CAISO Transmission Plans Fuel Debate Over Humboldt Offshore Wind

Workers at the Port of Humboldt Bay and households across the county are weighing the promise of offshore wind against a stark price tag after local coverage on March 7, 2026 highlighted conflicting transmission cost estimates that could slow projects and jobs. Lost Coast Outpost’s EcoNews synthesized recent planning analyses and put local questions about ports, cables and jobs squarely on the table.

State planning documents show why. The California Independent System Operator’s 2023-2024 Transmission Plan, which the CAISO Board approved on May 23, 2024, and the ISO 20-Year Transmission Outlook Update from July 31, 2024, lay out multiple routes to move power from the Humboldt Wind Energy Area to major load centers. CAISO’s maps and captions cite options labeled “To Fern Road 3GW Multi-Terminal HVDC,” “2 GW point to point HVDC,” “3 GW point to point HVDC” and a “New Humboldt 500 kV AC Substation,” reflecting choices between subsea/underground HVDC and long 500 kV AC builds.

Capacity scenarios vary widely across agencies and studies. The CPUC’s base portfolio submitted to CAISO assumed 1,607 MW of North Coast offshore wind while a CPUC sensitivity portfolio modeled 8,045 MW. CAISO ran sensitivity cases that included 2,600 MW in the Humboldt WEA and separate analyses priced transmission to access 2,000 MW at $2,300 million. The Schatz Energy Research Center modeled a roughly 1,800 MW farm and warned, “The output of an 1,800 MW wind farm is over 20 times the export capacity of existing lines serving Humboldt County.”

Those capacity choices drive large differences in cost estimates and market implications. CPUC staff converted CAISO’s $2.3 billion figure for 2,000 MW into about $18.4/MWh, but flagged that the CAISO-recommended projects in the Draft Plan could cost as high as $49.80/MWh, a gap CPUC staff called 170% higher than the original estimate. CAISO sensitivity alternatives for integrating up to 8,045 MW show total transmission costs in the $13.2 billion to $21.1 billion range, while Schatz Center scenarios put some large-scale expansions in a $2 billion to $5 billion window depending on specifics.

Environmental and supply-chain constraints add practical hurdles. The Schatz Center’s environmental analysis found “significant environmental challenges to build overhead lines along the coast from Del Norte to Humboldt to Cape Mendocino,” prompting CAISO to assume VSC-HVDC subsea or underground cables for some PoIs. CalMatters reporting highlights port upgrades and distribution bottlenecks, noting “Even after overcoming the substantial hurdles of getting the wind-generated power to shore, it will be a monumental task to gather the electricity in substations and distribute it over transmission and distribution lines to users.” That coverage also cited a federal analysis that found “only seven craft that meet the requirements” of U.S.-flag vessel rules for offshore work.

The local stakes are concrete. CalMatters notes Humboldt County faces persistent poverty, with “nearly a fifth of Humboldt County households live in poverty,” and that wind projects could produce employment “from a few hundred to several thousand new jobs.” The same reporting says projects off Humboldt and Morro Bay “would provide power to 1.5 million homes.” With CAISO, CPUC and CEC inputs driving divergent transmission outcomes, local leaders and port operators will need clear reconciliations of the $18.4/MWh capability estimate and the Draft Plan’s $49.80/MWh figure before cables are laid or cranes move in, or the county risks losing jobs and revenue while the state’s offshore ambitions remain uncertain.