Mapping available Ocean Thermal Energy Conversion resources around the main Hawaiian Islands with state-of-the-art tools

Abstract

This paper aims to demonstrate how the evaluation of Ocean Thermal Energy Conversion (OTEC) resources can benefit from currently available high-resolution ocean models. The case of waters around the main Hawaiian Islands is presented because of its relevance to the future development of OTEC. OTEC resources are defined here by ocean temperature differences between water depths of 20 and 1000 m, with little loss of generality. Using state-of-the-art tools like the HYCOM+NCODA (1/12°) model affords the possibility to track changes on a daily basis over a wide area (e.g., 17 °N to 24 °N and 153 °W to 162 °W). An examination of numerical data over a time period of 2 years reveals interesting geographical patterns. It is found that average OTEC temperature differences are consistently higher (by about 1 °C) west of the islands, whereas the amplitude of the yearly cycle globally decreases from north to south as expected. Better OTEC resources in the lee of the islands are attributed to the narrow eastward-flowing Hawaiian Lee Counter Current. All other things being equal, a change of 1 °C in the resource typically would amount to a 15% variation in net OTEC power output.