State agencies that oversee energy in California are looking at various electricity sources to provide additional power to California over the next several decades, and Southern California Edison (SCE) is recommending a balanced approach of energy-saving programs and system upgrades or additions to maintain reliability.

The California Energy Commission, California Public Utilities Commission and the California Independent System Operator are working together to assess the best way to meet the state’s future energy needs as a result of two issues — the retirement of the San Onofre nuclear plant and the scheduled closure of some coastal plants in 2020.

“It will be very important to get the right mix of resources to ensure reliability while balancing environmental interests, affordability for our customers and maintaining a safe system for the public and employees,” said Mark Nelson, SCE’s director of Integrated Planning and Strategy.

“The California Independent System Operator has identified more than 7,300 megawatts of generation resources that have been retired, or will be retired, in the SCE and San Diego Gas & Electric service areas by 2021,” he said. “That poses both challenges and opportunities for the grid and our employees.”

As part of its planning, SCE filed a long-term procurement plan last August with the California Public Utilities Commission for local reliability needs. SCE’s analysis provides recommendations for the long-term replacement of 1,700 megawatts of power its customers had received from the San Onofre nuclear plant.

This effort comes after the commission issued a decision in February 2013 for a separate part of the proceeding that addresses local reliability needs once coastal power plants that use ocean water for cooling are retired in 2020.

In the August testimony, SCE recommended a balanced approach of using what are known as preferred resources — including energy efficiency, incentive programs for customers to reduce energy use and generation created from small energy sources like rooftop solar — along with transmission and generation upgrades or additions.

A highlight of SCE’s plan is the Preferred Resources Pilot, which is being conducted in Southern Orange County. The pilot focuses on clean energy, using programs to help customers reduce their energy usage and energy storage to meet grid reliability needs in that community. Pilot results will help the utility determine whether there will be a need for a traditional, natural gas-power plant in the area.

SCE recommended it be allowed to obtain 500 megawatts of new resources to meet the California Independent System Operator’s reliability standards. Those resources could either be preferred resources or a traditional plant powered by natural gas, which would come from third parties implementing programs or building new facilities. The amount of generation requested typically is found in one natural gas-powered plant.

SCE also recommended building the Mesa Loop-In Project, which would be built in existing rights-of-way and within the footprints of existing substations. The project would involve upgrading the Mesa Substation in Monterey Park, which is located near several high-voltage transmission towers. The independent system operator is considering whether to approve the project. If the project is approved, SCE would submit an application to the utilities commission for construction.

In a proposed decision issued on Feb. 11, an administrative law judge recommended that the utilities commission authorize 400 megawatts of preferred resources and up to 300 megawatts of new resources from any source to meet reliability standards. SCE believes the best way to provide resources for its customers would be for the commission to allow all of the additional energy to come from any source.

SCE’s vision to fulfill the state’s long-term energy needs is part of a utilities commission process known as the Long-Term Procurement Plan. These long-term procurement plans are submitted every two years and are the basis for utility procurement while comprehensively integrating all commission decisions from procurement-related proceedings.