I'm not fixing the currency to anything because neither a commodity nor a unit of currency is a unit of account. A unit of account is a standard unit of measure for value by reference to which commodities, currencies and other value may be exchanged.

A simple yes/no question: does your idea work just as well if instead of being denominated in energy units (say, in joules), the prepay certificates are denominated in... I don't know, wazeegles?

Finance is the brain [tumour] of the economy