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Where would new onshore electricity infrastructure be located?

​The process of electricity infrastructure planning in California involves three different agencies. First, the California Energy Commission (CEC) determines how much electricity the State needs to meet load/demands in the Demand Forecast. In addition, they also analyze whether new energy sources, like offshore wind, are being built due to policy considerations.  The California Public Utilities Commission (CPUC) next determines how investor-owned utilities will meet their load in the Integrated Resource Plan. The California Independent Systems Operator (CAISO) then undergoes the Transmission Planning Process to determine what new transmission and/or upgrades are needed. (Source: NRDC, California Transmission Planning Ecosystem, pg. 5) (1)

​Onshore Transmission Infrastructure

CAISO finalized (2) its transmission planning recommendations (3) in June 2024. It is highly likely that new transmission lines will follow the existing right-of-ways for the electrical transmission infrastructure that currently serves Humboldt Bay, since there would be fewer impacts than creating new right-of-ways. If existing right-of-ways are followed, depending on the design specifics, they may need to be expanded or rerouted in sections to accommodate larger setbacks associated with larger towers and higher capacity transmission lines. The exact route will be decided by the project sponsor (or developer, who successfully bids on the project and is awarded the right to develop) as part of their proposal to CAISO. These proposed routes will be subject to CPUC regulatory authority and environmental review.

 

On July 17, 2024, the CEC published the Humboldt Wind Energy Area Transmission Corridor Evaluation: Volume 1: Report (4), prepared by Aspen Environmental Group, which aims to provide some analysis for potential project developers to assess permitting risks associated with transmission corridors. Figure 1 below shows these potential transmission routes, all of which already have existing transmission infrastructure:

Transmission Corridor Evaluation Map for the Humboldt Wind Energy Area.

Overview of Study Corridors, Transmission Corridor Evaluation, Humboldt Wind Energy Area.
Source: California Energy Commission, pg. 2 (4)

According to the Natural Resources Defense Council, factors for transmission path assessment included:​

  1. Land ownership and permitting jurisdiction: Federal, State, Tribal, private land; incorporated cities; density of private parcels

  2. Sensitive or protected lands: Parks, preserves, refuges, wilderness areas

  3. Biological resources: Critical habitat, important bird areas, records of wildlife and plant occurrences listed in the California Natural Diversity Database (CNDDB)

  4. Tribal and cultural resources: Proximity to Tribal lands, sacred lands defined by the Native American Heritage Commission (NAHC), and data obtained using a records search with California Historical Resources Information System (CHRIS) of the State Office of Historic Preservation

  5. Aesthetics: Proximity to Tribal land, wilderness, wild and scenic rivers, scenic highways

  6. Agriculture: Prime and unique farmland, Williamson Act land

  7. Disadvantaged Communities: CalEnviroScreen’s SB 535 mapping identifies Census Tracts and Tribal Areas that are disadvantaged communities

  8. Hazards: Wildfire risk, active fault zone, landslide susceptibility, contaminated lands

  9. Airspace: Airports, military, and special-use airspace

(Source: NRDC, California Transmission Planning Ecosystem [slide deck], pg. 11) (1)

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From this evaluation, the possible transmission corridors were placed into a high-, medium-, or low-risk Category. Figure 2 below shows a high-level overview of risks associated with potential transmission routes:

Overview of Siting Constraints, Transmission Corridor Evaluation, Humboldt Wind Energy Area.

Overview of Siting Constraints, Transmission Corridor Evaluation, Humboldt Wind Energy Area.
Source: California Energy Commission, pg. 6 (4)

Onshore Humboldt Substation

In addition to transmission infrastructure, CAISO’s 2023-2024 Transmission Plan (3) also calls for a new 500 kilovolt (kV) onshore substation in Humboldt to allow the electricity from the proposed Humboldt offshore wind turbines to “land” onshore and be transmitted Humboldt residents and the rest of California. On July 22, 2024 the CEC released a Substation Planning Evaluation Report for the Humboldt Wind Energy Area (5). The report takes a preliminary view at potential locations for the proposed Humboldt onshore substation within 3 miles of the existing Humboldt Bay 115 kV line, as required by CAISO’s 2023-2024 Transmission Plan (3).  The report considers both the Samoa Peninsula (which is almost entirely constrained by tsunami hazards and important bird habitat, as shown on Figure 6 below) and an area south/southeast of Eureka as potential sites for the onshore substation, and notes many of the potential obstacles and hazards to substation construction. The “potentially feasible areas” in the “Humboldt Study Area” south/southeast of Eureka, shown in green on Figure 5 below, are predominantly zoned for agriculture and commercial timber production.

Humboldt Study Area - Avoidance Areas and Potentially Feasible Areas, Substation Evaluation, Humboldt Wind Energy Area.

Humboldt Study Area - Avoidance Areas and Potentially Feasible Areas, Substation Evaluation, Humboldt Wind Energy Area.
Source: California Energy Commission, pg. 24 (5)

Samoa Study Area Siting Constraints, Substation Evaluation, Humboldt Wind Energy Area.

Samoa Study Area Siting Constraints, Substation Evaluation, Humboldt Wind Energy Area.
Source: California Energy Commission, pg. 27 (5)

Watch this March 2024 video from the Schatz Energy Research Center at Cal Poly Humboldt discussing offshore wind and transmission infrastructure (6) in Northwest California or view the slides here (7):

References​

  1. Natural Resources Defense Council. (2024, July 15). California Transmission Planning Ecosystem [slide deck]. 

  2. California Independent Systems Operator. (2024). 2023-2024 Transmission planning process. https://stakeholdercenter.caiso.com/RecurringStakeholderProcesses/2023-2024-Transmission-planning-process 

  3. California Independent Systems Operator. (2024, April 1). Draft 2023-2024 Transmission Plan. https://stakeholdercenter.caiso.com/InitiativeDocuments/DRAFT_2023-2024_TransmissionPlan.pdf 

  4. California Energy Commission. (2024, July 15). Transmission Corridor Evaluation Vol 1 Updated. https://efiling.energy.ca.gov/GetDocument.aspx?tn=257784&DocumentContentId=93688

  5. California Energy Commission. (2024, July 22). Substation Planning Evaluation Report Humboldt Wind Energy Area. https://links-2.govdelivery.com/CL0/https:%2F%2Fefiling.energy.ca.gov%2FGetDocument.aspx%3FDocumentContentId=93800%26tn=257888%26utm_medium=email%26utm_source=govdelivery/1/01010190dccc5546-8b6ea7a4-70ae-482e-97f6-3b115fb670d2-000000/ErRKJGF4fS1b6L5hbZyZCI4fOUbxGD2y6hG4SkyWc-s=362 

  6. Schatz Energy Research Center. (2024, March 29). Offshore Wind and Transmission Infrastructure in Northwestern California [Video]. YouTube. www.youtube.com/watch?v=HeWSdGb_SNY 

  7. Schatz Energy Research Center. (2024, March 25). Offshore Wind & Transmission Infrastructure in NW CA [Slide Deck]. https://schatzcenter.org/docs/SchatzCenter-OSW-Transmission-Webinar-20240325.pdf 

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