Energy and the Environment

1. Energy and the Environment Fall 2014 Instructor: Xiaodong Chu Email：chuxd@sdu.edu.cn Office Tel.: 81696127, 13573122659

2. Transportation: Vehicle Power and Performance • The transmission is a device attached to the engine that provides stepped speeds to the drive shaft that connects it to the wheels • There are two forms of transmission: manual and automatic • In a manual transmission, the vehicle operator disengages a clutch (脱开离合器)and manually shifts to a different gear before engaging the clutch again • In an automatic transmission, a fluid coupling (液压耦合装置) replaces the clutch and gear shifting (换档) is accomplished by computer-controlled hydraulic actuators(液压执行器) • The more operator-friendly automatic transmission is less efficient than the manual one by about 10 percentage points

3. Transportation: Vehicle Power and Performance Transmission with a five-speed + reverse gearbox

4. Transportation: Vehicle Power and Performance • The drive shaft (驱动轴) connecting the engine/transmission to the wheels, either front or rear (or both in the case of four-wheel drive), utilizes a differential gear (差速器) to apply equal torque to both drive wheels (驱动轮)while allowing different wheel speeds during maneuvering • The drive shaft provides for the vertical motion of wheels with respect to the chassis (底盘) and for the steering motion (转向运动) when using a front-wheel drive

5. Transportation: Vehicle Power and Performance

6. Transportation: Vehicle Power and Performance • For constant-speed travel, the engine power demand rises rapidly with vehicle speed, as the aerodynamic drag outpaces rolling resistance • At any vehicle speed, the vertical distance between the “demand” (dash–dot) curve and the “maximum supply” (solid) curve is the maximum power available for vehicle acceleration and hill climbing

7. Transportation: Vehicle Power and Performance • At low vehicular speeds, this difference is greatest for the lowest shift level (变速级), while at the highest speed this difference is least, shrinking to zero at the vehicle’s top speed • The lower gear levels are needed to provide high acceleration at low vehicular speed

8. Transportation: Vehicle Power and Performance • Only a small fraction of the maximum engine power is used at steady vehicle speeds, reaching about 40% at cruising speed (巡航速度) and the remainder is available for acceleration and hill climbing • For average vehicle duty cycles, only a fraction of the time is used in acceleration, and the portion of that at which the engine power is a maximum is small • The vehicle capacity factor, the time-averaged fraction of installed power that is utilized by a moving vehicle, is less than 50%for the average duty cycle • Nevertheless, for satisfactory performance reserve power is required over the normal speed range of the vehicle

9. Transportation: Vehicle Power and Performance • For a steady vehicle speed, the engine relative efficiency is at best 50% for speeds less than half the cruise speed, rising to about 80% at cruise speed • The normal practice of downshifting (降档) at low speeds leads to even lower relative efficiencies • Taking into consideration the short periods of acceleration within a typical driving cycle, the time-averaged relative engine efficiency is certain to be less than 80% • A method is to employ a continuously variable transmission (连续变速传动)that can reach higher relative engine efficiencies over a range of steady speeds, but will downshift when acceleration is needed

10. Transportation: Vehicle Power and Performance Variable-diameter pulley for CVT

11. Transportation: Vehicle Fuel Efficiency • Traditionally, the efficiency of use of fuel by a vehicle is measured by the distance it moves in a trip divided by the fuel consumed • The vehicle’s fuel efficiency determines both the fuel cost of the trip and the accompanying carbon emissions to the atmosphere • The vehicle operator is concerned with the fuel cost while national authorities are concerned with the effects of aggregate vehicular fuel consumption on the problems of maintaining a reliable fuel supply and, most recently, on the contribution of vehicles to the national budget of greenhouse gas emissions

12. Transportation: Vehicle Fuel Efficiency • In the United States, fuel efficiency of new passenger vehicles and light trucks is regulated by the National Highway Traffic Safety Administration of the U.S. Department of Transportation, which had its origin in the oil shortages of the 1970s caused by an embargo on oil exports by OPEC nations • To ameliorate the nation’s future dependence upon imported oil, Corporate Average Fuel Economy (CAFE) standards were promulgated, beginning with the 1978 model year • These standards required automobile manufacturers to design vehicles so that their sales-averaged vehicle fuel economy did not exceed the level designated for each of two vehicle classes: passenger vehicles and light trucks (pickup trucks, vans, sport utility vehicles)

13. Transportation: Vehicle Fuel Efficiency • Could you please make a survey on China vehicle fuel efficiency regulations?

14. Transportation: Vehicle Fuel Efficiency • The measurement of vehicle fuel economy is based upon dynamometer (测功机) simulations of typical driving cycles for urban and highway travel, originally devised by the U.S. EPA for evaluating vehicle emissions (Urban Dynamometer Driving Schedule, UDDS) • The test vehicle is operated in a stationary position, while the drive wheels turn a dynamometer that is adjusted to provide the air resistance and acceleration/deceleration loads • While the dynamometer does not precisely simulate these forces at each point in the test, it suffices to provide a reasonable average for characterizing the emissions and fuel economy of the test cycle

15. Transportation: Vehicle Fuel Efficiency • Two test cycles are used for measurements of vehicle fuel efficiency, one for urban driving and the other for highway travel

16. Transportation: Vehicle Fuel Efficiency • There are two major methods to improve vehicle fuel efficiency: improvements to the vehicle design and to the power source

17. Transportation: Vehicle Fuel Efficiency • There are three major parameters for improving vehicle performance, which are vehicle mass m, rolling resistance coefficient CR, and the vehicle drag area CDA

18. Transportation: Vehicle Fuel Efficiency • Vehicle Mass: In current conventional vehicles, mass is the parameter that best correlates fuel economy • Large, heavy vehicles require big engines to perform well; they consequently consume more fuel • For a given vehicle size, reducing vehicle mass will permit reductions in engine and transmission mass, tire and wheel mass, braking system mass, fuel storage mass, steering system mass, engine radiator (发动机散热器) mass, and so on, compounding the gains in direct mass reduction of the vehicle frame(车架)

19. Transportation: Vehicle Fuel Efficiency • The principal means for reducing mass is the substitution of lighter materials of equal strength and stiffness(强度和刚度), such as aluminum alloys or fiber-reinforced plastic for steel and plastic for window glass, as well as the redesign of the vehicle structure to minimize structural mass • Reducing vehicle mass by material substitution (材料替代) may have implications for vehicle safety • Vehicle frames are designed to absorb the vehicle’s kinetic energy in a crash while protecting the occupants from harm • In a two-vehicle collision of vehicles of unequal mass, the lighter vehicle absorbs more than its own kinetic energy and thereby suffers a safety disadvantage

20. Transportation: Vehicle Fuel Efficiency • Aerodynamic Resistance: Reduction of aerodynamic resistance is limited to lowering the drag coefficient CDby careful streamlining of the entire body, because the frontal area A is essentially fixed by the requirements of providing an enclosure for the passengers • The bulky form of the automobile limits what can be done to reduce aerodynamic drag, but attention to details can bring the drag coefficient into the range of 0.20–0.25 for passenger vehicles

21. Transportation: Vehicle Fuel Efficiency • Rolling Resistance: The rolling resistance coefficient CR can be lowered to 0.005 from current values of 0.010–0.014 by improvements in tire design, but it is difficult to maintain durability, performance, and safety (traction) while reducing rolling resistance • Light alloy wheels reduce sprung mass, which is desirable, but more complex suspension systems (悬挂系统) will be needed to recover normal performance with low-resistance tires

22. Transportation: Vehicle Fuel Efficiency • There are several paths to improving the efficiency of engines while supplying the requisite power needed by the vehicle • One is to improve the fuel (or thermal) efficiency of the engine, especially at off-optimum conditions where the engine is usually operated • A second is to utilize transmissions that permit the engine to maximize its efficiency for a required power output • A third is to reduce engine mass, for a given power, so as to improve vehicle efficiency • However, there are serious constraints imposed on engine efficiency improvements by the requirements for limiting exhaust pollutant emissions

23. Transportation: Vehicle Fuel Efficiency • Reducing Intake Stroke Losses in SI Engines: At partial load the cylinder pressure during the intake stroke is lowered to reduce the fuel amount in the cylinder, resulting in a loss of efficiency • This loss may be offset by varying the timing of the inlet and exhaust valves with the engine load • Variable valve timing (VVT) systems (可变气门正时系统) are currently used in four-valve engines, adding to the peak power output and engine mass reduction benefit • Another alternative is direct fuel injection (DI) into the cylinder during the intake stroke, forming a non-uniform fuel–air mixture at higher overall pressure and lower intake stroke power loss • The recirculation of exhaust gas into the cylinder during the intake stroke so as to reduce exhaust pollutant emissions can be arranged to reduce intake losses and improve engine efficiency at part load

24. Transportation: Vehicle Fuel Efficiency • Replacing SI Engines by CI Engines: The indirect injection CI engine enjoys about a 25%advantage in fuel economy over the SI engine and does not suffer as much efficiency loss at part load as does the SI engine • Direct injection CI engines have even higher fuel economy advantage, about 30–40% Indirect injection CI Direct injection CI

25. Transportation: Vehicle Fuel Efficiency • On the other hand, the CI engine is heavier, for a given power, thereby incurring a vehicle mass efficiency penalty, and is more expensive • It is more difficult to reduce NOx and particulate emissions in the CI engine

26. Transportation: Vehicle Fuel Efficiency • Supercharging(增压): Both SI and CI engines can be supercharged (or turbocharged) to increase maximum engine power for a given displacement and engine mass, with some improvement in engine efficiency at higher loads

27. Transportation: Vehicle Fuel Efficiency • Continuously Variable Transmission: The traditional multistep transmission does not permit the engine to operate at maximum thermal efficiency over the entire vehicle duty cycle • Indeed, the engine seldom operates at best efficiency • A continuously variable transmission (CVT) can be controlled to maximize the engine efficiency at any power level needed by the vehicle • Current CVT transmissions have shown that overall vehicle efficiency can be improved, provided that the transmission efficiency is close to that of conventional transmissions

28. Transportation: Vehicle Fuel Efficiency • Engine Idle-Off(发动机怠速关闭): In congested urban driving, considerable time is spent with the engine idling while the vehicle is stationary • If the engine is stopped during these intervals, fuel will be saved and exhaust emissions will be reduced • However, stopping the engine and restarting also consumes fuel, so that the length of the idle period has to be sufficient for there to be a fuel reduction in idle-off control

29. Transportation: Electric Drive Vehicles • In the earliest years of the development of the automobile, some were powered by electric drive motors (电力驱动电机) energized by lead-acid storage batteries (铅酸蓄电池) • In the last few years, advances in energy storage systems and the energy savings to be made by storing vehicle braking power make such vehicles attractive from both the emissions and vehicle efficiency point of view

30. Locomotives Golf Carts Fork Lifts Busses Nuclear Submarines Elevators Transportation: Electric Drive Vehicles

31. Hydrogen Fuel Cell Solar Racer Hybrid MIT CityCar Full-Size Battery Electric Neighborhood Electric Transportation: Electric Drive Vehicles

32. Transportation: Electric Drive Vehicles • 1830’s • Battery electric vehicle invented by Thomas Davenport, Robert Anderson, others - using non-rechargeable batteries • Davenport’s car holds all vehicle land speed records until ~1900 • 1890’s • EV’s outsold gas cars 10 to 1, Oldsmobile and Studebaker started as EV companies • 1904 • Krieger Company builds first hybrid vehicle • 1910’s • Mass-produced Ford cars undercut hand-built EV’s Ford Electric #2 Detroit Electric

33. Battery Fuel Battery Fuel Motor/Generator Engine Motor/Generator Engine Transmission Transmission Transmission Transportation: Electric Drive Vehicles Conventional Hybrid Battery Electric

34. Transportation: Electric Drive Vehicles Well-to-Tank Tank-to-Wheels 31% 23% Generation 33% Transmission 94% Plug-to-Wheels 76% 31% 76% = 23% Refining 82% Transmission 98% Pump-to-Wheels 16% 13% 80% 80% 16% = 13%

35. Transportation: Electric Drive Vehicles • Several manufacturers currently produce passenger cars (乘用车)and pickup trucks that are battery-powered • They have limited passenger- or freight-carrying capability compared to conventional vehicles and have much smaller travel range between recharges of the onboard (车载) energy supply • These vehicles are powered by AC induction motors (交流感应电动机) drawing their power from battery banks • The traction motor (牵引电机) can regenerate a partial battery charge during periods of vehicle deceleration

36. Transportation: Electric Drive Vehicles EV electric vehicle EVSE electric vehicle supply equipment Power Protections AC Power Supply Pilot Inverter AC charging plug On board charger AC charging cable DC charging plug Motor Battery

37. Transportation: Electric Drive Vehicle

38. Transportation: Electric Drive Vehicles • The limited range of current battery-powered electric vehicles is tied to the low energy storage densities of currently available batteries

39. 340kg 2.7 kg Transportation: Electric Drive Vehicles Gas 1 Gallon Batteries 21 Li-ion batteries(Car battery size) 135 MJ of energy

40. Transportation: Electric Drive Vehicles • Limited Range • Large battery weight/size • Long Charge times • High initial cost • Battery life • Consumer acceptance • Grid Integration

41. Transportation: Electric Drive Vehicles • Hybrid vehicles are those that combine conventional power sources (SI or CI engines) with electric motors to power the vehicle • The motor/generator can store energy in a battery bank when excess power is available, during deceleration or when the power need is less than what the combustion engine can deliver, and can deliver extra power to the wheels when it is temporarily needed for acceleration or hill climbing

42. Transportation: Electric Drive Vehicles • Hybrid vehicles are more fuel efficient (for equal mass) • This substantial advantage of the hybrid over conventional design of equal mass is a composite of braking energy recovery, more efficient engine operating conditions (despite the same driving cycle), and possibly a higher peak engine efficiency

43. Transportation: Electric Drive Vehicles

44. 2009 2010 2011 2012 Tesla Model S Cadillac XTS PHEV Sport/Luxury Tesla Roadster Volvo V70 PHEV Audi A1 PHEV Fisker Karma Porsche 918 PHEV Compact Toyota Prius Wheego LiFe Mini EV Honda insight PHEV Zenn EV Think City Mitsubishi i-MiEV Smart for two Sedan/SUV GM Volt Nissan Leaf Coda EV Toyota Rav4 EV BYD e6 EV Ford Focus EV Light Trucks Smith Electric Edison Navistar eStar Ford Transit Connect Mercedes Vito E-cell Renault Kangoo Bright Auto Idea Transportation: Electric Drive Vehicles

45. Transportation: Electric Drive Vehicles Battery Electric Vehicles (BEV): 2010 Coda Automotive Sedan 2010 Mitsubishi iMiEV BEV 2010 Nissan LEAF 2010 Ford Battery Electric Van 2010 Tesla Roadster Sport EV 2010 Chevy Volt Extended Range EV 2011 Peugeot Urban EV* 2011 Renault Kangoo Z.E. 2011 Renault Fluence Z.E. 2011 Tesla Model S 2011 BYD e6 Electric Vehicle 2011 Ford Battery Electric Small Car 2011 Opel Ampera Extended Range* 2012 Fiat 500 minicar 2012 Renault City Car* 2012 Renault Urban EV* 2012 Audi e-tron 2013 Volkswagen E-Up* 2016 Tesla EV Hybrid Electric Vehicles (PHEV): 2010 Lexus HS 250h 2010 Mercedes E Class Hybrid 2010 Porsche Cayenne S Hybrid 2010 Toyota Camry Hybrid 2010 Toyota Prius Hybrid 2011 Audi A8 Hybrid (likely introduction) 2011 BMW 5-Series ActiveHybrid 2011 Honda CR-Z sport hybrid coupe 2011 Lexus CT 200h Hybrid Hatchback 2011 Peugeot Diesel Hybrid* 2011 Suzuki Kizashi Hybrid 2011 Audi Q5 Crossover Hybrid 2011 Hyundai Sonata Hybrid 2011 Infiniti M35 Hybrid 2014 Ferrari Hybrid

46. Americas Europe Asia United States Offers up to $7,500 for qualified vehicles (Chevrolet Volt, Nissan Leaf, Coda sedan, Tesla Roadster). $2.8 billion overall budget allocated. Canada Plans to have 1 in 20 vehicles driven in Ontario to be electrically powered by 2020. Quebec offers up to $8,000. MexicoMexico City signed an agreement with Nissan to deliver recharging infrastructure for EVs in 2011. BrazilPlans to develop electric vehicles and build solar-powered charging stations in near future. United Kingdom Offers £ 5,000 max or 25% of retail. Plans to have more than 1,000 electric vehicles for its fleet and 25,000 charging points by 2015 to support running of a target 100,000 electric vehicles. France Offers €5000 or 20% of retail, valid up to 2012. Offers up to 1,000 charging stations. €400 million budget allocated for incentives, technology, and infrastructure. Germany €3,000 to 5,000 for the first 100,000 vehicles. €500 million budget allocated for EV incentives, technology, and infrastructure. China Offers up to USD $8,800 in subsidies. Plans to invest USD $15 billion to help domestic automakers put 20 million fuel-efficient vehicles on China’s roads by 2020. IndiaOffers $2,200 or 20% of retail for electric vehicles, plus other smaller subsidies for electric 2-wheelers which is majority of the market. JapanEnforces periodic vehicle inspection, testing, and taxation based on engine size to drive adoption. By 2020, 1 in 5 will be an EV vehicle. ¥106 billion budget allocated. Transportation: Electric Drive Vehicles

47. Transportation: Electric Drive Vehicles • Prototypes of electric drive vehicles whose electric power is supplied by fuel cells have been under development for several decades • Such vehicles could potentially provide higher vehicle fuel efficiencies than conventional vehicles with little or no air pollutant emissions

48. Transportation: Electric Drive Vehicles • The most economical and energy efficient source of hydrogen, a synthetic fuel, is by reforming from a fossil fuel such as natural gas, oil, or coal, or from another synthetic fuel like methanol or ethanol • The reforming operation preserves at best only 80% of the parent fuel’s heating value • If hydrogen is liquified for storage on the vehicle, rather than being stored as a compressed gas in tanks, an additional energy penalty of about 30% is incurred because energy is needed to liquify hydrogen at the very low temperature of −252.8◦C • The synthetic fuel transformation penalties diminish the fuel efficiency advantage of fuel cells compared to conventional internal combustion engines in vehicles fueled by conventional hydrocarbon fuels

49. Transportation: Vehicle Emissions • By the middle of the twentieth century, vehicle exhaust emissions (废气排放/尾气排放) were recognized to be an important contributor to urban photochemical air pollution (光化学的空气污染), e.g., high level of ground ozone concentrations(臭氧浓度) • These problems are more acute in lower latitude locations, especially in developing countries where vehicle emission controls are not yet stringent • Vehicles are mobile and more numerous than stationary sources(固定污染源), and they present different problems for abatement(消减) • It is more effective to require a few vehicle manufacturers to install control equipment on millions of new vehicles rather than to require millions of vehicle owners to try to reduce their own vehicle’s emissions

50. Transportation: Vehicle Emissions • Vehicle emissions to the atmosphere are of two kinds: exhaust emissions (废气排放/尾气排放) and evaporative emissions(蒸发排放) • The first are the combustion gases (燃烧气体)emitted while the engine is running • The second are emissions of fuel vapors (燃油蒸气)from the fuel supply system and the enginewhen the engine isnot operating • The federal government regulates both of these emissions by requiring the manufacturers of new vehicles sold in the United States to provide the technology needed to limit these emissions for the useful life (使用寿命) of the vehicle and to warrant the performance of these control systems