Biochemical Simulation of a 100 MW OTEC Plume

Pat Grandelli, Greg Rocheleau
Makai Ocean Engineering, Inc., United States

Keywords: OTEC, modeling, plume, plankton, biochemical

This paper describes numerical modeling work to simulate the biochemical effects of the warm and cold seawater plumes discharged by a 100 megawatt Ocean Thermal Energy Conversion OTEC) plant. To predict the effect of OTEC plant configuration and phytoplankton response, Makai Ocean Engineering adapted an EPA-approved biological and physical model to simulate the ocean waters surrounding O`ahu. The model calculates the biochemical response of picoplankton (such as prochlorococcus), nanoplankton, and microplankton (such as diatoms). This model was \"nested\" within a sophisticated physical oceanographic Regional Ocean Model operated by the University of Hawai`i and the National Atmospheric and Oceanic Administration. The combined model was peer-reviewed and is the most realistic OTEC plume model yet developed. With no OTEC plant, the modeled results closely agree with phytoplankton concentrations and variability (patchiness) observed within the Hawaii Ocean Time Series (HOTS) data. With OTEC, it was demonstrated that altering the depth of the OTEC plant’s discharge will determine the adjacent phytoplankton’s response. Some OTEC configurations will create an obvious biochemical signature. Other configurations will cause productivity increases small enough to be within naturally occurring variability. Funding: CEROS, USDOE, Lockheed, Makai

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