I’m not worried at all about the energy density of the ESS iron-salt flows. The life span of lithium is a huge issue. Each time the battery cycles, crystals form, if and when those crystals reach across the battery, they short and start a chemical fire. Every lithium battery has a lifespan and cycle limit.
Anyone who wants a reliable, long-term grid storage option would choose low density, high cycle limit and lifespan. Plus the cold weather is not nearly as big of a problem for iron-salt flow as lithium. Not to mention the cost difference.
Again, the only thing keeping GWH from being a true market leader is their technology. Its probably unproven and I have serious doubts about the efficiency. If their capabilities really are as great as they say, its criminal for them to not be marketing their battery. ESS should be a household name by now. Youtube videos are not enough. Social media ads, paying influencers, there are so many no-brainer options. Get a kid to make memes for christ sake. This market shyness is suspicious.
News 
Market Data 
Discover 
