Análise energética, exergética e de sustentabilidade do setor elétrico brasileiro

Abstract

Ensuring sustainability in power generation processes is a major concern for states since the use of electricity is increasingly present in the routine of contemporary society. In this context, the exergy analysis presents itself as a useful tool to evaluate the efficiency and sustainability of the economic sector of power generation. In this study, the use of energy and exergy by the Brazilian power generation sector is investigated in the period from 2000 to 2020. Based on data provided by the Balanço Energético Nacional and by the Anuário Estatístico de Energia Elétrica, the exergy analysis for the sector was performed considering the generation of energy from wind, hydraulic and thermal power sources, the latter being based on natural gas and sugarcane bagasse. Then, the sustainability assessment of the sector was carried out, where indicators that create a correlation between exergy and environmental sustainability were used. The results of this research shows that the general exergy efficiency for the sector varied from 63.3 to 75.0% over the years and the thermal power generation processes have the greater Improvement Potential. For the evaluated sustainability indicators, the Depletion Number varied between 0.25 and 0.37, while the Exergy Sustainability Index varied from 2.73 to 4.00. The highest values obtained for the Relative Irreversibility and Lack of Productivity indicators were attributed to hydraulic and natural gas sources that were exchanged during the studied period. The Waste Exergy Ratio showed its maximum for generation using natural gas, with values between 0.016 and 0.149, the same behavior was observed for the Environmental Effect Factor which varied from 0.021 to 0.236. During the evaluated period, the Cumulative Exergy Loss increased by 359%. In addition, a hypothetical scenario with no natural gas power generation was evaluated and compared, results showed a huge potential for exergy savings. It is believed that the present study can help to improve energy policy-making towards sustainable development of the country.