Tidal Energy to Increase Energy Resilience and Advance Renewable Energy Goals
Orcas Power and Light Cooperative (OPALCO) is a non-profit cooperative electric utility providing service in San Juan County, WA in the heart of the Salish Sea. As an island community, San Juan County is at risk of unreliable electricity, as the vast majority of OPALCO’s power comes from submarine cables from mainland WA state. Because of this OPALCO is committed to implementing local energy generation resources and microgrids that strengthen the resilience of infrastructure, increase safety and reliability for the co-op members while keeping rates affordable.
As the US rushes to decarbonize, the northwest is forecasted to double load while initially reducing capacity, through the decommissioning of coal power plants. To prepare for near term capacity shortfalls, and long-term load doubling, OPALCO has been exploring local generation options to ensure resilience, reliability and ability to support the beneficial electrification and regulatory clean energy goals. To date, OPALCO have several solar and battery projects in service and in development.
Solution: OPALCO/Orbital Marine Power Floating Tidal Turbine
Through a US DOE TEAMER project (PNNL-32302, Environmental Information for Siting and Operation of Floating Tidal Turbines in U.S. Waters), OPALCO and our project partners have explored siting of a ~2 MW floating tidal stream Orbital Marine Power turbines. The Rosario Strait was identified as a viable site with strong tidal flows in proximity to OPALCO infrastructure for interconnection, within minimal environmental impacts. The site is capable of hosting multiple tidal stream generators. With water being 800 times the density of air, tidal stream energy is to the northwest what solar is to the southwest. While solar is minimal in the winter, tidal power is strong and predictable year-round, but more importantly, it can be firmed with a small fraction of the storage, solar, or wind would require. It is estimated that each Orbital O2 tidal turbine would be able to power 400 homes in the OPALCO service territory.
Proprietary Technology: Orbital Marine Floating Tidal Turbine
The Orbital Marine Power O2 floating tidal turbine has a 242- foot hull with suspended rotors underneath that can be raised for on-site service. The turbine is anchored to the seafloor with mooring lines (See image to right). Floating approximately 5 feet above the waterline and 7.5 feet below, the unit houses two turbines with a combined output of ~2 MW. The device is 197 feet wide including the span of the blades when raised above water. This technology has been deployed for 11 months in the Orkney Islands, Scotland for operational and demonstrational purposes. It is the third grid connected device that Orbital has installed.
For deployment in the San Juan Islands, Orbital will install a ~2 MW unit with a 22-27% capacity factor. Estimated annual production is anticipated to be 4.6 to 5.6 GWh.
Work Completed to Date
In 2018 OPALCO began investigations of multiple tidal device types and deployment logistics in the San Juan Islands. OPALCO found the floating turbine technology to have the most promise considering the service ability, marine traffic and environmental parameters.
- Established relationship via MOU with Orbital Marine Power in Q1 2021 with informal exchange of information having previously started in mid-2019.
- PNNL and Orbital awarded US DOE TEAMER Grant (PNNL-32302, Environmental Information for Siting and Operation of Floating Tidal Turbines in U.S. Waters) Site assessment study completed Q4 2021.
- University of Washington and Orbital awarded US DOE TEAMER Grant (Orbital Marine Power, San Juan Islands Tidal Energy Characterization, Facility: University of Washington and Pacific Northwest National Laboratory).
- OPALCO awarded WA DOC CEF4 Grid Modernization Grant in Q4 2021 for preliminary design and permitting of floating tidal generation in Rosario Strait
Objectives and Funding
OPALCO proposes to install one floating tidal turbine in the Rosario Strait near Blakely Island, WA, or on Orcas Island, WA. For both sites the interconnection would be via an existing 18” conduit that were installed in 2004 from OPALCO underground vault on northwest Blakely Island and Southeast of Orcas Island to the sea floor. The maximum capacity would be ~2 MW with an annual output of 4.6 to 5.6 GWh, per device. The interconnection would connect to a substation on Blakely Island or Orcas Island where the energy would be transmitted via OPALCO’s 69kV transmission system to subsequent islands.
As part of the permitting process, OPALCO is commencing engagement with the following agencies:
- U.S. Army Corps of Engineers
- National Marine Fisheries Service
- U.S. Fish and Wildlife
- Washington Department of Fish and Wildlife
- Washington Department of Ecology
- Washington Department of Natural Resources
- Federal Energy Regulatory Commission
Once the necessary environmental studies have been completed, permitting the deployment of this system is expected to take approximately 24 months.
Estimated Project Cost – $50 Million
Procure, fabricate, assemble, construct, install, operate and maintain a single floating tidal generator in Rosario Strait, WA, and deliver electricity to the OPALCO distribution system. Here are the estimated costs and work breakdown:
- Phase 1 (FY23) – FEED Study, Environmental Studies, Stakeholder Outreach, Permitting – $2M
- Phase 2 (FY24) – Mooring Infrastructure, Transmission Upgrades, Orbital Component Fabrication, Final Assembly – $43M
- Phase 3 (FY25) –Deployment and Demonstration Monitoring, O&M –