Stem cells to desalinate salt water?

[Myuncle]

Fish excrete salt through cells in their gills. Can we make large quantities of these from stem cells, and use them to desalinate salt water?

[Enthalpy]

Desalinate needs energy, even if not much. A tissue alone won't suffice: it needs some input, like Sunlight or digested food - my fear is that we're heading to a complete organism just to replace a pump and a membrane.

 

Does it take stem cells to produce gills? Can't these grow exaggerately under quasi-normal conditions, say if you split the iniital tissue as it's still tiny?

 

From all the fish we eat, can't we keep enough gills?