The *dirt battery I have in mind would be a vertical pulley system with small dirt scoops spaced at regular intervals. The scoops would pull dirt from the bottom of the pulley system and bring the material to the top were it is dumped into a mechanically locked, very large container. Over time the container would fill up, and when that stored energy is needed the container could be unlocked, at which point it would power a clockwork of turbines on its way down.
Thoughts, critiques?