4.1 Avoid-Shift-Improve (ASI) Framework

The most prominent and frequently quoted definition of sustainability is published in the Brundtland Report, where it is written that “sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their needs” (World Commission on Environment and Development, 1987, p. 8). According to Daly (1990), there are three main operational guidelines that should be followed to ensure sustainable development, namely:

  • Renewable resources should not be used faster than their regeneration rates.

  • Non-renewable resources should not be used faster than substitutes become available.

  • Pollution emissions should not exceed the assimilative capacity of the environment.

It is well known that the transportation sector extensively contravenes all of these three guidelines (McKinnon et al., 2015; Szyliowicz, 2003). Transport contributes a quarter of total greenhouse gas emissions in the EU-28, most of which comes from road transport (Figure 4.1). Nearly three quarters of the total transport GHG emissions stems from road transport, followed by aviation (13.9%) and maritime transport (13.3%). The share of emissions from railways and other transport modes (inland waterway transport, pipelines,…) amounts to 1% and are therefore negligible (European Environment Agency, 2019b).

Figure 4.1
figure 1

(data from European Environment Agency, 2019b)

Share of European transport GHG emissions by transport mode.

Figure 4.1 clearly underlines that strategies have to be implemented to mitigate the environmental impact of road transport. The avoid-shift-improve (ASI) approach is a well-known framework to summarize the three main strategies that exist to reduce GHG emissions from transport in general, and from road transport in particular (Bongardt et al., 2019). These three main strategies constitute the three pillars of ASI (Dalkmann and Brannigan, 2014):

  1. (1)

    Avoid or reduce transport: Aims to improve the overall efficiency of the transport system as a whole by implementing strategies that reduce the number of shipments or trip length.

  2. (2)

    Shift transport: Aims to improve individual shipment efficiency by promoting a modal shift from the most energy consuming transport mode (road) towards low-carbon transport modes (railways, waterways).

  3. (3)

    Improve transport: Aims to improve the energy efficiency of transport modes and related vehicle technology, e.g. by using low-carbon fuels and increasing fuel efficiency.

The ASI approach is focused on demand side measures for sustainable transport and offers a holistic framework for an overall optimization of the transport system regarding sustainability aspects (Bongardt et al., 2019). The initial development of the ASI approach dates back to the early 1990s in Germany, where ASI was established to structure policy measures for sustainable transport (Bongardt et al., 2019). ASI was first mentioned in 1994 in a report by the German parliament´s Enquete Commission (Deutscher Bundestag, 1994). There is a hierarchy among the three pillars of the ASI approach which should be observed when implementing sustainable transport measures: Avoid strategies should be of first priority as they have the highest potential to reduce the environmental impact of freight transport. However, avoid strategies are challenging to implement as they are bound up with renunciation and abandonment (Mauch et al., 2001). Next, shift strategies should be implemented; and finally, when the other two strategies are fully exhausted, improve strategies should be realized (Kagermeier, 1998). The ASI approach is a universal framework into which a large range of diverse policies, regulatory instruments and best practices fit. ASI does not stipulate the scope of the measures- gradual and incremental changes are covered as well as radical paradigm shifts (Bakker et al., 2014). There is increasing attention on the ASI framework. A number of international NGOs and development organizations have already dedicated themselves to the ASI approach, not only in Europe, but also on other continents like Asia or Latin America (Huizenga and Leather, 2012). The International Energy Agency also refers to the ASI approach in their scenarios depicting the GHG emissions mitigation potential of the transport sector to reach the 2° C limit of global warming by 2050 (Fulton et al., 2013).

In the following subchapters, the three pillars of ASI will be investigated further. For each pillar, one strategy to implement this pillar will be introduced in detail, namely:

  • Horizontal collaboration and bundling in a PI network (AVOID)

  • Multimodality (SHIFT)

  • LNG as an alternative fuel (IMPROVE).

The state-of-the-art knowledge on these strategies will be presented and it will be justified why these three strategies have been chosen to represent the respective ASI pillar.

4.2 Avoid Transport—PI Collaboration & Bundling

Heavy goods vehicles are estimated to run empty 30% of the time in Europe (Freight Transport Association, 2019). Before considering how to increase the efficiency of freight transport by modal shift or technological improvements, it should therefore be carefully appraised whether it is possible to avoid or reduce transport activities to avert empty trucks. Avoiding transport is the most effective, but also the most difficult strategy to achieve more sustainable transport. For the sustained reduction of freight transport, a paradigm shift will be necessary to change the habits and behavior of transport stakeholders (McKinnon, 2018; Wittenbrink, 2015). The formation of collaborative relationships is a key strategy to avoid transport by bundling transport streams and increasing the utilization of transport assets (Bretzke, 2014). Partnerships between different organizations in the logistics chain are seen as a promising solution to overcome the problem of increasing freight volumes in future (Punte et al., 2019; Wittenbrink, 2015; Bretzke, 2014). Based on the level of interaction among organizations involved in the partnership it is distinguished between coordination, cooperation and collaboration (Kotzab et al., 2018). Coordination denotes the lowest level of interaction where single activities are harmonized or synchronized between organizations. Cooperation means working together as equal partners, whereas collaboration calls for organizations to act as one single entity (Kotzab et al., 2018).

Collaboration in the context of logistics and supply chain management dates back to the mid-1990s when the strategy of collaborative planning forecasting and replenishment became popular (Barratt, 2004). Horizontal logistics collaboration is a particular type of partnership that involves active collaboration between two or more organizations that operate on the same level of the supply chain and perform comparable logistics services (Pomponi et al., 2015). Mason et al. (2007) stated that horizontal transport collaboration comes along with various synergies such as cost minimization, value creation, improved service levels or increased end customer satisfaction. There exist several requirements to realize these synergies, including trust among partners, common suppliers and delivery bases, a capable orchestrator and an effective business model, including a fair gain sharing system (Sanchez Rodrigues et al., 2015; Cruijssen et al., 2007). Horizontal collaboration constitutes a megatrend in transport and logistics that is predicted to influence the logistics industry tremendously during the coming decades (Grazia Speranza, 2018; Stank et al., 2015).

In past, several types of collaboration models evolved in logistics each of which has distinct characteristics and operating principles (Figure 4.2). A myriad of different names were attached to these collaboration models, including transport marketplaces, alliances, coalitions, logistics pooling, synchromodality or the Physical Internet, to name just a few (Pan et al., 2019).

Figure 4.2
figure 2

Comparison of collaboration models in logistics

The Physical Internet (PI) is a recently emerging logistics concept which can be considered as the most advanced collaboration model currently existing in transport and logistics (Figure 4.2). The PI is a vision which uses today's interdependent IT networks and the digital internet environment as a role model to reorganize freight transport (Montreuil, 2011; Montreuil et al., 2013). Collaboration plays a central role in the idea of the PI. PI involves horizontal collaboration among logistics service providers and also among shippers to reduce the environmental impact of their freight transport activities (Ambra et al., 2019).

Compared to the other concepts presented in Figure 4.2, the PI is progressive. The PI tries to utilize the advantages of several collaboration models by minimizing their disadvantages. For example, partnerships in the PI aim for global long-term relations, as opposed to transport marketplaces, where short-term, operational transactions take place only to perform single transport requests between individual partners (Caplice, 2007). Long-term collaboration is desirable because it involves mutual trust, increased commitment and higher reliability compared to short-term relationships (Humphries and Wilding, 2004). However, transport marketplaces are designed for cooperation at a temporary, operational level and they are mostly based on bilateral peer-to-peer agreements (Huang and Xu, 2013). Single LSP collaborations (or single carrier collaborations, Hernández et al., 2011) also take place on a bilateral level as there are only two parties involved which collaborate with each other. However, compared to transport marketplaces, single LSP collaborations are entered for a longer period of time, and not only for single transport requests (Hernández et al., 2011). The goals of single LSP collaborations from an LSPs’ viewpoint are reduced transport costs, the acquisition of external capacities and improved customer services (Buijs et al., 2016; Puettmann and Stadtler, 2010). Due to the bundling of transport requests, there will also be positive environmental effects resulting from single LSP collaboration.

An alliance or coalition between transport companies already promotes a more integrated and holistic view of freight transport as compared to transport marketplaces and single LSP collaborations (Pan et al., 2019). In an alliance/coalition the collaboration is more stable and efficient, because it is no longer based on bilateral exchange, but on multilateral exchange (Pan et al., 2019). The terms alliance and coalition are sometimes misused interchangeably, however, the difference is that an alliance is based on decentralized planning while a coalition is based on centralized planning (Dai and Chen, 2012; Li et al., 2015).

Logistics pooling is an approach that is even more integrated than an alliance or coalition between transport companies. Logistics pooling is a collaboration model where vertical and horizontal collaboration are combined to exploit synergies between different supply chains (Mason et al., 2007, Rodrigues et al., 2015). Resources such as warehouses or transport resources are pooled and shared between the partners (Pan et al., 2019). It is therefore quite a strategic and long-term type of collaboration model (Figure 4.2).

Synchromodality and the Physical Internet are the two most integrated and most strategic types of collaboration. Synchromodality and PI are interrelated to each other and reinforce each other (Ambra et al., 2019). Both are quite new transport concepts that have been developed during the past ten years (Ambra et al., 2019). Synchromodality and PI promote a holistic view of freight transport, including and combining all available transport capacities in a transport network in a highly flexible way (Montreuil, 2011; Behdani et al., 2016). Compared with scheduling each transport request individually, the integrated network approach of synchromodality and PI provides a more efficient transportation plan resulting in a higher overall utilization of resources. An important principle which distinguishes synchromodality and PI from other logistics collaboration models is the fact that there is a central orchestrator, that means a neutral entity, which is allowed to modify transport constraints imposed by the shipper (van der Vorst et al., 2016; Vanovermeire et al., 2014). The central network orchestrator is sometimes also referred to as the “control tower” (Monios and Bergqvist, 2015). The central orchestrator has a holistic view of all transport demands and available resources in the network and is therefore able to consolidate freight flows, which leads to a better use of network capacities. (van Riessen et al., 2015). In synchromodality, shippers book a-modal or mode-free transport services (Behdani et al., 2016; Pfoser et al., 2018a), which means that the shipper only determines basic framework conditions (delivery time, price cap) but not the transport mode. The a-modal booking allows the central orchestrator to make optimized decisions and real-time changes to the transportation plan (Guo et al., 2017). Synchromodality is already a quite advanced type of collaboration (and could be a first step to realize PI), but PI is even more progressive. Unlike synchromodality, PI is additionally characterized by highly modularized, standardized and interoperable transport operations (Pan et al., 2019). In PI, freight is moved in similar ways to data (packets) – smart, seamlessly within synchronized corridors and through hubs using the (open) networks of others (Lemmens et al., 2019; Sáenz, 2016). Interoperability between all players involved in PI requires revolutionized planning, selection and pricing strategies in logistics networks with competitors collaborating (i.e. coopetition). The vision of PI also employs open and shared networks, using standard technical protocols, dynamic routing, deployment logics, control and optimizing intelligence and modular containers etc. (Montreuil, 2009).

The PI collaboration model was chosen as the focus of this thesis because it is the most advanced concept which entails the highest potential to exploit synergies between the collaborating partners. The implementation of the PI is also high on the political agenda in Europe. The technology platform ALICE includes the concept PI in their roadmap for logistics and supply chain management innovation (Zijm and Klumpp, 2016). ALICE anticipates a diverse number of benefits bound up with the full-fledged implementation of a PI network (Punte et al., 2019; Sternberg and Norrman, 2017 Sarraj et al., 2014; Montreuil, 2011):

  • Load consolidation: Efficient pooling and cross-docking of loads from different suppliers and shippers. High capacity vehicles can be used for bigger load volumes and weights for longer distances. Pallets can be built from a mixture of different products, which allows for mixed load and weight volumes utilizing available space.

  • Asset sharing, open warehouses and transport networks: Companies make use of the same vehicles (and other assets) to share idle capacities and increase asset utilization.

  • Back-hauling: Empty returns can be avoided by picking up or delivering freight for collaborating partners on return trips.

  • Modular packaging and boxes: collaborative re-design of transport packaging and containers to introduce modularity and optimal fit, allow efficient handling, consolidation and pooling.

Despite these numerous benefits, horizontal collaboration is challenging to achieve in the transport sector (Pfoser et al., 2016b; van der Horst and Langen, 2008). Realizing the PI constitutes a paradigm shift in the current organization of transport and logistics (Ambra et al., 2017). For the successful implementation of the PI it is necessary to know what influences the willingness to collaborate in a PI network, and how organizations can be encouraged to enter the PI network. These questions will be assessed in the subsequent Chapters 5 and 6.

4.3 Shift Transport—Multimodality

As illustrated in the introduction, the majority of freight transport is carried out by truck, and this is problematic because road transport causes a lot of negative externalities. Figure 4.3 compares the emission range of different transport modes. The numbers are based on default factors from the Global Logistics Emissions Council (GLEC) Framework, a globally recognized methodology for harmonized calculation and reporting of the logistics GHG footprint (Greene and Lewis, 2019). As can be seen in Figure 4.3, road transport and air transport produce much more emissions than any other transport mode. The emission ranges in Figure 4.3 represent well-to-wheel (WTW) emissions, which means that not only the environmental effects of burning the fuel in the vehicle are considered, but also the effects of producing and distributing the fuel are taken into account (Ramachandran and Stimming, 2015). The emission level of road freight transport depends on the type of vehicle that is used. Light-duty vehicles like vans or urban trucks cause far more emissions per ton kilometer than heavy goods vehicles (HGV). Anyway, the emissions of HGVs are still much higher than the emissions of inland waterways or railways. This illustrates the need for a modal shift away from roads to sustainable transport modes to reduce the environmental impact of logistics.

Figure 4.3
figure 3

(Greene and Lewis, 2019)

Indicative emission ranges for different types of freight transport.

The concept of multimodal freight transport (in short: multimodality) was already proposed four decades ago in order to shift cargo from road transport to sustainable transport modes. The original definition was set up by UNCTAD (1980) and characterizes multimodal transport as “the carriage of goods by at least two different modes of transport”. Due to the combined use of multiple transport modes, the strengths of each mode can be utilized and the weaknesses can be compensated by the other mode(s). Thus, the cost effectiveness and sustainability of railway and waterways can be combined with the flexibility and speed of road transport (SteadieSeifi et al., 2014).

Ever since the first definition of multimodality, a number of associated concepts arose which have to be distinguished carefully (Figure 4.4). These concepts include intermodal transport, combined transport, and co-modal transport. Out of all these transport concepts, multimodal transport is the most generic since it only requires the use of two or more modes of transport. Intermodal transport can be considered as a specific type of multimodal transport, “whereby two or more modes of transport are used to transport the same loading unit or truck in an integrated manner, without loading or unloading, in a [door to door] transport chain” (UN/ECE, ECMT, EC, United Nations, 2001). This means the cargo remains in one and the same loading unit during the whole transport chain, as opposed to split transport where cargo is reloaded during the transport process (Posset et al., 2014). Combined transport then again is a specific type of intermodal transport, where environmentally friendly transport modes (rail, inland waterways or short sea) are used for the major part of the journey (ECMT, 1998). Any pre- and post-haulage processes carried out by road are attempted to be kept as short as possible. Thus, combined transport adds the aspect of sustainability to the concept of intermodal transport (Reis, 2015). In respect of combined transport, it can be further differentiated between accompanied and unaccompanied transport, depending on whether the driver is travelling together with the truck on the long leg of the journey. Accompanied transport is possible on railroads as well as waterways. For railroads, the rolling motorway is a well-known example of accompanied transport (Danielis and Rotaris, 2014). On the rolling motorway, road trucks or trailers are carried by rail, and drivers may be seated in accommodation wagons or couchettes during rail travel (Dalla Chiara et al., 2008). On waterways, so-called roll-on/roll-off (ro-ro) vessels can be used for accompanied, but also for unaccompanied transport. Road trucks, trailers or rail cars can be carried by ro-ro vessels (Fischer et al., 2016). It is sometimes stated that multimodal transport solutions are only cost-efficient if they are carried out in an unaccompanied manner (López-Navarro et al., 2011). In fact, the principal advantage of unaccompanied multimodal services is the reduction in personnel costs during the railborne / waterborne leg of the journey (Morales-Fusco et al., 2018). However, the difficulty of unaccompanied shipments is the availability of drivers for the last mile of the transport chain, which will most probably be carried out on roads at the final freight destination.

Figure 4.4
figure 4

(based on Posset et al., 2014 and Reis, 2015)

Classification of multimodal transport concepts.

In the further course of this thesis, the term multimodal transport will be used to denote the modal shift concepts presented in Figure 4.4, as multimodality serves as an umbrella term, which is often interchangeably used in the scientific literature and in practice. There is one more concept related to multimodality, which is not depicted in Figure 4.4, namely co-modal transport. Co-modality was defined by the European Commission in the midterm review of the White Paper on Transport (European Commission, 2006). The concept of co-modality strongly focuses on efficiency and the optimized use of transportation modes. It is defined as „the efficient use of different modes on their own and in combination” (European Commission, 2006, p. 4). Compared to the other transport concepts (multimodality, intermodality and combined transport), co-modality rather neglects the aspect of sustainability as unimodal road transport could also achieve the goal of co-modality, namely highest efficiency (Reis, 2015). A modal shift is therefore not inherent in co-modal transport. It should be noted that the term co-modality was mainly used by the European Commission and did not gain much practical importance. Co-modal transport is not within the scope of this thesis as sustainability is not a main goal of co-modal transport.

Although the idea of multimodal transport is already 40 years old, the relevance of this concept is still very high today. There exist strong political efforts to promote multimodal freight transport. For example, the European Commission has called for 2018 to be the “Year of Multimodality”—a year during which the Commission raised the importance of multimodality for the EU transport system in a series of activities (van Leijen, 2018). This commitment shows that European politics has strongly dedicated itself to multimodal freight transport as an effective way to improve the quality of life of European citizens, reduce air pollution and congestion, and reach the sustainability goals. Nevertheless, the share of sustainable transport modes is still very small compared to road transport in all European countries (European Commission, 2019). In 2014, the European Commission carried out a public consultation on multimodality and combined transport to get insights whether and how they should go on and promote these modal shift concepts (European Commission, 2014). Responses were collected from 18 EU member states and two non-member states, the respondents were mainly business representatives. The results were unambiguously in favor of multimodal transport. The vast majority of the respondents (94%) claimed that the European Commission should definitely continue to support multimodal transport operations (European Commission, 2014). Otherwise they expect a reverse shift, i.e. back from multimodal transport to unimodal road transport. The use of effective measures is therefore necessary to support the expansion and reinforcement of multimodal freight operations in future.

4.4 Improve Transport—LNG as an Alternative Fuel

Improve strategies aim to increase the eco-efficiency of (mostly road) vehicles and fleets (Mauch et al., 2001). The increase in eco-efficiency is enabled by a number of clean technologies, for example low rolling-resistance tires, lightweight design (e.g. aluminum wheels) or truck platooning (Punte et al., 2019). Particular potential for eco-efficiency lies also in the development of alternative fuels and propulsion systems. In the recent decades, several alternative fuel technologies have emerged including hydrogen, biofuels, electric and natural gas vehicles. In the area of medium and heavy truck transport, natural gas is the alternative which in the short-term is considered to be the best substitute for conventional fuels since it comprises the potential to reduce environmental impacts and it is readily available and accessible (Yeh, 2007). LNG, i.e. natural gas in its liquid state, is the only alternative fuel which is well suited for heavy trucks of more than 18 metric tons (Table 4.1).

Table 4.1 Application range of different alternative fuel technologies. (based on Feldpausch-Jaegers et al., 2016)

The energy density of LNG is very high compared to other fuels. To convert natural gas to LNG, it has to be cooled down to a temperature of −162 °C where it becomes liquid and reduces its volume roughly 600 times (Arteconi et al., 2010). Due to this volume reduction, the energy density of LNG is much higher than, for example, of CNG (compressed natural gas), which is the reason why LNG can conveniently be used for heavy-duty and long distance transport, while CNG is rather used for passenger transport. The maximum driving range of LNG trucks is currently 1600 kilometers, while the maximum driving range of CNG vehicles is only 500 kilometers (Anderhofstadt and Spinler, 2019). The driving range of electric vehicles is even less, namely only up to 200 kilometers. This restricts the application areas of electric vehicles to urban logistics with short-distance transports and light vehicles (Anderhofstadt and Spinler, 2019). Further barriers for electric trucks consist in the high weight of battery packs which reduces the payload; and the recharging time, which is significantly longer and requires more energy for electric trucks than for electric cars (Engerer and Horn, 2010). Another type of alternative fuels is biofuel, e.g. bioethanol or biodiesel. Biofuels are gaseous or liquid fuels generated from biomass such as plant or animal waste (Kluschke et al., 2019). The main problem with biofuels is their limited availability which occurs because land use is primarily dedicated for food production (Duarte et al., 2014; Simio et al., 2013).

Due to the above described shortages of existing alternative fuel technologies, several truck manufacturers like Iveco and Scania currently focus on the development of LNG fueled trucks. Pioneering fleet owners have already started to purchase these LNG trucks. In summer 2018, the German Federal Ministry of Transport started a funding program to subsidize energy-efficient heavy-duty vehicles producing low CO2 emissions. Statistics from October 2019 reveal that out of 1390 funding requests, 994 trucks were LNG-fueled, 339 trucks were CNG-fueled and only 57 trucks were electric (Völklein, 2019). Later on in February 2020, in total 1915 funding requests were submitted to the German Federal Ministry of Transport, out of which a high number of 1500 requests encompass LNG-fueled trucks, despite the fact that at that time the toll exemptions for LNG trucks were expected to expire at the end of 2019 (Landwehr, 2020).

In the long run, hydrogen is considered a highly promising alternative fuel technology by many experts (Table 4.2). Hydrogen trucks have an on-board hydrogen storage to generate electricity within a fuel cell (Kluschke et al., 2019). Prospects for the introduction of hydrogen as a transport fuel already started in the 1970s and tended to be too optimistic throughout the last decades, with early forecasts predicting an important role for hydrogen as transport fuel by 2010 or even much earlier (Moriarty and Honnery, 2019). Hydrogen vehicles could significantly reduce GHG from transport, but the production of hydrogen is very costly and needs further research and development (Durbin and Malardier-Jugroot, 2013). There are still many unresolved questions regarding the production, distribution and storage of hydrogen (Gondal and Sahir, 2012). Passenger cars running on hydrogen are already commercially available in Germany and Austria, but hydrogen trucks are still in their prototype stage (Anderhofstadt and Spinler, 2019). Notably, it is predicted that hydrogen will predominantly be important for freight transport and not so much for passenger transport (Moriarty and Honnery, 2019). Already in the early 2000s it was recommended that the ecological benefits and cost efficiency would be higher if hydrogen was introduced for freight transport (Farrell et al., 2003). The reason is that freight transport entails “a small number of relatively large vehicles that are operated by professional crews along a limited number of point-to-point routes or within a small geographic area” (Farrell et al., 2003, p. 1357). Furthermore, heavy-duty vehicles are produced to order and each vehicle receives considerable engineering attention, which facilitates technological innovation (as compared to passengers cars which are manufactured in large quantities on assembly lines) (Farrell et al., 2003).

Table 4.2 Impact and timeframe of alternative fuels for road freight transport. (based on Punte et al., 2019)

The impact of LNG is estimated to be rather low and short-term according to Table 4.2. Apparently, conventional natural gas is still a fossil fuel and therefore not suitable to comply with the 2050 zero emission logistics targets of the European Union (Punte et al., 2019). Despite that, LNG can play an important role along the way to zero emission logistics in several respects. On the one hand, natural gas is considered to be a bridge fuel in the transition process from oil and coal to a (near-)zero emission energy system (Zhang et al., 2016). Though natural gas is fossil, it is the cleanest burning fossil fuel. The combustion of LNG causes nearly 99% less particulate matter (PM) and sulfur oxide (SOx) emissions, around 80% less nitrogen oxides (NOx) and around 20% less carbon dioxide compared to diesel (Kumar et al., 2011). Vehicles fueled with LNG also produce lower noise levels, which allows them to enter zones with driving bans, like specific inner cities or making deliveries at night time (Peters-von Rosenstiel et al., 2015). And most importantly, the LNG technology is already available and ready to use, as opposed to hydrogen. The first use of natural gas vehicles dates back to the 1930s, and today there is a wide range of natural gas vehicles available (Osorio-Tejada et al., 2015; Yeh, 2007). Using LNG trucks could be a first step to reduce emissions from freight transport until zero emission fuel cell trucks are mature and ready for the market. Recent literature also suggests that there are synergies between natural gas and hydrogen technology in a way that natural gas infrastructure could help enable a transition to the long-term application of hydrogen in transportation (Ogden et al., 2018). The synergies result from the fact that natural gas and hydrogen share some physical similarities (both can be stored as compressed gases or cryogenic liquids) and they use similar infrastructural components (such as compressors, storage tanks and pipelines) (Ogden et al., 2018). It is therefore being discussed whether natural gas infrastructure can be re-used or designed for compatibility with the emerging hydrogen technology to promote the introduction of hydrogen. For example, the existing natural gas pipeline network could be used to distribute hydrogen initially. Blending hydrogen and natural gas is technically possible up to a mix of 17% hydrogen (Gondal and Sahir, 2012). This way, the use of natural gas (and LNG) at present can promote the future deployment of zero emission fuels like hydrogen.

On the other hand, the environmental impact of LNG can be further improved if bio-methane from renewable sources is used to produce LNG. LNG made from bio-methane is then referred to as “renewable LNG” (r-LNG) or “bio-LNG”. Fossil methane and bio-methane can be mixed to produce LNG. LNG purely made from bio-methane has the potential to reduce CO2 emissions between 43–67% (depending on the engine technology) as compared to diesel vehicles (Alamia et al., 2016). Shell even announced that they are going to construct a liquefaction plant in Germany which enables them to provide CO2-neutral bio-LNG in the upcoming years (Reichel, 2020). For the distribution of bio-methane the same infrastructure and networks as for LNG and CNG can be used. The risk associated with the introduction of bio-methane as alternative fuel is therefore expected to be limited (Thrän et al., 2014). The production costs of renewable LNG are relatively high at the moment compared to the production costs of fossil LNG or diesel (Scheitrum et al., 2017). However, it is estimated that bio-methane will become more widely available in the upcoming years due to advancements in biomass gasification technologies and integration with the distribution networks of LNG and CNG (Alamia et al., 2016). Therefore, the use of LNG trucks could serve as a transitional solution until the large-scale production of bio-methane is possible at competitive price in the coming years (Osorio-Tejada et al., 2017).

The above discussions show that LNG is currently the only viable alternative for heavy-duty vehicles and long-haul transportation. In some European countries, LNG is already a fully accepted technology. For example, the development stage of LNG as transport fuel in Spain, the Netherlands and the United Kingdom is estimated to be between demonstration and early market (Osorio-Tejada et al., 2017). Nevertheless, in countries like Germany and Austria, the use of LNG is rather moderate and demand is fairly low except for some first pioneer users (Anderhofstadt and Spinler, 2019). It is therefore necessary to learn the reasons which cause the hesitation of the fleet owners and find measures to encourage the widespread adoption of LNG.

4.5 Comparison of the ASI Pillars

Sections 4.24.4 presented three different strategies for sustainable freight transport, each of which can be classified as a different pillar of the ASI approach. Table 4.3 gives an overview of the characteristics of these three strategies under further investigation in this thesis. As can be seen, a variety of specific strategies for sustainable freight transport are covered which allows the analysis and comparison of similarities as well as differences between the acceptance and promotion of these diverse strategies.

Table 4.3 Comparison of sustainable freight transport strategies in this thesis

Environmental science adopts three basic principles that lead to sustainable development: sufficiency, consistency and efficiency. Each ASI pillar, and accordingly each implementation strategy under study in this thesis, is subject to one of the three principles. The avoid pillar is based on the sufficiency principle, which aims to lower the level of transports (Muller, 2008). “Sufficiency means more intensive utilization or shared utilization of goods” (Mauch et al., 2001, p. 133). This is exactly what the PI network aims to achieve by means of horizontal collaboration: transport resources should be shared among all partners for a better overall utilization. Sufficiency is aimed at the change of human behavior. Human beings need to alter their lifestyles and move towards more sustainable patterns of consumption (Samadi et al., 2017). The shift pillar is based on the consistency principle, where a certain level of transports should be provided using other, less polluting ways of transport. Consistency aims at fundamental changes in transport by substituting high emission transport modes like road transport with environmentally friendly modes (Samadi et al., 2017). Multimodality is an example for realizing the consistency principle, as multimodality allows the shift of freight to more sustainable transport modes. The improve pillar is based on the efficiency principle, which rests on technological innovations to increase resource productivity and resource efficiency. According to the efficiency principle, a certain level of transport services should be provided with lower resource input (Muller, 2008). Notably, the introduction of improve/efficiency measures bears the risk of rebound effects. A rebound effect describes the paradox between resource efficiency and resource consumption (Wang and Lu, 2014). The efficiency gains of improved technologies may be offset due to changes of consumer behavior (for example, due to the introduction of alternative fuels for road vehicles the use of road transport may increase, which offsets the efficiency gains of alternative fuels) (Matos and Silva, 2011). There is widespread agreement that to achieve a sustainable development of the transport sector, a combination of all three principles (sufficiency, consistency and efficiency) will be needed (Muller, 2008; Mauch et al., 2001). This thesis will therefore cover all three principles to compare them and gain knowledge about how to promote the implementation of the principles.

As regards the type of change, the strategies for sustainable freight transport either involve organizational change, technological change, or both. Horizontal collaboration in a PI network is subject to organizational change: Due to the collaboration, the transport organization is modified, e.g. transport requests are shared with others, transport capacities of collaborating partners can be taken into account etc., but there is no (substantial) additional technology required. Multimodality also involves organizational changes, as new transport modes and their requirements must be regarded in the transport organization (e.g. booking of train slots,…). Partly, multimodality may also involve technological change, for example infrastructure to enable smooth transition between transport modes (terminals, cranes, etc.). Alternative fuels such as LNG require technological change, as the transition towards alternative fuels is bound up with new technology like propulsion systems, fueling stations, etc.

Finally, the three strategies for sustainable freight transport under study in this thesis also cover a diverse range of transport distances. While bundling transport streams in a PI network is basically possible for every distance (short, medium and long distance), a modal shift is limited to long distance transport. A distance of 300 kilometers is suggested by the European Commission as the minimum where multimodal transport constitutes an economically feasible alternative (European Commission, 2011). Practitioners suggest that 500 kilometers is a more realistic minimum distance. The use of alternative fuels is possible for every type of distance (Table 4.1), but the use of LNG is particularly recommended for medium or long distances. This is due to the high energy density and the (currently) limited network of filling stations (Anderhofstadt and Spinler, 2019).