I have an RV with a propane fridge in it... and it seems to run cooler on propane than when plugged in... I was fascinated by this, and wondered why the marine world didn't use these... after all, they do have propane.

Then I started reading up on them, and found out that the propane aspect is quite inefficient, energy wise, considering the potential power provided by propane verses the power of electricity. I also later realized that I can make electricity anytime... by just firing up the engine or grabbing some sunlight, whereas getting propane means being near the right kind of dock facility... you are not going to charge a propane cylinder out in the middle of nowhere.

Suddenly marine refrigeration, as it exists, made more sense to me.