Energy poverty, defined as a lack of access to reliable electricity and reliance on traditional biomass resources for cooking, affects over a billion people daily. The World Health Organization estimates that household air pollution from inefficient stoves causes more premature deaths than malaria, tuberculosis, and HIV/AIDS. Increasing demand for energy has led to dramatic increases in emissions. The need for reliable electricity and limiting emissions drives research on Resilient Hybrid Energy Systems (RHESs), which provide cleaner energy through combining wind, solar, and biomass energy with traditional fossil energy, increasing production efficiency and reliability and reducing generating costs and emissions. Microgrids have been shown as an efficient means of implementing RHESs, with some focused mainly on reducing the environmental impact of electric power generation. The technical challenges of designing, implementing, and applying microgrids involve conducting a cradle-to-grave... [more]

This paper started with the explanation of the conditions for using the momentum equation and with the presentation of the actuator disc theory. Focusing on the flow model used in actuator disk theory, both the Froude-Rankine theorem and Betz’s law have been examined. It has been found that the Froude-Rankine theorem is not justified because a stream-tube that is used as the control volume does not really exist (pseudo stream-tube). The theorem is also not justified because an unfounded velocity (v2) is used to connect the thrust of the actuator disc with the total power loss. Two flaws have been identified in Betz’s law. First, the use of both the unjustified Froude-Rankine theorem and the incorrect flow model totally violates the condition of determining the thrust of the actuator disc using the momentum equation. Second, the unfounded velocity (v2) from the Froude-Rankine theorem is misinterpreted and used for the volumetric flow rate through the actuator disc. These two main flaws... [more]

(1) The use of renewable energy for power and heat supply is one of the strategies to reduce greenhouse gas emissions. As only 14% of German households are supplied with renewable energy, a shift is necessary. This shift should be realized with the lowest possible environmental impact. This paper assesses the environmental impacts of changes in energy generation and distribution, by integrating the life cycle assessment (LCA) method into energy system models (ESM). (2) The integrated LCA is applied to a case study of the German neighborhood of Herne, (i) to optimize the energy supply, considering different technologies, and (ii) to determine the environmental impacts of the base case (status quo), a cost-optimized scenario, and a CO2-optimized scenario. (3) The use of gas boilers in the base case is substituted with CHPs, surface water heat pumps and PV-systems in the CO2-optimized scenario, and five ground-coupled heat pumps and PV-systems for the cost-optimized scenario. This technol... [more]

The research of pore and permeability characteristics of tight sandstone reservoirs in coal-measure is critical for coal-measure gas development. In this study, the pore systems of tight sandstones were studied based on low-field nuclear magnetic resonance (LF-NMR) data. The permeability of tight sandstones was obtained by the tester based on the pulse transient method. The permeability variation with the effective stress, grains, and pore characteristics was analyzed. The results show that the tight sandstone reservoirs in the coal-measure have low total porosity (2.80−4.14%), low effective porosity (0.51−1.56%), and low permeability (0.351 × 10−6−13.910 × 10−6 um2). LF-NMR T2 spectra of the testing sandstones show that the micropores are the most developed, but most of the micropores are immovable pores. The pore characteristics are significantly affected by the grain size of sandstones. The pore connectivity ranks from good to poor with decreasing sandstone particle size. The total... [more]

Numerical simulation is an effective tool for the thermal management of propulsion systems. Moreover, it contributes to the design and performance assessment of solar greenhouses for mushroom ventilation. Because the planning and design of the clustered solar greenhouse are still undiscovered, this study has developed a 3-D mathematical model suitable for a large-scale park of mushroom solar greenhouses based on computational fluid dynamics (CFD) theory. The effects of the orientation arrangement, horizontal spacing, vertical spacing of the cultivation racks, and the building distance between adjacent greenhouses on the ventilation performance were analyzed. The numerical simulation showed good agreement with the experimental measurement. The CFD results indicated that the reasonable layout of cultivation racks in mushroom solar greenhouses is a north-south arrangement. The horizontal spacing of cultivation racks has a significant influence on the wind speed and cooling rate, and the o... [more]

The transition of residential communities to renewable energy sources is one of the first steps for the decarbonization of the energy sector, the reduction of CO2 emissions, and the mitigation of global climate change. This study provides information for the development of a microgrid, supplied by wind and solar energy, which meets the hourly energy demand of a community of 10,000 houses in the North Texas region; hydrogen is used as the energy storage medium. The results are presented for two cases: (a) when the renewable energy sources supply only the electricity demand of the community, and (b) when these sources provide the electricity as well as the heating needs (for space heating and hot water) of the community. The results show that such a community can be decarbonized with combinations of wind and solar installations. The energy storage requirements are between 2.7 m3 per household and 2.2 m3 per household. There is significant dissipation in the storage−regeneration processes... [more]

The development of energy production from renewable sources includes the production of energy from photovoltaic installations by prosumers. In Europe, RES development is driven by political goals and requires subsidies during the deployment period, at least as long as the cost of renewable electricity does not reaches grid parity. The study attempts to determine the importance of factors in the development of energy production by prosumers from PV installations in Polish regions. In 2019, the ‘Moj Prad’ program was introduced, applying subsidies to investment costs and the settlement of energy production in the net-metering system. Almost 900 thousand prosumer PV installations were built by the end of 2021, with a total capacity of 5.9 GW. Solar energy share grew from 0.1 to 2.1%. Spatial econometrics models were use in research to determine factors of prosumer PV systems development in Poland (at NUTS-2). Spatial regimes were found in the studied regions, as indicated by a positive au... [more]

Continental faulted basins are widely distributed in eastern China. Many of these basins, in which the faults block oil and gas reservoirs, have been explored. The heterogeneity of the reservoirs in fault block is very strong, shich restricts the further efficient development of these kinds of oil and gas fields. In this study, porosity and permeability tests, the use of thin sections of rock, mercury injection experiment and CT scan were used to investigate reservoir quality characteristics and control factors. The results showed that the content of quartz, feldspar, and debris in rock had a significant control function on the quality of the reservoir. Reservoir performance improved with increase of quartz and feldspar content, and worsened with increase of debris content. Taking the Ek1 reservoir in the Wang Guantun area as the specific research object, we developed the following understanding. On the one hand, the main compaction in the study area was mechanical compaction. When the... [more]

The study concerns the preparation of post-consumer food packaging for selective collection that takes place in households. The previously reported results suggested that the economic cost of washing the packaging exceeded the value of recyclable materials. A shortage of up-to-date papers on the economic balance of packaging washing, taking into account current trends in the increase of prices of materials and energy carriers, has been identified. The main objective of this study was to determine the effect of the application of particular heat sources on the total cost of preparing the glass and plastic packaging for selective collection, as well as to compare the cost with the economic value of recyclables. Over the last ten years, a drop in the purchase price of glass cullet and post-consumer plastic, as well as an increase in the cost of cold and hot water, have been reported. Accordingly, the profit of packaging cleaning, defined as the difference between the value of recyclable m... [more]

Recent studies have shown that relative permeability can be modeled as a state function which is independent of flow direction and dependent upon phase saturation (S), phase connectivity (X), and fluid−fluid interfacial area (A). This study evaluates the impact of each of the three state parameters (S, X, and A) in the estimation of relative permeability. The relative importance of the three state parameters in four separate quadrants of S-X-A space was evaluated using a machine learning algorithm (out-of-bag predictor importance method). The results show that relative permeability is sensitive to all the three parameters, S, X, and A, with varying magnitudes in each of the four quadrants at a constant value of wettability. We observe that the wetting-phase relative permeability is most sensitive to saturation, while the non-wetting phase is most sensitive to phase connectivity. Although the least important, fluid−fluid interfacial area is still important to make the relative permeabil... [more]

Energy is at the center of human society and drives the technologies and overall human well-being. Today, artificial intelligence (AI) technologies are widely used for system modeling, prediction, control, and optimization in the energy sector. The internet of things (IoT) is the core of the third wave of the information industry revolution and AI. In the energy sector, tens of billions of IoT appliances are linked to the Internet, and these appliances generate massive amounts of data every day. Extracting useful information from the massive amount of data will be a very meaningful thing. Complex event processing (CEP) is a stream-based technique that can extract beneficial information from real-time data through pre-establishing pattern rules. The formulation of pattern rules requires strong domain expertise. Therefore, at present, the pattern rules of CEP still need to be manually formulated by domain experts. However, in the face of complex, massive amounts of IoT data, manually set... [more]

There is increasing growth in load demands and financial strain to upgrade the present power distribution system. It faces challenges such as power losses, voltage deviations, lack of reliability and voltage instability. There is also a sense of responsibility in the wake of environmental and energy crises to adopt distributed renewable resources for power generation. These challenges can be resolved by optimally allocating distributed generators (DGs) at different suitable locations in the radial power distribution system. Optimal allocation is a non-linear problem which is solved by powerful metaheuristic optimization algorithms. In this work, an objective function is introduced to optimally size four different types of DGs by utilizing honey badger algorithm (HBA), and comparison is drawn with grey wolf optimization (GWO) and whale optimization algorithm (WOA). The objective is to boost the voltage profile and minimize the power losses of the standard IEEE 33bus and 69-bus radial po... [more]

The significant proliferation of renewable resources, primarily inverter interfaced distributed generation (IIDG) in the utility grid, leads to a dearth of overall inertia. Subsequently, the system illustrates more frequency nadir and a steeper frequency response. This may degrade the dynamic frequency stability of the overall system. Further, virtual inertia has been synthetically developed in IIDG, which is known as a virtual synchronous generator (VSG). In this work, a novel STO-STC-based controller has been developed, which offers flexible inertia following system disturbance. The controller is based on the super-twisting algorithm (STA), which is a further advancement in the conventional sliding mode control (SMC), and has been incorporated in the control loop of the VSG. In this scheme, two steps have been implemented, where the first one is to categorize all states of the system using a super-twisting observer (STO) and further, it is required to converge essential states very q... [more]

The increasing popularity of electric vehicles (EVs) has been attributed to their low-carbon and environmentally friendly attributes. Extensive research has been undertaken in view of the depletion of fossil fuels, changes in climatic conditions due to air pollution, and the goal of developing EVs capable of matching or exceeding the performance of today’s internal combustion engines (ICEs). The transition from ICE vehicles to EVs can reduce greenhouse gases significantly over a vehicle’s lifetime. Across the different types of EVs, the widespread usage of batteries is due to their high power density and steady output voltage, making them an excellent energy storage device (ESD). The current downsides of battery-powered electric vehicles include long recharge times, the impact of additional strain on the grid, poor societal acceptance due to high initial costs, and a lack of adequate charging infrastructure. Even more problematic is their short driving range when compared to standard I... [more]

The current work presents the electro-oxidation of olive mill and biodiesel wastewaters in an alkaline medium with the aim of hydrogen production and simultaneous reduction in the organic pollution content. The process is performed, at laboratory scale, in an own-design single cavity electrolyzer with graphite electrodes and no membrane. The system and the procedures to generate hydrogen under ambient conditions are described. The gas flow generated is analyzed through gas chromatography. The wastewater balance in the liquid electrolyte shows a reduction in the chemical oxygen demand (COD) pointing to a decrease in the organic content. The experimental results confirm the production of hydrogen with different purity levels and the simultaneous reduction in organic contaminants. This wastewater treatment appears as a feasible process to obtain hydrogen at ambient conditions powered with renewable energy sources, resulting in a more competitive hydrogen cost.

The increasing penetration of renewable energy sources creates a challenge for the stability of current power systems due to their intermittent and stochastic nature. This paper presents the field results of an efficient demand response solution for controlling and adjusting the electric demand of buildings in an energy district through the activation of their thermal mass while respecting the occupants’ thermal comfort constraints. This multilevel control approach aims to support grid flexibility during peak times by constraining the energy exchange with the grid and increasing the self-consumption of the district. The results show a great potential for increasing the self-consumption up to 37% for offices, as well as improving the indoor environment, based on real data collected from a case study in Greece.

Climate change is a growing global concern, threatening the worldwide environment, health, and economy [...]

Among all the energy production technologies based on renewables, the photovoltaic panels are the ones with the highest rate of development and applications worldwide. In this context, significant efforts are put into research on innovative materials in order to improve the performance of photovoltaic cells. Nevertheless, possibilities available to enhance the energy yield of existing technologies also exist and are explored, such as the cooling of photovoltaic modules. This approach can decrease the mean operation temperature of photovoltaic cells, leading to an increase in efficiency and energy produced. In the present paper, this method is investigated by developing and testing a dedicated water cooling system for photovoltaic panels. In order to investigate the performance of the cooling system, two market-available monocrystalline photovoltaic panels with a power of 50 and 310 Wp were tested under laboratory and real operation conditions, respectively. Based on the results obtaine... [more]

Production of syngas from the gasification of a biomass is attracting attention with an eye to the concepts of circularity, sustainability, and recent needs, triggered by socio-political events, to increase the level of self-sufficiency of energy sources for a given community. This manuscript reports on the gasification of spruce wood chips in a demonstration fluidised bed gasifier (1.5 MWth, height of 5.40 m, internal diameter of 1.2 m), with 0.2−0.4 mm olivine inventory (1000 kg). Gasification was carried out in air, at four different values of equivalence ratio (from 27% to 36%). The bed was fluidised at about 0.6 m/s, and the bed temperature resulted in the range of about 960−1030 °C as a function of the different tests. A mass flow rate of biomass in the range of about 360−480 kg/h (as a function of the different tests) was fed to the fluidised bed gasifier. Syngas lower heating value, specific mass and energetic yield, and chemical composition, were reported along with data on th... [more]

Pinewood biomass in Portugal can be considered a major source of biochar for soil physical, chemical, and biological edaphic amendment. This work intended to evaluate the aptitude of lab produced biochar for upgrading soil moisture dynamics’ relationships considering mixtures of biochar with silica-based sand. The methodology used focused on the carbonization of pine biomass with inert atmosphere at 300 °C, 400 °C, 500 °C and 600 °C, followed by a chemical proximate and thermogravimetric analysis, scanning electron microscopy, Fourier Transform Infrared analysis, numerical modeling, and characterization of biochar porosity by gas adsorption (Brunauer−Emmett−Teller) and mercury porosimetry. The results showed the increased amounts of soil water retention and plant available water, evaluated through pF curves, due to biochar application. The thermogravimetric analysis mass loss patterns and FTIR transmittance, reflected major structural modifications in carbonized products by comparison... [more]

Pipeline transportation of crude oil has great advantages over traditional oil transmission methods, in terms of economic and environmental protection. The main costs in the oilfield surface system are the fuel costs for heating the crude oil during transportation and the electricity costs for the pumping units. In the northeast of China, where winter temperatures are extremely low and the oil has a high freezing point and high viscosity, higher temperatures, and pressures are required to transport crude oil. With machine learning widely used in many industries and achieving better results, the digital management of oil pipelines has stored a large amount of production and operation data, which has laid the foundation for the research of oil pipeline process calculation using machine learning methods. In this paper, a crude oil pressure drop calculation of an oil pipeline in Northeast China is carried out based on a neural network. For pipeline pressure drop calculation, the back propa... [more]

The current stage of development of autonomous energy systems is characterized by a rapid increase in renewable energy sources’ installed capacity. Such growth is observed both in centralized and isolated energy systems. Renewable energy sources show high efficiency in the electrification of rural remote settlements around the world. The power of such power complexes varies from several kilowatts to tens of megawatts. When solving the problems of rural remote settlements electrification, the main issues of optimizing the composition of equipment and the structure of the energy systems play an extremely important role. Moreover, depending on the specifications of the problem being solved, criteria for evaluating efficiency are used, which are different. For example, the following are used as objective functions: minimization of the levelized cost of energy and fossil fuel consumption; maximizing the standard of people living and reliability indicators; the payback period of the project... [more]

The aim of this study is to identify non-technological critical success factors (CSFs) that influence the different phases of the project life cycle for the deployment of centralized biogas projects; as there is a knowledge gap in this area. This was performed by applying a longitudinal process analysis approach and an analytical framework based on findings from previous studies. Data were collected through extensive document collection and analysis, combined with in-depth semi-structured interviews. The study resulted in the identification of a total of 30 non-technological critical success factors in the case of Solrød Biogas. These were subsequently linked to one of the different phases of the project lifecycle (conceptualization phase, planning phase, execution phase) or categorized as general CSFs. We hope that the findings in this study can help ensure better management of biogas projects and enhance the capabilities of governmental bodies in supporting projects in the future, so... [more]

With the rapid development of machine learning, deep reinforcement learning (DRL) algorithms have recently been widely used for energy management in hybrid electric urban buses (HEUBs). However, the current DRL-based strategies suffer from insufficient constraint capability, slow learning speed, and unstable convergence. In this study, a state-of-the-art continuous control DRL algorithm, softmax deep double deterministic policy gradients (SD3), is used to develop the energy management system of a power-split HEUB. In particular, an action masking (AM) technique that does not alter the SD3′s underlying principles is proposed to prevent the SD3-based strategy from outputting invalid actions that violate the system’s physical constraints. Additionally, the transfer learning (TL) method of the SD3-based strategy is explored to avoid repetitive training of neural networks in different driving cycles. The results demonstrate that the learning performance and learning stability of SD3 are una... [more]

Current research assesses the impact of industrialization and the renewable energy sector on greenhouse gas emissions, proxied by CO2 emissions in Europe and Central Asia. We rely on a two-step system GMM estimator on a sample of 48 countries over the period 2000−2018. Empirical results show that industrialization has a positive effect on CO2 emissions: a 10% increase in industry value added as % of GDP leads to an increase of 2.6% in CO2 emissions. In contrast, renewable energy mitigates CO2 emissions. Ten percentage points increase in renewable energy consumption reduces CO2 emissions per capita by 2.2%. The interaction term between renewable energy and industry value added is negative, suggesting that renewable energy consumption compensates for the negative effect of industrialization on environmental quality. Our main results also confirm the U-shaped inverted relationship between GDP per capita and CO2 emissions. Our study has a number of policy implications and avenues for futur... [more]