Larry, somehow the saying "there ain't no such thing as a free lunch"
kept popping into my head as I read your post. It is my
understanding that phase change methods of water purification take
about an order of magnitude more energy than filtration systems to
convert sea water to drinkable water. So, it seems to me that if you
are going to harness the "excess" heat or the excess velocity of the
exhaust gases to convert sea water to potable water you would be much
better off using R/0 in pure heat terms. Doubtlessly I am missing
something obvious but perhaps I am not alone in this as most cruise
ships and municipalities that do seawater conversion use R/O even
though they tend to have lots of heat available from their diesel
generation systems. Sorry to be dense about this. What am I missing?

-- Tom.