From 1982 through early 1990, an engineering feasibility project was undertaken to evaluate the technical and economic challenges of installing a large-scale 500-megawatt geothermal/interisland submarine cable. About $26 million (Federal and State funding) was expended in studies, design, engineering, fabrication, and testing for the Hawaii Deep Water Cable Project. Figure 8 shows the proposed route for the Hawaii Deep Water Cable. The design criteria stated that the cable(s) would have to be able to withstand the stresses of at-sea deployment (including strong currents, large waves, and strong winds), the undersea environment (including corrosion and abrasion), and be able to reliably conduct electricity for thirty years. Since the Alenuihaha Channel is nearly 2,000 meters deep, both deployment (laying of the cables) and operating environment posed unique engineering challenges. The rationale for the project was that the primary source of geothermal energy was on the island of Hawaii, and the major electrical load was on the island of Oahu, where Honolulu is located. The scheme under consideration was to use the geothermal energy to generate power and transmit it to Oahu. At the time it was estimated that up to 500 MW could be used on Oahu, whereas only about 100 MW were needed on the Big Island….

Two large-scale tests were conducted to examine the technical feasibility of the Hawaii Deep Water Cable. The first was the laboratory test where the cable was subjected to the electrical and mechanical loads expected during the 30 years of service. Second, the at-sea tests examined the ability of the projected, integrated control system to place the cable at the bottom accurately and to control the residual tension…. Read the rest