Comparison Between Air And Rail Transport Engineering Essay

Comparison Between Air And Rail exile Engineering EssayIntroductionAccording to the ground Energy Council (WEC, 2011), transport sector global force consumption in 2010 was almost 2,200 million tons of oil equivalent (MTOE), representing about 19% of knowledge base nil resources.Currently, more than 96% of total animation supply to transport comes from oil (WEF, 2011) in 2010, around 60% of oil production worldwide was swal minord by the transport sector (IEA, 2012).In particular, transport accounted for 38% of total energy consumption in the UK in 2011 (DECC, 2012), and for 27.8% in the U.S. the same year (EERE, 2012).Carbon emissions ar closely related to energy consumption in the transport sector and in 2010 it accounted for about 23% of global levels of speed of lightic acid gas emissions (WEC, 211).Economic development and existence appendage are increasing the energy consumption of transport (WEC, 2011) however dependence on oil supplies, inefficient expend of reso urces and associated CO2 emissions make the growth of this sector a completely unsustainable process (WEF, 2011).It is necessary to evaluate the energy strength of transport sector and improve its processes through with(predicate) technology and practice in order to achieve world sustainable development goals.The purpose of this report is to evaluate and compare advertise and rail transport, in terms of their relative workout of energy and their CO2 emissions, and also consider the potential strategies to improve the energy efficiency and reduce CO2 emissions from these modes of transport. Air transport is the fastest-growing mode of transport (WEF, 2011) and it is considered to be, afterwards diesel railway locomotive cars, the most contaminating one (Chapman, 2007) and rail transport is commonly referred to as the cleanest alternative.DefinitionsIt is convenient to clarify some concepts in order to perk up a more precise comprehension of how energy use and energy efficiency are measured in the transport sector, before the analysis of air and rail transport.Energy efficiency is defined as the affinity between the energy consumed and the output produced by that energy (EEDO, 2012 19). When efficiency is high, more products or function can be produced with the same amount energy. This information is useful when comparing similar technologies or processes however, air and rail transport are different technologies that consume energy in different ways to produce the same service, so it is more practical to compare them in terms of energy intensity (EERE, 2012a), which is basically the inverse of energy efficiency and in transport is the amount of energy required to move one passenger over 1 kilometer, or passenger-km (NRC, 2011). For pack transport energy intensity would be energy per ton-km, but this report will focus on passenger transport to reduce the number of variables in intensity calculation and simplify the comparison.Use of energyAs illustra ted in Fig 1., road transport is responsible for the majority of total transport energy consumption in 2010, around 76%, while air transport accounted for about 10% of the total and rail transport for 3% approximately (WEF, 2011).Fig. 1. 2010 Transport energy consumption by mode (total 2,200 MTOE) (WEF, 2011)These percentages represent the absolute values of air and rail transport energy use with respect to total consumption. In order to compare them with respect to each other, it is necessary to analyze first where they take energy from and how each mode of transport invest the energy to be able to move and transport people, in this case, from one location to another.Currently, rail transport energy supply comes mainly from diesel (88%) and electricity (12%) (IEA, 2008). Due to the low resistance of rail vehicles on railways (steel on steel) and high efficiencies of electric and diesel engines, diesel engine efficiency is around 45% (Beggs, 2009), rail transport presents a potentia l advantage over other modes of transport, but the determinant aspects on rail passenger transport efficiency are the services on board, the technology, the vivify of the train and the tenancy (Fraser J., et al 1995).Aerodynamic trains can be very energy efficient compared to previous model, however, when their speed increases over 200 km/h, energy consumption also increases significantly due to air drag (Beggs, 2009).As passenger trains can weight up to 90 tons, the energy efficiency of an inane train is almost the same as if it is full. Intensity increases kJ/p-km as number of passenger decrease therefore energy efficiency is very related to occupancy rates (Fraser J., et al 1995).Fuel accounts for 20% of modern aircraft total operating costs therefore fuel consumption reduction is a priority for aircraft and engine manufacturers to increase energy efficiency (Kahn S., et al 2007).Similarly to trains, aircrafts need to use energy to overcome the air drag force, but, unlike train s, planes also consume energy standing up (Mackay 2008).Studying the relative energy consumption per seat, for a London to Edinburgh journey with different occupancy rates, Kemp (2004) as cited by Beggs (2009), found that rail transport is indeed more efficient than air transport. However, this statement is not true when it applies to rail vehicles travelling at 350 km/h or more, where it consumes pretty more energy than the aircraft, as illustrated in Fig. 2.Fig. 2. Energy consumed by various modes of transport from London to Edinburgh (Beggs, 2011).Carbon emissionsIn the transport sector CO2 emissions are closely related to energy consumption. CO2 emissions from air transport will vary depending on technology, occupancy rat and route (DTF, 2011), although aircrafts produce other nursery gases apart from CO2 such as water , ozone and nitrousoxides (Mackay 2008).The following figure, Fig 3., presents CO2 emissions per passenger-km and per mode of transport in Europe. Rail transport is the uphold less polluting mode of transport and according to the European Environment Agency (EEA, 2011), shifting from diesel to electric trains has decreased the carbon emissions of rail transport by about 27 % from 1995 to 2009. CO2 emissions of air transport have also decreased by 29% due to aircraft technologies improvements and higher occupancy rates.Fig. 3. Specific CO2 emissions per passenger-km and per mode of transport in Europe, 1995-2009 (EEA, 2011)Potential improvementsEnergy efficiencies of air transport can be improved by reducing fuel consumption through aircraft technology improvements, infrastructure improvements, operations improvements and use of biofuels (WEF, 2011). Reducing weight and drag are some of the objectives, although according to Mackay (2008 35) no redesign of a planeis difference to radically improve its efficiency.Regarding rail transport, again, it is important to reduce weight and aerodynamic resistance improving trains infrastructure to re duce energy consumption and carbon emissions. Also, higher efficiency propulsion system and better regenerative brake mechanisms are some of the potential improvements (Kahn et al, 2007).ConclusionsThis report intended to present a general view of the relationship between transport sector and global energy, focusing on a comparison between air and rail transport modes in terms of their use of energy and their CO2 emissions, based mainly on global official energy agencies and organizations.It was found that rail transport appears to use energy more efficiency than air transport, as well as lower CO2 emissions. However, rail vehicles speed and occupancy rates are determinant aspects when evaluating energy efficiency and carbon emissions.In order to evaluate captivately the energy efficiency of modes of transport and present reliable results, it is necessary to consider all the energy system inputs and outputs.With appropriate practices and technology developments it is possible to ac hieve higher transport efficiencies and decrease the environmental impact of the transport sector.