This article presents a critical mini-review of research conducted on bioelectrochemical reactors with emphasis placed on microbial fuel cells (MFC) and microbial electrolysis cells (MEC). The principle of operation and typical constructions of MFCs and MECs were presented. The types of anodes and cathodes, ion-selective membranes and microorganisms used were discussed along with their limitations.

The optimal energy management (OEM) in a stand-alone microgrid (SMG) is a challenging job because of uncertain and intermittent behavior of clean energy sources (CESs) such as a photovoltaic (PV), wind turbine (WT). This paper presents the effective role of battery energy storage (BES) in optimal scheduling of generation sources to fulfill the load demand in an SMG under the intermittency of theWT and PV power. The OEM is performed by minimizing the operational cost of the SMG for the chosen moderate weather profile using an artificial bee colony algorithm (ABC) in four different cases, i.e. without the BES and with the BES having a various level of initial capacity. The results show the efficient role of the BES in keeping the reliability of the SMG with the reduction in carbon-emissions and uncertainty of the CES power. Also, prove that the ABC provides better cost values compared to particle swarm optimization (PSO) and a genetic algorithm (GA). Further, the robustness of system reliability using the BES is tested for the mean data of the considered weather profile.

This paper discusses the impact of the European Green Deal policy on the clean energy transformation in the European Union, focusing on the generation of electricity reaching a significant milestone for the EU in 2020 – renewable energy sources for the first time in history surpassing combined fossil fuels in the generation of electrical energy. This achievement, although partially influenced by the exceptional circumstances of the COVID-19 pandemic and the electricity demand shock, is primarily an effect of the Clean Energy for all Europeans Package implementing the European Green Deal strategy designed to position the EU as a global leader in the green transformation, leading by example and turning climate challenges into a growth opportunity, and in doing so presenting an optimistic policy perspective for a global transformation towards a 100% renewable energy world, thus supporting mitigation of the global-warming threats by significantly cutting greenhouse-gas emissions. With the immediate effects of the 2018 recast Renewable Energy Directive (2018/2001/EU) and other related clean-energy policies under the umbrella of the European Green Deal, coal and lignite electric generation has fallen in 2020 by as much as 22% (87 TWh) and the nuclear generation has dropped by 11% (79 TWh), with natural gas to a much lesser extent, yet still noting an annual drop of 3%, while renewables grew, surpassing the combined fossil fuels electricity output in the whole of the EU. This is an impressive result confirmed in late 2021 and a hallmark of the European Green Deal initial success, the sustainability of which is yet to be assessed in the coming years, especially in view of the recent international situation of major destabilization. In this context, it should be added that although the newest 2022 Global Energy Review report by the IEA confirmed in 2021, the highest global CO ₂emission level in history (following the post -pandemic economic rebound and also due to the gas-price crisis of late 2021 causing gas-to-coal shifts in electricity-mix, which in the EU, resulted in a 7% relative annual emissions increase), Europe’s emission level has remained in a diminishing trend following the European achievements of 2020, with an overall CO ₂ emissions decrease of 2.4% in comparison with the level of 2019. Most likely, however, the 2021 gas-price crisis was only a mere prelude to a much more robust long- -term perturbation that will be expectedly due to the war in Ukraine and the necessary sanctions policy, especially impacting the energy market and probably further hampering the green-transition process jointly with other economic factors.

The growing interest in green energy observed in recent years has become the basis for pilot studies on its electricity production role in Poland. The diagnostic survey method allowed us to learn about young people’s opinions on renewable energy sources in the context of four identified research areas (the need for RES, planning its installation, costs, environmental impact). The authors proposed a method based on fuzzy logic (fuzzy relations and optimistic fuzzy aggregation norms) to develop and interpret the survey results to understand the selected community’s knowledge about the importance of RES (or not) in the national energy system. The survey shows that although there is no significant difference between respondents in all research areas, rural women are more interested in using green technologies. They have a high self-awareness of their beneficial effects on the environment. Rural respondents, compared to those from the cities, are willing (despite the high cost of equipment) to invest their capital to purchase green energy carriers, which is dictated by their lower knowledge about the forms of external support. Depending on the residence place, respondents selected various government aid programs for renewable energy. People from the city decided mainly on those that would improve the air’s comfort and quality in their place of residence. On the other hand, the rural areas’ inhabitants focused their attention on the aid possibilities, which would reduce the energy costs of the farms they run in the future. All the respondents agree that investments in clean energy (coming from natural sources) will translate into broadly understood environmental protection, bringing mutual benefits for everyone.

Conventional fuels are the primary source of pollution. Switching towards clean energy becomes increasingly necessary for sustainable development. Electric vehicles are the most suitable alternative for the future of the automobile industry. The battery, being the power source, is the critical element of electric vehicles. However, its charging and discharging rates have always been a question. The discharge rate depends upon various factors such as vehicle load, temperature gradient, surface inclination, terrain, tyre pressure, and vehicle speed. In this work, a 20 Ah, 13S-8P configured lithium-ion battery, developed specifically for a supermileage custom vehicle, is used for experimentation. The abovementioned factors have been analyzed to check the vehicle’s overall performance in different operating conditions, and their effects have been investigated against the battery’s discharge rate. It has been observed that the discharge rate remains unaffected by the considered temperature difference. However, overheating the battery results in thermal runaway, damaging and reducing its life. Increasing the number of brakes to 15, the impact on the discharge rate is marginal; however, if the number of brakes increases beyond 21, a doubling trend in voltage drops was observed. Thus, a smoother drive at a slow-varying velocity is preferred. Experiments for different load conditions and varying terrains show a rise in discharge with increasing load, low discharge for concrete, and the largest discharge for rocky terrain.