Battery Energy Storage Pairs with Solar Energy to Bring Independence and Reliability to a Remote Archipelago

An ocean lies between the San Juan Islands and the main source of its power. The archipelago’s energy supply comes from hydropower generated in mainland Washington and Oregon, transmitted by ageing submarine cables that cross the Salish Sea to serve 20 islands. Orcas Power & Light Cooperative brought us on board for its first two battery energy storage projects, designed to sustainably extend the life of the subsea cables and add reliability to the islands’ grid.

We served as owner’s engineer for the award-winning Decatur Island Energy Storage project. Our role expanded on the San Juan Island Hybrid Energy Storage System, supporting OPALCO with the procurement process for a 2+ megawatt solar photovoltaic array and two battery energy storage systems. When procurement is complete, we’ll finalize design of the solar and battery balance-of-plant and collection system, and serve as owner’s engineer for the project.

As the first of many planned microgrids for OPALCO, the Decatur Island and San Juan Island sites provide the archipelago a small, local power supply to sustain critical parts of the community during mainland system outages. The projects offer a series of benefits:

• Extending the life of the submarine cables: The batteries charge when power demand is low, and discharge when demand is high, reducing the maximum load on the cables. This effectively defers the eventual costly upgrade of the cables, providing significant savings to OPALCO and its members.
• Maximizing battery technology: On San Juan Island, using a two-battery energy storage systems is a strategic move, featuring two distinct battery technologies to form a “hybrid energy storage system” -- a unique way to maximize the advantages of two different technologies to meet multiple project uses.
• Reducing peak system load: The battery systems reduce the peak on OPALCO’s overall system load, resulting in lower demand charge payments to the transmission system from which OPALCO purchases power.  
• Building independence and grid reliability: Variable energy generated from the solar arrays is stored and dispatched using a controlled, strategic system. The projects are designed to supply backup power during an outage to specific customers on Decatur and San Juan Islands.

Both battery energy storage projects received Washington Clean Energy Fund grants to support clean energy projects in the state. OPALCO was awarded a $1 million grid modernization grant for the Decatur Island Battery Energy Storage System as part of Washington Clean Energy Fund II, and a $2.4 million grant for The San Juan Island Hybrid Energy Storage System from Washington Clean Energy Fund III.