Right, there is no advantage in maximizing rotational velocity. Flywheels are the best when you need to store only a few seconds' worth of power, and may need

Right, there is no advantage in maximizing rotational velocity. Flywheels are the best when you need to store only a few seconds' worth of power, and may need to store or retrieve it at a very high rate. Still, spinning spare "Starship" cans on the ends of a girder might be a good way to store solar energy on the moon, during the long night. Maybe the girder is made from basalt fiber.