Increasing the use of renewable energy sources is one of the strategic objectives of the European Union. In this regard, it seems necessary to answer the question: which of the member countries are the most effective in its implementation? Therefore, the main goal was to distinguish groups of European Union countries, including the Visegrad Group, differing in the use of renewable energy sources in transport, electricity, heating and cooling (based on cluster analysis). All members of the EU were determinedly selected for research on 1 February 2020 (27 countries). The research period embraced the years 2009–2019. The sources of materials were the literature on the topic and data from Eurostat. Descriptive, tabular, graphical methods and cluster analysis were used in the presentation and analysis of materials. In 2019 wind and hydro power accounted for two-thirds of the total electricity generated from renewable sources. In 2019, renewable energy sources made up 34% of gross electricity consumption in the EU-27. Wind and hydro power accounted for two-thirds of the total electricity generated from renewable sources (35% each). Moreover, it was determined that there were 5 clusters that differed in their use of renewable energy sources. The highest average renewable energy consumption in transport, heating and cooling in 2019 was characterized by a cluster consisting of Sweden and Finland. In contrast, the highest average renewable energy consumption in electricity was characterized by a cluster consisting of countries such as: Austria, Croatia, Denmark, Latvia and Portugal. Finally, in a group that included countries such as Belgium, France, Luxembourg, Malta, the Netherlands and the entire VG (Hungary, Czechia, Slovakia and Poland), renewable energy consumption rates (in transport, electricity, heating and cooling) were lower than the EU average (27 countries).

The main aim of this study is to present a systematic literature review (SLR) of the sustainable energy development (SED) and emphasize important activities relevant to this concept. The following set of research tasks was adopted to achieve the main aim: (1) presentation of the distribution of articles by year (both journal and conference papers) on the SED concept; (2) identification of the most frequently cited articles on the SED concept; (3) identification of the countries that have contributed most to the development of the SED concept through publication activities; (4) demonstration of the subject areas most frequently associated with the SED concept; (5) presentation of the various definitions of the SED; (6) identification of the most important activities carried out under the SED; and (7) presentation of future research directions for the SED. It is worth noting that the research tasks undertaken will be both quantitative and qualitative. The data search was conducted on 31 August 2022, and the selected peer-reviewed database was Scopus. The exclusion process resulted in a total of 607 journal and conference papers. The most important conclusion to be derived from this study is that there is no one unified definition of the SED. Moreover, three activities must be undertaken to realize the SED concept: (1) increasing the use of renewable energy sources in the energy mix, (2) enhancing energy efficiency, and (3) reducing emissions of greenhouse gases and air pollutants. The article also presents the authors’ conceptual model that can serve as a starting point for further analyses in this area.

The ability to share knowledge in an organization may determine its success. Knowledge is one of the basic resources of an enterprise, being also the basis for undertaking various types of strategic actions. Knowledge management should be focused in the organization on such processing of all available information to lead to the creation of value defined by employees of the organization and by customers. In order to raise the issue of knowledge sharing, trust should be mentioned. Trust is a factor conditioning effective atmosphere and cooperation in an organization. The main purpose of the article is to present the relationship between trust and knowledge sharing, taking into account the importance of this issue in the efficiency of doing business. To formulate conclusions, data from surveys carried out in 148 different tourist facilities were used. Data were collected by applying the diagnostic survey method and by using a survey technique based on a prepared questionnaire. The results showed that trust is important in sharing knowledge and was found to play an important role in achieving a high level of performance efficiency. The study consists of an introduction, literature review, research results and discussion of results. At the end of the article, conclusions, restrictions and recommendations for future research are presented.

The primary aim of this study was to assess and compare EU countries in terms of the use of renewable energy sources in road transport. The following research tasks were undertaken to realize this aim: (1) a review of the literature concerning the negative externalities in road transport, the concept of sustainable development, and legal regulations referring to the utilization of renewable energy sources; (2) presentation of changes in energy consumption (both traditional and renewable) in road transport in EU countries in the years 2008–2019; and (3) identification of leaders among the EU countries in terms of consumption of renewable energy sources in road transport. The aim and tasks were realized using the literature review and TOPSIS method as well as descriptive, tabular, and graphic methods. The analysis was conducted for 28 EU countries according to the status for 2019. The period of 2008–2019 was investigated. Sources of materials included literature on the subject and Eurostat data. Although renewable energy sources accounted for as little as 6% of total energy consumption in road transport in EU countries in 2019, this is a significant topical issue. It results from the direction in which changes need to be implemented in terms of energy generation in this area of human activity. It turned out that blended biodiesel and blended biogasoline were the most commonly used fuels originating from renewable sources. The application of the TOPSIS method resulted in the identification of five groups of EU member countries, which differed in terms of the degree of utilization of renewable energy sources in road transport. Luxemburg, Sweden, and Austria were leaders in this respect. In turn, Malta, Estonia, and Croatia were characterized by very low consumption of renewable energy. The greatest progress in the utilization of renewable energy sources in road transport was recorded in Sweden, Finland, and Bulgaria (changes in the relative closeness to the ideal solution from 0.15 to 0.27), while the greatest reduction in relation to other countries was observed in Austria, Germany, and Lithuania (changes from −0.35 to −0.22).

The primary aim of this study was to assess and classify selected EU countries to groups differing in terms of the degree of implementation of innovative energy technologies to alleviate adverse externalities in road transport. This aim was realised using three groups of research methods: collection of empirical data, data processing and presentation of study outcomes. When collecting the research material, the authors used the method of critical literature review and the documentation method. The research material was processed using the agglomerative clustering technique, which was one of the hierarchical clustering methods. The distance between objects (here, selected EU countries) was determined based on the Euclidean distance. The outcome of this analysis was a dendrogram, which constitutes a graphical interpretation of obtained results. The study was conducted on 21 EU countries. The analyses covered the years 2013–2019. The sources of materials included literature on the subject and the Eurostat data. The problem of innovative energy technologies in road transport is presently of considerable importance. This results from the current situation related to human activity. As a result of the conducted cluster analysis, groups were distinguished based on differences in the use of innovative energy technologies alleviating negative externalities generated by road transport. The first group comprised Sweden, the Netherlands and Finland. Compared to the other groups, this group was distinguished by the highest values of four indexes, i.e., the share of renewable energy sources used in transport in 2019, the share in the market of electric passenger vehicles in 2019, the share in the market of electric lorries in 2019, as well as the share in the market of hybrid automobiles in 2019. Countries which participated the least in the elimination of negative externalities generated by road transport included Romania, Hungary, Greece, Poland, Latvia and Estonia.

The outbreak of war in Ukraine has severely disrupted global food and agricultural markets and affected commodity prices. The grain agreement, also known as the Black Sea Initiative, was concluded on 22 July 2022 by Ukraine, Russia, Turkey, and the United Nations, to alleviate the global food crisis caused by the conflict. This study aims to ascertain whether the agreement has resulted in the stabilization of cereal markets, examining the evolution of prices of wheat and corn, which are of significant importance in Ukrainian exports, throughout the duration of the agreement, including its signing, implementation, and expiration. The analysis, based on the GARCH model and using daily quotations of corn and wheat futures contracts of the European futures exchange Euronext from December 2021 to May 2024, indicates that prices were characterized by exceptionally high volatility in the period preceding the signing of the agreement, and at the time of its expiration. The uncertainty regarding cereal trade conditions has triggered shocks, with a long-lasting impact on price volatility.