1. Southern California Edison The San Onofre Nuclear Generating Station April 14, 2011

2. Page: 1 Southern California Edison SONGS Basics  Capacity – 2,150 MW : Serves approximately 1.4 million customers SCE78.21% SDG&E 20.00% City of Riverside1.79%  Average Energy Produced:16,600 GWhr/Year* 6% of CA State Load (estimated for 2012) 21% of SCE bundled load (estimated for 2012) * 25 year average gross output of the SONGS plant

3. Page: 2 Southern California Edison  SONGS operating license expires in February, 2022 for Unit 2 and November, 2022 for Unit 3  The estimated net present value ratepayer benefit for SONGS extended operation (2023-2042) is in excess of $4 billion (2011$, 100% level)  The estimated nominal ratepayer benefit for SONGS extended operation is in excess of $37 billion (100% level)  Net Benefit of Continued Operation = Avoided costs of replacement energy and capacity assuming SONGS is permanently shut down in 2022, less Incremental SONGS operation costs assuming SONGS is permanently shut down in 2042  The net benefit is based on assuming Combined Cycle Gas Turbines as the replacement generation for energy and capacity.  The net benefit does not include the benefits provided by deferring the incremental transmission needed if SONGS were shut down in 2022 Replacement Power

4. Page: 3 Southern California Edison  Without SONGS operating beyond 2022 The southern CA grid loses voltage support, stability support and import capability. To mitigate the above condition, in-basin generation and additional transmission will be needed to maintain the import capability and this allows the import of renewables into the grid.  Replacement Generation: Combined Cycle Gas Turbines 2,150 MW (new and out of the basin)  Transmission: New Transmission Will Be Needed To Interconnect the new generation Upgrade the existing grid Impacts – SONGS Not Operating

5. Page: 4 Southern California Edison  Simultaneously siting and licensing the replacement generation facilities and needed transmission will be challenging  There is currently no means to assure timely acquisition of necessary air pollution credits for replacement generation  Siting high voltage transmission lines and 230/500 kV substations in Los Angeles basin will be challenging and time consuming (may require condemning property, will likely impact several communities)  Approximate time period required to modify and/or fix the grid infrastructure is at least 10 years Impacts - SONGS Not Operating (continued)

6. Page: 5 Southern California Edison  Fuel price and deliverability effects: Natural Gas prices will likely rise due to substantially increased demand Gas deliverability on peak days will be impacted due to increased demand and natural gas and/or power curtailment to residential customers on peak days could occur Potential natural gas infrastructure upgrades 2 – 4 years (est)  Electric energy prices are expected to be higher as the least cost source of supply is not available  Incremental Emissions without SONGS: 6-10 Million Metric tons (CO2 equivalent) per year Equivalent to removing 1.2 – 2.0 Million passenger cars/year Risking California’s ability to meet AB-32 goals 280 Metric Tons of NOx /Year 1,100 Metric Tons of PM-10/Year (particulate emissions) Approximately three to four times current South Coast Air Quality basin PM-10 emissions emanating from electricity sector Other Issues – SONGS Not Operating

7. Page: 6 Southern California Edison If SONGS were replaced prior to its license expiration, in addition to the aforementioned costs, environmental impacts and replacement power and transmission needs, we could expect the following:  Grid reliability problems due to transmission line overloads and low voltage conditions will require significant new generation and transmission facilities in southern California to mitigate the above challenges  More costly replacement power, with higher emissions implications  The need to accelerate transmission and generation licensing and siting to mitigate duration of reliability problems, including challenges raised by SCAQMD environmental regulations for air permits and by SWRCB limitations on once-through cooling of generation facilities Premature SONGS Replacement

8. Page: 7 Southern California Edison  Replacement Power cannot all come from renewables  To replace SONGS with renewables, new procurement would predominantly be for delivery after 2020 as SCE and other load serving entities are already aggressively pursuing renewables to meet the State’s 33% goal  Neither CAISO nor SCE have determined that the grid would be operable with renewables above 33%. The current studies only address the grid operability needs for at a renewable level of 33%.  Without SONGS, additional in-basin resources would be needed to maintain the local capacity requirements and to allow additional renewables to be imported Replacement Power – Renewables

9. Page: 8 Southern California Edison  New renewables 1 that would be needed to replace SONGS (plus undefined integrating resources) Wind 6,600 MW + peakers of 1,600 MW Land Need - 59,000 Acres for wind Approximately 6 new transmission lines Solar 6,000 to 8,000 MW Land need – 64,000 acres (assuming Solar Thermal) Approximately 8 new transmission lines Replacement Power – Renewables (continued) 1)Preliminary estimates subject to change and refinement

10. Page: 9 Southern California Edison  There will be challenges in devising transmission fixes that are required to meet the existing grid reliability standards  There will be substantial adverse environmental impacts which will significantly affect the State’s goals  There will be rate increases needed to reflect the impact of more costly replacement power resources and transmission  There is an immediate need to start planning and permitting of replacement generation and transmission facilities if SONGS does not operate beyond 2022 Conclusion – SONGS Replacement