Potential impacts from OTEC-generated underwater sounds

Oahu has been selected by the Ocean Thermal Corporation as the site for the first commercial ocean thermal energy conversion (OTEC) plant. The plant will be constructed offshore at Kahe Point in a water depth of 50 feet. The purpose of this paper is to report on research on the probable nature of the underwater sound generated by UTEC activities based on the plant design. Those findings will be applicable to assessing the plant´s potential impact on marine biota, and possibly on the U.S. Navy Fleet Operational Readiness Accuracy Check Site (FORACS) range which is located nearby. Approximately 200 cubic meters of seawater must be pumped through the plant per second to generate the planned 40 megawatts of electricity. The seawater pumps will be the dominant source of underwater noise. A simple model of spherical acoustic spreading of the generated noise indicates that OTEC generated pump noise would have a spreading loss of 70 decibels at 3500 yards from the source, and would fall below the measured ambient noise of a sea state 1.