High speed rail and its impact on the environment + formation of ozone + effect of cfc

Mazen Abdo Mohammed Alqadi | Air & Noise Pollution | May 30, 2016
High speed rail and its impact
on environment
EFFECT ON AIR AND NOISE POLLUTION
&
EFFECT OF CFC ON OZONE DEPLETION

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Q1: An electrified high speed rail line is proposed to be built from Kuala Lumpur
to Kota Bhrau in year 2025. Discuss pros and cons of the proposed project in term
of environmental impact particularly on air and noise pollution.
Answer:
1. Introduction
Electrified high speed rail (HSR) has been the breakthrough in the world of
transportation system. Decision makers however usually worry about the high cost of
its construction, forgotten the environmental benefits gained from construction such
project. HSR investment is a complex decision that includes technical, social,
economic, and environmental tradeoff considerations. The discussed HSR in this
report would connect between Kuala Lumpur, Federal Territory of Kuala Lumpur,
Kota Bharu, Kelantan, Malaysia. It cover a distance of 440 kilometres which take
around 7 hours drive by car. The aim of this assignment is to discuss the advantages
and disadvantages of HSR project.
Figure 1: Distance between Kuala Lumpur and Kota Bharu

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2. Advantages of building HSR from Kuala Lumpur to Kota Bharu
The investment in a HSR infrastructure can offer transportation energy
consumption and GHG emission reductions over the conventional transportation
mean. Construction of such project would improve the socioeconomic status of
Kelantan state since it will be connected with the centre of the Malaysian economic
market. It will strengthen the regional economic structure of Kelantan as well as the
adjacent areas of Malaysia; improve the accessibility of the north; and reduce air and
noise pollution resulting from using other transport type such as car, bus or air flight.
President Obama said on the 16th
April, “Building a new system of high speed rail in
America will be faster, cheaper, and easier than building more freeways or adding to
an already over-burdened aviation system - and everybody stands to benefit."
Supporters of HSR often list environmental sustainability among its virtues.
Some argue it's a greener alternative to car and air travel and see it as an easy win in
weaning people of fossil fuels. According to Anthony [10], electricity is an energy
carrier, it can be generated from a mix of sources that incorporate the growing share
of geothermal, hydro, solar, and wind energy that will be produced in the years ahead.
And because electric motors are three to four times more efficient than internal
combustion engines, an immediate improvement will precede introducing renewable
energy into transportation. Over two thirds of the world's electricity comes from fossil
fuels so until (or unless) power stations are weaned off fossil fuels, electric trains will
still have a significant climate impact, although rail travel is still better than flying or
driving. Therefore, for the HSR to be environmental friendly, its electricity should
come from renewable sources.
The advantages of electrified HSR can be summarised in the following:
 Shorter time travelled
 Reduce traffic jam, where HSR means fewer cars on the road and plane in the
sky
 Improve Air quality
 Reduce greenhouse gases (GHG)
Figure 2 and 3 shows how HSR is more energy efficient as well as low external cost.

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Figure 2: Incredible energy efficiency of high speed train. Source [12]
Figure 3: external cost of different transport types. Source [12]

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3. Disadvantage
The impact of HSR operations on the environment is usually portrayed in a positive
light since it is considered to impact the environment less than other modes of
transport, especially the aircraft. However, HSR operations lead to negative
environmental impacts including local air pollution (LAP), climate change, noise and
land take. HSRs are predominantly electric powered and therefore emissions from
HSR operations are considered to be linearly related to energy consumption and the
sources used to generate the electricity. Moreover, railway infrastructure is more
energy intensive compare to road infrastructure [11].
The higher the level of renewable sources and nuclear power used to generate
the electricity, the lower the level of emission associated with HSR operations.
Usually, it is assumed that the electricity is supplied from the national grid and
emission is calculated based on the average electricity generation mix [1]. The use of
electric power also means virtually zero emissions from the HSR along the line and at
the stations.
The most harmful pollutants related to HSR operation are sulphur dioxide
(SO2) and nitrogen oxides (NOx). The former affect the environment mainly by
contributing to LAP, and the latter to both LAP and climate change. In general, HSR
operations are not considered to contribute significantly to climate change, while their
contribution to LAP can be significant depending mainly on the levels of SO2 emission
associated with HSR operations [2]. These levels depend mainly on the share of coal
used to generate the electricity [3]. Usually, power plants are located away from
densely populated areas, which means that the actual impact from HSR operation on
LAP is lower than suggested by the mix and amount emitted due to the relatively low
number of people exposed to the emission. Locally, along the HSR lines, noise
nuisance from HSR operations can be considered as the main environmental impact of
the HSR. The level of noise generated depends mainly on the speed of the train. At
speeds between 50 and 300 kph, rolling noise is the most important noise source [4]
and it depends mainly on the smoothness of the wheels and railhead. The high
standards of the HSR infrastructure (the trains used and the construction and

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maintenance standards) probably leads to less noise generated from HSR operations
in comparison with conventional trains running at the same speed. Only at speeds
above 300 kph does aerodynamics become the main source of noise. Thus, even for
HSRs, rolling noise is probably the dominant source of noise [4]. At high speeds HSR
operations result in high levels of noise, yet the impact of this (the actual noise heard
and number of people exposed to it) is lower than can be expected since in densely
populated areas the speed of the HSR is usually at its lowest (due to the distance
required for the HSR to stop, which means speed is reduced far from the station). In
addition, it is possible to ‘protect’ people from railway noise by building barriers,
trenches or tunnels [1, 5]. Moreover, land-use is an important environmental impact
related to HSRs. Land use leads to other environmental impacts including habitat loss,
frag mentation and community severance [1].
In comparison with other type of transportation, HSR operations result in less
environmental impact than aircraft operations in terms of LAP and climate change
impacts on all the routes where the modes compete [2]. In terms of LAP, the advantage
of the HSR depends mainly on the level of SO2 emissions related to HSR operations.
The impact of aircraft operations on climate change is higher than the impact of the
HSR due to higher emission rates of carbon dioxide and NOx and the fact that NOx
emissions at high altitude effect climate change much more than emissions at ground
level, by a factor of more than 100 [6].
With regard to noise pollution, it is less clear whether the aircraft or the HSR
leads to more noise pollution, and analysis on a route basis is required [1], yet it is
easier to provide protection from railway noise than from aircraft noise. With regard
to car emission, it was suggested that HSR operations result in lower energy
consumption and less emissions, but because HSR operations result in more SO2
emissions, it might result overall in a higher impact on the environment through a
higher LAP impact (since different pollutants have different impacts and comparing
only emissions might be misleading) [1, 7].
In conclusion, HSR infrastructure and operations certainly result in adverse
impacts on the environment, mainly by affecting LAP, causing a noise nuisance and
consuming land. However, LAP impacts are significantly reduced if renewable and

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nuclear energies are used to generate electricity for the HSR. There is also evidence
that HSR operations impact the environment less than the aircraft and the car when
these modes are compared on the same basis. However, whether the introduction of
new HSR infrastructure and services leads to environmental benefits is totally depends
on the balance between the substitution effect (how many passengers using the HSR
were shifted from the aircraft and the car) and the traffic generation effect (how much
new demand was generated by the HSR).
Q2: A: Discuss the photochemistry of ozone in the upper atmosphere, How
ozone is formed?
B: How CFC destroy the ozone layer?
Answer:
A: Ozone is formed throughout the atmosphere in multistep chemical processes
that require sunlight. In the stratosphere, the process begins with an oxygen molecule
(O2) being broken apart by ultraviolet radiation from the Sun. In the lower atmosphere
(troposphere), ozone is formed by a different set of chemical reactions that involve
naturally occurring gases and those from pollution sources.
Stratospheric ozone is formed naturally by chemical reactions involving solar
ultraviolet radiation (sunlight) and oxygen molecules, which make up 21% of the
atmosphere. In the first step, solar ultraviolet radiation breaks apart one oxygen
molecule (O2) to produce two oxygen atoms (2 O). In the second step, each of these
highly reactive atoms combines with an oxygen molecule to produce an ozone
molecule (O3). This process is explained in figure 1. These reactions occur continually
whenever solar ultraviolet radiation is present in the stratosphere. Therefore, the
largest ozone production occurs in the tropical stratosphere.

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Figure 1: Stratosphere ozone formation
The production of stratospheric ozone is balanced by its destruction in
chemical reactions. Ozone reacts continually with sunlight and a wide variety of
natural and human produced chemicals in the stratosphere. In each reaction, an ozone
molecule is lost and other chemical compounds are produced. Important reactive gases
that destroy ozone are hydrogen and nitrogen oxides and those containing chlorine and
bromine.
Tropospheric ozone. Near Earth’s surface, ozone is produced by chemical
reactions involving naturally occurring gases and gases from pollution sources. Ozone
production reactions primarily involve hydrocarbon and nitrogen oxide gases, as well
as ozone itself, and all require sunlight for completion. Fossil fuel combustion is a
primary source of pollutant gases that lead to tropospheric ozone production. The
production of ozone near the surface does not significantly contribute to the abundance
of stratospheric ozone. The amount of surface ozone is too small in comparison and
the transport of surface air to the stratosphere is not effective enough. As in the
stratosphere, ozone in the troposphere is destroyed by naturally occurring chemical
reactions and by reactions involving human-produced chemicals. Tropospheric ozone
can also be destroyed when ozone reacts with a variety of surfaces, such as those of
soils and plants.

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B: There are strong interactions between ozone depletion and changes in climate
induced by increasing greenhouse gases (GHGs). Ozone depletion affects climate, and
climate change affects ozone. The successful implementation of the Montreal Protocol
has had a marked effect on climate change. Calculations show that the phase-out of
chlorofluorocarbons (CFCs) reduced Earth’s warming effect (i.e., radiative forcing)
far more than the measures taken under the Kyoto protocol for the reduction of GHGs.
The amount of stratospheric ozone can be affected by the increases in the concentration
of GHGs, which lead to decreased temperatures in the stratosphere and accelerated
circulation patterns, which tend to decrease total ozone in the tropics and increase total
ozone at mid and high latitudes. Changes in circulation induced by changes in ozone
can also affect patterns of surface wind and rainfall. In the 1970s, scientists discovered
that chlorofluorocarbons (CFCs) could destroy ozone in the stratosphere [8, 9].
Ozone depletion occurs when the natural balance between the production and
destruction of stratospheric ozone is tipped in favour of destruction. Although natural
phenomena can cause temporary ozone loss, chlorine and bromine released from man-
made compounds such as CFCs are now accepted as the main cause of this depletion
[10].
Chlorofluorocarbons or CFCs (also known as Freon) are non-toxic, non-
flammable and non-carcinogenic. They contain fluorine atoms, carbon atoms and
chlorine atoms. The 5 main CFCs include CFC-11 (trichlorofluoromethane - CFCl3),
CFC-12 (dichloro-difluoromethane - CF2Cl2), CFC-113 (trichloro-trifluoroethane -
C2F3Cl3), CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2), and CFC-115
(chloropentafluoroethane - C2F5Cl). CFCs were widely used as in refrigeration and
air conditioners, as solvents in cleaners, particularly for electronic circuit boards, as a
blowing agents in the production of foam (for example fire extinguishers), and as
propellants in aerosols. Chlorofluorocarbons are not "washed" back to Earth by rain
or destroyed in reactions with other chemicals. They simply do not break down in the
lower atmosphere and they can remain in the atmosphere from 20 to 120 years or more.
As a consequence of their relative stability, CFCs are instead transported into the
stratosphere where they are eventually broken down by ultraviolet (UV) rays from the
Sun, releasing free chlorine. The chlorine becomes actively involved in the process of

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destruction of ozone [8] The net result is that two molecules of ozone are replaced by
three of molecular oxygen, leaving the chlorine free to repeat the process:
Cl + O3 = ClO + O2
ClO + O = Cl + O2
Ozone is converted to oxygen, leaving the chlorine atom free to repeat the
process up to 100,000 times, resulting in a reduced level of ozone. Bromine
compounds, or halons, can also destroy stratospheric ozone. Compounds containing
chlorine and bromine from man-made compounds are known as industrial
halocarbons. Emissions of CFCs have accounted for roughly 80% of total stratospheric
ozone depletion. The ozone depletion mechanism is shown in figure 2 [8].
Figure 2: ozone depletion by CFC

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Reference
1. Watkiss, P., et al., A Comparative Study of the Environmental Effects of Rail
and Short-haul Air Travel. Report for Commission for Integrated Transport
ED50021 September, 2001.
2. Givoni, M., Aircraft and high speed train substitution: the case for airline and
railway integration. 2005, University of London.
3. Button, K., Transport, the environment and economic policy. Books, 1993.
4. Brons, M., et al., Railroad noise: economic valuation and policy.
Transportation Research Part D: Transport and Environment, 2003. 8(3): p.
169-184.
5. Nijland, H., et al., Costs and benefits of noise abatement measures. Transport
policy, 2003. 10(2): p. 131-140.
6. Dings, J., et al., External costs of aviation. 2002: CE, Solutions for
environment, economy and technology.
7. Van Essen, H., et al., To shift or not to shift, that's the question. The
environmental performance of freight and passenger transport modes in the
policy-making context. 2003, Centre for Energy Conservation and
Environmental Technology CE.
8. Sivasakthivel, T. and K.S.K. Reddy, Ozone layer depletion and its effects: a
review. International Journal of Environmental Science and Development,
2011. 2(1): p. 30.
9. Robinson, S.A. and S.R. Wilson, Environmental Effects of Ozone Depletion
and its Interactions with Climate Change: 2010 Assessment. 2010.
10. Anthony , How green is high-speed rail?
http://edition.cnn.com/2011/11/18/world/how-green-is-hsr/ [cited 30 of May
2016].
11. Svingheim, N. 2014. High-speed rail services can be run on a commercially
viable basis. Jernbaneverket 2012 [cited 10th of May 2014].
12. http://www.ushsr.com/benefits/sustainability.html

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