Net air emissions from electric vehicles: The effect of charging strategy and carbon price

1. Net air emissions from electric vehicles: The effect of charging strategy and carbon price Plug-in Hybrid Electric Vehicle (PHEV) Conventional Vehicle (CV) Hybrid Electric Vehicle (HEV) Battery Electric Vehicle (BEV) Scott Peterson Jay Apt Jay Whitacre Engineering & Public PolicyCarnegie Mellon University

2. Net air emissions from electric vehicles: The effect of charging strategy and carbon price Plug-in Hybrid Electric Vehicle (PHEV) Conventional Vehicle (CV) Hybrid Electric Vehicle (HEV) Battery Electric Vehicle (BEV) Scott Peterson Jay Apt Jay Whitacre Engineering & Public PolicyCarnegie Mellon University

3. Preview of results • CO2 and NOX emissions decline • SO2 heavily dependent on future regulations • Carbon price on electricity alone will not reduce emissions unless it is high enough to encourage carbon capture

4. Model assumptions - Grid • Modeled PJM and NYISO two ISOs in NE US both in 2005

5. Model assumptions - Grid • Modeled PJM and NYISO • Used eGRID2005 database and cost and quality of fuels to estimate short run marginal cost and emissions

6. Model assumptions - Grid • Modeled PJM and NYISO • Used eGRID database and cost and quality of fuels to estimate short run marginal cost and emissions • Added $50/tonne CO2tax • -0.1 price elasticity of demand for no-PHEV load • Consumers do not change PHEV demand because electricity is cheap compared to gasoline

7. Model assumptions - Grid • Modeled PJM and NYISO • Used eGRID database and cost and quality of fuels to estimate short run marginal cost and emissions • Added $50/tonne CO2tax • Modeled CCS on coal plants by de-rating capacity 20% and lowering CO2 emissions 80% • SO2 decreases below 10 ppm • Little change in NOX

8. Short run marginal cost curves PJM • Load combined with SRMC curve to determine plants used Peterson, S.B., J.F. Whitacre, and J. Apt, Net Air Emissions from Electric Vehicles: The Effect of Carbon Price and Charging Strategies, Environmental Science & Technology, 2011, 45(5): 1792-1797.

9. Model assumptions - Grid • Modeled PJM and NYISO • Used eGRID database and cost and quality of fuels to estimate short run marginal cost and emissions • Added $50/tonne CO2tax • Modeled CCS on coal plants • No congestion (a plant anywhere in PJM can meet load anywhere in PJM)

10. Model assumptions - Grid • Modeled PJM and NYISO • Used eGRID database and cost and quality of fuels to estimate short run marginal cost and emissions • Added $50/tonne CO2tax • Modeled CCS on coal plants • No congestion • No imports and exports modeled • No accounting for ramp up and down in wind case • Natural gas case assumed 45% efficiency

11. Model assumptions - Vehicles • Only focus on use phase • Majeau-Bettez et al. found quite different upstream emissions than previously reported (2-3x increase)

12. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from national household travel survey (NHTS). Lists trips taken by household members

13. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from NHTS • No change in fleet (same proportion of cars, vans, SUVs, trucks)

14. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from NHTS • No change in fleet • Charge depleting (CD) and Charge sustaining (CS) efficiency and usable battery size

15. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from NHTS • No change in fleet • CD, CS efficiency and battery size • Three charging strategies • Home – Vehicle charges one time after last trip of day • Smart – Vehicle charges one time during low load • Work – Vehicle charges two times, once at work and once after last trip of the day

16. Example load curves with 50% PHEVs Load on day of maximum hourly demand (Tuesday, July 26, 2005) in PJM, 50% PHEVs with (a) small batteries and (b) large batteries Peterson, S.B., J.F. Whitacre, and J. Apt, Net Air Emissions from Electric Vehicles: The Effect of Carbon Price and Charging Strategies, Environmental Science & Technology, 2011, 45(5): 1792-1797.

17. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from NHTS • No change in fleet • CD, CS efficiency and battery size • Three charging strategies (Home, Work, Smart) • Charge rate 7.2kW

18. Charge rate only matters for large batteries Work and Home Charge Home only Charge Load per PHEV driven given work charging for (a) small batteries on a weekday, (b) small batteries on a weekend, (c) large batteries on a weekday, (d) large batteries on a weekend. Peterson, S.B., J.F. Whitacre, and J. Apt, Net Air Emissions from Electric Vehicles: The Effect of Carbon Price and Charging Strategies, Environmental Science & Technology, 2011, 45(5): 1792-1797.

19. Model assumptions - Vehicles • Only focus on use phase • Driving patterns from NHTS • No change in fleet • CD, CS efficiency and battery size • Three charging strategies (Home, Work, Smart) • Charge rate 7.2kW • 10% PHEV results shown

20. CO2 emissions likely decline

21. CO2 emissions likely decline

22. CO2 emissions likely decline

23. CO2 emissions likely decline

24. NOX emissions likely decline

25. SO2 emissions far lower with CATR • SO2 emissions likely increase, but if US clean air transport rule is implemented the change will be much smaller, or negative if operating at cap

26. Take away • PHEVs will lead to decreases in CO2 and NOX emissions compared to conventional vehicles • A carbon price only on electricity will not lead to decreases in CO2 or other emissions • Future regulation such as the proposed clean air transport rule will determine SO2 emissions

27. Acknowledgements • Co-authors • Prof. Jay Apt (CMU)Tepper School of Business & Engineering& Public Policy • Prof. Jay Whitacre (CMU)Material Science & EngineeringEngineering & Public Policy • Carnegie Mellon • Vehicle Electrification Group • Support • Carnegie Mellon Philip and Marsha Dowd Engineering Seed Fund • Toyota Motor Corp