The siren call of the flow battery has lured many a renewable energy researcher with its promise of large scale, long duration energy storage. In contrast to conventional battery arrays that pour out the juice for four hours or so, flow batteries can store a day’s worth of wind or solar power. That kind of long duration output is something that the US Department of Energy has been dreaming about, and with that in mind let’s take a look at the flow battery specialist ESS Inc.
US Energy Department Hearts Long Duration Energy Storage
Even though the previous administration professed a love for all things fossil, the US Department of Energy has been holding the torch for energy storage and renewable energy all throughout the past four years. That includes a focus on flow batteries and other forms of long duration energy storage, and now it looks like all that hard work is about to pay off.
Flow batteries work through the magic that happens when two specialized liquids flow adjacent to each other, separated only by a thin membrane (or not, as the case may be). Scaling is simply a matter of building larger (or smaller) tanks to keep the liquids apart until needed.
So, what’s holding things up? Cost is one key factor. The Energy Department has tapped various federal labs and private companies to help push down the cost of flow batteries, and it looks like earth-abundant, low-cost, non-toxic iron has been tasked with the heavy lifting.
In 2016 the agency’s cutting edge energy R&D funding office, ARPA-E, awarded a $2. 8 million grant to ESS for the development of a new iron-based flow battery — and not just any old new flow battery.
“Energy Storage Systems (ESS) is developing a cost-effective, reliable, and environmentally friendly all-iron hybrid flow battery,” enthused ARPA-E. They went on to note that “The ESS flow battery technology is distinguished by its cost-effective electrolytes, based on earth-abundant iron, and its innovative battery hardware design that dramatically increases power density and enables a smaller and less costly battery.”
“Creating a high-performing and low-cost storage system would enable broad adoption of distributed energy storage systems and help bring more renewable energy technologies—such as wind and solar—onto the grid,” ARPA-E added.
ESS Brings The Iron To Long Duration Energy Storage
There being no such thing as a free lunch, back in 2016 ARPA-E noted that there was just one little thing in the way.
“Currently, flow batteries account for less than 1% of the grid-scale energy storage market because of their high system costs,” they explained.
Well, that was then. ESS showcased its all-iron flow battery at Intersolar North America in 2017 and reached another milestone in 2019 when the US Department of Defense — a big fan of clean tech — installed the company’s Energy Warehouse™ flow battery at Marine Corps Base Camp Pendleton in San Diego, where renewable energy has been a thing since 2011. The new energy storage system complements an existing solar array and integrates with a CleanSpark microgrid for up to eight hours of storage.
In the latest development, earlier this week ESS launched a new version in the form of the Energy Center™, which it describes as a “flexible, scalable, and environmentally sustainable long-duration battery storage system.”
They’re not kidding. The Energy Center sports the next-generation of the ESS flow battery, which is good for 6 to 16 hours of energy storage, depending on scale. ESS also fine-tuned its containerized design to allow for stacking and other configurations, which provides for fitting and scaling the battery into existing facilities and campuses.
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