World’s Largest Iron Chromium Flow Battery From Enervault

June 9. 2014. 3 mins read

According to the Department of Energy’s global energy storage database, there are only 24 recognized flow battery installations in operation in the United States using technologies such as vanadium, zinc bromide, hydrogen bromine, and zinc-nickel oxide. One company that recently added their battery storage technology, iron chromium, to this list of successful installations is EnerVault.

About EnerVault

Founded in 2008, Sunnyvale California based EnerVault has taken in around $26 million in funding so far from the likes of Oceanshore Ventures, TEL Venture Capital, Total Energy Ventures, Mitsui Global Investment, and 3M. The Company has an executive team with backgrounds from SunPower, Tesla, and a number of other fuel cell and battery companies. EnerVault’s flow batteries use iron and chromium which are blended into the water inside its tanks. Both materials are safe to handle and very abundant. According to an article by MIT Technology Review last year, the iron chromium chemistry materials are one sixth the cost of the vanadium used in some flow batteries. The battery systems themselves are easy to assemble, with elements that arrive at the site in modules that are made from easy-to-procure components.

Enervault’s First Installation – On an Almond Farm

Enervault’s first battery installation was announced last month on an almond farm in Turlock, California. The farm has 186KW of onsite solar that helps power the irrigation system for the almond trees on the farm. These solar panels can be seen in the background of the below picture: Evervault_Installation In the foreground of the above picture, you can see the 4 beige tanks that make up the flow battery system that provides 250kW over a four-hour period for the purpose of keeping the almond trees stay irrigated and saving on the farm’s electrical bills. The use case for this installation is that the almond trees need the most water between the hours of noon and 6 p.m. The farm uses nearly 225 kW of electricity to power the pumps that get the water to the trees. Since onsite solar panels can only supply 186kW at peak power, this is not quite enough energy for watering the trees throughout the day. While the balance of the energy needed could be taken from the grid, this would mean purchasing electricity during peak hours which is most expensive from noon to 6 p.m. Instead, the batteries are charged during the night when electricity is cheap. They can then provide the supplemental energy needed to water the almond trees during peak power when electricity is most expense. According to the previously referenced MIT Tech article, this first installation cost around $9.5 million, almost half of which was funded by the US Department of Energy.


The Turlock facility is a unique application where extra supplemental electrical power is needed during peak hours when grid energy is more expensive. In addition to farming, there are certainly other potential applications that could benefit from this type of installation as well. However. this type of installation seems quite cost prohibitive for most farmers who work on tight margins, have unpredictable revenue streams, and probably don’t have $9.5 million in capital lying around. Will government funding continue to be in place to encourage more installations? If not, will financing options be offered by EnerVault to increase adoption? Who maintains the flow battery system and at what cost to the farmer? While a first installation is encouraging, announcements of future installations will show that the system is economically viable enough to be scalable.


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