ANSWER: None of the above
Ocean thermal energy conversion (OTEC) uses the temperature difference between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity. However, since the temperature differential is small, the efficiency is low, decreasing the economic feasibility of ocean thermal energy for electricity generation. It needs a working fluid with low boiling point and hence refrigerants like ammonia or R-134a are used. In some cases vapor given out by seawater itself is used. Currently the world’s only operating OTEC plant is in Japan, overseen by Saga University. In 2002, India tested a 1 MW floating OTEC pilot plant near Tamil Nadu. The plant was ultimately unsuccessful due to a failure of the deep sea cold water pipe.