OTEC för Tarawa
Ocean Thermal Energy Conversion, OTEC, a technology using the temperature difference between cold deep seawater and warm surface water, can extract the work in the form of electricity. OTEC gives also synergies of drinkable fresh water. The temperature difference has an impact on the efficiency of the technology, which means that the feasibility of OTEC is geographically limited. The project intends to explore the possibility of replacing the atoll Tarawa?s present electricity generation with an OTEC plant and to explore synergies. In the present situation all of Tarawa?s electricity is generated by fossil fuels. Tarawa is located at the equator in the Pacific Ocean and has geographical as well climatically conditions for the installation of an OTEC facility. There are three different types of systems: open, closed and hybrid. Through mathematical models, based on a literature study, the systems are modeled with the program EES (Engineering Equation Solver). After evaluation a system is proposed, which is considered to meet Tarawas needs, mainly of electricity and fresh water standpoint. The hybrid system was considered to be the system that met the needs after calculations had been made. The hybrid cycle is effective in electricity generation and has the most important synergy effect of freshwater production. The results show that it is possible to cover both Tarawa?s present need of electricity and fresh water, according to the UN's recommendations. Electricity costs have been calculated and the results show that an OTEC facility is a cost effective option when the price of oil does not fall below 35 U.S.$/Barrel. An OTEC facility has the opportunity to raise living standards as the supply of fresh water is deficient in Tarawa. Very limited amounts of carbon dioxide is released into the atmosphere during production, which means that the environmental benefits are huge compared to today's production by fossil fuels, the largest single source of carbon emissions. Since there are no commercial facilities at the present, additional studies and trials are needed before the technology becomes realizable.