A flow battery storage system is to be installed on an island off the coast of Washington state with potential to be replicated across other island grids.


The 0.5MW/2MWh vanadium redox flow battery (VRFB) energy storage system will be installed in the first quarter of 2019 on Decatur island, in the San Juan archipelago. The flow battery system, which Unienergy Technologies is supplying, will be operated by Orcas Light and Power Coop Utility (OPALCO).

OPALCO was awarded a $1 million grid modernisation grant in 2016 by the Washington Clean Energy Fund (CEF), to support the battery’s investment.

The battery will connect a 0.5MW community solar PV plant to the grid. The system will provide peak shaving and load shifting, by optimising self-consumption of solar electricity. This will help save on demand charges levied by the Bonneville Power Administration (BPA), a self-funded federal power marketing administration in the Pacific Northwest, which is part of the US Department of Energy.

BPA markets wholesale electrical power, mainly from federal hydroelectric projects in the Northwest.

Decatur is connected to the mainland grid via an eight-mile submarine transmission line cable. By regulating current, a power intensive function, the VRFB storage system will extend the operational lifetime of the copper cable, deferring future infrastructure investment, by as much as five years.

The flow battery will also provide back-up capability, ensuring that the fibre optic-based communications infrastructure is powered for at least eight hours.

The battery will be installed after a substation upgrade early next year.

Should the project on Decatur prove successful, there is potential for OPALCO to install energy storage on other islands in

UET’s flow battery technology is unique in being able to address power intensive applications, like frequency regulation, as well as the energy duration applications that are associated with flow batteries (Courtesy: UET)

the San Juan archipelago.

According to Russ Weed, UET’s vice president of business development and marketing, the project will help to demonstrate the suitability of UET’s vanadium flow battery system for other island grids, as the company has developed the technology to provide both short term power-based as well as long duration, energy-based, services and functions.

VRFBs are rugged and robust, able to perform well in both very cold and warm as well as humid environments, with very little degradation, compared with technologies such as lead acid and lithium ion. They are also non-flammable.

For the Decatur island project UET is providing whole system integration, which involves integrating its proprietary VRFB technology with a third party inverter. UET’s controls, based on open architecture engineering software licensed from Siemens, will control and manage the VRFB.