There is a theory that the value of energy expended by proof of work is converted to coin value, in effect "storing" the value for later consumption. Assuming that energy and the coin have value to people at some future time, they can again be traded.

Yet this is at best a poor metaphor. Miners trade energy for units. However all merchants who accept units of the coin trade something for it, and all things offered in trade represent demand. The theory errs in the implication that energy value expended in mining is unique in its contribution to value. Apart from magnitude, one source of demand cannot be a generally greater determinant of value than another. As such the theory is invalid.

Furthermore, it is a similar error to assert that money is a store of value. Money is a store of money. Only objects can actually be stored. The value of money derives entirely from the value of what it can be traded for, to the people trading. As value is subjective, it is human preference, subject to constant and unpredictable change, and cannot be stored.