Design and Construction of an Ocean Thermal Energy Conversion Test Plant

1980 ◽  
Vol 102 (1) ◽  
pp. 41-46 ◽  
Author(s):  
L. C. Trimble ◽  
R. L. Potash
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Cold Water ◽  
Seawater Temperature ◽  
Test Plant ◽  
Deep Seawater ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Power Plant Control ◽  
Ocean Thermal Energy

Mini-OTEC, shown in Fig. 1, is the first at-sea, closed-loop Ocean Thermal Energy Conversion (OTEC) system using surface and deep seawater to generate electric power. The Mini-OTEC cycle is installed on a moored barge incorporating the cold water pipe (CWP) in the single anchor leg. The design seawater temperature difference (ΔT) of 36°F provides thermal resource for a gross power output of 50 kW. This paper presents an overview of the Mini-OTEC project, including a description of the power plant, control system, instrumentation, and CWP mooring system.

scholarly journals Dynamic Simulation of System Performance Change by PID Automatic Control of Ocean Thermal Energy Conversion

2020 ◽  
Vol 8 (1) ◽  
pp. 59 ◽  
Author(s):  
Lim Seungtaek ◽  
Lee Hoseang ◽  
Kim Hyeonju
Keyword(s):  
Control System ◽  
Energy Conversion ◽  
Thermal Energy ◽  
Temperature Difference ◽  
Pid Control ◽  
Seawater Temperature ◽  
Ocean Thermal Energy Conversion ◽  
Control Value ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

Near infinite seawater thermal energy, which is considered as an alternative to energy shortage, is expected to be available to 98 countries around the world. Currently, a demonstration plant is being built using closed MW class ocean thermal energy conversion (OTEC). In order to stabilize the operation of the OTEC, automation through a PID control is required. To construct the control system, the control logic is constructed, the algorithm is selected, and each control value is derived. In this paper, we established an optimal control system of a closed OTEC, which is to be demonstrated in Kiribati through simulation, to compare the operating characteristics and to build a system that maintains a superheat of 1 °C or more according to seawater temperature changes. The conditions applied to the simulation were the surface seawater temperature of 31 °C and the deep seawater temperature of 5.5 °C, and the changes of turbine output, flow rate, required power, and evaporation pressure of the refrigerant pump were compared as the temperature difference gradually decreased. As a result of comparing the RPM control according to the selected PID control value, it was confirmed that an error rate of 0.01% was shown in the temperature difference condition of 21.5 °C. In addition, the average superheat degree decreased as the temperature difference decreased, and after about 6000 s and a temperature decrease to 24 °C or less, the average superheat degree was maintained while maintaining the superheat degree of 1.7 °C on average.

scholarly journals Potential effects of deep seawater discharge by an Ocean Thermal Energy Conversion plant on the marine microorganisms in oligotrophic waters

2018 ◽  
Author(s):  
Mélanie Giraud ◽  
Véronique Garçon ◽  
Denis De La Broise ◽  
Stéphane L'Helguen ◽  
Joël Sudre ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Thermal Effect ◽  
Thermal Energy ◽  
Pilot Plant ◽  
Phytoplankton Community ◽  
Deep Seawater ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy ◽  
The Impact

Abstract. Installation of an Ocean Thermal Energy Conversion pilot plant (OTEC) off the Caribbean coast of Martinique is expected to use approximately 100 000 m3 h−1 of deep seawater for its functioning. This study examined the potential effects of the cold nutrient-rich deep seawater discharge on the phytoplankton community before the installation of the pilot plant. Thermal effect induced by the deep seawater upwelled by the OTEC was described using the Regional Ocean Modeling System. Numerical simulations of deep seawater discharge showed that a 3.0 °C temperature change, considered as a critical threshold for temperature impact, was never reached during an annual cycle on the top 150 m of the water column on two considered sections centered on the OTEC. The thermal effect should be limited, less than 1 km2 on the area exhibited a temperature difference of 0.3 °C (absolute value). The impact on phytoplankton of the resulting mixed deep and surface seawater was evaluated by in situ microcosm experiments. Two scenario of water mix ratio (2 % and 10 % of deep water) were tested at two incubation depths (deep chlorophyll-a maximum: DCM and bottom of the euphotic layer: BEL). The larger impact was obtained at DCM for the highest deep seawater addition (10 %), with a development of diatoms, whereas 2 % addition induced only a limited change of the phytoplankton community. This study suggested that the OTEC plant would significantly modify the phytoplankton assemblage only in the case of a discharge affecting the DCM and would be restricted to a local scale.

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