Exergy Analysis of the Annual Operation of a Sugarcane Cogeneration Power Plant Assisted by Linear Fresnel Solar Collectors

Abstract

In this work, the exergy analysis of two configurations of hybrid solar–sugarcane cogeneration power plant is proposed in order to evaluate the overall efficiency enhancement of the cycle. Solar thermal energy was coupled to a sugarcane cogeneration power plant localized on the tropical region of Brazil, in order to preheat the feeding water supplied to the steam generators and to reduce the fuel consumption during the sugarcane-harvesting season in order to stock the unused fuel for its use during the off-season. The exergy analysis of the cycle was proposed based on a thermodynamic model, which considered real operational states, and allowed to quantify the main parameters of performance, such as the solar-to-electricity (STE) efficiency, the power generation increasing, the percentage of fuel saved, and the exergy destruction rates of the equipment. The results showed that, under design conditions, almost 10% of fuel was saved, and the overall exergy destruction decreased 11% approximately. Additionally, as a result of the hourly analysis of the annual operation, it was found that the power plant operated 331 extra hours, 8.50 GWh of electricity were generated, and due to this fact, it has attained economic benefits for the operation of the sugarcane cogeneration power plant.