**5. Rail freight**

According to a study by SCI traffic "Rail Transport Markets-Global Market Trends 2016–2025," global rail freight traffic fell by 4.4% in 2015 [31]. Thus, the rail freight traffic has recorded negative growth for the first time since many years. The reason for this is the slowdown in the transport of coal and steel due to weaker production activity and also the decline in international trade growth. In the face

*Transportation Systems Analysis and Assessment*

India, and the co-author of the report.

to halt artificial global warming [23].

dangerous tipping points.

**4.2 The Kyoto Protocol**

gas effect is used for global warming [22]. The presence of gases with GWP results in an increase in temperature and thus the greenhouse gas effect. Many scientific predictions suggest that the Earth will continue to warm without a reduction in CO2 emissions [23], e.g., by 2°C when the atmospheric CO2 concentration can be kept at or below 650 ppm, and significantly higher if it cannot [10]. In August 2018, the IPCC has released a special report, pledging to limit global warming to 1.5°C [24]. "Limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on ecosystems, human health, and well-being," said Priyadarshi Shukla, Chair of the Global Centre for Environment and Energy, Ahmedabad University,

Under the 2015 Paris Agreement [25], countries have agreed to keep global temperatures increase below 2°C, which might not be enough to avoid exceeding

The Kyoto Protocol [26] is an agreement made in 1997. It regulates the United Nations Framework Convention on Climate Change (UNFCCC) and focuses on climate protection. In doing so, an international and joint agreement was achieved, which should gradually reduce CO2 emissions worldwide. The Kyoto Protocol is designed to slow down the progressive effects of greenhouse gases and, if possible,

The statistics in **Figure 4** shows the 10 largest CO2-producing countries by share of global CO2 emissions in 2016. With a very high proportion of over 28% of global carbon dioxide emissions, China was the world's largest CO2 emitter in 2016. Second only in the list of climate sinners come the USA with almost 16%. In addition to carbon dioxide, the Kyoto Protocol includes another five greenhouse gases: methane (CH4), nitrous oxide (N2O), "F-gases" hydrofluorocarbons (HFCs), perfluorocarbons (PFC), and sulfur hexafluoride (SF6). Nitrogen trifluoride (NF3) must be additionally included since 2015. In 2015, Germany was able to reduce almost all greenhouse gases compared to the year 2000 (with the exception of hydrofluorocarbons) and thus already meets the requirements of the Kyoto Protocol [27].

**118**

**Figure 4.**

*The 10 countries with the largest share of CO2 emissions worldwide in 2016. Modified from [27].*

of growing protectionism, transport demand is expected to be negatively impacted worldwide. Coal transport in North America has declined significantly as a result of the change in the energy mix [31].

In Asia, above all, the Chinese transport market, which is shrinking in rail freight transport [31], dominates. The rising tariffs in rail freight traffic are the cause of the reduction. The strong expansion of road infrastructure with highways, which has made road transport more attractive, also led to a decline in rail traffic. However, there is a desire in the Chinese area for a sustainable improvement in air quality, which can also be achieved by shifting the modal split in favor of greener rail. However, it is still unclear whether and to what extent the corresponding political decisions will take place and whether they will be able to compensate for the declining coal transport by rail [31] (compare **Figure 6**).

The basis for rail freight transport is freight wagons in regular or special design. These are coupled to wagon groups (half trains or block trains). Newer trains have a total length of up to 700 meters. Each wagon has a payload of 25–62 tonnes. The first railways were driven with the power of steam engines. However, this technique is no longer used today due to the low efficiency. At present, mainly internal combustion engines and electric motors are used for the drive. Here the drive is in locomotives or in the railcar. While a railcar carries the goods to be transported, a locomotive pulls wagons with the goods to be transported [32].

Freight trains are divided into different types of trains:

*Block trains*: Carriage of goods or a shipment from one customer to another one; between the departure station and the destination station, the whole train remains unchanged. The wagons of the same design are put together. This favors standardized loading processes for consignors and consignees as well as equipment that is specially tailored to the type of wagon [33].

*Mixed freight wagonload/single wagonload freight trains*: Individual wagons are used to build trains for different customers, which must be dismantled and reassembled in shunting yards [33].

*Mixed block trains*: Mixed block trains stand for trains that consist of several blocklike segments that carry different goods and/or have different routes. This is intended to combine the flexibility of wagonload traffic with the efficiency of block train traffic [33].

In internal combustion engines (as in everyday traffic), typically commercial diesel fuel is used. By the invention of the electric motor (1837) and generators

#### **Figure 6.**

*Worldwide rail services; index 100 (average) = 2005, pkm (person kilometers), tkm (tonne kilometers). Reproduced with permission from [31].*

**121**

*Energy Efficiency Management: State of the Art and Improvement Potential Analysis…*

and transformers (1866), it was possible to develop the first electrically operated railways. The energy required was initially supplied directly via batteries or via the tracks. AC motors or DC motors are used [32] (AC = alternating current,

In order to increase energy efficiency, unnecessary transport routes must be avoided. Traffic avoidance can be achieved by means of dynamic route planning by telematics systems. It uses information technologies and communication technologies as well as up-to-date traffic information for tour planning and tour control. Data streams from location, navigation, data and voice communication, and vehicle data are transmitted, collected, processed, and sent back in real time to the vehicles for their control. This relieves traffic infrastructure and the environment [32].

Apart from that, measures to optimize capacity utilization are important, since the means of transport are mostly only moderately utilized and empty trips (trips without goods to be transported) are not uncommon. This includes, for example, bundling. In "time bundling," future requirements of a target area are combined to transport blocks, while in "spatial bundling," orders from neighboring customers,

e.g., by transshipment point or cross-docking, are pulled together [32].

At the 2012 American Society of Mechanical Engineers (ASME) Joint Rail Conference, technology options for use in new rail systems, retrofits, or systemwide energy efficiency gains were assessed as being proven and highly promising. Among other things, it was recognized that the most important factor in improving energy efficiency is the modernization of the traction and propulsion system. The modernization of the heat, ventilation, and air conditioning (HVAC) system control for railcars allows further system-wide energy efficiency gains [34].

• Frequency converters for refrigerant compressors, which save energy for heat-

• Permanent magnet motors, which increase the efficiency. They also reduce the

Improved rail and facility efficiency lighting system options (including stations, depots, and rails, as well as multimodal terminals) include daytime lighting, automatic ambient light sensors, and motion detectors. Furthermore, incandescent lamps and fluorescent lamps are being replaced by long-lasting, low-power, light-

Regenerative braking can be used to store and reuse generated electricity. The electricity is gained by dynamic braking; the electric motor is driven backward and should slow down the train. The electric motor can act as a generator with the aid of dynamic braking. Currently, most of the trains used to convert this dynamic braking energy and deploy resistance bridges. The resistance bridges heat up during this process. Usually, a cooling grid is arranged at the top of the locomotive for the braking resistors. The use of electronically controlled pneumatic (ECP) brakes is increasing, but energy savings can only be realized here, as long as all railcar brakes are connected. For regenerative braking to be used, an onboard rechargeable energy storage system (RESS) is required. Only with the RESS, the recovered kinetic energy can be stored and returned if needed. Normally, this kinetic energy converts

ing and ventilation (saving potential can reach up to 70%).

**5.1 Existing and emerging fuel-efficient locomotives**

The focus here is on integration:

size and weight of compressors/pumps.

• Variable fans or dampers.

emitting diodes (LEDs) [34].

*DOI: http://dx.doi.org/10.5772/intechopen.86552*

DC = direct current).

*Energy Efficiency Management: State of the Art and Improvement Potential Analysis… DOI: http://dx.doi.org/10.5772/intechopen.86552*

and transformers (1866), it was possible to develop the first electrically operated railways. The energy required was initially supplied directly via batteries or via the tracks. AC motors or DC motors are used [32] (AC = alternating current, DC = direct current).

In order to increase energy efficiency, unnecessary transport routes must be avoided. Traffic avoidance can be achieved by means of dynamic route planning by telematics systems. It uses information technologies and communication technologies as well as up-to-date traffic information for tour planning and tour control. Data streams from location, navigation, data and voice communication, and vehicle data are transmitted, collected, processed, and sent back in real time to the vehicles for their control. This relieves traffic infrastructure and the environment [32].

Apart from that, measures to optimize capacity utilization are important, since the means of transport are mostly only moderately utilized and empty trips (trips without goods to be transported) are not uncommon. This includes, for example, bundling. In "time bundling," future requirements of a target area are combined to transport blocks, while in "spatial bundling," orders from neighboring customers, e.g., by transshipment point or cross-docking, are pulled together [32].

### **5.1 Existing and emerging fuel-efficient locomotives**

At the 2012 American Society of Mechanical Engineers (ASME) Joint Rail Conference, technology options for use in new rail systems, retrofits, or systemwide energy efficiency gains were assessed as being proven and highly promising. Among other things, it was recognized that the most important factor in improving energy efficiency is the modernization of the traction and propulsion system. The modernization of the heat, ventilation, and air conditioning (HVAC) system control for railcars allows further system-wide energy efficiency gains [34].

The focus here is on integration:


Improved rail and facility efficiency lighting system options (including stations, depots, and rails, as well as multimodal terminals) include daytime lighting, automatic ambient light sensors, and motion detectors. Furthermore, incandescent lamps and fluorescent lamps are being replaced by long-lasting, low-power, lightemitting diodes (LEDs) [34].

Regenerative braking can be used to store and reuse generated electricity. The electricity is gained by dynamic braking; the electric motor is driven backward and should slow down the train. The electric motor can act as a generator with the aid of dynamic braking. Currently, most of the trains used to convert this dynamic braking energy and deploy resistance bridges. The resistance bridges heat up during this process. Usually, a cooling grid is arranged at the top of the locomotive for the braking resistors. The use of electronically controlled pneumatic (ECP) brakes is increasing, but energy savings can only be realized here, as long as all railcar brakes are connected. For regenerative braking to be used, an onboard rechargeable energy storage system (RESS) is required. Only with the RESS, the recovered kinetic energy can be stored and returned if needed. Normally, this kinetic energy converts

*Transportation Systems Analysis and Assessment*

declining coal transport by rail [31] (compare **Figure 6**).

locomotive pulls wagons with the goods to be transported [32]. Freight trains are divided into different types of trains:

specially tailored to the type of wagon [33].

sembled in shunting yards [33].

train traffic [33].

the change in the energy mix [31].

of growing protectionism, transport demand is expected to be negatively impacted worldwide. Coal transport in North America has declined significantly as a result of

In Asia, above all, the Chinese transport market, which is shrinking in rail freight transport [31], dominates. The rising tariffs in rail freight traffic are the cause of the reduction. The strong expansion of road infrastructure with highways, which has made road transport more attractive, also led to a decline in rail traffic. However, there is a desire in the Chinese area for a sustainable improvement in air quality, which can also be achieved by shifting the modal split in favor of greener rail. However, it is still unclear whether and to what extent the corresponding political decisions will take place and whether they will be able to compensate for the

The basis for rail freight transport is freight wagons in regular or special design. These are coupled to wagon groups (half trains or block trains). Newer trains have a total length of up to 700 meters. Each wagon has a payload of 25–62 tonnes. The first railways were driven with the power of steam engines. However, this technique is no longer used today due to the low efficiency. At present, mainly internal combustion engines and electric motors are used for the drive. Here the drive is in locomotives or in the railcar. While a railcar carries the goods to be transported, a

*Block trains*: Carriage of goods or a shipment from one customer to another one; between the departure station and the destination station, the whole train remains unchanged. The wagons of the same design are put together. This favors standardized loading processes for consignors and consignees as well as equipment that is

*Mixed freight wagonload/single wagonload freight trains*: Individual wagons are used to build trains for different customers, which must be dismantled and reas-

*Mixed block trains*: Mixed block trains stand for trains that consist of several blocklike segments that carry different goods and/or have different routes. This is intended to combine the flexibility of wagonload traffic with the efficiency of block

In internal combustion engines (as in everyday traffic), typically commercial diesel fuel is used. By the invention of the electric motor (1837) and generators

*Worldwide rail services; index 100 (average) = 2005, pkm (person kilometers), tkm (tonne kilometers).* 

**120**

**Figure 6.**

*Reproduced with permission from [31].*

to frictional heat and is thus lost. The recovered braking energy can be redirected back into the system or used for peak load requirements such as accelerating or uphill driving. Modern or newer electric train systems are able to save and reuse 10–20% of energy consumption with the aid of the regenerative braking function. For rail freight traffic with numerous stops, this is particularly interesting in terms of energy efficiency [34].
