Page | 54
IEA 2019. All rights reserved.
The Future of Rail |
IEA 2019. All rights reserved. |
Opportunities for energy and the environment
Figure 1.28 Energy intensities of passenger (left) and freight (right) rail, 2016
|
1 000 |
|
400 |
|
|
900 |
|
350 |
|
|
|
|
||
|
800 |
|
300 |
|
passenger-km |
700 |
|
||
/ tonne-km |
|
|||
600 |
250 |
|||
|
||||
500 |
200 |
|||
400 |
|
|||
kJ / |
kJ |
150 |
||
|
||||
300 |
|
|||
|
|
100 |
||
|
200 |
|
||
|
|
|
||
|
100 |
|
50 |
|
|
|
|
||
|
0 |
|
0 |
North Europe Russia Japan India China World |
Japan Europe North India China Russia World |
America |
America |
Sources: IEA Mobility Model (IEA, 2018a) using assessments based on UIC (2018a); National Bureau of Statistics of China (2018); Eurostat (2018); Indian Railways (2018a); Japan Ministry of Land, Infrastructure and Tourism (2018); AAR (2017) and Russian Federation State Statistics Service (2018).
Key message • Trains in the United States and the European Union are less energy efficient per passenger-kilometre than trains in Asia, primarily due to lower occupancy. Freight trains in Russia and China are the most energy efficient due to high loading and electrification.
GHG emissions and local pollutants
In this report, the environmental factors related to rail transport focus primarily on GHG and local pollutant emissions. Local pollutants have the greatest impact on human health in densely populated urban areas (see Box 1.8). Other environmental impacts (e.g. those related with landuse change, habitat disruption, effects of noise and visual disruption, impacts of mineral extraction related to the high steel and concrete demand, as well as consequences of the use of pesticides on rail tracks) are not assessed here.
Well-to-wheel GHG emissions in rail transport
In 2016, the transport sector as a whole accounted for 24% of direct CO2 emissions from fuel combustion, or 7.9 gigatonnes (Gt) (IEA, 2018b).35 Rail transport accounted for 89 million tonnes (Mt) of these CO2 emissions, or 0.3% of total energy-related emissions. Measured on the more comprehensive well-to-wheel (WTW)36 basis and including all GHG emissions, 230 Mt carbon-dioxide equivalent (CO2-eq) were emitted. Compared with other modes, passenger rail accounted for less than 2% of all WTW GHG emissions from passenger transport, a figure comparable with rail’s share (1.1%) of final energy use by all forms of passenger transport, and well below the 8% share of passenger rail in total passenger-kilometres travelled in all forms of transport. In transporting freight, trains released around 4% of all the WTW GHG emissions of the freight transport sector as a whole, a similar figure to the 3% share of freight rail in total final energy use and lower than rail’s share (7%) of all freight transport activity.
35Direct emissions from other sectors include electricity and heat production with 41%, manufacturing industries and construction with 19%, residential sector with 6% and others 10%. Direct emissions, in contrast to well-to-wheel emissions, only account for emissions from direct fuel combustion, neglecting the impacts of extraction, transport and refining.
36Well-to-wheel emissions include the sum of emissions due to the conversion of fuel to kinetic energy for vehicle propulsion during combustion or use in the vehicle (tank-to-wheel) plus those occurring to produce, store and transport the
fuel (or energy carrier) to the vehicle (well-to-tank).
IEA 2019. All rights reserved.
IEA 2019. All rights reserved. |
The Future of Rail |
|
|
|
|
Opportunities for energy and the environment |
|
|
|
|
|
Box 1.7 |
Sector coupling: linking renewables-based power generation with rail power demand |
|
|
|
|
|
|
As rail is the only mode of transport that is widely electrified today, it is uniquely positioned to take advantage of the growing role that renewable forms of energy are playing in electricity mixes. Many railway operators take this further, ensuring that they source their energy from renewables, thus reducing the overall carbon intensity of the transport services they offer.
In Europe, rail companies purchase renewable energy certificates and guarantees of origin |
Page | 55 |
|
|
which, in 2017, on average, contributed to reducing specific passenger CO2 emissions by over |
|
15%, compared to electricity sourced directly from the national grids. Freight specific CO2 |
|
emissions were reduced by only 6%, suggesting that sector coupling measures were more |
|
frequently adopted in the presence of a direct relationship with consumers than in case of |
|
business-to-business relationships (UIC, 2017b). Since 2017, NS, the railway company in the |
|
Netherlands, has sourced all of its tractive energy from domestic wind installations and others |
|
in Belgium and Scandinavia, resulting in no net CO2 emissions (NS, 2017). Also in 2017, |
|
renewable energy sources accounted for 42% of Deutsche Bahn’s traction energy mix, on the |
|
way to its goal of achieving CO2 free rail transportation by 2050 (DB, 2018). |
|
Worldwide, rail operators and infrastructure managers are increasingly taking advantage of the |
|
land they own to reduce dependence on the grid by operating their own renewable energy |
|
production means. For example, as of 2018, Japan Rail-East operates wind turbines, solar |
|
panels and a 12.4 megawatt (MW) biomass power plant (JR-East, 2017). The railway operator |
|
in Switzerland (SBB CFF FFS) owns and operates six hydroelectric plants, which provide |
|
around 75% the company’s traction power needs, while Austrian Railways (ÖBB) have installed |
|
hydropower capacity of 279 MW (UIC, 2017b). In Santiago, Chile, the city metro operator built |
|
two solar photovoltaic power plants in 2017, which supply 60% of the metro’s energy use, |
|
bringing the share of energy sourced from renewables to 76% (Metro de Santiago, 2017). |
|
|
|
Box 1.8 Opportunities for rail to reduce air pollution
Air pollution is a major externality of the transport sector and poses health risks especially to urban populations. In 2015, transport accounted for 53% of global nitrogen oxides (NOX) emissions and for 11% of total particulate matter (PM) emissions (IEA, 2018c). Rail transport accounted for 4% and 5% of total transport-related NOX and PM emissions.
Almost all cities (98%) with more than 100 000 inhabitants in lowand middle-income countries are exposed to air quality levels which exceed World Health Organization (WHO) limits.37 This percentage is 56% in developed economies (WHO, 2018). Urban air pollution from transport originates from fuel combustion in the internal combustion engines of two/three-wheelers, passenger cars, buses and commercial vehicles, as well as from non-tailpipe pollutant emissions, including the wear and tear of brakes and tyres. Many countries have imposed tailpipe pollutant emission standards for passenger cars, such as the Euro standards, which set permissible emissions per vehicle-kilometre for pollutants such as carbon monoxide (CO), NOX and PM. Global best practice on emission standards (e.g. Euro VI for trucks and Euro 6d for cars, or Tier 3 standards in the United States) do effectively reduce pollution from road traffic. But many lowand middle-income counties have yet to adopt best practice. Moreover, actual driving emissions have been widely found to significantly exceed regulated limits (Bernard et al., 2018).
37 Lower income populations also are more affected by key negative externalities from transport, such as air pollution and road accidents (Rode et al. 2014; Drabo, 2013).
The Future of Rail
Opportunities for energy and the environment
IEA 2019. All rights reserved.
In cities with good scope to limit personal vehicle ownership by offering all-electric transport options, rail is well placed to contribute significantly to reducing air pollution, particularly in developing countries.38
The carbon intensity of WTW GHG emission is the crucial factor explaining the differences Page | 56 between energy and GHG emission shares. Carbon intensity depends on the type of traction used by the trains (primarily diesel or electric), on the energy intensity of the rail service considered and on the WTW carbon intensity of the energy used. The carbon intensity of diesel traction does not vary significantly across regions. On the other hand, the carbon intensity of electricity depends on the fuel used to generate power. Figure 1.29 compares the WTW carbon intensities of diesel fuel and electricity produced from various primary sources. It shows that electric trains can effectively reduce emissions, compared with diesel-powered trains, but only if the power generation mix is not largely dependent on primary fuels with high carbon content, such as coal. Box 1.7 explores how the benefit of rail in terms of GHG emission reductions, compared with other forms of transport, can be enhanced further by voluntary actions within
the rail transport sector.
Figure 1.29 Average WTW carbon intensities for diesel powertrains, compared with electric powertrains using various primary sources
|
800 |
|
|
|
|
|
|
|
Diesel |
Electric |
|
|
|
|
|
|
700 |
|
|
|
|
|
|
energy |
600 |
|
|
|
|
|
|
500 |
|
|
|
|
|
|
|
/ MJ tractive |
|
|
|
|
|
|
|
400 |
|
|
|
|
|
|
|
300 |
|
|
|
|
|
|
|
CO |
200 |
|
|
|
|
|
|
g |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
100 |
|
|
|
|
|
|
|
0 |
|
|
|
|
|
|
|
Diesel |
Lignite |
Sub-bituminous |
Anthracite |
Natural gas |
Renewables |
Nuclear |
|
|
|
coal |
|
|
|
|
Notes: g CO2/MJ = grammes of carbon-dioxide equivalent per megajoule. Tractive energy is the final energy necessary to move the vehicle forward. These results are obtained assuming a diesel train efficiency of 35%, an electric powertrain efficiency of 90% and a power plant efficiency of 50%.
Source: Emissions factors per unit energy of fuel used from IEA (2012).
Key message • Electric trains are significantly less carbon intensive than diesel trains if they draw power from primary energy sources with low-carbon content.
IEA 2019. All rights reserved.
The much lower carbon intensity of rail (per passengeror tonne-kilometre) compared with most other modes of transport, means the rail sector already plays a key role in containing
38 A wealth of evidence has been collected showing a link between the opening of urban rail systems and cuts in ambient concentrations and intake of the harmful pollutants emitted by internal combustion engines (primarily PM, NOx, CO and a range of hydrocarbons). Gendron-Carrier et al. (2018) show that the construction of metro networks in cities results in a significant impact on air quality, reducing particulate concentration by 4% on average in a ten kilometre radius around the city centre. The effect is larger near the city centre; more highly polluted cities, especially in Asia, experienced larger pollution reductions after opening a metro network. Concentrations of CO, NOx, PM10 and sulphur dioxide along corridors have been shown to fall by around 5-10%. Specific case studies have shown that opening new urban rail lines can reduce local concentrations of selected pollutants or limit their increase with reductions of up to 23% observed in CO concentrations (Park and Nese Sener, 2019; Chen and Whalley, 2012). Case studies in Beijing, Guangzhou and Mexico City also observed significant air pollution reductions after opening metro systems (Yang, Zhang and Ni, 2014; Shang and Zhang, 2013; Bel and Holst, 2018).