Prices of conventional and renewable energy as determinants of sustainable and secure energy development: regression model analysis

Background The prices of energy resources are important determinants of sustainable energy development, yet associated with significant unknowns. The estimates of the impact of prices of energy products in the domestic market (for domestic consumers) are rare—hence the importance and novelty of this research. Therefore, the main goal of the paper is to assess the impact of domestic prices of gasoline, gas, coal, and solar energy on sustainable and secure energy future. Methods The research includes 14 countries (of which 7 are developed and 7 are developing countries) and a period of 5 years (2014–2018). The model also includes discrete variables: level of development (developing or developed), and the fact as to whether the country is an energy exporter or not. For the purposes of analysis, the following elements were used: Panel Data Analysis, Linear regression (with random and fixed effects), Durbin–Wu–Hausman test, and Honda test, with the use of R-studio software for statistical computing. Results The research showed that the biggest negative impact on energy sustainability was recorded by an increase in the price of coal and the smallest one by an increase in the price of solar energy. An increase in the price of gasoline has a positive impact, while an increase in the price of gas has no impact. The basic methodological result showed that the fixed effects linear model is more accurate than the random effect model. Conclusions The results of the paper, important as a sustainable energy policy recommendation, showed that the impact of changes in energy product prices is significantly greater in developing countries, but that the status of the country as an energy exporter has no significance. In addition, the paper points to the need to intensify the research on the assessment of the impact of energy product prices for domestic consumers on their ability to pay that price, because with a certain (so far undefined) increase in energy product prices, a certain group of domestic consumers moves into a category that is not in line with sustainable energy development and is extremely undesirable in every respect—energy poverty.

The deformation model of the DCB-sample with elastoplastic properties

The loading of a strip with a crack-like defect according to mode I is considered. In contrast to the classical representation of a crack in the form of a mathematical section, the proposed model defines a crack as a physical cut with a characteristic linear size. The mental continuation of a physical cut in a solid forms an interaction layer (IL). It is important that the stress-strain state of the layer at a finite value of the linear parameter does not introduce a singularity into the crack model. The process of elastoplastic deformation with a constant layer length is considered. We obtained a simplified analytical solution to the problem of deformation of two elastic bodies connected by a thin layer with elastoplastic properties. The dependence of the displacement and stress fields on the length and thickness of the interaction layer has been found. It is shown that, under the classical plasticity condition, the range of variation of the external load leading to a purely elastic behavior is possible only for a finite layer thickness. As the layer thickness tends to zero, as in the Dugdale model, the plasticity region is formed at an arbitrarily small external load. For small layer thicknesses, a local plasticity criterion is proposed, by using which it is possible to distinguish the intervals of the external load variations associated with elastic and plastic deformations. The local plasticity condition, determined by the critical value of the energy product, makes it possible to reflect the stage of elastic deformation at an arbitrarily small finite thickness of the interaction layer. An asymptotic dependence of the external load on the IL thickness and the reduced length of the plastic zone is obtained. At the same time, the separation of the external load into elastic and plastic components is preserved. From the analysis of the experimental data, an estimate of the elastic limit of the energy product for the AV138 adhesive was obtained.

A Regulatory Roadmap to the Past, Present and Future of Geothermal Energy in Greece

Greece is gifted with geologic features that promote geothermal heat flow. Geothermal energy exploration began in the late 60s, culminating in the first geothermal energy law in 1984 and the introduction of geothermal energy as a mineral resource under the amendment of the Greek Mining Code. Since then, low- and high-temperature geothermal activities followed their separate ways, with a modest utilization of the energy product in the primary sector (agriculture, aquaculture) and attempts for electricity production stalled since the mid-1990s. The adoption of green policies by both the EU and Greece, the acceptance of global warming as an existing threat, the adhesion to CO2 reduction goals, energy efficiency and the application on renewable energy solutions as means to combat the increase in global temperature have led to an increasing interest in the utilization of the geothermal energy applications. This paper presents the new legal framework for geothermal energy established by Law 4602/2019, as introduced by the Greek Ministry of Environment and Energy, Directorate-General for Mineral Raw Materials and discusses its scope and goals set by the implementation of its provisions. The paper offers a roadmap to successfully test those new policies and regulatory provisions and, finally, it maps the interfaces of stakeholders and geothermal industry in an attempt to highlight the steps of the necessary administrative procedures towards the facilitation of viable geothermal projects.

TOWARD LOW-ENERGY SPARK PLASMA SINTERING OF HOT-DEFORMED Nd-Fe-B MAGNETS

In this work, we present a newly developed, economically efficient method for processing rare-earth Nd-Fe-B magnets based on spark plasma sintering. It makes us possible to retain the technologically essential properties of the produced magnet by consuming about 30% of the energy as compared to the conventional SPS process. A magnet with anisotropic microstructure was fabricated from MQU F commercial ribbons by low energy consumption (0.37 MJ) during the deformation process and compared to the conventionally prepared hot-deformed magnet, which consumed 3-times more energy (1.2 MJ). Both magnets were post-annealed at 650 °C for 120 min in a vacuum. After the postannealing process, the low-energy processing (LEP) hot-deformed magnet showed a coercivity of 1327 kAm-1, and remanent magnetization of 1.27 T. In comparison, the highenergy processing (HEP) hot-deformed magnet had a coercivity of 1337 kAm-1 and a remanent magnetization of 1.31 T. Complete microstructural characterization and detailed statistical analyses revealed a better texture orientation for the HEP hot-deformed magnet processed by high energy consumption, which is the main reason for the difference in remanent magnetization between the two hot-deformed magnets. The results show that, although the LEP hot-deformed magnet was processed by three times lower energy consumption than in a typical hot-deformation process, the maximum energy product is only 8 % lower than the maximum energy product of a HEP hot-deformed magnet.

IMPACTS OF MORINGA OLEIFERA LEAF POWDER (MLP) ON THE PROTEIN CONTENT AND ENERGY VALUE OF COLOCASIA ESCULENTA (TARO) PORRIDGE: A TRADITIONAL INFANT FOOD IN GUINEA

Moringa oleifera leaf powder (MLP) has exceptional nutritional properties due to its high content of micronutrients, fatty acids, and especially protein. This makes it a suitable ingredient for the fortification of taro flour. Taro is a high-energy product but low in protein and fat, which weanling children need for their normal development. This study aimed to evaluate the protein-energy contribution of MLP powder in infant taro porridge. Three fortified taro porridges named FTP10% (Taro + 10% of Moringa), FTP15% (Taro + 15% of Moringa) and FTP15% (Taro + 15% of Moringa) were performed. Their analyses indicated significant increases (P<0.05) in crude protein content, energy value and titratable acidity from 0.580 0046% to 1.570 0052%, 82.137 143% to 88.807 1658% and from 0.130 0017g/100g to 0.380 0010 g/100 g respectively. KEYWORDS: Proximal composition, taro porridge, Moringa oleifera.

Bulk Nanocrystalline Permanent Magnets by Selective Laser Melting

Fe-Nd-B powders were processed by additive manufacturing using laboratory scale selective laser melting to produce bulk nanocrystalline permanent magnets. The manufacturing process was carried out in a specially developed process chamber under Ar atmosphere. This resulted in novel types of microstructures with micrometer scale clusters of nanocrystalline hard magnetic grains. Owing to this microstructure, a maximum coercive field strength (coercivity) μ0Hc of 1.16 T, a remanence Jr of 0.58 T, and a maximum energy product (BH)max of 62.3 kJ/mm3could, for example, be obtained for the composition Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8.

Additive Manufacturing of Anisotropic Sm-Fe-N Nylon Bonded Permanent Magnets

Fabricating a bonded magnet with a near-net shape in suitable thermoplastic polymer binders is of paramount importance in the development of cost-effective energy technologies. In this work, anisotropic Sm2Fe17N3 (Sm-Fe-N) bonded magnets are additively printed using Sm-Fe-N anisotropic magnetic particles in a polymeric binder polyamide-12 (PA12). The anisotropic bonded permanent magnets are fabricated by Big Area Additive Manufacturing followed by post-aligned in a magnetic field. Optimal post-alignment results in an enhanced remanence of ~ 0.68 T in PA12 reflected in a parallel-oriented (aligned) measured direction. The maximum energy product achieved for the additively printed anisotropic bonded magnet of Sm-Fe-N in PA12 polymer is 78.8 KJ m-3. Our results show advanced processing flexibility of additive manufacturing for the development of Sm-Fe-N bonded magnets in polymer media designed for applications with no critical rare earth magnets.

Anaerobic Biodegradation of Wheat Straw Lignin: The Influence of Wet Explosion Pretreatment

Large amounts of lignin residue is expected in the future when biorefineries for producing biofuels and bio-products will increase in numbers. It is, therefore, valuable to find solutions for using this resource for the sustained production of useful bioenergy or bio-products. Anaerobic digestion could potentially be an option for converting the biorefinery lignin into a valuable energy product. However, lignin is recalcitrant to biodegradation under anaerobic conditions unless the structure is modified. Wet oxidation followed by steam explosion (wet explosion) was previously found to make significant changes to the lignin structure allowing for biodegradation under anaerobic conditions. In this study, we examine the effect of wet explosion pretreatment for anaerobic digestion of wheat straw lignin under mesophilic (37 o C) conditions. Besides the biorefinery lignin produced from wheat straw, untreated lignin was further tested as feed material for anaerobic digestion. Our results showed that wet exploded lignin pretreated with 2% NaOH showed the highest lignin degradation (41.8%) as well as the highest methane potential of 157.3±9.9 ml/g VS. The untreated lignin with no pretreatment showed the lowest methane yield of 65.8±4.8 and only 3.5% of the lignin was degraded. Overall, increased severity of the pretreatment was found to enhance anaerobic degradation of lignin.

Grain Boundary Evolution of Cellular Nanostructured Sm-Co Permanent Magnets

Grain boundaries are thought to be the primary demagnetization sites of precipitate-hardening 2:17-type Sm-Co-Fe-Cu-Zr permanent magnets with a unique cellular nanostructure, leading to a poor squareness factor as well as a much lower than ideal energy product. In this work, we investigated the grain boundary microstructure evolution of a model magnet Sm25Co46.9Fe19.5Cu5.6Zr3.0 (wt. %) during the aging process. The transmission electron microscopy (TEM) investigations showed that the grain boundary region contains undecomposed 2:17H, partially ordered 2:17R, 1:5H nano-precipitates, and a Smn+1Co5n−1 (n = 2, 1:3R; n = 3, 2:7R; n = 4, 5:19R) phase mixture at the solution-treated state. After short-term aging, further decomposition of 2:17H occurs, characterized by the gradual ordering of 2:17R, the precipitation of the 1:5H phase, and the gradual growth of Smn+1Co5n−1 compounds. Due to the lack of a defect-aggregated cell boundary near the grain boundary, the 1:5H precipitates are constrained between the 2:17R and the Smn+1Co5n−1 nano-sheets. When further aging the magnet, the grain boundary 1:5H precipitates transform into Smn+1Co5n−1 compounds. As the Smn+1Co5n−1 compounds are magnetically softer than the 1:5H precipitates, the grain boundaries then act as the primary demagnetization sites. Our work adds important insights toward the understanding of the grain boundary effect of 2:17-type Sm-Co-Fe-Cu-Zr magnets.