WORLD ENERGY [R]EVOLUTION A SUSTAINABLE WORLD ENERGY OUTLOOK
11.2.3 step 3: efficiency improvements
Energy efficiency improvements are the third important way of reducing transport energy demand. This section explains ways for improving energy efficiency up to 2050 for each type of transport, namely: • air transport • passenger and freight trains
• the usage of electric propulsion technologies comprise advanced lightweight motors, motor controllers and power conditioning equipment.177 The scenario projects a 50% improvement in specific energy consumption on a per passenger-km basis for future aircrafts in 2050 based on 2009 energy intensities. Figure 11.11 shows the energy intensities in the Energy [R]evolution scenario for international, intraregional and domestic aviation.
• trucks • inland navigation and marine transport • cars.
figure 11.11: energy intensities (MJ/p-km) for air transport in the energy [r]evolution scenario
In general, an integral part of an energy reduction scheme is an increase in the load factor – this applies both for freight and passenger transport. As the load factor increases, less vehicles need to be employed and thus the energy intensity decreases when measured per passenger-km or tonne-km. In aviation there are already sophisticated efforts to optimise the load factor, however for other modes such as road and rail freight transport there is still room for improvement. Lifting the load factor may be achieved through improved logistics and supply chain planning for freight transport and in enhanced capacity utilisation in passenger transport.
11 transport | TECHNICAL AND BEHAVIOURAL MEASURES TO REDUCE TRANSPORT
Air transport A study conducted by NASA (2011) shows that energy use of new subsonic aicrafts can be reduced by up to 58% up to 2035. Potentially, up to 81% reduction in CO2 emissions are achievable when using biofuels.176 Akerman (2005) reports that a 65% reduction in fuel use is technically feasible by 2050. Technologies to reduce fuel consumption of aircrafts mainly comprise: • Aerodynamic adaptations to reduce the drag of the aircraft, for example by improved control of laminar flow, the use of riblets and multi-functional structures, the reduction in fasteners, flap fairings and the tail size as well as by advanced supercritical airfoil technologies. • Structural technologies to reduce the weight of the aircraft while at the same time increasing the stiffness. Examples include the use of new lightweight materials like advanced metals, composites and ceramics, the use of improved coatings as well as the optimised design of multi-functional, integrated structures. • Subsystem technologies including, for example, advanced power management and generation as well as optimised flight avionics and wiring. • Propulsion technologies like advanced gas turbines for powering the aircraft more efficiently; this could also include: • improved combustion emission measures, improvements in cold and hot section materials, and the use of turbine blade/vane technology;
6 5 4 3 2 1 MJ/p-km 0 International
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Domestic
2009 REFERENCE 2050 ENERGY [R]EVOLUTION
All regions have the same energy intensities due to a lack of regionally-differentiated data. Numbers shown are the global average. Passenger and freight trains Transport of passengers and freight by rail is currently one of the most energy efficient means of transport. However, there is still potential to reduce the specific energy consumption of trains. Apart from operational and policy measures to reduce energy consumption like raising the load factor of trains, technological measures to reduce energy consumption of future trains are necessary, too. Key technologies are: • reducing the total weight of a train is seen as the most significant measure to reduce traction energy consumption. By using lightweight structures and lightweight materials, the energy needed to overcome inertial and grade resistances as well as friction from tractive resistances can be reduced. • aerodynamic improvements to reduce aerodynamic drag, especially important when running on high velocity. A reduction of aerodynamic drag is typically achieved by streamlining the profile of the train. • switch from diesel-fuelled to more energy efficient electrically driven trains.
• investigation of all-electric, fuel-cell gas turbine and electric gas turbine hybrid propulsion devices; references 176 BRADLEY & DRONEY, 2011. 177 IBIDEM.
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Intra