Snohomish County Public Utility District No. 1

Skip navigation and go to content

Customer Service (M-F 8a-5:30p): 425-783-1000

Energy Storage

PUD Energy Storage Program

Background/Why Energy Storage?

The PUD has installed the first two battery systems as part of a multi-year program aimed at transforming the marketplace and how utilities manage grid operations. These battery storage systems are the first to be built using the cutting-edge Modular Energy Storage Architecture (MESA). The first set of lithium batteries is located at a utility substation near the PUD’s operations center. A second system, a set of vanadium flow batteries, was installed in early 2017. The installations are designed to improve reliability and the integration of renewable energy sources, which are rapidly growing in the Pacific Northwest. A third energy storage system is being designed for the new Arlington Microgrid and Clean Energy Technology Center.

The PUD recognizes that the electrical grid needs to change to take on more renewable power. MESA’s standards-based energy storage systems and software will play major roles in that change. MESA provides standard interfaces between equipment components such as the power conversion system, batteries and control system. It brings more choices for utilities, reduces projects’ complexity and promises to lower costs. The system offers a non-proprietary and scalable approach to energy storage.

Energy Storage Projects

The program, which forges partnerships with major U.S. and international business partners, includes the first set of two large-scale lithium ion batteries, one manufactured by GS Yuasa International Ltd. and supplied by Mitsubishi and a second manufactured by LG Chem. Both lithium ion batteries utilize a Parker Hannifin Power conversion system. The PUD also deployed the set of advanced vanadium flow batteries, built by UniEnergy Technologies, at a second PUD substation. Both systems include software and system design by Doosan GridTech.

The utility is managing its energy storage projects with an Energy Storage Optimizer (ESO), a software platform that runs in its control center and maximizes the economics of its projects by matching energy assets to the most valuable mix of options on a day-ahead, hour-ahead and real-time basis.


The project was made possible in part by a $7.3 million investment from the Washington State Clean Energy Fund.

The PUD has received an additional $1 million from the Clean Energy Fund for a partnership with the Bonneville Power Administration and the University of Washington to optimize the use of energy storage and demand response. The project will model how these assets may be used to move energy to:

  • Mitigate both technical and economic costs of congestion
  • Improve the reliability and operating costs of BPA’s transmission grid

Energy storage system at Hardeson Substation
Energy storage system at Hardeson substation

Second installation at Everett substation
Installation of 2nd energy storage system at Everett substation

Frequently Asked Questions (FAQs)

View all
What is energy storage?

Sandia National Laboratories (Sandia) states that energy storage mediates between variable energy sources and variable demand. Sandia goes on to say that “energy storage works by moving energy through time. Energy generated at one time can be used at another time through storage. Electricity storage is one form of energy storage. Other forms of energy storage include oil in the Strategic Petroleum Reserve and in storage tanks, natural gas in underground storage reservoirs and pipelines, thermal energy in ice, and thermal mass/adobe. Electricity storage is not new. In the 1780s Galvani demonstrated "animal electricity" and in 1799 Volta invented the modern battery.”

What is MESA?

MESA – or Modular Energy Storage Architecture – is the system that will offer standard electrical and communication interfaces to connect batteries, inverters and software components into modular energy storage systems. The architecture has been developed by 1Energy in coordination with the PUD and other partners.

What problem does this address for the energy industry?

Wind, solar and other renewable energy sources are intermittent and often may not be available during peak energy demand times. Effective energy storage is an invaluable resource that helps make clean energy available wherever and whenever it’s needed. The MESA project aims to provide more choice for utilities and give battery, inverter and software providers more ways to reach customers. Ultimately, it aims to transform the marketplace, making energy storage more economically and operationally viable.

Why is the PUD choosing to lead this effort?

The utility is committed to meeting load growth through conservation and a diverse mix of renewable energy sources. Given the intermittent nature of many renewable energy sources, they are often difficult to effectively integrate into the utility’s power portfolio. Energy storage provides a solution for the PUD as it moves toward greater use of renewable energy sources.

How much will this cost?

The PUD energy storage program includes six projects, which will be implemented over several years. The current projected budget is $21 million. The Washington State Clean Energy Fund has pledged $8.3 million toward PUD projects.

Are there other projects like this in the Pacific Northwest?

There have been regional test projects conducted by other utilities and other energy organizations. However, this project is much different in that it offers greater flexibility in regards to the components that can be used, the scalability and standardization. A central goal of the MESA project is to transform the market to make energy storage more economically and operationally viable.

Are there safety measures in place?

Four individual fire alarms are hardwired from the battery to the substation switchgear, and alarms are monitored through the utility’s SCADA system by Energy Control Center dispatchers. Flashing lights and audible alarms alert personnel if fire suppression has been activated. Hardwired resistant temperature detectors inside the battery also provide insight about the status of fires even when auxiliary power is lost.