Yes, I’m no expert either. Just trying to get myself solid on...

Yes, I’m no expert either. Just trying to get myself solid on the value proposition. The link I posted was regarding a Microgrid, and I don’t know if Microgrid stabilisation has the same requirements as grid FCAS services - would be interested in someone more knowledgeable on whether there’s any issue. Even if there is, it could presumably be overcome by coupling the ZBM with a small ultra capacitor with capacity to cover a few ms.
I’m not actually too concerned about other flow batteries as competition in MW storage - their RTE is lower than ZBM, and there will always be a sizeable market for anything with a higher RTE even if other flow batteries become really cheap.
But for the same reason, lithium is a real competitor. Why would you choose ZBM today over lithium for a grid connected MW system unless it’s price? Maybe if lithium price rises continue - but that’s a big IF, so hard to make a business case today on that basis.
Ultra caps are worth keeping an eye on - safe, very high RTE for short term charge/discharge, but more expensive and lower energy density than lithium, and leak >10% per day, but if a company like Skeleton, NAWA or Maxwell (now Tesla) just sorts out price and leakage, they could quickly become a real threat for stationary storage. I’m expecting the cost of Graphene production for ultra caps to drop massively (flash Graphene production from universalmatter.com for example goes into pilot production in Q1 2022), and energy density is not so much of a problem for stationary storage. If you’re cycling daily, maybe leakage is less of an issue.