California agencies says expanded transmission key to meeting renewable mandate

In order for California to meet its ambitious goals for increasing renewable energy and cutting carbon dioxide emissions, electric transmission infrastructure must be expanded, according to a draft of a joint report by a number of state agencies.

The draft Renewable Energy Transmission Initiative (RETI) 2.0 report issued Dec. 16 seeks to identify areas inside and outside of California where utility-scale renewable energy can be accessed. The report also seeks to identify opportunities to develop electric transmission.

The RETI 2.0 effort is a statewide initiative sponsored by the California Natural Resources Agency, the California Energy Commission, the California Public Utilities Commission (CPUC), the California ISO (Cal-ISO) and the U.S. Bureau of Land Management (BLM). Development of the plan involved extensive, public discussions with stakeholders at more than a dozen workshops over a 13-month period.

Transmission development and new renewable energy sources could help the state meet the mandates set by Senate Bill 350, which calls for generating half of California’s electricity from renewable sources by 2030, and Senate Bill 32, which requires California to reduce greenhouse gas emissions to 40% below 1990 levels by 2030.

The report found that utility-scale solar photovoltaic is cost competitive across much of California and that while many of the best and most accessible wind resources in the state have been developed, improvements in wind turbine technology could allow more wind resources to become cost-effective.

Tapping renewable energy in some of the state’s most renewable-rich areas such as the San Joaquin Valley, Imperial Valley, and the desert is feasible due to extensive planning efforts by local officials and stakeholders, but may require new transmission.

The report examined additional potential transmission challenges. One is the potential need for a new transmission line to deliver power from San Bernardino, Riverside, and Imperial counties. Two alternative projects were identified, either of which would face significant permitting challenges and costs of up to $1 bn.

Report looks at various constraints, mitigation options

California-Oregon Intertie

  • The California-Oregon Intertie (COI) consists of three 500 kilovolt (kV) transmission lines with a rated capacity of 4,800 MW connecting the Pacific Northwest and Northern California
  • There is currently no existing capacity available for new fully-deliverable resources from either generation in Northern California or imports from the Northwest
  • Providing new capacity could require new transmission from the Oregon border to the Tracy area, at an order-of-magnitude cost of $2bn-$4 bn
  • Capacity on the COI could potentially be increased through advanced transmission technologies or new transmission elsewhere in the Western Interconnection to reduce regional loop flow 
  • Operational improvements – scheduling coordination and dynamic line rating – could increase the utilization of existing capacity

San Joaquin Valley

  • The hypothetical study range of 5,000 MW would trigger a need for substantial upgrades to the 115 kV or 230 kV network, at an estimated order-of-magnitude cost of $400m-to-$500m
  • If a large quantity of new generation could be geographically concentrated and connected to the 500 kV system, it could potentially offer lower cost and greater system benefits
  • RETI 2.0 stakeholders also suggested that the San Joaquin Valley constraints could be an appropriate application of advanced technologies like power flow control

Desert Area Constraint

  • The Desert Area Constraint is a transmission constraint that affects deliverability of new renewable generation from a vast area including the Victorville-Barstow, Riverside East, and Imperial Valley TAFAs, as well as imports from the Eldorado or Palo Verde import-export paths
  • This constraint can take different forms – triggered by different contingencies and limiting facilities – depending on the resource development mix from different areas
  • The Cal-ISO, Southern California Edison, and Los Angeles Department of Water and Power (LADWP) are currently coordinating to address the most critical of these limitations – an upgrade of the Lugo-Victorville 500 kV line at an approximate cost of $34m
  • The second constraint arises at an incremental level of generation of as little as 2,000-4,000 MW (if concentrated in Riverside East) or as high as 5,500 to 8,500 MW (from all affected TAFAs combined)
  • Possible mitigations for this limitation could include either a new series compensated 500 kV line between Mira Loma substation in the Inland Empire and the Red Bluff substation near Desert Center or a new 500 kV line between Lugo and Eldorado substations. Either of these projects could have significant permitting challenges and an order-of-magnitude cost of $1bn
About Wayne Barber 4201 Articles
Wayne Barber, Chief Analyst for the GenerationHub, has been covering power generation, energy and natural resources issues at national publications for more than 20 years. Prior to joining PennWell he was editor of Generation Markets Week at SNL Financial for nine years. He has also worked as a business journalist at both McGraw-Hill and Financial Times Energy. Wayne also worked as a newspaper reporter for several years. During his career has visited nuclear reactors and coal mines as well as coal and natural gas power plants. Wayne can be reached at