Affects of the Cold Water Pipe Depth in Ocean Thermal Energy Converter Plants with respect to Power Generation Efficiency

Helia Danielle Giordani,Miguel Medina,Jade Tan-Holmes,Matheus Lages

doi:10.5130/pamr.v2i0.1395

Abstract

The Ocean provides an extensive renewable energy source. It is the exploitation of the thermal gradient between the warmed surface water and the deep cold water. A heat engine was developed to use the surface water as a heat source and the deep water as a cold source in order to convert thermal energy into mechanical energy and generate electricity. This process is called Ocean Thermal Energy Conversion (OTEC). This paper presents the three different types of OTEC power plants: closed-cycle, open-cycle and hybrid-cycle, showing real and conceptual examples of each. All three systems are analyzed in terms of gross power, net power, efficiency and size. Furthermore, the depth of the cold water pipe is discussed and related to the net power generation of the OTEC plant. The power generation efficiency of the plant increases as the gross power production increases. This is due to the depth of the cold water pipe and amount of power used by the cold water pipe pump.

Highlights

Man must not live on the planet he inhabits, but live with it
A Heat engine refers to a device that uses heat transfer to do work; in other words, thermal energy is converted to mechanical energy via a heat flow from a hot reservoir to a cold reservoir (Schulte 2015)
Once we were confident in our background knowledge of the topic, we began our search of specific examples of Ocean Thermal Energy Converter (OTEC) plants by searching for articles and journals on known OTEC systems

Summary

Introduction

Man must not live on the planet he inhabits, but live with it. For this half of the twenty-first century an electricity demand of 1028 (2.7x105 TWh) is expected. The surface layer of the ocean (50 to 100 meters deep) is a thermal power reserve available for man, which is nothing more than stored solar energy. D'Arsonval proposed in 1881 to mount a heat engine using the ocean surface water as heat source (25°C) and deep water as a cold source. This led to the practice of Ocean Thermal Energy Conversion. A Heat engine refers to a device that uses heat transfer to do work; in other words, thermal energy is converted to mechanical energy via a heat flow from a hot reservoir to a cold reservoir (Schulte 2015). A heat engine turns heat in a cyclic process from a hot reservoir into work The sun warmed surface water of the oceans is the heat source of an OTEC plant and the deep cold water is the cold source

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