Slovakia is renowned for its remarkable and rare natural beauty, abundant in natural resources with several noteworthy geological features. However, the protection of nature has primarily been understood as the protection of biodiversity in Slovakia. For the conservation of geological diversity and landforms, very little has been done. Geoconservation or the protection of geodiversity is being applied to specific places known as geosites, where significant earth elements (geological, paleontological, geomorphological, hydrological and pedological) are protected, preserved and managed. Most geosites benefit from existing protected areas. Their protection is random and does not result from the recognition of their values. As discussed in the paper, geotourism related activities can undoubtedly contribute to promoting the protection of geosites in protected areas. Besides, through a geotourism approach, geodiversity can obtain public attention and positively influence the state of protected areas by its activities. Such initiatives not only can improve the protection of geological sites but also can play a crucial role in sustainable tourism development.

The constant consumption of resources exerts pressure on the environment. In this sense, waste management has obtained increasing attention from the view of a circular economy. The European Union deals with these mentioned aspects, trying maintain long-term competitiveness and to provide sustainable development in accordance with all related environmental aspects. This paper focuses on the evaluation of the production of communal waste in 36 EU countries. The main aim is to evaluate the success of countries’ efforts to decrease waste production and increase recycling rates. The methodology used for the evaluation included data collected from the publicly available database Eurostat, consequent analyses and evaluation in the statistical software JMP 13 through regression, distribution, and cluster analysis, and the interpretation of the results. The results of the cluster analysis showed that despite clear EU waste management legislation, EU member states have significantly different waste management systems at the national level. However, generally, we could see positive correlation between the generation of waste and recycling rates. Although, Malta, Austria, Greece, and Norway recorded a decreasing level of waste recycling over the last several years, some countries (Slovakia, Poland, Czech Republic, Latvia, Lithuania) had significantly lower recycling rates accompanied by low landfill taxes. The evaluation of waste production and recycling can be used for government policy in the area of waste management, as well as for individual communities dealing with communal waste.

In the European Union, basic strategy results from the need to provide intelligent, sustainable, and inclusive growth, along with respect to social and economic impacts of waste treatment. The paper focuses on municipal waste and its separation. Generally, within global waste management initiatives, the main goal is to minimize the negative effects of waste on the environment, as well as to increase and optimize the sources’ efficiency in the waste economy. Research on municipal waste development and its separation was done in individual regions of Slovakia to find if socially weaker regions have worse waste treatment. The results were compared according to the waste development per inhabitant and per household, as well as through rate indexes, which are connected to relationships between waste, social, and economic indexes. The results confirmed research results from other countries that show that the volume of municipal waste is increasing due to increased living standards of inhabitants. However, on the other hand, waste separation rates also increased—mainly based on the legislative support.

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Slag is one of the by-products of the energy industry, which is suitable for secondary industrial processing. Although slag has been successfully used in industrial production for several decades, its use does not achieve the level of its potential. Today, to achieve a sustainable construction industry, alternative types of cement have been extensively investigated. Geopolymer is a kind of material which is obtained from the alkaline activator and it can be produced from the industrial wastes or by-products. In this study, SiO 2 /Na 2 O ratio and the amount of Na 2 O in activation solution parameters of alkali-activated materials were tested how they affect the strengths of hardened geopolymers from ground granulated blast furnace slag (GGBFS). Compressive and flexural strength tests were conducted, and the results were analyzed by analysis of variance (ANOVA). Strengths were tested after 7, 28, and 90 days.

In recent years, the mining industry has achieved an important position in the national economy due to its increasing productivity. However, since 2000, there have been signs of a slowdown, resulting from the national and local conditions of the mining industry. It is for these reasons that we have concluded that this type of industry must be assessed not only from the economic but also from the national and regional sectors, because the performance of the mining industry is directly affected by the value of mineral deposits and the structure of other industries. The present paper aims to analyze the development of the mining industry in Slovakia, in comparison with similar development in chosen European Union countries. Slovakia has been considered as a country with mineral resources and mineral-based products representing an important part of Slovakia’s foreign trade, with the significant imported mineral resources including mainly mineral fuels and ore raw materials. The development of the mining industry is assessed from the economics through the growth rate of gross domestic product (GDP) and through the national aspect through the rate of growth of the national economy. The aspects are evaluated by the multi-criteria method Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), with which we evaluated the country with the best mining industry development. The results of detailed quantitative analyses of the selected indicators for mining industry development for individual European Union countries show a fluctuating trend during the observed period, which is characterized by development disparities. Such results can be used to determine raw material policies in the relevant countries.

Recently, the use of photovoltaic (PV) cells and the increase in the number of photovoltaic power plants has led to a detailed examination of their operating parameters. In this article, we discuss material and operating parameter influences on the performance and efficiency of photovoltaic panels in a photovoltaic power plant. The plant consisted of 3600 pieces of polycrystalline PV panels from Renewable Energy Corporation (REC) Solar (type REC 230AE) with a maximum power of 230 Wp. Parameter measurements were made three years after the power plant was started. The measured and computed data were statistically processed using multidimensional statistical methods where the relationships between input and output variables were examined, which was subsequently quantified by regression analysis. Using the ANOVA, the variability of the measured efficiency of the panels and the performance for individual years was examined. Efficiency has been found to increase significantly over the years. The reason for this is the statistically proven prevailing operating time of the PV power plant in conditions with lower temperature than standard operating conditions (25 °C). Ageing was not confirmed in optimal conditions and calculated efficiency was constant.

The paper deals with the elimination of heat losses in a flat low-pressure solar collector caused by direct contact of outlet pipefitting and the Al–Mg collector box. This is manifested by reduced thermal efficiency of the solar collector, especially in cold season, which is in direct conflict with its application, i.e., high-temperature application and application in cold conditions. The solution lies in the proposed new structural element—the vacuum thermal insulation bushing, which is able to simultaneously provide vacuum tightness of the collector box and interrupt the existing thermal conductive connection. The design philosophy was to transfer the vacuum insulating function component from the original pipe—collector box connection to the thermally insulated place bushing—collector box. Two prototypes were constructed and built into experimental vacuum chamber. Significant increase in the temperature gradient was found in performed experiments. Thermal insulation function, vacuum tightness, and resistance to thermomechanical stress have been demonstrated. The thermal insulation function has also been described through the simulations on a computational model, using finite volume method. The proposed solution of bushing has also successfully become the subject of patent protection.