Tunneling and Drilling for OTEC Cold Water Pipes

Abstract

This report summarizes the results of a study to determine the feasibility of using a tunnel or large-diameter drilled shaft as a conduit for transporting cold water from an ocean depth of 2000 ft to an ocean thermal energy conversion (OTEC) plant located on shore. The report identifies five possible cold water pipe (CWP) approaches that are dependent on the geologic formation and hydrology of the site. For this survey, the site under consideration is Keahole Point on the west coast of the big island of Hawaii. The site was chosen because of the easy access to deep cold water provided by the steep offshore slope, the proximity to air and sea transportation, and the availability of land. The survey concludes that although many site-specific factors must be considered, tunneling or drilling is in general a viable option for meeting the long-term OTEC cost goals. This study was carried out for the United States Department of Energy (DOE) by the Energy Technology Engineering Center (ETEC) as part of the OTEC Cold Water Pipe Technology program.