January 25, 2021
New Energy and Industrial Technology Development Organization (NEDO)
Sumitomo Electric Industries, Ltd.

NEDO Extends a Redox Flow Battery System Project to Conduct anAdditional Demonstration of a Microgrid as a Solution to PowerOutages in California
World's First Dual-Use Operation of a Battery System with a Microgrid
and Its Value on the Electricity Wholesale Market
The New Energy and Industrial Technology Development Organization(“NEDO”) and Sumitomo Electric Industries, Ltd. have installed a redox
flow battery (RFB)＊1 system for a demonstration project to improve thepower quality of the transmission and distribution network in the U.S.
state of California. NEDO has decided to extend the project to conduct anadditional demonstration of a microgrid, in which a part of the distributionline, including residential customers, will be isolated under the operationof the RFB system. The project is scheduled to run until December 2021.
It aims to demonstrate not only the technical features that strengthen
resilience, but also the commercial value of the RFB system as a powersource for a microgrid in emergency situations as well as for market
participation in normal times. Grid resilience is increasingly important as
California grapples with more frequent Public Safety Power Shutoffs (atool implemented statewide to reduce wildfire risk) and also reliability
concerns during peak summer periods. California experienced its firstrotating outages in 20 years in the summer of 2020.

Fig. Redox flow battery (RFB) system installed in California

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1．Overview
In California, U.S.A., the government has passed Senate Bill No. 100 declaring
an ambitious policy stating that renewable energy and zero-carbon resources
will supply 100% of electricity consumed by California’s end-use customers andstate agencies by 2045. The government has also been promoting theintroduction of energy storage facilities as a solution to the problem of power
quality deterioration caused by the mass adoption of renewable energy.
In September 2015, NEDO concluded a memorandum of understanding with
the California Governor's Office of Business and Economic Development (GoBiz). Under this agreement, the demonstration project*2 has been conducted in
San Diego, California in cooperation with Sumitomo Electric Industries, Ltd. anda major power utility company.
In California, planned power outages have been implemented as measures toprevent disasters such as major wildfires (Public Safety Power Shutoff) in recent
years and rotating power outages were conducted to lessen energy demandduring extreme heatwave, which are becoming a social problem. In the past,certain customers with critical loads such as data centers have implemented
protections against power outages, but there is an additional need forcountermeasures against widespread power outage and for strengthening theresilience of power grids. One solution is a microgrid with energy storage
systems that power isolated distribution lines.
As part of the planned microgrid demonstration＊3, in order to analyze any
technical issues, part of the distribution network which the RFB system with anenergy capacity of 8 MWh and approximately 70 consumers are connected will
be isolated from the grid. The RFB system has been participating in theCalifornia Independent System Operator (CAISO) market since December 2018.
Redox flow batteries have the advantages of charging and discharging patterns
and the number of cycles not causing degradation, and real time measuring of
the remaining charge. This allows flexible bidding patterns without operational
constraints in the markets which has led to innovative bidding strategies toimprove revenue in both the energy and ancillary services ＊4 markets being
developed and successfully demonstrated. The project aims to demonstrate thecommercial value of the RFB system in which the power utility company cangenerate revenue from the CAISO markets during normal times in addition toproviding back up power from the microgrid to customers
in emergency situations.

2/4This “dual-use” capability will become the world’s first demonstration of its
kind and we hope to contribute to the greater market penetration of energy
storage based on the innovative achievements of the project.
2．Future Plan
We will develop the system by fall 2021, when wildfires are common, andconduct the microgrid demonstration until December 2021. RFB technology is
not only applicable in the U.S. but also in isolated microgrids with solar and wind
power facilities and in 100% renewable islands all over the world. After theproject, we will apply the technology to these fields, promote the introductionof energy storage, and contribute to the expansion of renewable energy and thereduction of greenhouse gas emissions as well as the strengthening of power
grid resilience.
Notes:*1 Redox flow battery (RFB) System
An RFB system consists of cells for battery reaction, tanks for storing active
material, pumps, and pipes for circulating the active material. In RFB
systems, the output (kW) and capacity (kWh) parts are independent of eachother, allowing for appropriate output power and energy capacity design
according to application. The charging and discharging reaction causes achange only in the valence of the ions in electrolytes, which preventsdegradation of the electrodes and the active material, making it suitable asa long-life large storage battery. In addition, because it can operate undernormal temperatures and is composed of non-combustible or flameretardant materials, the possibility of a fire with the batteries is extremely
low. As the state of charge is monitored accurately, the batteries ensure
maximum safety in system operations.
*2 Project
Project title:
International Demonstration Project to Prove Japanese Technology for
Improved Energy Consumption Efficiency/Demonstration Project Testing
Storage Battery Operation for Both Electricity Transmission andDistribution in California, USAProject period: FY2015 to FY2021

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*3 planned microgrid demonstration
The simulation results based on the demand history show that the RFB
system can power customers in the microgrid for more than 24 hours.
*4 Ancillary services
Technical and operational schemes to maintain power quality. They include
power balance monitoring, operating grids, and voltage/frequency
regulation. In the past, utility companies were in charge of ancillary services.
But in recent years, some functions of ancillary services have been identified,monetized, and built into the markets.
3．For more information, please contact:
NEDO Smart Community Department
Tel: +81-44-520-5274 e-mail：smartcommunity@ml.nedo.go.jp
Sumitomo Electric Industries Public Relation Group
Tel: +81-6-6220-4119 e-mail：web@info.sei.co.jp
4. Reference
SDG＆E News Release；Groundbreaking Flow Battery Project Helping To
Advance Clean Energy Microgrids
https://sdgenews.com/article/groundbreaking-flow-battery-project-helpingadvance-clean-energy-microgrids
Sumitomo Electric's Website
https://sumitomoelectric.com/4/4