Studies in Engineering and Technology Vol. 3, No. 1; August 2016 ISSN 2330-2038 E-ISSN 2330-2046 Published by Redfame Publishing URL: http://set.redfame.com 19 Load-based Exergetic Assessment of an Offshore Thermal Power Plant in an Equatorial Environment Sidum Adumene Correspondence: Sidum Adumene, Department of Marine Engineering, Rivers State University of Science and Technology, Port Harcourt, Nigeria. Received: October 28, 2015 Accepted: November 10, 2015 Online Published: November 19, 2015 doi:10.11114/set.v3i1.1177 URL: http://dx.doi.org/10.11114/set.v3i1.1177 Abstract The Load-based exergetic assessment of a thermal power plant for offshore utilization was carried out. The gas turbine systems were split into sub-systems and simplified into control volume to show inflow and outflow of exergy at different loading. The operating parameters of the plant were monitored for 12 months through human machine interface (HMI), and the data collected were used with thermodynamic relations to carry out the assessment. MATLAB 7.3 ® Software was used to evaluate the various model equations and results tabulated. The results show that for every 1% drop in the operational load, the thermal efficiency and exergy efficiency drop by 0.17% and 0.25% respectively. It further shows that there is about 0.006% decrease in fuel consumption under the same conditions, and at 44% loading the system has the highest percentage of exergy loss of about 21.3%. This means that as the operational load decrease, the percentage exergy loss increase proportionally. Enormous exergy is lost in the exhaust system due to absence of heat recovery steam generator. The assessment established that the components of the power plant degrade in the quality of exergy and performance at different loading of the plant due to mechanical loss and irreversibility. Keywords: thermal plant, exergy assessment, efficiency, operational load, irreversibility 1. Introduction The advances in gas turbine manufacturing and performance over the years had helped to solve critical energy need of humanity. Gas turbine converts the chemical energy of fuel into mechanical energy using air as the medium of conversion. The resulting mechanical energy can be used to drive many types of rotating equipment like alternators, pumps and compressor. The development of science and technology has enhanced our ability to harness energy and utilize it rationally. The international energy agency reports that fossil fuels supply over 85% of the world’s commercial energy, account for 65% of the world’s electricity and 97% of the energy for transportation. This shows that the world’s energy demand tilt towards fossil fuel with little attention to other energy resources. In recognition of this energy need, Sureh et al. (2006) remarked that “power plants should be operated in the most efficient manner to check the rate of depletion of fossil fuel reserves”. To achieve this, there is need for periodic performance evaluation of the power plant using a load-based exergetic technique. Exergy have been viewed by different researchers as available energy to be a quantitative measure of the mechanical work lost in any real thermodynamic system as a result of irreversibility in the system. Kwambai (2005) and Hermann (2005) view exergy as a “work potential” of a system. Their view was drawn from the fact that any system which is at a temperature, pressure or chemical composition above that of its surroundings is not in equilibrium and has a potential to do work. Therefore, when a system is at a state of equilibrium with its environment, there would be no work transfer, and its exergy is equal to zero. Kotas (1995) states that “the exergy of a steady stream of matter is equal to the maximum amount of work obtainable when the stream in brought from its initial state to the dead state by processes during which the stream may interact only with the environment”. Exergy corresponds to the “useful” part of energy. Whereas energy is conserved with respect to the first law of thermodynamics, exergy destroyed or degraded with respect to the second law of thermodynamic and helps to locate the wasteful uses of exergy in energy conversion system. In the past decades, exergy related studies have received considerable attention from various discipline ranging from mechanical engineering to chemical engineering from environmental engineering to ecology, and other fetch of engineering as well as the physical science. Consequent upon this, there is global attention on exergy studies (Dincer &