Just thinking aloud, but is chemical our most efficient method of storage and retrival of energy this side of nuclear energy? Sure kinetic and potential energy forms are utilized all the time by flywheels and springs, electrical energy is stored for short periods of time, but the only long-term easily used form of energy storage seems to be held exclusivily by chemistry. In effect, what I'm asking is a result of my surprise that in a quick metal survey, it seems the batteries and petro available at the start of the 20th century are still the best we forms of storage available (not counting splitting atoms to heat water since how many of those have been built since 3-mile island and Chernobyl) That the leyden jar has evolved into a capacitor that can be purchased for a few dollars but still offers an extremely limited amount of storage. That we've created countless alloys and polymer plastics with properties to be determined almost at free will, but still little storage ability. Not trying to start any battles or disrespect the accomplishments we've made, but in a late night insomnia state of mind it seems odd to think that its still quite improbable that some nano-tube capacitor or super-elastic polymer might offer enough energy storage to be practical without requiring a chemical reaction to accomplish the energy storage. By practical it could be used for transportation or lighting or heating/cooling. But maybe this post will seem humorous in the moring too.