Expansion of the Western Transmission Grid


On October 7, 2015, the Governor signed into law Senate Bill (SB) 350 - The Clean Energy and Pollution Reduction Act of 2015. Among several important energy policy objectives, SB 350 set forth statutory requirements related to the possible expansion of the California Independent Systems Operator’s (CAISO) authority from the existing California transmission system to a western regional independent system operator (ISO). The ISO would manage the operation of the transmission system in California’s and PacifiCorp’s service territories and potentially the transmission systems in other western states. The CAISO states that an expanded ISO could enhance grid reliability and reduce costs through efficient resource sharing across the western states, renewable energy integration, and resource diversity. The western states that have expressed interest include California, Idaho, Oregon, Utah, Washington, and Wyoming.

Under current California law, the CAISO is a nonprofit public benefit-based corporation that manages 80% of California’s and a small part of Nevada’s transmission systems. The CAISO manages wholesale energy markets and provides transparent information about the state of the transmission grid in real time and wholesale energy prices. The CAISO is overseen by the Federal Energy Regulatory Commission (FERC) and is presided over by a five-member independent Board of Governors appointed by the California Governor – each member is confirmed by the California Senate.

SB 350 sets forth the Legislature’s intent to expand the CAISO into a regional ISO, if it is in the best interest of California and its ratepayers. Specifically, SB 350 established Public Utilities Code Section 359.5 (a), which provides in part:

“ . . . for the transformation of the Independent System Operator into a regional organization to promote the development of regional electricity transmission markets in the western states and to improve the access of consumers served by the Independent System Operator to those markets, and that the transformation should only occur where it is in the best interest of California and its ratepayers.”

Expansion of the CAISO requires modifications to the CAISO’s current governance structure. As such, SB 350 requires the CAISO to prepare proposed governance modifications. It also must conduct one or more studies on the impacts of a regional ISO, including the overall benefits to ratepayers, creation or retention of jobs and other benefits to the California economy, environmental impacts in California and elsewhere, impacts on disadvantaged communities, emissions of greenhouse gases (GHG) and other air pollutants and, reliability and integration of renewable energy resources.

The CAISO has initiated a series of stakeholder processes in order to obtain public input on the required subjects listed above. SB 350 set forth a procedural schedule wherein the CAISO would submit its studies to the Governor who would transmit them to the Legislature by December 31, 2017 with the Legislature enacting a statute to implement necessary governance changes thereafter.



Public Advocates Office's (the Office) Participation

The Office is actively participating in the CAISO’s stakeholder processes and other regionalization discussion forums. Our participation has focused on ensuring that the benefits of regionalization accrue to California ratepayers. The Office’s comments focus on five major study areas: SB 350 Studies, ISO Governance, Transmission Access Charge, Resource Adequacy, and Greenhouse Gas Accounting.

SB 350 Studies

The Office agrees with the CAISO’s SB 350 Studies that regionalization would likely yield benefits to California ratepayers. However, the lower bound of the benefit range may be lower than the CAISO’s estimates. The CAISO’s SB 350 studies include analysis reflecting potential annual benefits as low as $767 million by 2030. The Office recommends that the CAISO conduct additional analysis, such as combining aspects of different scenarios, so stakeholders can see the cost impacts of various combined scenarios.

See the Office’s Comments to the CAISO:


ISO Governance

The Office recommends that the CAISO seek FERC approval of any proposed governance structure in advance of seeking FERC approval so that the western states understand whether FERC will provide approval that determines the states’ level of authority over transmission cost allocation and resource adequacy. The Office supports load-weighted voting for approving proposals within the primary authority of the Western States Committee. This voting structure will help ensure that each state’s policies are considered and that current CAISO ratepayers, who have funded the CAISO and existing transmission infrastructure, are not burdened with more than their fair share of costs for decisions that impact the expanded ISO.

See the Office’s Comments to the CAISO:


Transmission Access Charge (TAC)

This issue area considers who will pay for existing and new transmission facilities under a regionalized grid structure. The existing TAC collects the cost of existing transmission facilities from all customers at a common rate. The Office modeled several scenarios using the CAISO’s TAC Options Impact Assessment Tool, and found that the TAC could range from $13.44 per megawatt hour (MWh) to $16.35/MWh, under the new regional Independent System Operator depending on the allocation of these costs to sub-regions. The Office recommends the TAC allocation for existing facilities be based on the potential benefits to each sub-region.

See the Office’s Comments to the CAISO:


Resource Adequacy

The Office provided comments on the CAISO’s proposal to determine resource adequacy rules and reliability assessments for Load Serving Entities (LSEs), and recommended that the CAISO should adequately address the potential for “capacity leaning” to prevent an LSE from under-procuring capacity and unfairly relying on the excess capacity procured by another LSE. The CAISO should use penalties and enforcement for LSEs who fail to meet resource adequacy requirements. The Office recommends that each LSE be held accountable for meeting its individual procurement requirements.

See the Office’s Comments to the CAISO:


Greenhouse Gas Emissions (GHG) Accounting

Given California’s important environmental goals to reduce GHG emissions, a regionalization plan should establish a process to accurately measure the GHG emissions associated with regional resources. The Office submitted comments on the CAISO’s issue paper, Regional Integration California Greenhouse Gas Compliance recommending that California meets its GHG goals at the lowest possible cost.

See the Office’s Comments to the CAISO:



CAISO Stakeholder Engagement Webpage

California Energy Commission Western Regionalization Webpage