Personal Cars and China (2003) / Chapter Skim
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4. Present and Future Automotive Technologies
4. Present and Future Automotive Technologies
Pages 61-112
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From page 61... ...
This chapter describes the automotive technology options that are available today and some that may become available in the longer term, and it comments on their applicability to the development of China's automotive industry and road transportation fleet. The choice of automotive technology is closely related to the kinds of materials and fuels selected, the economic impacts of the technology, and infrastructure requirements.
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From page 62... ...
The European Unions has been enacting increasingly stringent emissions standards and now requires Euro III standards for its member nations, with Euro IV standards planned for implementation in Europe in 2005. State plans call for Chinese cars to attain the current Euro emissions standards by 2010.
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From page 63... ...
But these cars have poor fuel efficiency at low speeds and continue to burn fuel at a high rate when idling in urban traffic jams. Cars designed specifically for urban driving cycles could be much more fuel-efficient under these conditions.
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From page 64... ...
In urban driving, conventional engines continue to run, using energy and producing emissions, even if a vehicle is stopped or moving slowly in traffic. Because any comparison of vehicle options must take into account the typical local driving conditions, when emissions standards are set they are based on a specified "driving cycle." Figure 4-1 presents four examples of driving cycles specified by regulatory groups in the United States, Japan, and Europe.
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From page 66... ...
In the future, however, China may choose to implement new standards, with a driving cycle and emissions standards suited to its specific environment. Energy Use and Fuel Economy The energy use of a vehicle fleet depends on the size, weight, type, and efficiency of vehicles in the fleet and on the driving conditions encountered in their use.
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From page 67... ...
Veh c e — distribution, repair, and maintenance Vehicle | | purchaser or user ( Scrapping ` ~ recycling J FIGURE 4-2 Steps in the life cycle of automotive technology. SOURCE: Weiss et al.
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From page 68... ...
But because forecasting technology some 20 years in the future involves some uncertainty, the forecasts here related to evolutionary and advanced body combustion engine cars are subject to underestimation or overestimation by about 10 percent; the hybrids by about 20 percent, and the fuel cell and electric vehicles by about 30 percent. The uncertainties are greater for the rapidly evolving technologies because of the possibilities of technological breakthroughs or the identification of unanticipated barriers.
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From page 69... ...
However, the energy associated with producing a synthetic fuel by a Fischer-Tropsch process adds substantially to life cycle energy use, which is related to GHG emissions as well. The energy production requirement for electric vehicles is based on the mix of energy sources and power generation efficiencies of the U.S.
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From page 70... ...
AB = advanced body; F-T = Fischer-Tropsch; CNG = compressed natural gas; FC = fuel cell; MeOH = methanol; H2 = hydrogen; "C/km = grams carbon per kilometer. SOURCE: Weiss et al.
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From page 72... ...
For fuel cell vehicles, the total operating costs vary from the baseline of about 0.30 per kilometer to about $0.37 (RMB2.5-3.1) per kilometer.
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From page 73... ...
A partial hybrid that shuts the engine on and off in stop-and-go traffic can achieve some of the emissions reductions and energy savings of a true hybrid, with only a modest impact on cost. · The diesel engine offers some improvements in efficiency at a somewhat higher cost, but challenges remain as to whether it can meet emerging emissions standards for nitrogen oxides and particulates.
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From page 74... ...
NOTE: Improvements in power train efficiency also increase fuel economy. SOURCE: Horton and Compton (1984~.
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From page 75... ...
. Drag reduction is most important during high-speed driving conditions.
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From page 76... ...
Gasoline internal combustion engines (ICEs) burn air-fuel mixtures using spark ignition (SI)
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From page 77... ...
Although diesel engines were once prone to produce more noise and vibration than gasoline engines similar in size, recent design developments have produced smooth running, quiet diesel engine configurations that are barely distinguishable from gasoline engines (Flynn, 2000~. New diesel engines incorporate a wide variety of technologies that improve performance and fuel economy and reduce emissions.
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From page 78... ...
from the engine as a 0.4 0.2— oFuel cell propulsion system l l l I ' Diesel propulsion system .' Spark ignition ,~ / propulsion system 0 10 20 30 40 50 60 Power (kilowatts) FIGURE 4-6 Comparisons of power train efficiency of combustion engine and fuel cell systems.
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From page 79... ...
Figure 4-7 shows a typical performance map for a spark ignition engine. Performance maps depict how efficiency varies throughout the range of operation associated with particular driving cycles, with various patterns of requirements for power and acceleration.
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From page 80... ...
If low-octane fuels such as diesel are used, the pressures and temperatures at which these knock-like reactions take place are too low to allow compression and expansion ratios of above 8:1. Because these expansion ratios are similar to those in gasoline engines, the fuel economy of the cycle using diesel as its main fuel would be similar to that in gasoline engine operation, but without the output of the usual pollutants.
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From page 81... ...
Most fuel cells, especially those for transportation applications, operate with hydrogen fuel that can be either stored on board or chemically reformed from gasoline or other liquid hydrocarbon fuels. Liquid methanol can be used as a direct fuel for a fuel cell, but the technology is still far behind the hydrogen fuel cell technology.
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From page 82... ...
This level is well below peak efficiency for the gasoline and diesel engines, but it is where the fuel cell is most efficient. Thus potentially a fuel cell vehicle can be much more efficient than its internal combustion engine counterparts.
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From page 83... ...
for 400 miles (Ashley, 2001~. The comparison in Table 4-3 assumes that the hydrogen fuel cell vehicles are about twice as efficient as diesel vehicles.
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From page 85... ...
. Emissions Control Systems Gasoline Spark Ignition Emissions For gasoline internal combustion engines, three-way catalyst systems are highly effective (99+ percent)
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From page 86... ...
lust as for the gasoline engine, meeting the most rigorous of the emissions standards proposed today will require applying exhaust aftertreatment devices to diesel engines to bring their emissions of nitrogen oxides, unburned hydrocarbons, and particulates to the desired low levels. Because the exhaust of a diesel engine is cooler and contains more oxygen than that of a gasoline engine operating under stoichiometric conditions, removing the pollutants from the exhaust of a diesel requires a somewhat different technology.
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From page 87... ...
Diesel engines also have particulate emissions. The rich combustion process converts a significant portion of the carbon mass in the fuel to particulate precursors.
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From page 88... ...
Meeting Future Emissions Standards For diesel engines, both the particulate and NOx aftertreatment systems are likely to require active management of the exhaust system temperature and the fuel/air ratio. Presently, such systems are in their earliest demonstration phases, and much work remains to determine whether they can be produced for a wide range of operating requirements and environments.
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From page 89... ...
might have difficulty meeting the Euro III diesel standard, but if the mileage for that diesel engine were improved to 40 mpg, it could clearly meet the proposed Euro III diesel standard. Figure 4-11 indicates that some level of exhaust aftertreatment would be required to remove nitrogen oxides for diesel engines as the emissions limits are lowered.
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From page 90... ...
emissions standards versus capability. NOTE: SI = spark ignition; EGR = exhaust gas recirculation.
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From page 91... ...
For vehicles that use electric motors for propulsion, such motors could, in addition to powering accessories, serve as the starter-generator and support regenerative braking, producing higher efficiencies over a wider speed range. The traction motors, however, are still in the developmental stage.
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From page 92... ...
Electronic Controls Because they provide the increased sophistication needed to meet higher emissions standards while providing good fuel economy and good vehicle drivability, electronic controls have become ubiquitous in modern automobile technology. In fact, in recent years these controls have evolved to digital systems that are fully programmable.
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From page 93... ...
Fuels and Onboard Fuel Storage Present Fuel Technologies China's present road transportation sector is almost completely dependent on petroleum fuels, with some very limited use of electricity and compressed natural gas. Gasoline and diesel fuels are used widely in motorized vehicles because of their high energy storage density, compact and lightweight storage systems, and low cost relative to other fuels.
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From page 94... ...
will evolve from its current properties toward very low sulfur content, with possible changes in volatility, polynuclear aromatics, cetane, and other specifications Some of the near-term alternative fuels might be feasible in China. Natural gas is being used now as compressed natural gas in limited quantities for bus and taxi fleets in specific locations such as Beijing.
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From page 95... ...
Although other technologies are being developed, nickel metal hydride (NiMH) batteries are the technology of choice for automotive applications today, both for hybrids and electric vehicles.
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From page 96... ...
Table 4-4 lists the time and fuel use shares during 2 For hybrid systems, which are discussed next in this chapter, only the battery's specific power is critical, because discharged batteries can be recharged during operation of the internal combustion engine. High-power hybrid electric vehicle NiMH batteries currently have a specific power of about 400 W/kg and a specific energy of about 40 Wh/kg (at a 3hour rate.)
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From page 97... ...
The most efficient hybrid vehicle configuration also captures the regenerative energy from braking the car and uses it to recharge the battery. This type of hybrid offers major improvements in efficiency in urban driving cycles and results in lower total emissions because of the smaller engine which is switched off at idle if the battery system is fully charged.
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From page 98... ...
It differs in that a planetary gear system combined with a starter-generator can transfer power between the internal combustion engine and electric motor, both of which are coupled to the drive shaft. In this configuration, the internal combustion engine provides the primary power, with a power-split device (planetary gear with starter-generator)
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From page 99... ...
Batteries are certainly a major cost factor for all hybrids, and so like pure electric vehicles energy hybrids will carry a very substantial cost premium for the foreseeable future. A full hybrid is considered a more radical change than the other hybrids from the conventional internal combustion engine vehicle, whereas a mini or mild hybrid is considered a more natural evolution from a conventional vehicle, resulting from a historical trend of increasing vehicle onboard electric power.
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From page 100... ...
Comparing Commercial and Concept HEVs In recent years vehicle manufacturers have made great progress in developing and demonstrating commercially available and concept hybrid electric vehicles. These vehicles include commercially available gasoline hybrid cars (Toyota Prius and Honda Insight)
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From page 101... ...
Assessing the Benefits of Hybrid Vehicle Fuel Economy Because PNGV and other hybrid vehicles have such expensive drive trains, they have employed unprecedented levels of conventional vehicle fuel economy technologies such as aggressive load reduction measures. These measures include reducing weight and improving air/tire resistance as well as using lightweight materials and diesel engines to reduce weight.
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From page 102... ...
102 CD o 1 · o En ~ use ¢ ~ V)
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From page 103... ...
First, hybrid benefits depend strongly on the driving cycle. The fuel economy benefits of hybrid electric vehicles are much higher under stop-and-go traffic conditions than under free-flow highway driving conditions.
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From page 104... ...
The benefits and TABLE 4-6 Trade-offs for Hybridizing Fuel Cell Vehicles Trade-off Fuel Cell Vehicles Hybrid Fuel Cell/Battery Fuel cellstack High Reduced because of downsizing ''.
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From page 105... ...
Hybrid electric vehicles are many years from taking a significant market share from the conventional internal combustion engine vehicles. In turn, the economies of scale needed to reduce their cost disadvantage probably will not be realized for many years.
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From page 106... ...
Furthermore, because of the high cost of the facilities, several vehicle manufacturers may use the same components purchased from external suppliers, allowing an economy of scale in production that benefits all participants. As noted in Chapter 3, component suppliers Robert Bosch, Engelhard, and Corning already have subsidiaries in China that are following this pattern.
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From page 107... ...
A near-term focus on more conventional technologies still allows many opportunities for innovations that will enhance the competitiveness of a China car. APPENDIX: OTHER TYPES OF FUEL CELLS Of the many types of fuel cell, some are being developed for stationary power generation.
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From page 108... ...
Molten carbonate fuel cells, which promise high fuel-to-electricity efficiencies, operate at about 1,200°F or 650°C. To date, molten carbonate fuel cells have been operated using hydrogen, carbon monoxide, natural gas, propane, landfill gas, marine diesel, and simulated coal gasification products.
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From page 109... ...
Still a very young member of the fuel cell family, regenerative fuel cells would be attractive as a closed-loop form of power generation, in conjunction with a solar power source. Solar power can be converted directly to electricity, but there may be applications where the energy losses associated with a regenerative fuel cell are justified.
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From page 110... ...
2001. Technology Options for Improving the Fuel Economy of U.S.
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From page 111... ...
1998. Handbook of Air Pollution from Internal Combustion Engines: Pollutant Formation and Control.
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From page 112... ...
2000. The Innovation Process from the Internal Combustion Engine to Fuel Cells.
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