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Sustainability of HSR as a mass transportation mode in terms of efficient use of natural resources




                   Security of supply becomes a matter of political priority, which in turn leads to conflicts. World
                   oil demand increased by 38% between 1983 and 2006, and with the increase in demand comes
                   increases in global geopolitical instability (Cox, 2010). There are potential security threats to
                   many higher motorised economies. Liquid fuels will be running out in about forty years, gaseous
                   fuels in about sixty years and even coal has only around two hundred and fifty years of practical
                   extraction (The Railways, Challenges to Science and Technology, 1995). The way forward is to
                   develop and use advanced technology to cut fuel consumption and to produce less polluting
                   vehicles coupled with effective measures to promote the shift of traffic from road to railways.
                   However, transport is almost totally dependent on oil for energy as 95% of the total amount
                   of transport around the world depends on fossil fuels (Watson, et.al., 2016) and it seems that
                   there is little prospect for a major change even if oil prices rise substantially. HSR is a good
                   alternative to road transport as it is powered by electricity and the proportion of renewable
                   energy increases year by year. Some of HSR systems such as in Sweden is powered by 100%
                   renewable energy.
                   Railways have the significant advantage over road and air transport, as electrified railways
                   can use different types of energy; nuclear, wind, solar, water, oil. With the increasing use of
                   renewable energy sources, railways are getting more environmentally friendly. It was estimated
                   that using an airline will take 3 hours 50 minutes to get from Los Angeles city centre to San
                   Francisco  city  centre  but  using  a  train  will  take  3  hours  2  minutes.  The  fuel  consumption
                   difference will be more dramatical. One passenger uses 10.56 gallons of aviation fuel flying but
                   travelling  by  train  requires  only  0.74  gallon  of  fuel  (www.1001-home-efficiency-tips.com.l).
                   Fuel consumption difference is more than 14 times in favour of a train.

                   The energy consumption of a high-speed train depends on a number of factors including technical
                   characteristics of train, layout of line and number of stops. The number of curves and their radii
                   and length, the gradients of line and other factors can affect the train energy consumption.
                   Reducing the number of curves can increase the speed of a train and in its turn a train uses less
                   energy. Using regenerative brakes, high speed trains can recover some of the energy dissipated
                   by braking and this energy can be used by other trains or can be returned to the power network.
                   Improving the aerodynamics of trains can sufficiently reduce energy consumption. There is an
                   energy loss during the transmission and transformation from the power station to the train,
                   but there is a big difference in the losses for high speed lines electrified at 25kV and at 3kV as
                   the loss for a line voltage of 25kV is lower than that 3kV. There is a need to provide 8.8% more
                   electricity through a pantograph to operate a train at 25kV compared with 22.6% to operate a
                   train at 3kV (Garcia, 2010).

























                       Figure 4.1 Passenger-kilometres carried per unit of energy by different transportation modes (Source: www.ushsr.com)


                   International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor  397
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