6. Transport Transition Concepts

The 5.0 °C Scenario follows the IEA Current Policies Scenario (IEA 2017a) until 2040, with extrapolation to 2050. We model only minor electrification over all transport modes (see Fig. 6.5), with passenger cars and buses making relevant gains in electric vehicle (EV) shares. For example, we project a share of 30% for battery electric vehicles (BEV) in China by 2050 due to foreseeable legislation and technological advancements in that country (Cui and Xiao 2018), whereas for the world car fleet, the share is projected to increase to only around 10%. The growth in the share of the commercial road vehicle fleet and of the fleet of two- and three-wheel vehicles held of electric powertrains will be small, as will be the increase in further rail electrification. Aviation and navigation (shipping) will remain fully dependent on conventional kerosene and diesel, respectively.

Based on the low market share of BEV observed today (2018), minimal progress in electrification until 2020 is assumed in the 2.0 °C Scenario. Moving towards 2030, the innovator regions will experience strong electrification, encouraged by purchase incentives, EV credit systems, and tightened CO₂ fleet emission targets. Passenger cars and light commercial vehicles are projected to achieve shares of BEVs in the regional stocks between 21% and 30%, whereas heavy commercial vehicles and buses will attain even higher EV fleet shares of between 28% and 52% by 2030. This will require a massive build-up of battery production capacity in the coming years. Electric city buses and some trolley trucks will make a significant contribution to this development. Two- and three-wheel vehicles will be nearly completely electrified (batteries and fuel cells) in a couple of regions. OECD Pacific will head the fuel-cell-electric vehicle (FCEV) market introduction, which will account for up to 6% of passenger cars and light commercial vehicles by 2030, with Japan and South Korea the main market drivers. Higher shares of FCEV in innovator regions are more likely in the bus and heavy truck sector, which reach up to 10% in 2030. In 2050 in the innovative regions, only a minor proportion of vehicles will have ICE (up to 9%). Passenger cars and light commercial vehicles will predominantly be electrified, with a BEV share of around 80%. FCEV will also gain a significant share of 17% in OECD Pacific and OECD North America.

Looking ahead to 2050, 60–70% of buses and heavy trucks will probably be (battery) electric, whereas FCEV will increase their market share to around 37%. The proportion of buses and heavy trucks that will be BEV in 2050 will be around 60–70%. Two- and three-wheel vehicles will be nearly fully electrified in all regions (80–100%).

In the moderate regions, the BEV share of road transport vehicles is set in a range of 1–15%. Except for Latin America, the moderate regions will have an ICE share of 83% or less for passenger cars. For example, India is progressing with its current electrification strategy and up to 14% of its passenger cars will be battery-powered by 2030. It is likely that ICE will dominate buses and trucks in the moderate regions in 2030. Fuel-cell cars now have small shares of 1–2%. Non-OECD Asia is positively influenced by its innovator neighbour region, OECD Pacific. In the 2.0 °C Scenario, moderate regions will reach BEV shares of up to 67% for passenger cars and light commercial vehicles and between 54% and 65% for buses and heavy trucks by 2050. Compared with the innovator regions, the moderate regions will not experience a significant uptake of FCEVs. Africa and the Middle East will remain mostly dependent on ICE in 2050, with shares of around 90%. Only slow electrification will occur in Africa, with small and cheap BEVs (Fig. 6.6).

As an example of how different the electrification speeds will be across the world regions, Fig. 6.7 shows the uptake of electric and fuel-cell drivetrains in buses and two- and three-wheel vehicles, region by region, in terms of pkm. In 2015, a substantial proportion (15%) of China’s buses were already electrified. OECD Pacific and OECD Europe will follow, with substantial electrification after 2020, as will India, Non-OECD Asia, and Eurasia after 2030. The remaining regions will electrify their fleets predominantly after 2035. Fuel-cell drivetrains will not begin to penetrate the market to a significant extent until 2025. We project a fleet that is 40–70% electric (battery and trolley) and 10–30% fuel-cell electric by 2050 in the 2.0 °C Scenario.

Figure 6.8 plots the projected electrification of passenger and freight rail in terms of final energy demand. Substantial electric passenger rail was present in OECD Europe, OECD Pacific, and China in 2015, and substantial electric freight transport in OECD Europe and Eurasia. In most other world regions, freight transport by rail predominantly relied on diesel locomotives.

In most world regions, nearly all rail traffic is projected to be electric after 2040 in the 2.0 °C Scenario. Total diesel consumption in rail operations is projected to increase slowly until 2030, mainly because railway vehicles have long lifespans, and once diesel cars are put into operation, they are not replaced overnight. Furthermore, line electrification usually requires several years of planning and construction.

Aviation will probably remain predominantly powered by liquid fossil fuels (kerosene and bio- and synfuel derivatives) in the medium to long term because of limitations in electrical energy storage. We project a moderate increase in domestic pkm flown in electric aircrafts starting in 2030, with larger shares in OECD Europe because the flight distances are shorter than, for example, in the USA (Fig. 6.9). 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 would require fast-charging capable post-lithium battery chemistries.

In the 1.5 °C Scenario, an earlier and more rapid ramp-up of electric powertrain penetration is required than in the 2.0 °C Scenario and the innovative regions will be at the forefront. The moderate regions will also need to electrify more rapidly than in the 2.0 °C Scenario, but will end up with only a minimally higher share by 2050. In the passenger car sector in particular, plug-in hybrid electric vehicles (PHEVs) will ensure a sharp reduction in conventional combustion engine vehicles between 2030 and 2050. In the late adopter regions, there is no difference between the 2.0 °C and 1.5 °C Scenarios. The phasing out of internal combustion engine (ICE) vehicles will occur more quickly under the 1.5 °C Scenario than under the 2.0 °C Scenario (Fig. 6.10).

As of 2017, 99% of the passenger cars produced worldwide were estimated to be equipped with an ICE: the majority of them gasoline or diesel (95%), 3.4% hybrid electric vehicles (HEV), and 0.7% PHEV (BCG 2017). Only about 0.9% of the cars sold were pure battery electric vehicles (BEV). There are several options for energy efficiency improvements. The fuel consumption reduction potential of petrol engines as a result of engine improvements and hybridization is around 25–30%, and it is around 15–20% for diesel engines (van Basshuysen and Schäfer 2015). Maximum efficiencies of 38–40% can be reached by ICE (Schäfer 2016), whereas electric drivetrains have efficiencies of 80–85% (including [re]charging losses). Besides the reduction in engine losses, both lightweight construction and reductions in rolling resistance will result in additional fuel savings.

Hybrid systems increase the complexity of powertrains, resulting in higher masses and higher costs, but they offer additional fuel-saving potentials. Energy can thus be recovered by recuperation during braking in hybridized and all-electric vehicles. In BEV and FCEV, advanced battery technologies can reduce the overall vehicle mass. However, post-lithium technologies, such as lithium–sulfur and solid-state batteries with increased energy densities and lower systems masses compared with today’s Li-ion battery technologies, will probably not enter the transport sector before 2030 (Schmuch et al. 2018).

In total, we project a 1% increase in annual efficiency on a per passenger/km basis (the same for all drivetrains) for the 5.0 °C and 2.0 °C Scenarios. The efficiency improvements for 2050 in the 2.0 °C Scenario will be achieved in 2040 under the 1.5 °C Scenario (Fig. 6.13).

Like passenger cars, trucks are currently driven almost exclusively by conventional ICE. With a market share of 84% of diesel-fuelled vehicles in 2015 (IEA 2017c), the global fleet of trucks was predominantly operating on diesel (IEA 2017b). In some regions, such as the Middle East, trucks are also powered by gasoline to a considerable degree. Electric drivetrains will enter the truck sector gradually in coming years because of changes in exhaust emissions legislation and because the higher efficiency of electric drivetrains compared with ICE will offer economic advantages to road carriers (Fig. 6.14). Compared with diesel-powered trucks, fuel-cell electric drivetrains in trucks can substantially reduce the energy intensity per tkm, and allow higher operating ranges than battery-powered trucks. To achieve rapid improvements in energy efficiency in the truck sector, the hybridization of diesel powertrains, especially those operating in stop-and-go intensive urban environments, is promising (Burke and Hengbing 2017; Lischke 2017). However, after 2030, the hybrid diesel powertrain will be seen merely as a transitional technology before the advent of fully electric powertrains (overhead catenary, battery electric, and fuel-cell electric). Therefore, the development of battery recharging and hydrogen refuelling infrastructures will require massive investments in coming years. In the commercial sector, it is likely that many electrical charging stations will be set up on the private grounds of logistics operators. The market growth of BEV in the truck sector will require considerable public spending on the installation of overhead catenary lines along major highways for trolley trucks (hybridized with diesel, fuel cells, or batteries). The first pilot lanes are being developed in Germany, Sweden, and California (USA) (Siemens 2017).

State-of-the-art city buses operate on ICE (diesel or gas) or are trolley buses (all-electric or hybridized with an additional battery or diesel motor). Diesel hybrids have entered the city bus market and constitute a large proportion of the bus fleets in a range of cities today. The short distances between stations, small operating radii, and moderate daily mileages make the use of batteries in city buses a viable option, complemented by fuel cells for routes with higher ranges or difficult terrains. Battery electric buses are between the prototype/experimental stage and a mature technology. In China, battery electric buses are already an integral part of public bus transport systems, and the city of Shenzen has had a 100% electric bus fleet since 2016 (over 16,000 battery electric buses) (Sisson 2018). Fuel-cell electric buses still lag behind battery electric buses in terms of numbers, but are increasing. In 2017, about 80 fuel-cell electric buses were in operation in Europe (Element Energy Ltd. 2018) and 26 in the USA (Eudy and Post 2017). Full battery operation is more difficult to achieve in regional and long-distance buses and coaches, so the uptake of full battery electric and also fuel-cell powertrains will be slower than in city buses. Diesel-powered buses will remain in the market longer, complemented by diesel hybrid powertrains. Ultimately, fuel-cell-powered inter-urban coaches will probably be more common than fuel-cell-powered city buses. In our model, we divided the regions into innovators (i.e., China and OECD countries) and all the other regions lagging behind the innovators. We also identified a clear trend towards electrification.

We project a 0.5% (diesel, diesel-hybrid and natural gas) to 0.8% (electric and fuel cell hydrogen electric) increase in efficiency on a per passenger per km basis in all three scenarios (Fig. 6.15).

Two-wheel vehicles are probably the most important component of everyday traffic in large parts of Asia and Africa. The drivetrain efficiencies of e-scooters are reported to be 1.2–3 kWh/100 vehicle–km. China is by far the biggest market for electric scooters in the world, with more than 200 million electric scooters on the road by 2015, that translates to an electric share of about 70%.

Three-wheel vehicles (also country-specifically called ‘rickshaws’ or ‘tuk-tuks’) have at least two, and usually three or more seats, and are often overloaded in daily traffic. India alone is reported to have 2.5 million rickshaws on the road, each travelling 70–150 km/day (Abu Mallouh et al. 2010). Most three-wheel vehicles are fuelled by gasoline and some by liquid petroleum gas (LPG), although some communities incentivize the conversion of two-stroke engines to battery electric three-wheel vehicles. Electric tuk-tuks are increasingly emerging in South-East Asia, together with battery swap stations and solar-powered rickshaws (Moran 2018; Reddy et al. 2017). Thailand has announced that it plans to convert all existing two-stroke-powered tuk-tuks to battery electric powertrains within 5 years (Coconuts Bangkok 2017). In India, too, plans are repeatedly announced to electrify all new two- and three-wheel vehicles within the next two decades (Ghoshal 2017).

The efficiency of battery electric drivetrains is much better than that of conventional two-stroke engines in two- and three-wheel vehicles (Fig. 6.16). We project a 0.5% annual increase in efficiency on a per pkm basis (the same for all drivetrains) in all three scenarios.

No other transport mode is more suited to operate electrically than railways. Urban rail systems, for instance, are invariably electric. Electric trains consume about 60–70% less energy than diesel trains when their final energy use is compared (on catenary and tank levels, respectively). According to the International Railway Association, about 32% of the worldwide rail network was electrified in 2015 (UIC 2017). However, in terms of transport performance (pkm or tkm), the ratio of electric to diesel is higher because electrified rail lines usually experience more traffic than non-electrified lines. The electrification of rail lines with overhead catenaries has been the state-of-the-art technology for decades and new lines are almost exclusively equipped with overhead power lines right from the start.

However, line electrification, especially of existing lines, is often difficult to achieve due to unsettled and complex right-of-way issues, narrow tunnel diameters, or simply because line electrification is not economically viable due to low line utilization. The use of on-board batteries for mixed electrified/non-electrified lines and shunting operations and the use of fuel-cell hybrid powertrains for longer lines with little or no electrification whatsoever could be feasible fully electric alternatives to diesel power or full-line electrification. (Fuel-cell electric trains have not been modelled in this research).

We project a 0.5% annual increase in efficiency on a per passenger per km basis and a 0.8% annual increase in efficiency on a per tonne per km basis (the same for all drivetrains) in all three scenarios (Fig. 6.17).

The actual efficiency depends on the type of train and the world region. These differences are considered in every transport sub-model and are exemplified in Fig. 6.18 for freight and passenger trains.

Inland navigation will probably remain predominantly powered by ICE in the next few decades. Therefore, we did not model the electrification of inland navigation vessels. However, pilot projects using diesel hybrids, batteries, and fuel cells are in preparation (DNV GL 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 hybridization, and enhanced air traffic management systems (Madavan 2016; Vyas et al. 2013). We project a 1% annual increase in efficiency on a per pkm basis.

Flexibility and passenger-friendly usability is becoming increasingly important to users of public transport. Various app-based on-demand mobility services are currently being tested in pilot projects—for example, in the German city of Schorndorf (Brost et al. 2018). Under these business models, innovative vehicle concepts are tested for suitability. Automated battery electric (mini) buses can make public transit more flexible. Their modularity also allows them to connect to other modes of transport, such as rail and air transport, and thus opens up fundamentally new transport chains that are more energy efficient than traditional passenger car usage. However, decision-makers and transport planners must consider the potentially detrimental rebound effects of highly personalized automated mobility (Pakusch et al. 2018). For example, an increase in total energy consumption may occur as a result of the higher transport demand arising from transport options that are seen as more attractive than more-energy-efficient mass transit systems or cycling. Therefore, novel transport concepts could cancel out the gains in energy efficiency on a per vehicle level.

The automatization of road freight traffic can reduce fuel consumption. The technology for partially automated trucks is already available and being tested to make it widely available. In the Society of Automotive Engineers (SAE) automation level 3 (SAE 2018), (multi-brand) truck platooning has become possible, which is a driver-assistance technology (Janssen et al. 2015). With communication between the first truck and the following trucks, the control of the following vehicles is handed over to the leading vehicle. Thus, the following vehicles are driving in the slipstream and lower air drag is achieved, which can reduce energy consumption by up to 5% (Daimler 2018).

In urban freight transport, last-mile delivery concepts based on light commercial vehicles can help reduce fuel consumption. By fragmenting the transport routes into the main leg and urban traffic (last mile), different vehicle types and modes can be used more efficiently for specialized transport tasks. Like light commercial vehicles (electric), cargo bikes could shape the urban freight traffic of the future as they do already today in many countries in Asia.

Further novel logistic concepts, such as the use of drones for delivery and decentralized production using 3D printers, will help to reduce the overall transport demand and thus energy consumption through more-efficient operational solutions.