I saw a startup, Velkess with a flexible lasso type flywheel (safety), I think 15 kWh. It folded though. Do you know any companies doing in the 15kWh ballpark

I saw a startup, Velkess with a flexible lasso type flywheel (safety), I think 15 kWh. It folded though. Do you know any companies doing in the 15kWh ballpark type flywheel batteries? It's an idea I really like - I wanted to pair it with a small hydropower installation.