I'm assuming you're referring to Ocean Thermal Energy Conversion and by "else" I take it you mean other than the experimental facility on Hawaii that shut about 10 years ago.
It looks like one has been set up in India but it seems more focussed on desalination
http://indicview.blogspot.com/2007/04/niots-ot ec-based-desalination-plant.html
I guess OTEC is one of the few renewable sources that doesn't suffer from the typical problem of being dependant on transient conditions like wind or daylight but personally I'd be concerned about the very low efficiencies available from OTEC. It sounds to me that you'd need gigantic installations to produce significant power outputs and if the efficiency calculations turned out to be just a bit off it could become completely impractical.
It's also limited to locations where there is ready access to deep water