Stories of a short, fat bastard.

I've always wondered about an ammonia cycle turbine. This is the sort of thing proposed for OTEC-- Ocean Thermal Energy systems, where they were going to make electricity from the temperature difference between tropical surface water and deeper water.

Now, the deep water would be thirty, forty degrees f and the surface no more than 90. By using ammonia as the medium you can boil it and condense it again using that limited temperature difference. (Water is a strange solvent in a lot of ways. For one thing it has an unusually high boiling point for its molecular weight-- something to do with the molecule's "ionic" structure-- I forget the proper term for it-- with one end of the molecule tending to positive electric charge and the other to negative. Its high boiling point makes it less than ideal as a medium to run turbines, but it's so blasted common we're used to it.)

The reason this is interesting is that downhole temperatures in oil wells are commonly in the 120 f range. Or higher. So presumably you could use a tapped-out oil field as a heat source to evaporate ammonia and run turbines to generate electricity. This is an interesting use for abandoned wells, for one thing. For another, it would allow geothermal energy to be generated with much lower temperature gradients than using water.

I've sent off letters and stuff suggesting this process, but nobody's interested. I presume it wouldn't really work, since nobody's deigned to reply to me-- but I'd like to know WHY it wouldn't work.