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  1. 1. Reducing the Global Warming Impact of the Passenger Vehicle Fleet Harriet Gu Jason Martz Sara Soderstrom
  2. 2. Global Warming Reduction via Greening the Automotive Powertrain <ul><li>Objective: </li></ul><ul><li>To evaluate the impact of passenger vehicles on the feasibility of achieving the Kyoto Protocol standards for CO 2 emission reductions </li></ul><ul><li>Engineering Design </li></ul><ul><ul><li>Relate fuel efficiency to carbon dioxide production </li></ul></ul><ul><li>Policy Development </li></ul><ul><ul><li>Relate fleet composition to total carbon dioxide production </li></ul></ul>
  3. 3. Global Warming Figure from
  4. 4. Radiative Forcings Data from ME 599 coursenotes
  5. 5. U.S. Greenhouse Gas Emissions Figure from
  6. 6. Kyoto Protocol <ul><li>Agreement negotiated among 160 industrialized nations </li></ul><ul><li>Establishes binding greenhouse gas emission reductions </li></ul><ul><li>Target achievement between 2008 and 2012 </li></ul><ul><li>United States </li></ul><ul><ul><li>7% below 1990 emissions </li></ul></ul><ul><ul><li>Currently 10% above 1990 levels! </li></ul></ul><ul><ul><li>Under current growth  33% greater than 1990 levels </li></ul></ul>
  7. 7. Challenges to Kyoto Protocol <ul><li>Can targets be met? </li></ul><ul><ul><li>American Council for Energy-Efficiency Economy </li></ul></ul><ul><ul><ul><li>Proactive sector involvement </li></ul></ul></ul><ul><ul><ul><li>Increased R&D efforts </li></ul></ul></ul><ul><ul><ul><li>Strengthened state programs and policies </li></ul></ul></ul><ul><ul><ul><li>Focused effort to develop and transform markets for low-carbon energy options </li></ul></ul></ul><ul><ul><li>American Society of Mechanical Engineers </li></ul></ul><ul><li>Can sinks (trees, agriculture, etc.) be counted? </li></ul><ul><ul><li>Reduces U.S. emission decreases to 3-4% below 1990 levels </li></ul></ul><ul><li>Can tradeable permits be used? </li></ul>
  8. 8. Transportation Fleet <ul><li>18% of CO2 emissions are from cars, SUVs, and passenger trucks </li></ul><ul><li>201 million vehicles in 1997 </li></ul><ul><li>1.1% vehicle growth/year </li></ul><ul><li>64% automobiles, 36% SUVs & trucks </li></ul><ul><li>CAFE automobile standards = 24 mpg </li></ul>
  9. 9. Transportation Ownership and Usage <ul><li>18.5% of household expenses for transportation (1997) </li></ul><ul><li>17.3% of households have 3 or more vehicles (1990) </li></ul><ul><li>Average travel per vehicle per year = 11,800 miles </li></ul><ul><li>Average occupancy </li></ul><ul><ul><li>Automobile 1.6 persons </li></ul></ul><ul><ul><li>Pickup Truck 1.4 persons </li></ul></ul><ul><ul><li>SUV 1.7 persons </li></ul></ul><ul><ul><li>Van 2.1 persons </li></ul></ul><ul><li>13.4% of workers carpool (1990) </li></ul>
  10. 10. Automobile Age Profile
  11. 11. Automobile Usage Profile
  12. 12. Current US Passenger Car Configuration <ul><li>Engines oversized for performance </li></ul><ul><ul><li>Allow for high accelerations, but … </li></ul></ul><ul><ul><li>These performance requirements are not required for the majority of the vehicle operation </li></ul></ul><ul><li>Large vehicle mass </li></ul><ul><ul><li>Requires larger engine sizes to maintain performance </li></ul></ul><ul><li>Non-optimal vehicle drag coefficients </li></ul><ul><ul><li>Vehicle experiences higher drag forces at a given speed </li></ul></ul><ul><li>High tire rolling resistance </li></ul><ul><ul><li>Rolling losses due to friction in the tire as it flattens to conform to the road </li></ul></ul><ul><li>Overall Effect: High vehicle fuel consumption </li></ul>
  13. 13. What Does This Mean? <ul><li>Lower fuel economy means more fuel is consumed to perform a desired task </li></ul><ul><li>An increase in fuel consumption results in an increase CO2 production </li></ul><ul><li>Fortunately, organized research is being conducted in order to increase vehicle fuel economy </li></ul>
  14. 14. PNGV <ul><li>PNGV: Partnership for a New Generation of Vehicles </li></ul><ul><li>Collaboration between the Federal Gov’t and the Big Three </li></ul><ul><li>Goal is for each company to produce an 80 mpg family sized sedan concept vehicle by 2004, that has performance, safety and cost characteristics similar to today’s family sedans </li></ul>
  15. 15. PNGV Goals <ul><li>Obtain 80 mpg goal by integrating the following concepts into the auto: </li></ul><ul><ul><li>Efficient fuel converters, such as fuel cells, turbocharged direct injection diesels, hybrids </li></ul></ul><ul><ul><li>Better sizing of powertrain components </li></ul></ul><ul><ul><li>Lighterweight components </li></ul></ul><ul><ul><li>Bodies with lower drag coefficients </li></ul></ul><ul><ul><li>Tires with lower rolling resistances </li></ul></ul><ul><ul><li>Effect: Higher fuel economy </li></ul></ul>
  16. 16. PNGV Performance Constraints
  17. 17. Study Data Goals <ul><li>Isolate the effects that powertrain components have on vehicle fuel economy </li></ul><ul><li>Base study on components and fuels that are available in the near future </li></ul><ul><li>Model the components in a PNGV type vehicle </li></ul><ul><li>Maintain constant body and tire characteristics throughout the study, except for baseline vehicle case, which is representative of a contemporary passenger vehicle </li></ul><ul><li>Study accomplished using Advisor, which allowed for easy substitution of powertrain components within a given vehicle configuration </li></ul>
  18. 18. Simulation Inputs
  19. 19. Advisor <ul><li>Forward/Backward vehicle simulation developed by NREL </li></ul><ul><li>Available as freeware at </li></ul><ul><li>Capable of modeling conventional, fuel cell, electric, and hybrid electric vehicles of all types </li></ul><ul><li>Allows designers and policy makers to search for an optimal combination of powertrain components, or to simulate existing powertrain components for a given design objective </li></ul><ul><li>Not an engineering design tool for individual components </li></ul>
  20. 20. Simulated Powertrain Component Characteristics <ul><li>Spark Ignition Engines </li></ul><ul><ul><li>Low compression ratios, throttle intake manifold for load control </li></ul></ul><ul><ul><li>Low thermal efficiencies compared to diesel engines. </li></ul></ul><ul><li>Diesel Engines </li></ul><ul><ul><li>High compression ratios, vary equivalence ratio for load control, no throttling </li></ul></ul><ul><ul><li>More efficient than Spark Ignition </li></ul></ul><ul><ul><li>Turbocharged </li></ul></ul><ul><ul><li>NOx and particulate emissions are relatively high </li></ul></ul>
  21. 21. <ul><li>Fuel Cell </li></ul><ul><ul><li>Uses a fuel reformer to produce H2 from hydrocarbon based fuels </li></ul></ul><ul><ul><li>Relatively high thermal efficiency at mid and high loads </li></ul></ul><ul><ul><li>Output energy from the fuel cell is stored in a battery, so the fuel cell can be used in its efficient load regimes </li></ul></ul><ul><ul><li>Battery powers a DC motor </li></ul></ul><ul><li>EV1 </li></ul><ul><ul><li>Electric vehicle </li></ul></ul><ul><ul><li>Stores energy obtained from the electric grid in batteries, limited range </li></ul></ul><ul><ul><li>Batteries power an electric motor </li></ul></ul><ul><ul><li>No vehicle emissions, but emissions from powerplant that produced the electricity for the vehicle </li></ul></ul>
  22. 22. <ul><li>Honda Insight </li></ul><ul><ul><li>Hybrid electric vehicle: Starter/Alternator type </li></ul></ul><ul><ul><li>Uses a motor/generator in combination with an IC engine. Motor generator used to load the engine to its efficient operating regime, or to suppliment the engine under high load conditions </li></ul></ul><ul><ul><li>Smaller IC engines can be used as a result of the motor </li></ul></ul><ul><ul><li>Energy for the motor is stored in batteries </li></ul></ul><ul><ul><li>Engine cannot be disconnected from the motor gearbox, so both are always turning </li></ul></ul>
  23. 23. <ul><li>GM Precept </li></ul><ul><ul><li>Parallel hybrid electric vehicle </li></ul></ul><ul><ul><li>Similar to the Starter/Alternator HEV, except that the engine can be decoupled from the motor/generator </li></ul></ul><ul><ul><li>Parallel 50 input is a slightly more hybridized parallel vehicle </li></ul></ul><ul><li>Toyota Prius </li></ul><ul><ul><li>Similar to Parallel hybrid, except that the vehicle uses a CVT transmission, and has a separate generator and motor </li></ul></ul><ul><li>SUV </li></ul><ul><ul><li>Sports Utility Vehicle used to model trucks later in the project, as a performance comparison to cars </li></ul></ul>
  24. 24. Backward Facing Simulation <ul><li>Assumes vehicle will meet a given speed trace without violating the performance constraint inputs </li></ul><ul><li>Advisor contains two different optimization routines for the selection of optimal component configurations </li></ul><ul><li>PNGV Performance Constraints were used for the comparison of vehicles in the performance study </li></ul><ul><li>Powertrain components are sized according to the given optimization objective and its constraints </li></ul><ul><li>The MatLab based bisection optimization routine for minimizing component capacity (power) requirements was used, when necessary for this study </li></ul><ul><li>Component performance data is contained in a series of lookup tables </li></ul>
  25. 25. <ul><li>Performance data was obtained from steady state tests, conducted by private and public sources </li></ul><ul><li>Component capacity is linearly scaled by the optimization routine to find an optimal solution </li></ul><ul><li>This feature allows for the integration of optimally sized components, whose characteristics are based on one original parent component </li></ul><ul><li>Components that were already close to the PNGV configuration were not optimized </li></ul><ul><li>The performance of the vehicles was verified to be close to the PNGV vehicles, by running the vehicle through a single load step that outputs vehicle performance, which can be checked against PNGV constraints, in the Simulation Results Screen </li></ul>
  26. 26. Forward Facing Simulation <ul><li>Once the size of the powertrain components has been determined, the vehicle is run through a drive cycle to determine fuel economy and emissions </li></ul><ul><li>Drive Cycles: </li></ul><ul><ul><li>Combined City/Highway </li></ul></ul><ul><ul><li>SAE J1711 (for hybrid electric vehicles) </li></ul></ul>
  27. 27. Advisor Vehicle Input Screen
  28. 28. Autosize Optimization Routine
  29. 29. Drive Cycle Selection
  30. 30. Simulation Results Screen
  31. 31. Simulation Results – Fuel Economy
  32. 32. Simulation Results – Vehicle Mass
  33. 33. Fuel Economy  CO 2 Production Note: For electric vehicle, fuel efficieny is multiplied by 0.32, the efficiency of the electrical distribution grid.
  34. 34. CO 2 Production Levels
  35. 35. Fleet Characterization <ul><li>Predicted miles traveled by automobiles in 2012 </li></ul><ul><li>Determination of 1990 CO 2 production by automobiles </li></ul>
  36. 36. Fleet Projections
  37. 37. Effect of Future Fleet on CO 2 Emissions 4.4% reduction
  38. 38. Policy Requirements <ul><li>Increase CAFE standards </li></ul><ul><ul><li>Automobiles  ~57 mpgge </li></ul></ul><ul><ul><li>Trucks  ~48 mpgge </li></ul></ul><ul><li>New standards effective 2009 </li></ul>
  39. 39. Policy Feasibility <ul><li>Knowledge/understanding of consequences of global warming </li></ul><ul><ul><li>Political and corporate acceptance </li></ul></ul><ul><ul><li>Public awareness and consumer acceptance </li></ul></ul><ul><li>Oil/gasoline availability and cost </li></ul><ul><li>Cost of new technology </li></ul><ul><li>Similar vehicle performance </li></ul>
  40. 40. Model Uncertainties and Weaknesses <ul><li>Advisor </li></ul><ul><ul><li>Use of available components in simulations </li></ul></ul><ul><ul><ul><li>Use of “real” data </li></ul></ul></ul><ul><ul><ul><li>Data for most recent technology is not available </li></ul></ul></ul><ul><ul><li>Emission predictions are qualitative at best </li></ul></ul><ul><ul><li>Optimization routine linearly scaled components </li></ul></ul><ul><ul><ul><li>Heat transfer, friction don’t scale linearly! </li></ul></ul></ul><ul><ul><li>Based on steady-state data, not on dynamic performance </li></ul></ul><ul><li>Fleet characterization </li></ul><ul><ul><li>Automotive, SUV, and truck growth and use rates assumed constant </li></ul></ul><ul><ul><li>Vehicle age distribution assumed constant </li></ul></ul>
  41. 41. Future Considerations <ul><li>Cost/benefit analysis for automotive changes versus energy consumer changes </li></ul><ul><li>Effects of economic incentives for carpooling and mass transportation usage </li></ul><ul><li>Cost analysis for mass transportation development and improvements </li></ul><ul><ul><li>Mass transport currently takes 2x’s longer! </li></ul></ul><ul><li>Cost/effect of future technology </li></ul>
  42. 42. Conclusions <ul><li>Kyoto Protocol is a good guideline for initially decreasing CO 2 emissions </li></ul><ul><li>Advisor is a useful tool for designers and policy-makers to explore future vehicle designs </li></ul><ul><li>Model predictions </li></ul><ul><ul><li>Improved vehicle technology can lead to achievement of Kyoto Protocol standards </li></ul></ul><ul><li>Policy incentives are needed </li></ul><ul><ul><li>CAFE standards: autos  57 mpgge, trucks  48 mpgge </li></ul></ul><ul><li>Multiple political, consumer, and technological issues will also affect implementation </li></ul>