Schatz CenterOur latest report estimates the ratepayer impacts over time associated with developing major new infrastructure – including a substation and two 500kV transmission lines – to enable offshore wind power from the Humboldt Wind Energy Area to reach the broader California electric grid.
This analysis focuses on the two transmission projects approved by the California Independent System Operator (CAISO): (i) a new 500 kV substation, plus a transmission line connecting the Humboldt Bay region to the Collinsville substation (near Pittsburg), and (ii) a second 500 kV line, extending from Humboldt Bay to the Fern Road substation (northeast of Redding). These projects are currently scheduled to come online by the end of 2034. The sponsor (developer) for both projects is California Grid Holdings LLC, a subsidiary of Viridon Holdings LLC (Viridon).
Our findings show that Viridon’s recoverable costs, when spread across all customers on the CAISO-managed grid over the expected 50-year project lifetime, result in an estimated average cost to ratepayers of $0.28/MWh – or approximately $1.68 per year for the average California household (in 2025 dollars).
As shown below, ratepayer costs associated with this transmission development are expected to peak in 2035 (when the projects come online) at $0.75/MWh – $4.52/year for the average household – and decline steadily to $0.03/MWh by 2083.
Figure 1: Ratepayer impact over time in 2025 dollars (10-year rolling averages)
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For more information, contact: schatzenergy@humboldt.edu or 707-826-4345.
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