GLOBAL ENERGY [R]EVOLUTION A SUSTAINABLE GLOBAL ENERGY OUTLOOK
hybrid vehicles Hybrid drive trains consist of at least two different energy converters and two energy storage units. The most common is the hybrid-electric drive train, although there are also proposals for kinetic and hydraulic hybrids. Advantages of the combination of the internal combustion engine with a second source of power arise from avoiding inefficient working regimes of the internal combustion engine (ICE), recuperation of braking energy, engine displacement downsizing and automated gear switch. For hybrid-electric vehicles, there are several different architectures and levels of hybridisation proposed. Hybrid vehicles have been available since the 1990s. In 2006, approximately 400,000 hybrid cars were sold, which is less than 1% of world car production. An increasing number of hybrid models are being announced, however. For this study we have used reference values of 491, 4.592, 8.393 lge/100 km respectively for small, medium and large gasoline vehicles94. For the reference target vehicles in 2050, we have projected the following values, depending on the vehicle segment.
12 cars of the future |
small segment: As explained above, the small segment vehicles will be of the ‘1 litre car’ type - smaller and lighter than today. A dedicated vehicle in the 500 kg class, with three seats and with a highly efficient propulsion system, will be standard by 2050, especially for commuting or other journeys were no multi-purpose family type vehicle is necessary. The fuel consumption for this type of vehicle is projected to be 1.6 lge/100 km. medium segment: We developed our vision of reaching 60 g CO2 per km for the medium segment following the technological building blocks described below, although this might not be the only way to reach the target.
ENERGY [R]EVOLUTION
• A 25% emissions reduction is envisaged by using turbo charging with variable turbine geometry, external cooled exhaust gas recirculation, gasoline direct injection (2nd generation) and variable valve control/cam phase shifting with respective scavenging strategies. These measures all result in a downsizing and down speeding of the engine95. • An additional potential for a 25% saving, related to the previous step, will come from hybridisation and the benefits in terms of start/stop improvements, regenerative braking and further downsizing. Waste heat recovery by thermoelectric generators will contribute to the onboard power supply, which saves an additional 3 to 5%96 97. • A reduction in the vehicle’s mass from 360 kg to 1,000 kg will reduce energy demand by about 18%98. To achieve lightweight construction, methods such as topology optimisation, multi-material design and highly integrated components will be used. Mass reductions of 60 to 120 kg for midsized cars have already been achieved99. The production and recycling processes of lightweight materials such as magnesium and carbon fibres will also be improved in 30-40 years time, thus avoiding a shift in emissions from the utilisation to the production phase. • Aerodynamic resistance, aerodynamic drag and frontal areas offer further potential for improvements. By optimising the car’s underside, engine air flows and contours we project an additional lowering of energy demand by 8%.
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• Rolling resistance depends on the material used for the tyre, the construction of the tyre and its radius, tyre pressures and driving speed. The tyre industry has proposed new concepts for wheels which are intended to lower rolling resistance by 50% by 2030100 101. Reducing the rolling coefficient by 1/1000 will lead to fuel savings of 0.08 l/100 km102. This results in an additional 12% CO2 savings. • Further potentials for energy savings will come from ‘intelligent controllers’ which improve energy management and drive train control strategies by recognising frequently driven journeys. Improved traffic management to help a driver find the energy optimised route might also make a contribution. Other options for hybridisation could come from free piston linear generators, which produce electricity with a constant high efficiency, at the same time avoiding part load conditions because of the variable cylinder capacity103. From the technologies and potentials described here, we project that within the next 40 years an improvement of 64% in energy consumption for hybrid vehicles is achievable, resulting in 2.6 l/100 km or 60 g CO2/km for a middle sized car in the NEDC test cycle. This corresponds to an annual improvement of 2.2%. It is likely that other combinations will lead to similar results, for example by following full hybridisation first, with a potential saving of 44%104[26] and adding complementary measures. We have also applied an 18% increase in fuel consumption based on a realistic assessment of driving patterns. The Volkswagen Golf V FSI 1.6 l, with a 1,360 kg mass and 163 g CO2/km in NEDC was used as a starting point105. large segment: For large vehicles, the same technologies as described for the medium segment can be applied. We believe, however, that the potential for improvements is higher and project fuel consumption in 2050 at 3.5 lge/100 km. In addition, we assume that political measures to reduce the sales of very large SUVs for passenger transport have been introduced, so that the size of vehicles within the segment will also decrease. references 91 OWN ESTIMATE 92 TOYOTA PRIUS II IN NEDC TEST CYCLE 93 LEXUS RX 400 H IN NEDC TEST CYCLE 94 KBA FUEL CONSUMPTION AND EMISSIONS TYPE APPROVAL FIGURES WITH A NATIONAL OR EC WHOLE VEHICLE TYPE APPROVAL, KRAFTFAHRT-BUNDESAMT: FLENSBURG.
95 FRAIDL, G.K., P.E. KAPUS, K. PREVEDEL, AND A. FÜRHAPTER (2007): DI TURBO: DIE NÄCHSTEN SCHRITTE. IN 28. INTERNATIONALES WIENER MOTORENSYMPOSIUM, WIEN: VDI. 96 THACHER, E.F., B.T. HELENBROOK, M.A. KARRI, AND C.J. RICHTER (2006): TESTING OF AN AUTOMOBILE EXHAUST THERMOELECTRIC GENERATOR IN A LIGHT TRUCK. PROC. IMECHE VOL. 221 PART D: J. AUTOMOBILE ENGINEERING. VOL. 221(JAUTO51). 97 FRIEDRICH, H.E., P. TREFFINGER, AND W.E. MÜLLER (2007): MANAGEMENT VON SEKUNDÄRENERGIE UND ENERGIEWANDLUNG VON VERLUSTWÄRMESTRÖMEN, IN DOKUMENTATION CO2 - DIE HERAUSFORDERUNG FÜR UNSERE ZUKUNFT, VIEWEG / GWV FACHVERLAGE GMBH: MÜNCHEN. 98 RELATED TO THE ALREADY LOWER ENERGY USE OF THE PREVIOUS STEP 99 SLC (2007): SUSTAINABLE PRODUCTION TECHNOLOGIES OF EMISSION REDUCED LIGHT-WEIGHT CAR CONCEPTS: SUPERLIGHT-CAR/SLC, COLLABORATIVE RESEARCH & DEVELOPMENT PROJECT CO-FUNDED BY THE EUROPEAN COMMISSION UNDER THE 6TH FRAMEWORK PROGRAMME. 100 MICHELIN (2005): DIE REIFEN-FELGEN-KOMBINATION „TWEEL“ KOMMT VÖLLIG OHNE LUFTDRUCK AUS. PRESS RELEASE. IN NORTH AMERICAN INTERNATIONAL AUTOSHOW (NAIAS). 101 WIES, B. (2007): IST DER GUMMI AUSGEREIZT? PRÄSENTATION IM NATURHISTORISCHES MUSEUM, WIEN, 1. OKTOBER 2007. 102 POSZNANSKI-EISENSCHMIDT (2007): VDA TECHNICAL CONGRESS. 103 ACHTEN, P.A.J., J.P.J.V.D. OEVER, J. POTMA, AND G.E.M. VAEL (2000): HORSEPOWER WITH BRAINS: THE DESIGN OF THE CHIRON FREE PISTON ENGINE, IN SAE TECHNICAL PAPER SERIES, 2000-01-2545; MAX, E. (2005): FREE PISTON ENERGY CONVERTER, IN ELECTRIC VEHICLE SYMPOSIUM 21: MONACO; POHL, S.-E. AND M. GRÄF (2005): DYNAMIC SIMULATION OF A FREE PISTON LINEAR ALTERNATOR, IN MODELICA 2005, SCHMITZ, G.: HAMBURG. 104 SCHMIDT, G. (2006): ANTRIEBE FÜR DEN EUROPÄISCHEN MARKT UND DIE ROLLE VON HYBRIDKONZEPTEN, IN 10. HANDELSBLATT JAHRESTAGUNG AUTOMOBILTECHNOLOGIEN. 105 KBA FUEL CONSUMPTION AND EMISSIONS TYPE APPROVAL FIGURES WITH A NATIONAL OR EC WHOLE VEHICLE TYPE APPROVAL, KRAFTFAHRT-BUNDESAMT: FLENSBURG.