EDISON INTERNATIONAL

SCE obtains the power, energy, and local grid support needed to serve its customers primarily from purchases from external parties. SCE estimates that approximately 19% of power delivered to SCE's customers in 2024 came from SCE's own generating facilities.

Natural Gas Supply

SCE requires natural gas to fuel its Mountainview and peaker plants, which are generation units that operate in response to wholesale market signals related to power prices and reliability needs. The physical natural gas purchased by SCE is sourced in competitive interstate markets at trading points on the SoCalGas local distribution company system. SoCalGas is the primary provider of intrastate pipeline transportation service to the gas-fueled generation stations that SCE controls. In 2015 – 2016, SoCalGas experienced a significant natural gas fuel leak at its Aliso Canyon underground gas storage facility that resulted in reduced capacity and usage of the facility. Currently, Aliso Canyon is authorized to operate at up to 79% of its maximum capacity. CPUC has established a biennial assessment process to evaluate the reliability and cost impacts of minimizing or eliminating reliance on Aliso Canyon. To date, SCE has found that gas storage-use restrictions combined with SoCalGas pipeline maintenance constraints contributed to increased electricity costs for customers but did not impact grid reliability. However, there is no certainty that these restrictions or pipeline constraints will not impact grid reliability in the future. Price increases faced by customers would not affect SCE's earnings because SCE expects recovery of these costs through the ERRA balancing account or other CPUC approved procurement plans. However, these higher prices may impact cash flow due to the timing of those recoveries. For more information on cost-recovery mechanisms, see "—Overview of Ratemaking Process" above. SCE is actively monitoring legislative and regulatory processes that are addressing pipeline and electric grid operations impacted by the Aliso Canyon leak, including an Order Instituting Investigation issued by the CPUC in February 2017 to consider the feasibility of minimizing or eliminating the use of the Aliso Canyon facility. SCE has also made additional procurement efforts to alleviate the impact of the partial closure of Aliso Canyon, including accelerating existing contracts for new capacity, procuring energy storage from third-parties, contracting for design, build, and transfer of utility-owned storage, procuring additional demand response and contracting for firm gas transportation capacity.

CAISO Wholesale Energy Market

The CAISO operates a wholesale energy market primarily in California through which competing electricity generators offer their electricity output to market participants, including electricity retailers. The CAISO schedules power in hourly increments with hourly prices through a day-ahead market in California and schedules power in fifteen-minute and five-minute increments with fifteen-minute and five-minute prices through two real-time markets that cover California and portions of ten neighboring states through the Western Energy Imbalance Market. Both markets optimize energy procurement, ancillary service procurement, unit commitment and congestion management. SCE participates in the day-ahead and real-time markets for the sale of its own generation and generation under contract and for purchases for its load requirements. In December 2023, the FERC approved an Extended Day-Ahead Market ("EDAM"), giving utilities in the Western Energy Imbalance Market the option of joining a centralized day-ahead market run by the CAISO. The EDAM gives utilities an opportunity to lock in energy prices a day in advance, and thereby substantially avoid volatility in the real-time energy market.

The CPUC's Resource Adequacy program imposes resource adequacy requirements on load-serving entities like SCE that are designed to provide sufficient resources to the CAISO to ensure the safe and reliable operation of the grid in real time. The CPUC has adopted a central procurement structure in SCE's distribution service area for local resource adequacy that transfers the responsibility for procuring local resource adequacy from other local load-serving entities to SCE as a central procurement entity ("CPE") for its distribution service area. Under this structure, while SCE procures local resource adequacy to meet the local resource adequacy requirement for its distribution service area, other load-serving entities can also procure their own local resources. Load-serving entities that procure their own local resources can: (i) sell the capacity to SCE, (ii) utilize the resources, or (iii) voluntarily show the resources to meet their own needs, thereby reducing the amount of local resource adequacy the CPE will need to procure and reducing the total CPE procurement costs shared by all load-serving entities in that distribution service area.

Following state-wide rotating outages in August 2020 that impacted a significant number of SCE's customers, the CPUC has taken action towards ensuring reliable electric service in the event that an extreme heat events occur during summer. The CPUC has issued decisions requiring at least an aggregate of 15,500 MW of additional net qualifying renewable or zero-emitting capacity to be procured collectively by all of the load-serving entities subject to the CPUC’s Integrated Resource Planning purview. The aggregate additional capacity is required by 2028, with 2,000 MW required by 2023, an additional 6,000 MW required by 2024, an additional 1,500 MW required by 2025, an additional 2,000 MW required by 2026, an additional 2,000 MW required by 2027, and an additional 2,000 MW of long-lead time resources, comprised of 1,000 MW of long-duration storage and 1,000 MW of firm zero-emitting resources required by 2028; 2,500 MW of the aggregate procurement requirement through 2025 must be through generation or generation paired with storage.

SCE's allocation of the requirements is 705 MW by 2023, 2,114 MW by 2024, 529 MW by 2025, 684 MW by 2026, 684 MW by 2027, and 705 MW of long-lead time resources, comprised of 353 MW of long-duration storage and 352 MW of firm zero-emitting resources by 2028, for a total of 5,421 MW; 880 MW of the aggregate procurement requirement through 2025 must be through generation or generation paired with storage.

SCE has met its capacity requirements through 2027, and its long-duration storage requirement for 2028. SCE expects to meet its firm zero-emitting requirement in the first quarter of 2025, which will fully satisfy SCE’s overall procurement requirements. As of December 31, 2024, SCE had procured approximately 5,583 MW of additional qualifying renewable or zero-emitting capacity with expected online dates in 2023 through 2028; approximately 1,900 MW of this capacity has come online. SCE has procured approximately 658 MW (and expects to have 729 MW, fully meeting the requirements, in the first quarter of 2025) of qualifying capacity with expected online dates by 2028 toward the long-duration storage and firm-zero emitting resource procurement requirements. SCE has procured the capacity and generation needed to meet its 880 MW aggregate procurement requirement for generation or generation paired with storage by 2025, but some of that generation is not expected to come online until 2026 and 2027. In September 2024, the CPUC issued a decision allowing temporary zero-emitting or RPS-eligible incremental bridge resources to meet the 2025 procurement requirement for generation or generation paired with storage. This allows SCE to use certain temporary bridge resources for up to three years to meet its 880 MW procurement requirement for generation or generation paired with storage by 2025, until its contracted resources expected to come online in 2026 and 2027 are online. SCE has procured sufficient temporary bridge resources to meet the 880 MW procurement requirement by 2025 until its other contracted resources come online in 2026 and 2027.

In February 2024, the CPUC adopted a decision approving SCE’s integrated resource plan identifying the resources needed to meet California’s greenhouse gas emissions and reliability targets and authorizing SCE to procure the resource needs identified in its plan. Additionally, the CPUC approved a process to request extensions of the 2028 procurement requirement for long-duration storage and firm zero-emitting resources to no later than 2031. The CPUC also denied SCE’s request for extension of the 2025 aggregate procurement requirement for generation or generation paired with storage to 2027, although a subsequent decision issued in September 2024 allowed temporary zero-emitting or RPS-eligible bridge resources to meet the requirement as discussed above.