A Nation-Sized Battery?

The Intermittency Challenge and the approaching need for massive storage of rapidly dispatchable energy has led the concept of the National Battery, a unified facility that holds the aggregated outputs from an array of intrinsically episodic renewable sources, releasing energy as demand requires. In this contribution, the original demonstration of Murphy that lead-acid batteries are inappropriate is first reviewed and then extended to show that no commercially available battery technology is at present appropriate. However, prospectively, underground pumped hydro storage could suffice, and at a lesser cost than suitable batteries.