Relationship between petrological characteristics and gross calorific value of coal

In this work, an attempt has been made to understand the relationship between petrological parameters and the gross calorific value (GCV) of coal. This study aims to enhance the understanding of how compositional parameters govern GCV, providing insights into the broader influence of coal's petrological characteristics on its energy content. In this regard, coal samples of wide variation in ash yields obtained from density fractionation were analyzed for the detailed petrological parameters along with the GCV. The petrological study of the density fractionated coal samples showed the difference in macerals composition, maturity, and maceral-mineral associations that potentially affect GCV. Given the number of parameters, identifying the factors influencing GCV posed challenges such as visualization, dimensionality, multicollinearity, and overfitting. Therefore, principal component analysis (PCA) was performed towards better understanding of the intricate relationships among variables, addressing multicollinearity, and visualizing GCV variability as well as its influencers. The analysis indicated that both reactive macerals (vitrinite and liptinite) and so-called "inert" macerals from the inertinite group contribute to GCV in distinct ways. The analysis also showed that GCV is favored by both vitrinite and semifusinite, with vitrinite's high reactivity and semifusinite's link to coal maturity playing key roles. The findings highlight the need to consider multiple factors, such as maceral type and maturity, in combination for future quantification attempts.