Plug-in Vehicles and the Electric Grid Mark Kapner, PE Senior Strategy Planner Austin Energy

1.How Many PHEVs Can the Power System Accommodate without Additional Generating Capacity ? 2.How does the Replacement of Conventional IC Engine Vehicles by PHEVs Affect Greenhouse Gas Emissions ? 3. How will Large-scale Deployment of PHEVs Effect the Grid ? Questions

Methodology to Answer Question 1 Estimate existing idle generation capacity in a NERC region using a “valley filling” methodology System load profile data from NERC and EIA Simplified hourly load profiles to two 24 hour dispatches, a typical summer and typical winter day Simulate the economic dispatch of generators Generation available to charge PHEVs = available capacity minus generation dispatched to meet load. Assumed that peaking plants are not used to charge PHEVs Coal and Natural gas-fired units de-rated to account for planned outages

Austin Energy Generation

Summer Day Typical Load Profile Nuclear Coal Comb Cycle Other Gas- fired Peakers

Typical Winter Day Nuclear Coal Comb Cycle

NERC Map

Specific Energy and Energy Storage Requirements by Vehicle Class Vehicle ClassSpecific Energy in kWh per mile Battery Capacity Compact Mid-Size Sedan Mid-size SUV Full-size SUV

Conclusion (assuming max 2 kW charging rate) NERC RegionTechnical Potential in Million PHEVs ECAR28.6 ERCOT15.5 MACC10.4 MAIN13.1 MAPP6.1 NPCC15.6 FRCC6.5 SERC32.5 SPP15.1 NWP2.8 AZ & RMP5.8 CNV6.0 Total USA158 million PHEVs

GreenHouse Gas Emissions

Nitrogen Oxides - grams per km

Findings  Valley Filling can charge approximately 75% of all light duty vehicles in the US, if they were PHEVs  Potential Gasoline Displacement by PHEVs = 6.5 Million Bbls per Day (71% of total gasoline consumption)  Assuming utilities have some control over when charging occurs, PHEVs could increase minimum system load, increase the utilization of baseload units, and decrease plant cycling, and increase utility profits (and/or reduce electric rates).

Findings  PHEVs charging on today’s coal-fired generation have about 33% lower GreenHouse Gas emissions per mile than conventional vehicles, charging on gas-fired combined cycle, have about 78% lower GHG emissions.  Deployment of PHEVs facilitates the introduction of more wind energy in regions where wind generation is strong at night.  Distribution engineers have expressed concern that distribution transformers may not be designed to sustain a constant high loading without a daily “cool down” period.

Studies  Pacific NW National Laboratory: Impacts Assessment of Plug- In Vehicles on Electric Utilities and Regional US Power Grids  EPRI and NRDC: Environmental Assessment of Plug-In Hybrid Vehicles  NREL: An Evaluation of Utility System Impacts and Benefits of Optimally Dispatched Plug-In Hybrid Electric Vehicles