United States’ San Juan Islands set sights on tidal power for local energy resilience

An electric utility providing services to San Juan County in the US state of Washington has started exploring the feasibility of developing a tidal energy project that would provide another layer of energy resilience for the island communities in the Salish Sea.

Orcas Power and Light Cooperative (OPALCO), a local member-owned, non-profit cooperative utility providing energy services to 20 rural-remote islands in San Juan County, is investigating the possibility of adding tidal power generation to its energy mix to ensure the supply of clean energy and additional level of energy security for the residents of the archipelago.

As an island community, San Juan County is at risk of unreliable electricity, as the vast majority of OPALCO’s power comes from subsea cables from mainland Washington state.

In addition, 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.

In that regard, the utility received a grant from the US Department of Commerce to do some preliminary work on design and siting studies for tidal energy turbines.

“There are no simple solutions for figuring out the complexities of our future energy supply. OPALCO is exploring all possible technologies to build reliable, sustainable, and clean resources to meet the energy needs of San Juan County.

“Tidal Energy is one of those technologies that could make sense but there are big hurdles to overcome such as environment studies, success in grant funding, regional partnerships to share costs, waterfront land to bring the power up and onto OPALCO’s system and staff capacity to operate and maintain a tidal generator.

“OPALCO won’t proceed beyond investigation until we have good information to share with our members and time to engage the stakeholders,” the utility said in a statement.

Supported by the Pacific Northwest National Laboratory (PNNL), OPALCO selected Rosario Strait as a favorable location to develop a tidal energy project, due to its persistent strong tidal currents and lower abundance of sensitive marine species such as orcas, humpback whales, and rockfish.

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.

Therefore, OPALCO signed memorandum of understanding (MoU) with Scottish company Orbital Marine Power in early 2021 to collaborate on a potential tidal energy project, with informal exchange of information having previously started in mid-2019.

Supported by the US Department of Energy’s (DOE) TEAMER project, OPALCO and its project partners have explored siting of Orbital Marine Power’s 2MW O2 floating tidal stream turbine, which has already been proven through several demonstrations in Scottish Orkney Islands.

Also, TEAMER supported the University of Washington and Orbital Marine Power with grant funding for San Juan Islands tidal energy characterization project, which was followed by a government grant awarded to OPALCO in 2021 for preliminary design and permitting of floating tidal generation in Rosario Strait.

For tidal energy installation in Rosario Strait, OPALCO proposes a site near Blakely Island or on Orcas Island.

For both sites, the interconnection would be via an existing conduit that was installed in 2004 from OPALCO underground vault on northwest Blakely Island and Southeast of Orcas Island to the sea floor.

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 has started engaging with a number of governmental agencies, including U.S. Army Corps of Engineers, National Marine Fisheries Service, U.S. Fish and Wildlife, Washington Department of Ecology, and Federal Energy Regulatory Commission (FERC), among others.

Once the necessary environmental studies have been completed, permitting the deployment of this system is expected to take approximately 24 months, according to OPALCO.

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