Analysis of varying levels of methane emissions from coal mines in poland

In Poland the fundamental energetic material for many years is hard coal. According to draft of energy policy such state will be maintained at least until year 2050. Therefore it is necessary to carry out researches and take actions in order to limit emission of harmful products associated with production and utilization of this mineral. Nowadays, pro-ecological activities, mainly focus on development and application of technology the purest processing of coal into thermal and electrical energy. However less attention is devoted to limitation of harmful gases emission during exploitation process of this material. During the coal mining process, a lot of different harmful gases are released into the mining atmosphere. The most unfavorable of them is methane. This gas is side product accompanying hard coal exploitation and next to carbon dioxide has the greatest impact on global greenhouse effect. In recent years, due to the exploitation of seams with large amount of methane remaining at progressively deeper levels, a significant growth of its emission takes place. Part of this methane is captured by the methane drainage installations and used in economic purposes. Unfortunately, a significant part of this emission goes into the atmosphere and natural environment. In the paper, results of analysis aimed to determine amount of methane emitted into the atmosphere through hard coal mines in Poland in the years 2011-2016 are presented. Thanks to applied taxonomic methods, classification of mines based on amount of emitted methane into the atmosphere in this period was performed. Detailed analysis was performed using one of the non-hierarchical clustering methods, which is the k-means method. Application of this method enabled to isolate homogenous subsets of analyzed objects (mines) for which as measure of similarity the Euclidean distance was assumed. In the analysis six variables describing each of mines were taken into account. Mines were grouped into clusters according to the similarity scale. As a basic criterion the total emission of methane into the atmosphere and the emission per ton of extracted coal were assumed. Obtained data clearly indicate mines (objects) which in particular way contribute to worsening the state of atmosphere. Simultaneously, they are a significant information for the emergency services responsible for limitation of harmful emission of greenhouse gases and improvement of environment state. Obtained data could also be the basis for undertaking the practical actions, in order to reduce the harmful emission of methane into the atmosphere.