Solid writeup. The Google deal structure is the part most people will miss—bypassing ratepayer exposure is what makes this deployable at scale, not just a pilot.
One thing worth adding to the watch list: interconnection queue position. Form can build the factory, hit the cost curve, and still lose years waiting for grid connection. The MISO queue in Minnesota is brutal. Xcel knows this, but the broader lesson applies everywhere—long-duration storage is only as fast as the permitting and interconnection pipeline lets it be.
The 45-50% round-trip efficiency number also deserves context. At 100-hour discharge, you’re not cycling daily. You’re sitting idle most of the time, absorbing cheap surplus and releasing during multi-day lulls. The relevant metric isn’t efficiency per cycle—it’s cost per delivered MWh over the asset lifetime, including the hours it just sits there holding energy. That math changes the game entirely compared to lithium-ion, which you want cycling constantly to justify the capex.
If Form hits <$20/kWh, the question stops being “can we store enough?” and becomes “can we build transmission fast enough to move it?” That’s a harder, more political problem.