Thanks for the link. It is heartening to see utility-scale storage for a reasonable cost being developed.
20 years ago, there were a couple companies working on flywheel energy storage for mobile applications. They were using carbon-fiber flywheels, which could spin up to 100K RPM, but were expensive to manufacture. I would have predicted (back then) that carbon-fiber would have won out eventually for infrastructure applications as well, but I guess they were not able to get the costs down sufficiently.
20 years ago, there were a couple companies working on flywheel energy storage for mobile applications. They were using carbon-fiber flywheels, which could spin up to 100K RPM, but were expensive to manufacture. I would have predicted (back then) that carbon-fiber would have won out eventually for infrastructure applications as well, but I guess they were not able to get the costs down sufficiently.