Forging a Path for Long-Duration Energy Storage

Some types of energy, like coal, natural gas, or petroleum are easy to store for later use — much like the gasoline stored in underground tanks at gas stations, waiting to fill up your car. Electricity, on the other hand, is typically used immediately as it’s generated. Some electricity-generating resources, like coal or natural gas, can be stored at a generating facility and used when needed for the grid. Other resources, like renewable wind or solar facilities will generate electricity for immediate use on the grid as the wind blows and sun shines. As states and utilities — including here in Oregon — move toward a 100 percent clean electricity grid, more electricity storage options will be needed to store those variable renewable resources for times the wind doesn’t blow or after the sun has set.

Some battery technologies store electricity for shorter durations, say two to six hours. But energy grid planners and utilities have identified the need for long-duration storage options — 100 hours or more.

In the Oregon Department of Energy’s 2022 Biennial Energy Report, we highlighted some of the cool energy stories happening around the state, including this feature on a local Oregon business that’s working to forge a path for long-duration energy storage. This story originally appeared in our “Energy 101” on long-duration energy storage, which dives into energy storage’s current trends, potential technologies, and more.


In August 2022, Oregon Department of Energy Director Janine Benner joined U.S. Department of Energy Secretary Jennifer Granholm, Oregon Senators Ron Wyden and Jeff Merkley, Oregon Governor Kate Brown, and others on a tour of ESS, Inc.’s Wilsonville campus.

ESS Inc. is ready to bring more long-duration energy storage to the market – and further accelerate the clean energy transition.

The Wilsonville-based company’s mission is to provide clean and sustainable long-duration energy storage options through its environmentally friendly iron flow batteries that use earth-abundant iron, salt, and water to store energy.

The chemistry also means the batteries are safer and non-toxic – which means they are easier to permit and site and significantly reduce the need for fire suppression or containment preparations. At the end of a battery’s 25-year life, it can also be recycled to keep materials out of landfills.

ESS has storage solutions for different customer types, including utilities, commercial businesses, and industries. The company’s Energy Warehouse product is designed to store up to 400 kilowatt-hours of electricity, providing storage durations of four to 12 hours. ESS’s Energy Center model is designed for utility-scale needs, providing megawatts of power with a duration of six to 12 hours. Energy Center capacity varies depending upon site design and customer needs, but a one-acre footprint can support approximately 8 megawatts, and 64 megawatt-hours.

As Oregon and other states work toward clean energy goals, including 100 percent clean electricity by 2040, long-duration energy storage solutions like these can support variable renewable energy resources, like wind and solar, to strengthen overall grid reliability and provide power when Oregonians need it.

Learn more about ESS’s work online: https://essinc.com/