Ocean Thermal Project In US

Mini-OTEC 500kW power station was designed and constructed under the support of Hawaii government and financed by private company in a fund of 3 million U.S dollars to build in a lighter barge rent from U.S Navy. The project was started in 1978, which totally took 15 months from design to generation. And then, 4 months experiment was conducted. The power station was employed the closed circulation system. The working medium was ammonia. The average temperature in the outlet of heat water was 26.1¡ãC, while the average temperature in the outlet of cool water was 5.6¡ãC. The length of cool pipeline was 645m. The diameter was 0.61m. The total area of heat exchanger was 407.8m². When the temperature difference was 21¡ãC, the heating circulation system efficiency exceeded 2.5%. The power station was in the output power of 53-47kW, in the average output of 48.7kW. Deducting the electricity consumption by itself system among which cool water pump was 11.9-13.6kW, heat water pump was 9.4-10.7kW, ammonia pump was 1kW and other device 10-19.2kW, the power station can provide an output power of 17.3-5.5kW to the utility grid with an average of 15kW.

The successful operation of Mini-OTEC drew the attention from U.S Department of Energy. The two main companies, who supported to the construction of Mini-OTEC in 1980, constructed another 1MW experimental device called OTEC-1 in Hawaii. This device was also a closed system, with the working medium of ammonia, mainly focusing on the research of heating system, in particular the performance of duct shell type heat exchanger and cool water duct. No any turbine generator sets was installed.

From 1986, PICHTR started an open circulation temperature differential energy utilization schedule to conduct the experimental research on nozzle of evaporator, air removal in warm seawater, humidity classification, and condensing capacity. On the basis of the experiment, they started to conduct the open circulation net work producing experiment in Hawaii from Nov. 1991, which was completed its construction in April, 1993, with the generation power of 210kW, net output of 40-50kW deducting the system itself consumption of electricity. The project can refresh the seawater. PICHTR also developed multifunctional temperature differential utilization system not only for producing electricity, but producing fresh water, air conditioning, refrigerating and breeding by seawater as well, which has a promising future in the islands around Pacific Ocean.