Have we decided what drives the economy on the moon? We have lots of choices (food, water, energy, other rare materials), but what is our commerce based on? Food and Water can be used to stimulate or stifle pop growth, so does that leave energy? I don't think gold works here. Energy credits?

Yeah, I think energy is the best choice here. You need it to convert/mine all the other basic stuff like volatiles, soil, metals and so on.

It would be interesting tho if we could change what powers the economy by era. Like at first its still the good ol' greenback (gold), but after Earth is out of the equation they have to come up with their own currency based on the necessity of that era.

I thought food was the first era equivalent of cash, at least for the moon. But for simplicity gold is easiest there.

This makes advanced techs very important to eliminate energy waste when storing and using energy for day to day activities.

Well, my thinking was that in the first era Earth still provides alot, if not all, of the necessary supplies so a money 'economy' is in full swing.

Famine and disease would likely occur after contact is severed, so fertilizer/soil and volatiles (water) would be the highest in demand then.