The global climate crisis forces the search for new ecological sources of energy and mining methods. Space mining can solve those problems, but, first, wide geological surveying space missions using drilling methods are necessary. Additionally, drilling methods will be important in geological, life searching, geoengineering, and many other studies of extraterrestrial objects. Space is becoming a new area of possible drilling applications. Designing future space drilling missions requires adapting drilling technologies, not only to the conditions of the space environment, but also to the economic and technological realities of the space industry. The possibility of constructing low mass coring devices with energy consumption below 100 W was investigated in this paper. Minimization of energy consumption and mass of a coring is essential for the device to be used in space missions, when lander instruments supplied by low power electric battery are expected to work reliably and the launch... [more]

Energy and exergy (EnE) efficiencies are considered the most important parameters to compare the performance of various thermal systems. In this paper, an analysis was carried out for EnE efficiencies of a flat plate solar collector (FPSC) using four different kinds of nanofluids as flowing mediums, namely, Al2O3/water, MgO/water, TiO2/water, and CuO/water, and compared with water as a flowing medium (traditional base fluid). The analysis considered nanofluids made of nanomaterials’ volume fractions of 1−4% with water. The volume flow rates of nanofluids and water were 1 to 4 L/min. The solar collector′s highest EnE efficiency values were obtained for CuO/water nanofluid among the four types of nanofluids mentioned above. The EnE efficiencies of the CuO nanofluid-operated solar collector were 38.21% and 34.06%, respectively, which is significantly higher than that of water-operated solar collectors. For the same volume flow rate, the mass flow rate was found to be 15.95% higher than wa... [more]

Direct steam generation is a promising alternative to conventional heat transfer fluids for solar thermal power plants using linear concentrators because water and steam do not have thermal and chemical stability problems. The novelty of this study, an energy and exergy (2E) analysis, was that it was performed on several configurations of a conceptual direct steam generation solar power plant with optimized Fresnel reflectors in Agua Prieta, Mexico coupled with a regenerative steam Rankine power cycle to quantify their efficiency and establish a reference for future implementation of this technology in concentrated solar power plants in Mexico. The thermal model was assumed to be a 1D steady-state flow and validated against results in the literature. It was then applied directly to a case study to determine the size of the solar field. The design point was the lowest solar irradiance day, and evaluating the solar multiple with the highest solar irradiance, taking care not to oversize t... [more]

In Poland, the development of photovoltaic (PV) installations is an important element in the development of the Renewable Energy Sources (RES) sector and supports the prosumer power industry. The purpose of the article is to present a case study of the PROSUMENT program. It analyzes the data available to date on the development of the PV market in Poland. Apart from the costs of installing the PV systems, the article analyzes the profitability of investment for different micro-power installation capacities. A calculation for micro-power installations subsidized under the PROSUMENT program for various PV capacities is presented, along with the actual amount of the subsidy. The adopted calculation methodology is a comparative verification analysis of the investment cost estimate for a for the two studied PV facilities, i.e., Micro-power installation 1 and Micro-power installation 2. The building’s annual energy demand was adopted at the same level for both examples, with fixed active ene... [more]

The role of the energy industry has always been central for one reason or another, being environmentalism the main motive in the last two decades. Therefore, attention and research have been directed in this sense. However, human resources—or human capital—have remained understudied, especially concerning the salaries received. Thus, this study is disruptive as it explored the factors that influence employee remuneration in the energy subsector, using Spain as a case study. For this, the PLS-SEM (Partial Least Squares Structural Equation Modelling) path modelling methodology was used, executing a traditional PLS analysis, bootstrapping and, finally, IPMA (Importance-Performance Analysis). Solid and significant relationships were found among labour conditions, human capital, market and wages, with the relationships between human capital and wages and between human capital and labour conditions being especially relevant. Besides, through IPMA, a series of considerations was made regardin... [more]

The growth in global electricity demand has expanded the search for new energy resources. Renewable sources such as photovoltaic (PV) systems have proven to be major alternatives. PV generators connected to distribution grids have exhibited significant growth in the last decade, so it is essential to analyse the impacts resulting from this increase. This work investigated the influence of high PV system penetration in distribution grids in terms of harmonic levels. In particular, this study addressed the distortions in voltage and current waveforms in the presence and absence of PV generators connected to a distribution grid. Additionally, the total harmonic content and the individual harmonic frequencies of voltage and current were analysed. This study was performed with an IEEE 37 bus distribution system and the Open Distribution System Simulator software (OpenDSS). The results show that the voltage limits of some phases far away from a substation can exceed the limits. Furthermore,... [more]

The combined microwave-assisted sorting and microwave-assisted comminution of minerals has been proposed to reduce the huge grinding energy consumption in mineral processing. However, gangue minerals would be discarded after the sorting process despite the microwave energy absorbed during their treatment. Therefore, this paper investigates the effect of microwave pretreatment on the Bond work index (BWI) of quartz and calcite samples, as they represent the dominant gangues in many ores and are key inputs in the cement industry, which requires intensive grinding. The samples were characterized using a scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX), and Fourier transform infrared (FTIR) and X-ray diffraction (XRD) methods. The BWIs of the two samples were determined before and after the microwave treatment (2.45 GHz, 1.7 kW) at 2, 4 and 6 minutes. SEM image analyses of the untreated and microwave-treated samples were performed using ImageJ software. The resul... [more]

Low-carbon development is one of the more significant problems of the Visegrad Group countries (Czech Republic, Poland, Slovakia, and Hungary). It is related, among others, to the improvement of life quality in economic terms while taking into account activities for environmental protection. The aim of the article is to identify and explain the problems connected with low-carbon development. The purpose of the analyses is also to prove the negative impact of the emission of greenhouse gas emission (GHG) and other harmful substances into the air on the quality of human life and the natural environment. During the research, an assessment of the eco-efficiency of the used energy resources and technologies that negatively affect the environment was carried out. Moreover, the paper also presents methods to use greener energy sources and analyses the potential of implementing solutions supporting low-carbon development. The study recommends actions that may contribute to the reduction of gre... [more]

This article presents a proposal for a wireless diagnostic system for checking the air tightness of the ventilation network. The solution is designed to increase crew safety in underground mining plants and increase the energy efficiency of the ventube ventilation system. The system is based on sensors measuring the pressure inside the ventilation duct in relation to the barometric pressure in the immediate vicinity of the duct. The flow of diagnostic data is based on a cascade transfer. The data from the first sensor are transferred successively to the last one. Based on the prior calibration of alarm thresholds in each device, the leakage or factor influencing the increase of air flow resistance is located. The article presents the genesis of the creation and discusses the principle and purpose of the system. In the following chapters, the progress of work related to testing the system in laboratory, industrial, and underground conditions at the Velenje Premogovnik mine (Slovenia) is... [more]

The constant problems evidenced in the Brazilian hydrological scenario, where the source of hydraulic potential corresponds to about 63.9% of the energy matrix, coupled with the exponential growth in the supply of renewable energy, corroborates the importance of thermal power generation as the basis of Brazilian’s energy matrix. With the operation of thermal power plants, which characteristically involve a large number of systems, subsystems, and auxiliary equipment, there is a high demand for the use of methodologies for monitoring and controlling processes, analyzing failures, and implementing improvements and actions that increase the reliability and, consequently, reduce the failure rate. In this context, decision-making about prioritizing criticality for operational monitoring of an asset’s components, from the perspective of operation and maintenance planning and based on reliability-centered maintenance (RCM) concepts, can be considered a complex task. Given this, the research s... [more]

The refurbishment of the building stock is a key strategy towards the achievement of the climate and energy goals of the European Union. This study aims at evaluating the energy and environmental impacts associated with retrofitting a residential apartment to improve its vertical envelope thermal insulation. Two insulation materials, stone wool and cellulose fibers, are compared. The life cycle assessment methodology is applied assuming 1 m2 of retrofitted vertical envelope as functional unit. Moreover, to estimate the net energy and environmental benefits achievable in the retrofitted scenario compared with the non-retrofitted one, a second analysis is performed in which the system boundaries are expanded to include the building operational phase, and 1 m2 of walkable floor per year is assumed as reference. The results show that the use of cellulose fibers involve lower impacts in most of the assessed categories compared to stone wool, except for abiotic resource depletion. In detail,... [more]

This paper quantifies the long-term impact of wind energy development on electricity prices across the residential, commercial, and industrial sectors in the United States. Our data set is made up of state level panel data from 2000 through 2018. This time period covers the vast majority of total wind energy capacity installed in the history of the USA. Our econometric model accounts for the primary factors that influence electricity prices, incorporating both fixed effects and general method of moments in order to more precisely isolate the effect of wind energy. The empirical results conclude that wind energy is positively and significantly related to electricity prices across all sectors, as indicated by the higher average electricity prices in states with higher percentages of wind energy. The price increase is largest in the industrial sector, followed by commercial, then residential. Wind turbine technology has become significantly more efficient, but the technical gains have bee... [more]

Energy and water have faced important levels of conflicts in the last 20−25 years in Chile. However, the way that they have been politically addressed in the last decade differs. These differences emerge from how these fields have been historically configurated, impacting on how the policy problems and policy options have been framed. Using thematic analysis of 93 interviews and documentary analysis, this article analyzes by contrasting two participatory processes which nourish the formulation of the energy and water policies in Chile in 2014−2015. It seeks to understand the factors that may influence why the development, impact and inclusion of new voices in public policies related to water and energy have been different, and how that can impact the water−energy nexus. Five factors emerge as determinants in this difference: structure of use, number of actors, governance and institutional framework, elite conformation, and legal framework. These factors impacted the policy processes an... [more]

To improve the proficiency of energy systems in addition to increasing the usage of renewable energies, thermal energy storage (TES) is a strategic path. The present literature review reports an overview of the recent advancements in the utilization of salt hydrates (single or binary mixtures) and composites as sorbents for sorption heat storage. Starting by introducing various heat storage systems, the operating concept of the adsorption TES was clarified and contrasted to other technologies. Consequently, a deep examination and crucial problems related to the different types of salt hydrates and adsorbents were performed. Recent advances in the composite materials used in sorption heat storage were also reviewed and compared. A deep discussion related to safety, price, availability, and hydrothermal stability issues is reported. Salt hydrates display high theoretical energy densities, which are promising materials in TES. However, they show a number of drawbacks for use in the basic... [more]

Water content is an important factor in the deformation-destruction process of coal bodies. To analyze the influence of water on the creep acoustic emission (AE) characteristics of coal rock surrounding a borehole, we conducted graded loading creep AE tests of single-hole specimens with different water contents (0%, 4%, 8% and water-saturation) under uniaxial loading. The findings include the following: the water content affects the creep mechanical properties of the coal body around a borehole. The creep transient strain and steady-state strain increased exponentially with rising water content; the saturated specimen showed the highest increase, reaching 44.5% and 28.6%, respectively. The specimen water content affected the cumulative ringing count (CRC) and the axial strain during creep. The axial strain increased with rising water content, the CRC increased linearly with rising axial strain. The higher the water content, the greater the CRC rise. At different stress levels, the CRC... [more]

Renewable energy is one of the most discussed topics nowadays, more so than traditional combustible energy sources and nuclear energy. There is an apparent need to study its public acceptance and the general public’s knowledge about it, especially in the context of more advanced inventions, such as smart grids, energy storage, or photovoltaic inverters. In this research, the results of a custom survey and those of several types of public social media datasets were processed to gain insights into the acceptance and awareness of these technologies. The second aim was to investigate technologies and related public opinions about manufacturers. One social media dataset was processed by a novel technology based on automatic data collection from popular social media sources, blogs, forums and public news. All the collected and anonymized data were restored in a custom-made data lake (unstructured database) and analyzed by a natural language processing (NLP) engine to extract the required inf... [more]

The aim of the article is to present and analyze the implementation of intelligent lighting within the concept of smart energies and smart cities. Motivation and research hypothesis: Electricity consumption in the world is based largely on non-renewable energy. Until these full changes, it is necessary to look for opportunities to save and use it efficiently. Today’s cities are increasingly implementing the smart concept, of which smart energy is one area. One of the smart city elements implemented by cities is smart energy. Within this framework, a supported concept is the replacement of traditional lighting with LEDs (Light-Emitting Diodes), which contributes to energy and cost savings and reduces the pollution of the sky with artificial light, while increasing the efficiency of urban lighting. Positive effects of modern solutions include reduced lighting expenses and increased safety of residents. Methods and results of the research: The authors chose the case study method for their... [more]

The thermal energy conversion of natural gas (NG) using appropriate configuration cycles represents one of the best nonrenewable energy resources because of its high heating value and low environmental effects. The natural gas can be converted to liquefied natural gas (LNG), via the liquefaction process, which is used as a heat source and sink in various multigeneration cycles. In this paper, a new configuration cycle is proposed using LNG as a heat source and heat sink. This new proposed cycle includes the CO2 cycle, the organic Rankine cycle (ORC), a heater, a cooler, an NaClO plant, and reverse osmosis. This cycle generates electrical power, heating and cooling energy, potable water (PW), hydrogen, and salt all at the same time. For this purpose, one computer program is provided in an engineering equation solver for energy, exergy, and thermo-economic analyses. The results for each subsystem are validated by previous researches in this field. This system produces 10.53 GWh electrica... [more]

This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values of three ejector efficiencies used to account for losses in the ejector are calculated by using a systematic approach (by employing CFD analysis) rather than the hit and trial method. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa working fluid has been used for low-grade heat applications, and Engineering Equation Solver (EES) has been employed for simulating the proposed model. The presented model is suitable for integration with any thermal system model and its optimization because of its direct, non-iterative methodology. This model is a non-dimensional model and therefore requires... [more]

The aim of the article is to identify and assess the relationship between the investment attractiveness of regions for agricultural enterprises and the energy factor. Classical theories of the location of agriculture emphasise the importance of the market factor. The energy factor has so far been ignored, despite the global trend related to the increasing importance of production scales and rising energy consumption in agriculture. There are also no methodological proposals that allow a comprehensive assessment of the investment attractiveness of regions for agricultural enterprises, taking into account the leading location factors. The article presents the author’s methodological model based on the weight-correlation method of valorisation of investment attractiveness of regions for economic entities that invest in agricultural production. It contains a sub-aggregate describing the energy factor. This proposal is a contribution to the theory of the location of agriculture in the field... [more]

Recently there has been an ongoing discussion about energy security. This has been caused by tensions affecting international relations, and the emergence of new geopolitical threats. As one of the main sources of primary energy, natural gas is an obvious subject of interest in this discussion. In Europe, the natural gas market is rapidly evolving, which has resulted in a lack of clarity regarding who is responsible for the security of the gas supply. It is not clear now how to measure the security of the gas supply in economic estimates and by whom that security should be financed. In this paper, the authors present an approach which can be used for valuation of energy security concerning the security of natural gas storage using stochastic modelling based on the mathematical model of the “Newsvendor problem”. The valuation is made from the point of view of countries and considers their individual attitudes to the risk of disruption of deliveries, which is a novel approach to the prob... [more]

The purpose of this study is to analyze the evolution of the scientific research regarding the relationship between energy and economic growth, in order to reveal preferred topics and less approached themes. We conducted an occurrence and cluster analysis, followed by a correspondence analysis using articles published between 1979 and 2019 in journals indexed in the Web of Science. The analysis was split into three periods taking into account the major economic and energetic milestones. The analysis focused on distribution of the topics studied both by years and by journals. The research revealed some major trends: there has been an explosive increase in studies based on Asian countries over the three periods as concerns for sustainable development intensified, and environmental issues were associated with research on the relationship between energy and economic growth. Even if the journals cover different scientific areas, during the last 10 years they contain articles with very simil... [more]

Climate changes are nowadays reality and affect all aspects of everyday life. One of the places where these changes influence the society the most is the Brazilian Ceará region and Jaguaribara basin that suffer long-lasting, devastating drought cycles. They have a dramatic negative impact on local economy, forcing change in business models. This work presents the valorisation of wastes and residues from local fish, prawns, and the vegetable-cultivation industry via biogas production forced to adapt to these new circumstances. Along a single year, as much as 189.74 tonnes of wastes and residues can be processed by the biogas production facility, producing as much as 94 GJ of cooling energy and 1 tonne of biofertiliser monthly. Even for such a small biogas production facility, the NPV is positive already after 11 years; its IRR is 6.2%, and accumulated ROI for 20 years of operation is as high as 77.8%. This work demonstrates that a valorisation of industrial wastes and residues via bioga... [more]

Photocatalysis is a classical solution to energy conversion and environmental pollution control problems. In photocatalysis, the development and exploration of new visible light catalysts and their synthesis and modification strategies are crucial. It is also essential to understand the mechanism of these reactions in the various reaction media. Recently, bismuth and graphene’s unique geometrical and electronic properties have attracted considerable attention in photocatalysis. This review summarizes bismuth-graphene nanohybrids’ synthetic processes with various design considerations, fundamental mechanisms of action, heterogeneous photocatalysis, benefits, and challenges. Some key applications in energy conversion and environmental pollution control are discussed, such as CO2 reduction, water splitting, pollutant degradation, disinfection, and organic transformations. The detailed perspective of bismuth-graphene nanohybrids’ applications in various research fields presented herein sho... [more]

Energy sustainability constitutes an important goal for development, as declared at the global and the European levels. Some conditions decisive for energy performance, as suggested by the Environmental Kuznets Curve (EKC) hypothesis, may be specified by the sectoral structure of production, as industries vary in the intensity of energy consumption. Nevertheless, sustainability is not automatically induced along with economic development and it is important to identify its determinants. The aim of the study is to empirically verify whether the sectoral structure of an economy differentiates energy sustainability within 28 European Union member states (the EU-28). To fulfil the task, a static approach was adopted and such taxonomic methods as the Ward agglomeration method and linear ordering based on the Hellwig synthetic measure were used. The hypothesis concerning the essential role of structural features in energy achievements was verified by a one-way analysis of variance. Our resul... [more]