Energy backed cryptocurrency?
Well, in a certain sense, electricity can be stored, if you're generating it via coal, natural gas, hydro, or nuclear power plants. (You store it by not generating it in the first place.) 

You could define a unit of currency as being a note issued by a power company saying, "IOU one megajoule." Cross region commerce would be handled by finding a middleman to exchange, for example, an Xcel IOU for a GDF Suez IOU.

There would be some problems with this approach. First, Bitcoin has a reliability of 99% to 99.99%, depending on how you define it. That's not reliable enough in a lot of contexts. For example, imagine if a hospital was unable to buy power for an hour each year.

Second, the exchange rates between the various IOUs will change based on speculation and changes in the fuel markets, so what you can buy with your money wouldn't stay stable week-to-week. For example, imagine if you were paid in Delmarva IOU's because you worked for a corporation headquartered in Delaware, but you lived somewhere where you needed to pay your bills in Xcel IOU's.

Theoretically, you could do this. I'm not sure that you'd want to, though.