Save Nic's Finger, page-50

I know about conservation of energy. I'm still deciding whether to be offended at the implication I don't.

Storage medium refers to a highly readily available, portable form of energy. The term "energy source" generally refers to less readily accessible but more widely available, less portable forms which require a major installation to convert into a more readily usable form.

The tide is an energy source, not a storage medium, because you aren't going to bolt an ocean to your car so you can put turbines in that ocean. That doesn't imply that the tide doesn't have energy "stored" in it