2 nd International Exchange and Innovation Conference on Engineering & Sciences Kyushu University, Fukuoka, Japan October 14 th , 2016 Study On Electrification of Remote and Isolated Tropical Islands Using OTEC Walid Bin Habib, Mahedi Hassan, Tahmid Hasan Rupam Department of Electrical and Electronic Engineering, University of Dhaka, Bangladesh Corresponding author email: walid.habib.1994@ieee.org Abstract: Apart from solar and wind energy as a form of renewable energy, ocean can also be considered one as approximately 2 to 3 billion MW power can be gained from it. Covering 71% of earth’s surface the ocean is the largest solar energy collector absorbing about 70% of day’s solar energy. On an average day the amount of heat energy absorbed by 60 million square kilometers of the tropical sea surfaces commensurate burning of 250 billion barrels of oil and when converted to electrical energy it can limit the demand of electricity for 260 million people per day. In this study we emphasized on converting this thermal energy from the sea to electrical energy in order to provide electricity to the isolated tropical islands. This can be practically done where there is at least 20 degrees Celsius temperature difference exists between the upper and lower surface of the ocean. The conversion process involves evaporating an intermediate fluid like ammonia or direct evaporation of the sea water of upper surface and in both case cold water from lower surface performs the condensing task. Though the converted electrical energy is not sufficient for a large power plant but it can be an alternate source for the remote isolated islands where power from central grid cannot be reached. Apart from this, byproducts like pure desalinated water that can be used for pure drinking water and in agriculture sector of those islands; salt and cold water from the lower sea surface and this water can be used as industrial cooling of those islands. . Keywords: Renewable energy; OTEC; Tropical islands; Temperature gradient; Electrification; 1. INTRODUCTION Finding energy sources to satisfy the world’s growing demand is one of society’s foremost challenges for the next half-century. This requires finding solution in renewable energy than traditional fossil fuel based energy and Ocean Thermal Energy Conversion (OTEC) is one of the potential sources that is ideally suited to provide the required thousands of megawatts of electric power with the least environmental impact. The oceans cover a little more than 70 percent of earth surface. This makes oceans the world’s largest solar energy collector and energy storage system. On an average day, 60 million square kilometers of tropical seas absorb an amount of solar radiation equal in heat content to about 250 billion barrels of oil [1]. Most of the developed countries of the world have taken plans to establish renewable energy based project and OTEC is the unique among all of the energy generation technologies where there is no generation of CO 2 , but it actually counteracts the effect of fossil fuel use. Therefore, it is clean, green renewable energy that doesn't involve burning fossil fuels, producing large amounts of greenhouse gases, or releasing toxic air pollution [2]. So, OTEC can be considered as a smart choice of renewable energy in Bangladesh. In this paper the purpose is to discuss the possibility of OTEC and the full research are based on the measurement of the depth level and temperature difference of the different region of Bay of Bengal and try to determine the possible geographical OTEC site selection for Bangladesh 2. OCEAN THERMAL ENERGY CONVERSION OTEC is a marine renewable energy technology which uses the ocean’s natural temperature gradient to produce electricity. Naturally, sunlight falls on oceans is strongly absorbed within a shallow mixed layer at the surface typically 35 to 100 m thick which is supposed to vary from 27 ° C to 29 ° C [1]. Beneath the layer, the more is the depth in the ocean and water of different temperature is found which is much colder than the surface. This means we have an oceanic structure where the surface waters are as hot as we can find and the deep waters are as cold as possible. This temperature difference is used in OTEC to generate electricity. The best place to find such a combination is in the tropics [3]. Basically OTEC uses the temperature gradient to drive a turbine connected to a generator which produces electricity. 2.1 Criteria for OTEC site selection OTEC projects have been around since the 1970s (Cohen, et al., 1986) [4]. Considering the OTEC site selection criteria as mentioned in multiple papers by L.A. Vega, who is one of the key researchers and an internationally figure on this subject matter, deliberating his mentioned factors like geographical location, surface and undersea temperature, land area, population, electric energy sources, electricity demand, current availability and future electricity demand are quite important [5]. 2.2 Basic process of OTEC OTEC works on the relationship of pressure (p), temperature (t) and volume (v) of a fluid which can be expressed by the equation [6]: PV/T=constant 2.3 Different OTEC technologies There are basically 3 types of OTEC systems developed so far. They are: Closed-cycle OTEC System, Open- cycle OTEC system and Hybrid OTEC system. In the closed cycle system surface water, with higher temperatures, is used to provide heat to a working fluid with a low boiling temperature, hence providing higher vapor pressure. Ammonia is usually used and is contained in large pipeline. Therefore, the system has