Exergy based evaluation of power plants for sustainability and economic performance identification

Abstract

Enhanced sustainability and efficiency are among the prime indicators to achieve in the power generation sector of any country. The decline in efficiency might be caused by improper utilization of fuels and increasing entropy in outdated generation units. Reduced efficiency in power generation is particularly detrimental for the sustainability in developing countries, as resources are limited and need to be carefully allocated and maintained. Exergy analysis based on the laws of thermodynamics are currently gaining traction among researchers to study the overall performances of power generation units. Taking Bangladesh as a case study, this work investigates the power generation data for the country since 2009 till 2019 to study the internal energy losses of natural gas, oil, high-speed diesel, coal, and hydro based plants and provides a baseline for investment policy formulation. Our study found that, due to lack of maintenance and proper planning during the initial phases, the overall energy efficiencies among these sectors are relatively low, staying in the range of 34.55%–36.1% while the exergy efficiencies are 35.07%–36.59%. Corresponding exergetic parameters as depletion number, exergy sustainability index, relative irreversibility, lack of production, cumulative exergy loss, waste exergy ratio, and environmental effect factor pointed to similar findings in terms of sustainability as well. Comparing these parameters, it is observed that hydroelectric plants are more sustainable and efficient compared to fossil fuel-based generation units. Cost estimation of fuels and financial losses in the power generation sector are also explored for a better understanding of the return on investment.