There's a video somewhere of a failing flywheel, it's a fairly energetic explosion. I follow the energy space, also, and ... while I didn't expect Li batteries to have grid scale roles, I didn't think flywheels were going to succeed there. They have properties more like ultracapacitors (discharge rate suitable for continuous backup, clean up messy grid sine waves). I thought pumped air/pumped water was more likely because it scaled up so well and was old tech. Fuel cells, too, seems to fall more into the backup/spot generation/remote generation+NG access niches.
Looking on the bright side, anything that drives Li efficiency/density research is probably a very good thing.
Looking on the bright side, anything that drives Li efficiency/density research is probably a very good thing.