVID-19 led many people to avoid using public transport and to switch to other transport modes—especially individual transport, such as private cars or (electric) bicycles. The Future of Public Transport (C40 Cities Climate Leadership Group and International Transport Workers’ Federation 2021), published in March 2021, reported that as ‘public transport ridership has fallen during the COVID-19 pandemic, so has revenue. Public transport agencies across cities worldwide face a critical funding shortfall that threatens jobs and services’.

The energy demand is likely to increase and there is currently no sign that these increases will slow in the near future. The increasing demand for energy for transport has mainly been met by greenhouse gas (GHG)-emitting fossil fuels. Although (battery) electric mobility has recently surged considerably, it has done so from a very low base, which is why, in terms of total numbers, electricity still plays a relatively minor role as an energy carrier in the transport sector.

Apart from their impact on climate, increasing transport levels—especially by car, truck, and aeroplane—also have unwanted side effects: accidents, traffic jams, noise and other pollutants, visual pollution, and the disruption of landscapes by the large-scale build-up of the transport infrastructure. However, road, rail, sea, and air transport are also integral parts of our globalised and interconnected world and guarantee both prosperity and intercultural exchange. Therefore, if we are to cater to people’s desire for mobility while keeping the economy running and meeting the Paris climate goals, fundamental technical, operational, and behavioural measures are immediately required.

In this analysis, we discuss potential pathways of transport activity and technological developments by which we can meet the requirement that warming does not exceed pre-industrial levels by more than 1.5 °C—while at the same time maintaining a reasonable standard of mobility. The scenarios in this analysis are based on global and regional scenarios developed by the German Aerospace Centre (DLR), published in February 2019 (Pagenkopf et al., 2019), which have been updated in more detail as part of the Transformative Urban Mobility Initiative (TUMI) research (Teske et al., 2021).

We structured our scenario designs around the following key energy- and emission-reducing measures:

• Powertrain electrification

• Enhancement of energy efficiency through technological developments

• Use of bio-based and synthetically produced fuels only within strict sustainability limits

• Modal shifts (from high- to low-energy-intensity modes) and overall reductions in transport activities in energy-intensive transport modes

The final global energy demand in the transport sector¹ totalled 103 EJ in 2019, according to the IEA Energy Balances (IEA, 2020b). Based on this estimate, the freight and passenger transport demands were estimated from statistical data and energy-efficiency figures.

Figure 8.1 shows that road passenger transport had the largest share of the final transport energy (53%) in 2019. Most of this consisted of individual road passenger modes (mostly cars, but also two- and three-wheel vehicles), which accounted for around 40% of all end energy in the transport sector. In total, road transport (passenger and freight) accounted for around 76% of the total final energy demand for transport.

Fig. 8.1

Global final energy use, by transport mode, in 2019 (without international aviation or navigation bunker fuels)

The majority of all passenger transport—in terms of overall kilometres—is by road. However, international freight transport is more strongly dominated by rail and shipping, which account for 45% of all tonne–kilometres. The high efficiency of rail and shipping means that their share of the global transport energy demand is small relative to the share of global tonnage transported.

Figure 8.2 shows the passenger (pkm) and freight transport (tkm) by transport mode in 2019 (OECD, 2021). Road transport clearly dominates. However, international freight often arrives by ship and is further transported by rail and/or road. OECD America and OECD Europe together make up half the total global energy demand, as shown in Fig. 8.3. China is at nearly the same level as OECD Europe, although it has about twice as many inhabitants as OECD Europe.

Fig. 8.2

Transport mode performances for road, rail, and aviation

Fig. 8.3

Final energy use by global transport in 2019, according to region

3.2 Global Transport Technologies

The energy intensities for different vehicle types and for each of the available drive trains play an important role in the final energy demand. Each transport mode has various different vehicular options, and each of the available vehicles has different drive train and efficiency options. The technical variety of passenger vehicles, for example, is extremely large. The engine sizes for five-seater cars range from around 20 kW to over 200 kW. Moreover, drive trains can use a range of fuels, from gasoline, diesel, and bio-diesel to hydrogen and electricity. Each vehicle has different energy intensities in MJ/pkm.

Figure 8.4 shows the powertrain shares of all transport modes in 2019 (in pkm or tkm) (IEA, 2020b). With a few exceptions, most modes were still heavily dependent on conventional internal combustion engines (ICEs). A small number of buses had electric powertrains (mainly trolley buses) and battery-powered electric buses also increased, predominantly in China. China also has a particularly large number of electric two- and three-wheel vehicles. Almost all battery-powered electric scooters were in China. Passenger rail was electrified to a large extent (e.g. metropolitan and high-speed trains), whereas freight trains were predominantly not electrified.

Fig. 8.4

Powertrain split for all transport modes in 2019, by transport performance (pkm or tkm)

4 Aviation

The 2020 pandemic led to significant travel restrictions and significantly affected the energy demands of global and domestic aviation (IEA, 2020c). The International Air Transport Association expects flight capacity utilisation to be, on average, 65% below the 2019 level in the second quarter (Q2) of 2020, 40% below in Q3 2020, and 10% below in Q4 2020 (Pearce, 2020). Data show that the global flight numbers were down by 70% at the start of April 2020 relative to those in the previous year. The consumption of kerosene in the whole of 2020 was expected fall by 26% (IEA, 2020c).

4.1 Energy Intensity and Emission Factors: Aviation

The energy intensity for aviation freight transport was assumed to be around 30 MJ/tkm in 2019 (Pagenkopf et al., 2019), decreasing by 1% per year until 2025. By 2050, the energy intensity for freight planes is estimated to be 25 MJ/tkm, 17% below today’s value. The energy intensity for aviation passenger transport will decrease from 5.8 to 4.2 MJ/pkm between 2020 and 2050. Technical improvements in the aerodynamics, materials, weight, and turbine efficiency for both freight and passenger planes are assumed. The volume of freight (in tkm) and the passenger–kilometres (pkm) are assumed to decrease by 30% globally between 2019 and 2050, an average reduction of around 1% per year.

The emissions factor for kerosene is calculated to be 73.3 g of CO₂ per MJ (gCO₂/MJ) (Jurich, 2016). The specific CO₂ emissions for aviation freight will decrease from 2.3 to 2.0 kgCO₂/tkm in 2025. By 2035, the specific emissions will more than halve, to 0.8 kgCO₂/tkm, and will be completely decarbonised by 2050.

In passenger aviation transport, specific CO₂ emissions will decrease from 425 gCO₂/pkm in 2019 to 350 gCO₂/pkm in 2025, will halve by 2035, and will be CO₂-free by 2050—analogous to freight transport. Both reduction trajectories will be achieved by the gradual replacement of fossil kerosene with organic kerosene, and after 2040, with synthetic kerosene that is generated with renewable electricity. Because aviation is a truly global sub-sector, the assumptions for aviation are the same for all regions.

5 Shipping

Of the global energy demand for shipping, 90% is for freight transport, and only around 10% is for passenger transport (mainly cruise ships and ferries). In 2018, the worldwide cruise ship passenger capacity was 537,000 passengers on 314 ships, and 26 million passengers were transported in 2018 (Cruise Market Watch, 2020). In comparison, around 53,000 merchant ships were registered globally in January 2019: approximately 17,000 cargo ships, 11,500 bulk cargo carriers, 7500 oil tankers, 5700 chemical tankers, and 5150 container ships. The remaining ships included roll-on, roll-off passenger and freight transport ships and liquefied natural gas (LNG) tankers (Statista, 2021).

5.1 Energy Intensity and Emission Factors: Shipping

The energy intensity for freight transport by ship was assumed to be 0.19 MJ/tkm in 2019 (Pagenkopf et al., 2019) and will decrease only slightly to 0.18 MJ/tkm in 2030 and 0.17 MJ/tkm in 2050. An equivalent trajectory is assumed for shipping passengers, from 0.056 to 0.054 MJ/pkm in 2030 and to 0.052 MJ/pkm in 2050. Shipping is already by far the most efficient transport mode. However, further technical improvements, especially in ship engines, are required. The volume of freight (in tkm) is assumed to increase by around 0.5% per year globally until 2050, whereas passenger transport volumes will remain at today’s levels over the entire modelling period.

The emissions factor for heavy fuel oil is calculated to be 81.3 gCO₂/MJ (Jurich, 2016). The specific CO₂ emissions for shipping freight will decrease from 15 gCO₂/tkm to 10 kgCO₂/tkm by 2030. By 2040, freight shipping will be completely decarbonised. The specific CO₂ emissions for passenger shipping transport will decrease from 5 gCO₂/pkm in 2019 to 3 gCO₂/pkm in 2030, and analogous to freight shipping, passenger transport by ship will be carbon neutral by 2040. Both reduction trajectories will be achieved by the gradual replacement of fossil fuels with biofuels and, after 2040, with renewables-generated synthetic fuels.

6 Land Transport

Although the most-efficient transport mode for long distances over land is railways, vehicular road transport for passenger and freight transport dominates by an order of magnitude.

Road transport is the single largest consumer of oil. In 2018, 64% of the global demand was attributed to road transport vehicles, for both freight and passenger transport. The pandemic in 2020 led to a unique development: as a consequence of global lockdown measures, mobility (57% of the global oil demand) declined at an unprecedented rate. The road transport in regions under lockdown decreased by 50–75%, with the global average road transport activity falling to almost 50% of the 2019 level by the end of March 2020 (IEA, 2020c).

Whereas electric-powered planes or ships are still in the early stages of development, there are no technical barriers to the phasing-out of ICEs or the transition to efficient electric vehicles (EVs) for passenger transport and to hydrogen or synthetic biofuels for heavy-duty vehicles. The vehicle technology required is widely available and market shares are rising sharply. In 2012, only 110,000 battery electric vehicles (BEVs) had been sold worldwide. Since then, sales have almost doubled every year, reaching 1.18 million BEVs in 2016, 3.27 million in 2018, and 4.79 million in 2019 (IEA, 2020d).

6.1 Energy Intensity and Emission Factors: Land Transport

Individual Transport

Passenger transport by road makes up by far the commonest and most important form of travel. There are numerous technical options to ‘move people with vehicles’—bicycles, motorcycles, tricycles, city cars, four-wheel drive SUVs—and each vehicle has very different energy intensity per kilometre. Although this research project aims for high-technology resolution, simplification is required. First and foremost, the data for all existing vehicles for each of the regions and for the global level are neither available nor practical to use. Figure 8.3 shows the energy intensities for the main vehicle types, which form the basis for the energy scenario calculations (Table 8.3).

Table 8.3 Energy intensities for individual transport modes—road transport

Public Transport

There are a wide variety of public transport vehicles, ranging from rickshaws to taxis and from minibuses to long-distance trains. The occupation rates for those vehicles are key to calculating the energy intensity per passenger kilometre. For example, a diesel-powered city bus that transports 75 passengers requires, on average, about 27.5 litres per 100 kilometres. If the bus is operating at full capacity during peak hour, the energy demand per passenger is as low as 400 ml per kilometre—lower than almost all other fossil-fuel-based road transport vehicles. However, if the occupancy drops to 10% (e.g. for a night bus), the energy intensity increases to 3.7 litres, equal to that of a small energy-efficient car. Occupation rates vary significantly and depend upon the time of day, day of the week, and season. There are also significant regional differences, even within a single country, and even more so across larger regions, such as OECD Europe, which is composed of over 30 countries from Iceland to Turkey.

Again, the parameters shown in Table 8.4 are simplified averages and are further condensed for the scenario calculations. Although high technical resolution is possible for the scenario model, it would imply an accuracy that does not exist, because the statistical data required for this are not available on either regional or global levels.

Table 8.4 Energy intensities for public transport—road and rail transport

Freight Transport

The energy intensity data for freight transport are not as diverse as those for passenger transport, because the transport vehicle types are more standardised and the fuel demand is well known. However, the utilisation rate of the load capacity varies significantly, and consistent data are not available for the regional and global levels calculated. Therefore, the assumed utilisation rate has a huge influence on the calculated energy intensity per tonne–kilometre. The average energy intensities per tonne–kilometres used in the scenarios are shown in Table 8.5 and are largely consistent with other sources in the scientific literature. The assumed energy intensities for electric and fuel cell/hydrogen freight vehicles are only estimates, because this technology is still in the demonstration phase. Therefore, none of the scenarios calculated factor in large shares of electric freight transport vehicles before 2035.

Table 8.5 Energy intensities for freight transport—road and rail transport

7 Global Transport Demand Projections

A variety of actions will be required for the transport sector to conform to the limit global warming to 1.5 °C. The set of actions described can be clustered into technical and operational measures (e.g. increases in energy efficiency, electrification of drive trains), behavioural measures (e.g. shifts to less-carbon-intensive transport carriers and an overall reduction in transport activity), and accompanying policy measures (e.g. taxation, regulations, urban planning, and the promotion of less-harmful transport modes).

The key requirements for achieving a reduction of the transport energy demand in the alternative scenarios follow a three-step approach:

• Reduction of transport kilometres for passengers and freight with behavioural changes, urban planning, increased local production, and transport logistics

• Shift to more-energy-efficient transport modes, e.g. from road to rail for passengers and from aviation to navigation for freight

• Innovation—replacing inefficient combustion engines with efficient electric drives

7.1 Projection of the Transport Service Demand

The first step in the projection of the global transport demand is calculating the actual service demand in passenger–kilometres travelled and tonnes of goods–kilometres transported. This is essential before the development of the chosen transport mode (road, rail, or ship) is projected.

Under the three scenarios, the global transport demand is the sum of the ten world regions plus bunker fuels. Bunker fuels are all the fuels required for interregional aviation and shipping transport and are therefore not part of any regional demand. The assumed development is based on the population and economic developments in $GDP provided in Table 8.2. The 1.5 °C scenario assumes a reduction in the global pkm of 30% relative to 2020, whereas the global freight demand will increase by 30% based on the assumption of a growing GDP (Tables 8.6 and 8.7).

Table 8.6 Global: development of behavioural changes in passenger travel (based on pkm) by transport mode

Table 8.7 Global: development of changes in freight logistics (based on tkm) by transport mode

7.2 Mode-Specific Technology Efficiency and Improvements Over Time

For passenger transport, trains and buses are much more energy efficient per pkm than passenger cars or airplanes. This situation does not change fundamentally if only electric drive trains are compared (Fig. 8.5). Railways and (especially) ships are clearly more energy efficient than trucks in transporting freight (Fig. 8.6). The efficiency data are based on both literature-reported and on transport-operator documents in this study and on Pagenkopf et al. (2019). Efficiency levels, in terms of pkm or tkm, depend to a large extent on the underlying utilisation of the capacity of the vehicles, which varies across world regions. The numbers presented are average values and differences are evaluated at the regional level.

Fig. 8.5

Energy intensities for urban and interurban passenger transport modes in 2019 (world averages). (Source: DLR/ IFFT 2019, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Fahrzeugkonzepte, Fahrzeugsysteme und Technologiebewertung, Stuttgart, Data from Johannes Pagenkopf et al. 2019)

Fig. 8.6

Energy intensities for freight transport modes in 2019 (world averages). (Source: DLR IFFT 2019)

7.3 Powertrain Electrification for Road Transport

Increasing the market penetration of highly efficient (battery and fuel cell) electric vehicles, coupled with the generation of clean electricity, is a powerful lever for decarbonisation and probably the most effective means of moving toward a decarbonised transport system.

All-electric vehicles have the highest efficiency levels of all the drivetrain options. Today, only a few countries have significant proportions of electric vehicles in their fleets. The total number of electric vehicles, particularly for road transport, is insignificant, but because road transport is by far the largest CO₂ emitter of overall transport, it offers a very powerful lever for decarbonisation.

In terms of drivetrain electrification, we cluster the world regions into three groups, according to the diffusion theory (Rogers, 2003):

• Innovators: OECD North America (excluding Mexico), OECD Europe, OECD Pacific, and China

• Moderate: Mexico, Non-OECD Asia, India, Eurasia, and Latin America

• Late adopters: Africa and the Middle East

Although this clustering is rough, it sufficiently mirrors the basic tendencies implemented in our scenarios. The regions differ in the speed with which novel technologies, especially electric drivetrains, will penetrate the market.

In addition to powertrain electrification, there are other potential improvements in energy efficiency, and their implementation will steadily improve these energy intensities over time. Regardless of the type of power train and the fuel used, efficiency improvements on MJ/pkm or MJ/tkm will result from (for example):

• Reductions in powertrain losses through more-efficient motors, gears, power electronics, etc.

• Reductions in aerodynamic drag

• Reductions in vehicle mass through light-weighting

• Use of smaller vehicles

• Operational improvements (e.g. automatic train operation, load factor improvements)

7.4 Projection of Global and Regional Modal Shifts

In 2019, road transport predominated over all other transport modes, with almost 95% of all pkm travelled by some form of road vehicle throughout the world. Based on the kilometres travelled, just over 3.5% of journeys were by train and about 2% by plane. Although ship transport is one of the most important means of transport for freight, marine-based passenger transport makes only a very minor contribution at the global level. To implement the 1.5 °C scenario, passenger transport must shift from road to rail. Efficient light rail in cities, commuter trains for short to medium distances, and high-speed trains that offer convenient services are therefore alternatives to individual car journeys.

In the context of urban transport, the use of road transport by cars will be significantly reduced and will move towards public transport by other road vehicles, such as buses or trains. The role of electric bikes and walking must also increase under the 1.5 °C scenario. However, road transport will remain dominant, at well over 80% (Fig. 8.7), until 2050. Therefore, the modal shifts within road transport systems, such as from individual cars to public transport, cycling, or mobility services (such as car sharing), are extremely important.

Fig. 8.7

World passenger transport by mode under the 1.5 °C scenario—shares based on passenger–kilometres

Maritime shipping is the backbone of world trade. It is estimated that some 80% of all goods are carried by sea. In terms of value, the global maritime container trade is estimated to account for around 60% of all seaborne trade, which was valued at around $US14 trillion in 2019 (Placek, 2021).

In terms of tonnage, aviation plays a comparatively minor role globally. In terms of tonne–kilometres, road transport dominates globally. Every second tonne is transported by road and only 10% by rail (Fig. 8.8). However, the different transport modes cannot be separated because goods delivered by ship are further distributed by road and rail. Therefore, a direct modular shift is often not possible. Ship transport cannot be replaced by trains in most cases, and vice versa. There is competition between road and rail, and modular shifts in favour of rail freight transport will occur. The 1.5 °C pathway assumes that about one-third of the freight transported by trucks will be shifted to rail transport systems.

Fig. 8.8

World freight transport by mode under the 1.5 °C scenario—shares based on tonne–kilometres

Compared with passenger transport, freight transport is far more diverse, and regional differences are significant. In Eurasia, a region very similar to the former USSR, rail transport shoulders about half of all freight transport in terms of tonnage. This reflects the significance of the Trans-Siberian Railway line connecting the European part of Russia with Mongolia (Ulan Bator) and China (Beijing).

In Non-OECD Asia, water transport is by far the most important transport mode, which reflects the situations in the island states Indonesia and the Philippines, as well as the vast coastlines of Southeast Asian countries.

7.5 Calculation of Transport Energy Demand

The calculation of the transport demand is based on a two-step approach, with all the parameters described in the previous subsections (Sects. 8.7.1, 8.7.2, 8.7.3, and 8.7.4):

• 1. Calibration of the model with statistics from the past 10–15 years (Table 8.8)

• 2. Projection of the transport demand based on the changing demand in kilometres and energy intensities by transport mode (Table 8.9)

Table 8.8 Calibration for transport demand calculations

Table 8.9 Projection of transport demand based on changing demand in kilometres

To calibrate the model, the transport demand of the past decade was recalculated on the basis of the available energy statistics. The International Energy Agencies’ (IEA) Advanced World Energy Balances provided the total final energy demands by transport mode—aviation, navigation, rail, and road—by country, region, or globally. However, there is no further specification of the energy usage within each of the transport modes. A further division into passenger and freight transport is therefore calculated using percentage shares. These proportions are determined with a literature research and from the average energy intensity for each of the transport modes for passenger and freight vehicles.

The annual energy demand divided by the average energy intensity by mode generates the annual transport demand in passenger–kilometres per year [pkm/yr] and tonne–kilometres per year [tkm/yr]. Those results are then compared with the OECD transport statistics, which provide both parameters, pkm/yr and tkm/yr. Calibrating the model with historical data ensures that the basis of the scenario projection for the coming years and decades has been correctly mapped and that the changes can be calculated more realistically.

For the forward projection of the transport demand, the calculation method is reversed. The transport demand for each transport mode is calculated on the basis of the annual change (as a percentage). The calculated total annual passenger–kilometres and tonne–kilometres are the inputs for the energy demand calculations.

7.6 Transport Service: Energy Supply Calculation

Like the transport demand calculation, calculation of the transport energy ‘supply’ begins with the calibration of the model based on historical data, as part of a two-step approach:

• 1. Calibration of the model with statistics from the past 10–15 years (Table 8.8)

• 2. Projection of the transport supply based on the transport mode and vehicle-specific parameters (Table 8.9)

As well as the final energy demand for each transport mode, the IEA Advanced World Energy Balances also provide the energy demand by source—soil, gas, biofuels, and electricity. To calculate the exact energy requirement for each transport mode with the corresponding transport requirement (in km), assuming different vehicle technologies, the status quo must be determined. For this purpose, the respective transport energy requirement for each transport mode and fuel type is calculated based on the current vehicle technology market shares and the technology-specific energy intensities per kilometre. The results provide a technology-specific illustration of each sector. Table 8.10 presents an overview of the calculation process for the calibration of the model.

Table 8.10 Calibration for transport demand calculations

Future energy demands based on the projected pkm and tkm are calculated from market shares and technology-specific energy intensities. In the first step, the overall transport energy demand, e.g. in passenger–kilometres, is distributed to each transport mode. A mode shift from road to rail can be assumed, and the sector-specific demand is further distributed to specific vehicle types—again by the assumption of market shares (Table 8.11).

Table 8.11 Projection of transport supply based on transport mode and vehicle-specific parameters

8 Transport: Energy Demand and Supply

In the previous sections, the global energy demand was calculated based on the documented assumptions. However, the transport sector is among the most diverse sectors of all the end-use sectors analysed. A whole range of logistical, technical, and political measures are required to reduce the overall energy demand while maintaining freedom of movement and mobility. The transport sector is closely related to the buildings sector, because urban planning and urban designs go hand in hand with the transport demand—in terms of the distances travelled or goods transported—and the most suitable technical solutions to provide those services. Furthermore, the carbon intensity of the electricity consumed for transport is directly related to the renewable energy share in power generation.

8.1 Shipping and Aviation: Dominated by Combustion Engines for Decades to Come

Navigation will probably remain predominantly powered by ICEs in the next few decades. Therefore, we did not model the electrification of freight vessels. However, pilot projects using diesel hybrids, batteries, and fuel cells are in preparation (DNV, 2015). We assumed the same increase in the share of bio- and synthetic fuels over time as in the road and rail sectors.

In aviation, energy efficiency can be improved by measures such as winglets, advanced composite-based lightweight structures, powertrain hybridisation, and enhanced air traffic management systems (Vyas et al., 2013; Madavan, 2016). We project a 1% annual increase in efficiency on a per pkm basis and a 1% annual increase in efficiency on a per tkm basis.

Aviation will probably remain predominantly powered by liquid fossil fuels (kerosene and bio- and synthetic fuel derivatives) in the medium to long term because of the limitations in electrical energy storage. We project a moderate increase in domestic pkm flown in electric aircraft starting in 2030, with larger shares in OECD Europe, because the flight distances are shorter than, for example, in the USA or Australia. Norway has announced plans to perform all short-haul flights electrically by 2040 (Agence France-Presse, 2018).

However, no real electrification breakthrough in aviation is foreseeable unless the attainable energy densities of batteries increase to 800–1000 Wh/kg, which will require fast-charging post-lithium battery chemistries.

That said, it is estimated that over 200 electric aircraft programs are in progress around the world (Downing, 2019). While small electric planes (up to car size) are in the demonstration phase, long-haul flights with electric planes are currently unviable with contemporary battery technology.

From the perspective of technological innovation, electric aviation is an important field of engineering, and investment in this sector must occur now to achieve results in the mid-2030s. Domestic aviation—mainly short-distance flights of up to around 700 km—makes up about 45% of all global flights (Downing, 2019). The electrification of passenger planes for these distances will most likely start in this market segment.

However, this research has focused on the rapid reduction of CO₂ in the global transport sector, and realistically, electric aviation will not play a role in the reduction of large amounts of carbon before 2040. Nevertheless, the development of this technology is important in the long term (Tables 8.12 and 8.13).

Table 8.12 Aviation—energy demand and supply

Table 8.13 Shipping—energy demand and supply

A key target for the global transport sector is the introduction of incentives for people to drive smaller cars and use new, more-efficient vehicle concepts. It is also vital to shift transport use to efficient modes, such as rail, light rail, and buses, especially in large expanding metropolitan areas. Furthermore, the 1.5 °C scenario cannot be implemented without behavioural changes. It is not enough to simply exchange vehicle technologies, but the transport demand must be reduced in terms of the kilometres travelled and by an increase in ‘non-energy’ travel modes, such as cycling and walking.

With population increases, GDP growth, and higher living standards, the energy demand of the transport sector is expected to increase without technical and behavioural changes. Under the 1.5 °C scenario, efficiency measures, modal shifts, and the behavioural changes mentioned above will reverse the trend in permanent growth (Table 8.14).

Table 8.14 Road transport—energy demand and supply

The proportion of BEVs among all passenger cars and light commercial vehicles in use is projected to be between 8% and 15% by 2030. This will require a massive build-up of battery production capacity in the coming years. New car sales will already be dominated by battery electric passenger vehicles in 2030 under the 1.5 °C scenario. However, with an assumed average lifetime of 15 years for ICE passenger cars, the existing car fleet will still predominantly use ICEs.

Under the assumption that new ICE passenger cars and buses will not be produced after 2030, BEVs will dominate the passenger vehicle fleet of 2050 under the 1.5 °C scenario. OECD countries and China are assumed to lead the development of BEVs and therefore to have the highest shares, whereas Africa and Latin America are expected to have the lowest BEV shares. Fuel cell-powered passenger vehicles are projected to play a significantly smaller role than BEVs and will only be used for larger vehicles, such as SUVs and buses (Fig. 8.9).

Fig. 8.9

Proportions of powertrains in (fleet) passenger cars and buses by region in 2030 (left) and 2050 (right)

The shares of electric trains and diesel-powered locomotives vary significantly by region (Fig. 8.10). Under the 1.5 °C scenario, all diesel locomotives will be phased out in all regions by 2050. It is assumed that biofuels and synthetic fuels, as well as hydrogen, will play a minor role and that around 90% of all trains—for both passenger and freight transport—will use electric locomotives. The highest utilisation rates of diesel locomotives in 2019 were in the Middle East (98%) and OECD North America (95%), whereas the majority of trains in Europe were electrified.

Fig. 8.10

Proportions of electrified passenger and freight rail in 2019 (left) and 2030 (right)—1.5 °C scenario

Highly efficient drives—with a focus on electric mobility—supplied with renewables will result in large efficiency gains. By 2030, electricity will provide 5% of the transport sector’s total energy demand under the 1.5 °C scenario, whereas in 2050, the share will be 37%. The majority of electricity consumed in the transport sector will be for land transport—road and rail. Hydrogen and other synthetic fuels generated with renewable electricity will be complementary options to further increase the share of renewable energy in the transport sector, especially for aviation and shipping. In 2050, up to 7700 PJ/yr of hydrogen will be required under the 1.5 °C transport pathway (Table 8.15).

Table 8.15 Transport sector—final energy demand and supply

The high reliance on renewable electricity, used either directly in BEVs or to produce synthetic fuels, will require close cooperation between the transport sector and the power sector, not only in terms of the decarbonisation of the power sector itself but also in terms of the increasing electricity demand. In our analysis, the electrification of the transport sector—especially the replacement of ICEs with BEVs—will roughly double the electricity demand of an industrialised country if no further efficiency measures are taken in other sectors, such as the residential and service sectors.

9 Transport: Energy-Related CO₂ Emissions

The overall energy-related CO₂ emissions are directly linked to the power sector, as stated above. Under the assumption that electricity generation is fully decarbonised by 2050 (see Power sector trajectory, Chap. 12), Tables 8.16, 8.17, and 8.18 show the carbon intensities and total CO₂ emissions for aviation, shipping, and road transport, respectively, under the 1.5 °C scenario. Both the aviation and shipping values include domestic and international transport. Emissions intensity is an important key performance indicator (KPI) for the finance industry, for both Climate Change Stress Tests (see Chap. 2) and the evaluation of investment portfolios that include transport industry assets. For the automobile industry, carbon intensities (in gCO₂/km) are an important KPI and have already been used for mandatory efficiency standards, such as those in the European Community (EU, 2021).

Table 8.16 Aviation—energy-related CO₂ emissions

Table 8.17 Shipping—energy-related CO₂ emissions

Table 8.18 Road transport—energy-related CO₂ emissions

10 Transport Equipment

According to the OECD definition, ‘Transport equipment (assets) consists of equipment for moving people and objects, other than any such equipment acquired by households for final consumption’(OECD SP, 2021). According to the 2020 edition of the International Energy Agency’s World Energy Balances Database Documentation (IEA, 2020b), the energy demand for ‘transport equipment’ includes industries under Divisions 29 and 30 of the International Standard Industrial Classification of All Economic (ISIC) Rev. 4 (ISIC, 2008). Table 8.19 shows the industries that are classified under ‘transport equipment’. Based on this classification, the economic values for all sub-sectors were estimated.

Table 8.19 Industries classified under ‘transport equipment’

Table 8.20 shows the estimated economic breakdown of all sub-sectors of the transport equipment industries. The literature provides various different definitions and economic values for the global automotive industries and for the aviation and shipping industries. However, some of the much higher values (e.g. for the car industry) include the value added for sales and other related services.

Table 8.20 Global transport equipment—global GDP shares

Table 8.21 shows the calculated global values for all sub-sectors of the transport equipment industry. The purpose of this analysis is to estimate the energy demand for the manufacture of vehicles, ships, and planes, because the exact statistics for the energy demands of those industries are not available on the global level. To maintain consistency in our methodology, the energy demand for transport equipment provided by the IEA database was used. However, further research is required to determine the industries’ exact energy demands.

Table 8.21 Global transport equipment—estimated GDP values by sub-sector and projection until 2050

In the absence of more-detailed information about the energy intensity of the industries analysed, the same values have been assumed for the manufacture of cars, locomotives, ships, and planes. Consistent with this assumption, the same efficiency progress ratio of 0.5% per year has been assumed over the entire scenario period until 2050. More research is required to estimate the energy demand and supply for these industries in the future (Table 8.22).

Table 8.22 Global transport equipment—estimated energy intensities by sub-sector and projection until 2050

Based on IEA statistics, the share of electricity in the total energy demand has been calculated as 47%, whereas the remaining 53% is required for heat. The breakdown by temperature level has been estimated as 72% for low-temperature heat (<100 °C) and 10% for medium-temperature heat (100–500 °C), and the remaining demand is for process heat (5% for 500–1000 °C; 13% for >1000 °C). More-detailed assessments of the process heat requirements were not available for this analysis (Table 8.23).

Table 8.23 Global transport equipment—calculated energy demand by sub-sector

Finally, the calculated energy-related CO₂ emissions for transport equipment are shown in Table 8.24. The emissions are based on the 1.5 °C pathways for electricity and (process) heat generation (see Chap. 12). The values shown here were used for the Scope 1, 2, and 3 analyses reported in Chap. 12 (Results: industry pathways) and Chap. 13 (Scope 3: industry emissions and future pathways).

Table 8.24 Global transport equipment—calculated energy-related CO₂ emissions