Thermocline Energy

while looking at the article Generating Energy From the Deep in the New York times i read about a renewable energy I have never heard about before. This is a developing technology called ocean thermal energy conversion that is currently being pursued by multiple companies. Lockheed Martin is one of the main companies leading in this new technology. The idea behind thermal energy conversion is to use the ocean's warm surface water to heat pressurized liquid and generate steam and use the ocean's cool water from the depths to cool the steam and transform it back into a liquid. This is possible due to the type of liquid used in the system. So far ammonia is mostly used because of it's low boiling point. In tropical areas the warm seawater can be warm enough to boil it. Of course this energy is limited to areas where the sea water warm but it can still provide a large step off of oil dependence.
The advantages of this are of course that it is a renewable energy but also can produce energy 24 hours a day unlike solar that can only produce energy when the sun is shinning and wind turbines that can only produce energy when the wind is blowing. The disadvantages are that it is expensive, can only work in limited places and that there is relatively little knowledge on the topic. It has not been tested thoroughly there for little is know about the environmental impacts it could cause, the efficiency of the system, and problems we could face in the future with it.
Currently Hawaii has plans for a test plant with Lockheed Martin and the industrial Technology Research Institute. Also the Japanese company, Xenesys is also exploring possibilities for a plant in Cuba and Tahiti. This technology was briefly explored in the past during the 1970's oil crisis but was soon abandoned shortly after. Today the technology is far more advance and the motivation is greater. The possibilities for a plant in the near future are high.
If you would like to see a demonstration of how this system works, check out this you tube video Ocean thermal energy conversion system