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Energy systems are a typical example of complex and dynamic systems and the study of their structure is of particular interest in theoretical and practical terms. Becoming the main trend of diversification and, renewable energies play important role in the evolution and dynamics of energy balances at the international, national, and local levels. Usually, natural sciences use Information Theory and the concept of entropy to assess diversity, uncertainty, and chaos in systems with a high number of components. An alternative approach to assess system complexity is to consider these issues from point of view of the concentration of resources, dominance, and hierarchy in the interactions between system components. This report presents an original method developed by the author for assessing the hierarchy in energy mix structures and the role of renewable energies. The author’s studies in the field of energy explore the evolution of markets and energy balances (energy mixes) on an international, regional and national level with a special focus on the European Union and Bulgaria. The hierarchy approach provides results in a more logical, objective, and balanced format and improves the analysis in terms of energy security and diversification. In this paper, is presented a research on the structure of the energy mix in Bulgaria.

A major goal of politics, society, and industry is the reduction of carbon dioxide (CO2) emissions in order to prevent anthropogenic climate change and an increase in earth’s temperature. In addition, the expansion of renewable energies and the use of nuclear power, CO2 capturing (e.g. from exhaust gases), is regarded as a promising strategy to reduce global CO2 emissions. In this context, the Power-to-X technologies can provide an innovative energy storage concept by combining the main trends of energy systems aiming at high shares of renewable energies, reduction of CO2 emissions and sector coupling. A promising approach is the production of methanol as a chemical raw material or fuel. The goal of this paper is to present (i) an extensive thermodynamic analysis for the methanol production from carbon dioxide and hydrogen and (ii) an economic analysis for the process based on the thermodynamic studies. The thermodynamic analysis was carried out in the simulation tool Aspen Plus™ in order to investigate the impact of the operating temperature and pressure on the performance of the synthesis unit. Based on the thermodynamic results, an economic analysis has been performed in order to define the most feasible solution. For a defined optimal operating temperature, the fixed and operating costs and the methanol production cost were evaluated for different operating pressures. Finally, a sensitivity analysis has been performed in order to define the minimum methanol selling price that allows for a payback period of 10 years for different values of the electrical energy purchasing price.

The stability and accuracy of power sharing between DGs in isolated microgrids are key points for favouring renewable energy sources within a wider operating margin to extract the maximum available power. The conventional droop control method CDC and the improved virtual impedance droop control CDC-VI are proposed in this work to enhance the stability, improve the speed, robustness and accuracy of power distribution between two parallel DGs feeding three linear loads of different types connected to the AC bus within an isolated AC microgrid. A Matlab/Simulink simulation is carried out to validate our proposal, robustness, accuracy of power sharing between DGs and stability are well improved by the implementation of the proposed CDC and CDC-VI controllers. The main improvements brought by these controllers include improved power distribution with greater precision, enhanced stability even in the presence of disturbances, and faster response in dynamic scenarios. These improvements are crucial to ensuring efficient, reliable operation of microgrids, particularly in isolated environments where integration of renewable energies and management of critical loads are paramount for uninterrupted service continuity.

The growing demand for electricity in Honduras became a critical problem in 2022, evidencing an increase of 3.05%. This situation generated difficulties in the energy supply, and an increase of 10% to 15% in the cost of electricity was projected for the next quarter of 2023. Despite the efforts in renewable energies, the wave energy potential generated by the Atlantic waves is limited due to the lack of research in Honduras. To obtain a wave energy potential, meteorological data was collected on the swell, including wave height and wave interval, taking into account other factors such as density and sea depth. For this process, A variety of available resources were used, such as web scraping programming made in Python, and the data were obtained using the online software Windfinder. These were stored in Microsoft Excel, and mathematical models such as wave energy power and wave power formula were used, which considered parameters such as wave height and wave intervals. In addition, Airy’s theory equation was applied, taking into account the depth; these models allowed calculating the wave energy potential and comparing the results. Preliminary results indicate that the wave energy generation potential varies according to the model used, with the first model, wave energy power, varying 51%, the second, wave power formula, 46%, and Airy’s theory equation. This research was done to quantify the wave energy potential in the country of Honduras, specific to the Atlantic coast on the coasts of the departments of Cortés, Atlántida, Colón, Gracias a Dios, and Islas de la Bahía over a period of 10 weeks and contribute to future research.

Producing electricity at an affordable price while taking into account environmental concerns has become a major challenge in Morocco. Moreover, the technical and financial issues related to renewable electricity plants are still hindering their efficient integration in the country. In fact, the energy sector (both electricity and heat) accounted for more than half of all Greenhouse Gases (GHG) emissions in the kingdom due to the major reliance on fossil fuels for answering the growing local demand. The key strategies to alleviate this critical situation include the integration of more renewable energies in the total energy mix and the enhancement of energy efficiency measures in different sectors. This paper strives to (1) evaluate the potential of carbon dioxide mitigation in Moroccan electricity sector following the actual and projected strategies and (2) highlight the policy schemes to be taken in order to achieve the ambitious carbon dioxide mitigation targets in the mid-term. A system dynamics model was built in order to simulate different scenarios of carbon dioxide mitigation policies up to 2030. The results shows that the achievement of renewable energies projects by 2030 could save 228.143 MtCO2 between 2020 and 2030 and an additional 18.127 MtCO2 could be avoided in the same period by enhancing energy efficiency measures.