Construction And Deployment Of An Operational Otec Plant At Kona, Hawaii
Authors: McHale F. 
Published: October 2008

Under the terms of a cooperative research agreement, the State of Hawaii has combined with the Dillingham Corporation and the Lockheed Missiles and Space Company, Inc. to construct and deploy the world's first operational at-sea ocean thermal energy conversion plant. Offsite construction of heat exchangers and other plant components was begun in the latter part of 1978, and shipyard modifications to the test platform were begun in January 1979. Deployment at sea, in 3,000 ft. waters approximately 1.5 miles offshore of Keahole Point, Hawaii, is scheduled for May 1979. The 50 KW plant is known as the "Mini-OTEC" project.

INTRODUCTION

The State of Hawaii has long been conscious of its dependence on imported fuel supplies. As part of its search for energy self-sufficiency, the State agreed in 1978 to join with the Dillingham Corporation of Hawaii and Lockheed Missiles and Space Company, Inc. in the construction, deployment and operation of a 50 KW demonstration OTEC plant; The original division of responsibilities provided that Lockheed would furnish the OTEC cycle machinery and Dillingham, as construction manager for the State, would install the OTEC Plant on a barge and moor the barge at a selected location.

The U.S. Navy Barge YGN-70, scheduled for the mothball fleet, was identified in the Navy yard at Pearl Harbor, Hawaii. Arrangements were made for the lease of the vessel from the Navy to the State of Hawaii, and the barge was turned over to the State during January 1979 for conversion.

In 1974, the Hawaii Legislature created the Natural Energy Laboratory of Hawaii (NELH). The legislation set aside a 320 acre site on the Kona Coast and a Research Corridor extending seaward from Keahole Point near Kona on the Island of Hawaii. This site, which has received environmental impact approval from all concerned agencies, was specifically set aside for projects like Mini OTEC. At present, another separate and federally funded project known as the Seacoast Test Facility is under design for installation in the same research corridor. Also, the federally-funded OTEC-1 project being carried out by Global Marine will be moored near the same general area. Meteorological and oceanographic data has previously been gathered by University of Hawaii researchers.

SITE CONDITIONS

The Keahole site is characterized by generally benign weather conditions and blessed with the mild Hawaiian climate and sunshine. Mean air temperatures are 75 degrees fahrenheit in the area. Surface wind conditions are offshore night breezes and onshore day breezes with occasional strong southerlies. Surface waters are typically 75 degrees fahrenheit. The area is generally in the lee of the Island of Hawaii and protected from the prevailing tradewinds. Ocean currents at the surface in excess of 2 knots have been recorded. In conference with University of Hawaii experts, it was agreed that the Mini OTEC mooring would be designed to survive ocean conditions predicted by hindcasting data from hurricane Nina of 1957, the most severe hurricane ever known to have occurred in the general area. These conditions include a significant wave of 25.5 feet. In addition, a surface current of 2.2 knots, and a 30 knot wind are all presumed to be acting from the same direction. The ocean current is presumed to follow a normalized Bretschneider distribution.