Undersea cable to transmit geothermal-generated electrical energy from the island of Hawaii to Oahu : economic feasibility

Abstract

For Department of Business and Economic Development, State of Hawaii. Includes bibliographical references.In summary, geothermal power is an energy resource which, unlike other alternative-energy resources in Hawaii, offers the promise of a near-term, abundant, reliable, and cost-competitive source of baseload electrical energy. However, the complete geothermal/transmission system (drilling, steam gathering and disposal systems, generating plants, cables, converters, etc.) would be very expensive to develop-the capital costs are expected to be nearly $1.7 billion in 1986 dollars. Of this amount, an estimated$413 million (about 25 percent) would be for the overland and undersea transmission system linking the geothermal plants in the Puna District of the Big Island to Oahu. The high capital cost for the transmission system partially reflects the high cost of a specially designed undersea cable which would be much longer (138 miles) and would reach depths much deeper (6,300 feet) than any existing power cable. As mentioned above, this very large development cost would be offset by greatly reduced requirements to import expensive oil to fuel the conventional power plants on Oahu and Maui, along with other cost savings. A major issue is the economic feasibility of the geothermal/transmission system: would the fuel-oil and other savings be sufficient to compensate for the large costs required to develop and operate the geothermal power plants and transmission system? A positive and convincing answer to this question is necessary in order to proceed with development of the geothermal and transmission system. Otherwise, development should not proceed because of the risk of substantial financial losses; and it is very probable that development would not proceed because it would be extremely difficult to attract the substantial amount of investment capital required. In order to guide public and private decision-makers, this report presents an indepth analysis of the economic feasibility of transmitting geothermal-generated electrical energy from the Island of Hawaii to Oahu via an overland and undersea transmission system. In order to simplify the analysis, Maui is excluded from this report; however, in practice, the inclusion of Maui would either have no effect on the economic feasibility of the geothermal/tranmission system, or would enhance it