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Transmission for Renewables

California has a stated RPS goal of serving 33% of its electric load with renewable energy by 2020; however, transmission is a major barrier to achieving this goal. Renewable resources are location constrained. They are often far from the grid and load centers, requiring extensive and expensive transmission upgrades. In order to achieve cost-savings through economies of scale, and to limit environmental impacts and ultimate build-out time, large transmission projects are needed to access large geographic areas of developable, economic renewable resource potential. Proactive renewable transmission planning requires "big picture" judgment that coordinates transmission and resource / procurement planning to avoid piecemealed transmission solutions.

Participation in the California Independent System Operator's Annual Transmission Planning Process

CPUC staff participates actively in the annual Transmission Planning Process run by the California Independent System Operator (ISO), because nearly all of the transmission lines that come to the CPUC for permitting are evaluated in the ISO's planning process.

The ISO's 2011-2012 planning cycle is currently underway; documents, meeting notices and meeting materials are available on the ISO's website. On June 6, CPUC staff provided the ISO with a statewide 33% RPS in 2020 scenario that staff recommend as the base case for the ISO's 2011-2012 planning studies. The letter describes the scenario and staff's recommendations; Attachment 1 provides more detail and the assumptions under which the scenario was developed. The version of Attachment 1 included here also details a slight update to the scenario since the June 6 letter was sent.

To develop the scenario, CPUC staff used the 33% RPS calculator that was developed for the 2010 Long-Term Procurement Plan (LTPP) proceeding. Staff updated the calculator pursuant to the assumptions detailed in the June 6 letter.

Statewide Renewable Energy Transmission Initiative (RETI)

The Renewable Energy Transmission Initiative (RETI) is a statewide initiative to help identify the transmission projects needed to accommodate California's renewable energy goals, support future energy policy, and facilitate transmission corridor designation and transmission and generation siting and permitting. RETI will be an open and transparent collaborative process in which all interested parties are encouraged to participate.

RETI will assess all competitive renewable energy zones in California, and possibly neighboring states, that can provide significant electricity to California consumers by the year 2020. RETI will identify those zones that can be developed in the most cost effective and environmentally benign manner and will prepare detailed transmission plans for those zones identified for development.

The RETI effort is supervised by a coordinating committee comprised of California entities responsible for ensuring the implementation of the state's renewable energy policies and development of electric infrastructure, namely:

More information can be found on the RETI website

CPUC Investigation and Rulemaking on Transmission for Renewable Resources

The Commission has an ongoing proceeding to consider issues related to the development of transmission infrastructure to provide access to renewable energy resources for California. 

On February 26, 2009, CPUC staff held a workshop within the proceeding to consider whether the output of the Renewable Energy Transmission Initiative (RETI) could be used to support cost recovery for transmission planning and the Commission’s standards for determining "need" within the transmission permitting process, pursuant to Public Utilities Code 399.2.5.  More information on the workshop and specific discussion topics are available in the Ruling that scheduled the workshop and a Pre-Hearing Conference: To join the service list for this proceeding and receive information about future workshops, rulings, decisions, and other information, please contact the CPUC's process office,, with your request and the proceeding number, I.08-02-010 / R.08-03-009."  

Reports on Transmission Planning for Renewables

The CPUC, its regulated entities, and other interested parties have conducted several studies of the transmission needed to access renewables in California and surrounding areas. Several of these studies are provided below.

March 2008 Quarterly Progress Report on BC Renewable Energy Study

December 2007 Quarterly Progress Report on BC Renewable Energy Study

September 2007 Quarterly Progress Report on BC Renewable Energy Study

June 2007 Quarterly Progress Report on BC Renewable Energy Study

Tehachapi Collaborative Second Report
Tehachapi Collaborative Study Group; April 2006

Development Plan for Access to Renewable Resources in the Imperial Valley
Imperial Valley Study Group; September 2005

Transmission in the Tehachapi Wind Resource Area
Tehachapi Collaborative Study Group; March 2005

Electric Transmission Planning for Renewable Resources in California
CPUC Energy Division, prepared for CA Legislature; December 2003

Integrating Renewable Energy

Transmission Permitting

For more general information on transmission permitting, visit the CPUC's Transmission Section.

Last Modified: 6/28/2011

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