– 1 – A PRE-REVIEW STUDY OF OCEAN THERMAL ENERGY CONVERSION CYCLE WITH DIFFERENT WORKING FLUIDS Norazreen Samsuri 1 , Sheikh Ahmad Zaki Shaikh Salim 2 , Md Nor Musa 3 , Abu Bakar Jaafar 4 , Mohamed Sukri Mat Ali 5 Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Malaysia norazreen1989@gmail.com 1 , sheikh@ic.utm.my 2 , sukri@ic.utm.my 5 , UTM Ocean Thermal Energy Centre, Universiti Teknologi Malaysia, Malaysia mdnor@fkm.utm.my 3 , bakar.jaafar@gmail.com 4 ABSTRACT Malaysia has huge potential for developing Ocean Thermal Energy Conversion (OTEC) although it has not been established yet. The OTEC plant can be installed to operate between a heat source (surface seawater at 30°C and heat sinks (deep seawater at 1000m for 4°C). This ocean thermal energy is cheap and most importantly it is sustainable - as long as the sun keeps heating the ocean surface. The current best performance between all the OTEC cycles is that of Uehara Cycle which uses ammonia mixture as the working fluid – highly toxic. Therefore, the purpose of this paper is to explore the other potential friendly working fluids. The research is to improve performance of OTEC plant and at the same time the plant is operated using an environmentally safe working fluid. The results should lead to future development an OTEC plant at Malaysia. Keywords— Ammonia, Ocean Thermal Energy Conversion (OTEC), Uehara Cycle, Working Fluids 1. INTRODUCTION 1.1. Description of OTEC Location at Malaysia Energy is served all around us. Despite this, no one solution has been developed to meet global demand for secure, responsible and economic power. Ocean Thermal Energy Conversion (OTEC) has the potential to serve as a promising alternative energy source for our future. The ocean offers a single largest opportunity for mining our energy needs. It acts the world largest solar power by collecting 80% of the earth receives from the sun. OTEC energy formed by converting solar radiation stored in the upper ocean water layers into electric power. OTEC is a system of converting heat energy stored in parts of ocean into electricity by using temperature difference of surface water and cold water of about 15K over a depth 600 to 1000m in the tropical zone. This energy can be harnessed by an OTEC plant operates based on Rankine cycle. In 2008, upon the completion of marine survey at the South China Sea, it has been confirmed that the temperature and depth of the North-Borneo Trough which is Sabah Trough shown in Figure 1-4, is a suitable place to develop OTEC plant in Malaysia. A column of (Figure 1), of 2.5km deep, the same size area as Pahang, located near Pulau Layang- Layang, approximately 200km off-shore Sabah (Figure 2), offers a tremendous opportunity for an OTEC power plant to be installed for generating electricity, estimated to be about 50,000MW (Peninsular Malaysia uses 26,000MW) [1]. The temperature difference between SSW and DSW at Sabah Trough is more than 15K (Figures 3 and 4, respectively). In addition, the higher temperature difference, the higher efficiency of the OTEC cycle can produced [2]. This ocean thermal energy is cheap (or literally free) and most importantly it is sustainable - as long as the sun keeps heating the ocean surface. However, being too far off-shore it is not viable to transmit the electricity to the mainland. An intelligent option is to use this cheap electricity to produce cheap hydrogen and store it in a liquid form for export worldwide. The cheap hydrogen can now run fuel cells, gas turbine plants and internal combustion engines- all three systems generate a carbon-free by-product called WATER. USA, France and Japan have now had the OTEC technology commercialized. Fig. 1. The location area of Sabah Trough (Source: Abu Bakar Jaafar, 2012[1])