Sodium is the ideal chemistry for stationary storage that doesn't require fast response. While it's heavier, space and weight is typically not an issue for the use case, there is no thermal runaway potential, sodium is cheap and abundant, and passive cooling can be used to reduce costs and maintenance. Bit of a "holy grail" as it relates to the storage component for the renewables transition, as long as it can continue to decline and cost and scales up rapidly.