Seaside Energy Storage Project

Mortenson was Eolian’s selected engineering, procurement, and construction (EPC) partner to build the Seaside Energy Storage project in northwest Portland, Oregon. The facility included a 200MW / 800MWh battery energy storage system (BESS), designed around 61 Power Electronics PCS units and 244 BYD MC Cube Gen 2 battery units. The project also included a new substation with a 230/34.5kV configuration and a 240 MVA main power transformer supplied by the owner.

Seaside included a complex transmission and distribution scope including engineering and constructing a 230kV transmission line using three dead-end and five direct-embed steel structures, as well as rebuilding an existing 115kV line. The project also required relocating two existing overhead 12kV distribution circuits.

The facility connects to Portland General Electric’s Rivergate Substation and when combined with PGE’s existing generation assets, the system provides enough stored energy to power nearly 125,000 homes at peak demand for four hours.

The Seaside team overcame multiple challenges to successfully deliver this project including challenging weather and soil conditions. The PCS and BESS were installed on concrete foundations and supported by 100 ft deep rigid inclusions to overcome the poor soil conditions. Mortenson functioned as the integrator on Seaside and commissioning the BESS in these conditions required creative temporary weather protection solutions to keep schedule.

Despite environmental and technical hurdles, the team delivered Seaside successfully thanks to having the right execution plan and close coordination with PGE, Eolian, BYD and Power Electronics.