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Transmission_Alternative_25_8b (FeatureServer)

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Service Description: This data set was utilized in the Northern California and Southern Oregon Offshore Wind Transmission Study published in October 2023 by the Schatz Energy Research Center at Cal Poly Humboldt. The full report is available at: https://schatzcenter.org/. This study examined the development of floating offshore wind energy resources located off the coasts of northern California and southern Oregon ranging from 7.2 GW to 25.8 GW of cumulative capacity. The study examined numerous transmission alternatives that could accommodate the stated range of OSW development and assessed the estimated costs and benefits associated with each alternative. The economic costs and benefits were determined and compared via power flow analysis and production cost modeling. Considerations for transmission technologies and configurations included: onshore and offshore transmission routes, high-voltage AC and high-voltage DC technologies, radial connections, long-distance undersea HVDC cables, offshore meshed networks with shared HVAC or shared HVDC buses, and phase-shifting transformers to serve small coastal communities with OSW power. A high level assessment of permitting and environmental challenges was also conducted. One purpose for conducting this study was to ascertain, at a high level, a range of possible transmission solutions for GW-scale OSW development on the West Coast. This planning exercise allowed the project team to compare and contrast the potential costs and benefits across various alternatives. All transmission corridors studied were notional and assumed the expansion of existing corridors using overhead line technology and development assumptions. Actual pathways may differ from what was modeled.

Service ItemId: 0a144f729c1a40dd90ed1cd64b790433

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Supported query Formats: JSON

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Transmission Alternative 25.8b was developed to accommodate 25.8 GW of OSW development at wind farms located offshore of Coos Bay, Brookings, Del Norte, Humboldt and Cape Mendocino. This alternative features radial HVDC cables from the Coos Bay, Brookings, Del Norte and Humboldt wind farms to export power directly to shore. This alternative also features a meshed network of subsea HVDC transmission cables. Onshore transmission upgrades include new 500 kV HVAC and ±500 kV HVDC lines running overland along notional routes which follow existing rights of way. Onshore transmission upgrades extend from coastal communities to points of interconnection along the existing 500 kV HVAC grid network, which approximately follows the Interstate 5 Highway Corridor.  In this alternative, HVDC transmission infrastructure is included both overland and offshore. An offshore ±525 kV HVDC undersea cable mesh network connects the Brookings, Del Norte, Humboldt and Cape Mendocino wind farms to each other, and to onshore substations at Rogue, Del Norte, Humboldt, Martin and Moss Landing. An overland ±500 kV HVDC transmission line connects the Humboldt and Collinsville substations. For a more complete description of factors considered, please refer to the full report: Northern California and Southern Oregon Offshore Wind Transmission Study available at https://schatzcenter.org/.



Copyright Text: This work was authored by the Schatz Energy Research Center and the California Energy Commission. The Schatz Energy Research Center at Cal Poly Humboldt advances clean and renewable energy. Our projects aim to reduce climate change and pollution while increasing energy access and resilience. Our work is collaborative and multidisciplinary, and we are grateful to the many partners who together make our efforts possible. Learn more about our work at schatzcenter.org.

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