Hybrid Electric Powertrain Fuel Consumption Reduction Cost Effectiveness Trade-Offs Presentation at the 24 th USAEE/IAEE North American Conference Energy, Environment and Economics in a New Era July 8-10, 2004 Washington, DC Danilo J. Santini and Anant Vyas Center for Transportation Research Argonne National Laboratory A Laboratory Operated by The University of Chicago
We Conducted a Study of Studies of Cost Effectiveness of ICE and FC HEVs vs. Conventional ICEVs Studies that simulate energy economy on U.S. driving cycles were used to assess energy savings/km for comparable vehicles - Fuel consumption measured in km/l of gasoline energy equivalent - U.S. Combined weighted FTP and Highway cycles - Focus - CV, CI ICE, SI ICE HEV, CI ICE HEV - Degree of hybridization Studies also examining vehicle cost are used to examine cost effectiveness - Cost effectiveness metrics used in U.S. were criticized - After investigation, liters saved per 10,000 km driven per $1000 of incremental cost was selected as reliable cost effectiveness metric - Incremental cost = lower km/l vehicle price less higher km/l vehicle price 2
Several Degrees of ICE Hybridization were Examined Charge-sustaining hybrids, no grid charging option Minimal hybrid = idle off, perhaps some degree of regenerative braking (ISG), no grid connection Mild hybrid = between minimal (or nothing) and full, in any given study, no grid connection Full hybrid = idle off, considerable regenerative braking, electric launch, no grid connection Hybrids capable of both grid charging with charge depleting strategy and charge sustaining operation. (Operation examined here is only for the charge sustaining mode). HEV## = a grid connectable hybrid with ## miles of electric range Note: No single study included all of the above HEV types 3
Incremental Cost/Benefit Factors Control optimization Emissions control cost Diesel vs. gasoline engine Diesel vs. gasoline HEV Mild vs. Full HEV 12 to 8 sec 0-60 (pack and motor size, regeneration %) Engine technology level choice Effectiveness vs. order of adoption (C d, A, C r, mass) Transmission/motor interaction Ex factory gate RPE multiple Belly pan value in HEV vs. CV Driving patterns vs. fuel savings Engine, pack life vs. driving patterns 2wd vs. 4wd Gear & final drive ratios No. of electric machines, voltage levels Battery materials, subtypes Pack size increments Benefits? Pack life = car life All electric range option Cost - $ to add kwh, kw 4
Constant Glider MPG Gain Approximation for the 04 Prius Showed One Year Old Estimates Were Obsolete 70% 60% 50% 40% 30% 20% 10% 0% HEV MPG Gain Estimates EEA 150V EEA 300V TMC/ANL 500V EEA estimates from 2002 study for California, ANL for actual 2004 Prius Lower drag and rolling resistance (than 04 Prius) in the EEA cases EEA estimates greater increase in mass of HEV All are mid-size cars 5
Prius HEV MPG Gains Exceed ANL 1 For Several Reasons 2004 Prius D (add Atkinson Cycle engine effect) First U.S/ Prius C (C d C r, mass reduction, voltage increase) Combined City & Highway MPG 55 50 45 40 35 30 25 20 13 A Parallel Full HEV Parallel Mild HEV CV Prius-like Cases 12 11 B (increase motor & engine power, motor share) 2004 Toyota Camry 2.4 L with automatic 10 0-60 MPH Acceleration Time (s) 9 8 7 ANL 1 Estimates of HEV Fuel Economy Potential Compared to Actual Prius Results 6
04 Actual Consumption Drops of Full HEV & Diesel are Relatively Consistent w/ Earlier Estimates, But Better! Note: The Camrolla is a straight average of a Camry and Corolla. The Prius is exactly midway on EPA interior volume. 7
Civic MT Mild Hybrid is ~ Diesel, and Patterns For City vs Highway Differences are Similar, but Weak 0% City Combined Highway -10% -20% -30% -40% -50% Jetta to Diesel Civic LX to Hybrid -60% Change in Fuel Consumption Powertrain Switch with Manual Transmission 8
What About Cost Effectiveness to Achieve Such Fuel Use Reductions? 9
Among Gasoline HEVs, Minimal and Mild Hybrids With 8-9 Sec 0-60 Time Were Estimated to be Most Cost Effective e-liter (L Saved/10k km/1k $) 160 140 120 100 80 60 40 20 Minimal HEV CV-Minimal HEV CV-Mild HEV CV-Full HEV CV-HEV20 CV-HEV60 Mild hybrids w fastest 0-60 times 0 ANL 1 (12s) ANL 1 (10s) EF (Rev) EPRI (Base) EPRI (Low) ADL ANL 1 (8s) Sequentially ordered HEV cost effectiveness estimates L to R = minimal to full HEV, slow to fast 0-60 Note: By ANL 1 definition, the 2004 Toyota Prius is Mild 10
NRC Cost-effectiveness: Only Minimal Hybridization Competes w/ High-Tech SI ICE Valve Actuation ANL 1 mild (8 sec) EF Minimal HEV Minimal Hybridization Camless valve actuation Intake valve throttling High Low Cylinder deactivation Variable valve lift and timing Variable valve timing Multivalve, overhead camshaft Source: NRC 0 75 150 225 300 Liters saved per 10K km per $1000 11
At Present U.S. Sales Prices, the Prius and 2 Diesels Have Much Better e-liter Values than Study Results!! e-liter 400 350 300 250 200 150 100 Jetta to Diesel MB E320 to Diesel Camrolla to Prius Civic LX to Hybrid 50 0 City Combined Highway Cost Effectiveness of Powertrain Switch with Automatic Transmission Note: The Camrolla is a straight average of a Camry and Corolla. The Prius is exactly midway on EPA interior volume. 12
A For Manual Transmissions (Rare in U.S.), Jetta Diesels are More Cost Effective, Civic Hybrids Less 400 350 300 Jetta GL to Diesel Jetta GLS to Diesel Civic LX to Hybrid 250 e-liter 200 150 100 50 0 City Combined Highway Cost Effectiveness of Powertrain Switch with Manual Transmission 13
Specific Power (w/kg) Do Not Get Too Enthusiastic About Hybrids Yet Cold Weather May Penalize Hybrids Significantly 1800 1600 1400 1200 1000 800 600 400 200 0-40 -30-20 -10 0 10 20 30 40 50 60 Ambient Temperature/deg. C Specific Power as Function of Ambient Temperature, Panasonic HEV Battery 14
Conclusion The Omission of Detailed Examination of Diesel and Hybrid Powertrains in the Recent NRC Study of Cost vs. Benefit of Technologies to Reduce Fuel Consumption Should be Corrected 15