So this morning’s out of the blue (or out of the black, and into the blue, Hey Hey My My) insight during meditation is that it seems like it would be easy enough to harness the entropic “heat” of the internal combustion engine to produce steam, I mean, the radiator gets way wicked hot and has to be air cooled, and even though the old steam engine trains had to carry massive amounts of water to keep the engines running, and reload, surely by now we can devise a technology that allows the same tank of water to be recycled, a tank way smaller since we’re not going to be blowing off steam, only routing it through a closed system.
So a twenty or something gallon water tank that produces steam under pressure to run the drive train, continuously recycling that water by condensing it back down from steam to liquid water, still way hot enough to be converted back into steam quickly.
A closed system loop, much lighter weight and extractive than the batteries used in hybrids now, and a small gas tank to maintain boiling point for the water supplemented by solar roof panels and a standard 12V battery.
My quickie little search tells me that there is indeed such technology out there, but that there hasn't yet been “a market” for it.
It might be a great technology to pursue.
Water holds a whole lot of energy.