Energy Science & Engineering最新文献

Since the industrial revolution, global anthropogenic CO₂ emissions have surged dramatically to unsustainable levels, resulting in severe issues, such as global warming, extreme weather events, and species extinction. In response to this critical situation, extensive efforts have been undertaken across academia, industry, and policymaking sectors to deploy carbon capture, utilization, and storage (CCUS) technologies. Here, we present the annual summary of global CCUS for the year 2023. We begin by discussing the trends of anthropogenic CO₂ emissions and atmospheric CO₂ concentrations, and then offer an up-to-date summary of progress in academia, industry, and policy, respectively. In academia, we analyze the number and categories of publications and highlight some key breakthroughs. In the industry sector, we meticulously collect and present information on operational commercial carbon-capture and storage facilities. Furthermore, we elucidate significant policy announcements and reforms across diverse regions. This concise and comprehensive annual report aims to inspire ongoing efforts and collaboration among academia, industry, and policymakers toward advancing carbon neutrality.

Literature shows that only 56% of Kenyan households had access to electricity, with rural areas having the lowest access rate at percent. The high cost of extending the power grid to remote areas and power losses on distribution are significant challenges facing rural electrification. In addressing power accessibility problems, especially in rural areas, there is a need for tapping hydropower generation through the invention and implementation of in-duct turbines to maximize the utilization of already existing pressurized water ducts that supply water in various parts of Kenya for hydropower generation. Makueni County is endowed with gravity-fed water ducts with high potential for hydropower which can innovatively be produced by application of in-duct turbines. This paper focuses on the assessment of energy needs and applications in rural areas. The research design was exploratory and experimental in nature. It was exploratory because, through an assessment, it sought to explore and identify the potential areas within the water supply lines for the production of hydropower to supply hydropower in Makueni County. It was experimental because the researcher developed (designed and fabricated) a hydro turbine for use in the production of hydropower from gravity water ducts of a diameter raging 100 mm. The research revealed that 62% (98) used solar power for lighting their homes, while 17% (28), 12% (20), and 8% (12) used lanterns, electricity, and kerosene lamps, respectively. Among the fuels assessed was firewood which was identified as the most used fuel at 89% (140). This was followed at a distance far by paraffin at 6% (9) of respondents. The households at 100% (158) identified electricity as a potential source of lighting for their household. The study recommends harnessing hydropower to enhance reach to 100% of the rural communities. The energy availability will provide opportunities for communities and institutions in rural areas to open their minds to business development and engage in income-generating activities like the rearing of poultry and the development of light industries like the gridding of maize and other cereals.

The high-voltage pulse discharge technology, which is based on the electrohydraulic effect, can generate powerful, controllable, and repetitive electrohydraulic shock waves (EHSWs) in underground confined space, so it has been applied in the petroleum industry to improve the permeable of the reservoir. In this paper, a numerical model based on LS-DYNA is built to study the damage analysis of the cement sheath and rock subjected to EHSWs during perforation completion. The results show that the stress state of the cement sheath and rock surrounding the perforation hole is determined by the shock pressure from both the perforation hole and the wellbore; the damage of the cement sheath and rock is mainly caused by tensile stress; the damage zone of the cement sheath is mainly distributed on the inner surface and near the perforation hole, while the damage zone of rock is distributed near the perforation hole; after multiple discharges, the damage of cement sheath and rock gradually accumulates, and the damage zone eventually forms a vertical plane along perforation holes. Overall, these results provide guidance for the safe application of the high-voltage pulse discharge technology in the oil field.

To quantitatively characterize the complexity of shale pore structures and their controlling factors in the Longmaxi Formation of Western Hubei, our study focused on the organic-rich shale outcrops of the Longmaxi Formation in the Yidu-Hefeng compound anticline. We conducted tests for shale organic content, maturity, and whole-rock mineral composition, along with employing high-pressure mercury injection and low-temperature gas adsorption experiments. Utilizing the V-S, FHH, and sponge models, we calculated the fractal dimensions of micro-, meso-, and macropores. In the Yidu-Hefeng region, the Longmaxi Formation is characterized by calcium-rich shales that are abundant in organic matter. Our analysis of samples revealed a total organic carbon (TOC) ranging between 1.04% and 4.24%, with an average of 2.5%. The Ro values fluctuate between 2.98% and 3.57%, with a mean value of 2.845%, indicating an over-mature stage from early to late thermogenesis. Constituents such as quartz span from 39.8% to 51.3%, with a median of 44.3%, while feldspar oscillates between 3.8% and 12.4%, averaging at 8.48%. Clay minerals constitute 24.3% to 41.7% of the samples, with a mean of 34.16%. Shale porosity exhibits a segmented fractal nature. For instance, D1 varies from 2.1278 to 2.4056, with a mean of 2.2767; D2 fluctuates between 2.4995 and 2.7492, averaging at 2.6309; and D3 ranges from 2.6835 to 2.9427, centering around 2.8111. These variations indicate the intricacies of the macropore structure. Positive correlations between TOC and maturity with D1 and D2 are evident, whereas a negative association is observed with D3. The collaborative interplay between siliceous minerals and organics mirrors the relationship between the siliceous mineral content and its fractal dimensions, akin to TOC. Clay mineral transformations, due to accumulation and dehydration, predominantly contribute to macro-porosity, weakly aligning negatively with D1 and D2 but positively with D3. Variations in carbonate and siliceous minerals and their role in primarily yielding dissolution macropores manifest a subtle negative link with D1 and D2 while enhancing D3. Pore volume correlates positively with D1 and D2, exhibits no conspicuous association with D3, and trends negatively. The compaction and transformation processes of clay minerals seem to favor the generation of macropores, mildly aligning positively with D3.

Humidification and dehumidification (HDH) desalination units compared with the other thermal desalination systems have relative advantages due to working under ambient pressure and low temperatures and are more attractive. In this research, the application of an HDH desalination unit with indirect-contact of air and water streams in a steam power plant is investigated. To increase the energy efficiency of the system, a closed air cycle has been considered. Also, by application of the closed water cycle in the humidifier, the recovery rate of the desalination unit increases according to the concentration of discharge flow. The flow rate of boilers blowdown in the studied steam power plant is around 2.2 kg/s and can be used as a unique source of required thermal energy in the desalination system to produce freshwater from power plant chemical effluents. On the basis of the available cooling water (30 m³/day), this stream is considered as the limiting flow in the modeling. The detailed design of different parts of the desalination unit, including the humidification tower, condensers, wet air circulation fans, the required pumps, and the heat exchanger, is presented in this study. The maximum production of freshwater and the minimum energy intensity are obtained for the circulating air flow rate of 4 kg/s. By 14% recovery of lost steam in the power plant, 20.8 m³/h of desalinated water is produced. The gain output ratio and the energy intensity of the system are 1.025 and 2201 kJ/L, respectively. The production cost with the proposed indirect-constant HDH system is equal to 0.56 $/m³ of freshwater.

Pyrolysis of two types of pellets (T₁: 100% wheat straw, and T₂: 70% wheat straw; 10% sawdust, 10% biochar, and 10% bentonite clay) was performed in a pilot-scale reactor under a nitrogen environment at 20°C to 700°C. This was to investigate slow pyrolysis yields and gas composition as a function of temperature and residence time. The experimental data were obtained between 300°C and 600°C, with a residence time of 90 min, a nitrogen flow rate of 50 cm³/min, and a heating rate of 20°C/min. The results indicated that the maximum pyrolysis temperature is 605°C with a residence time of 55 min. The product analysis showed that the proportion of gas was higher than that of biochar and bio-oil. The conversion efficiency increased with higher temperatures and varied between 66% and 76%. The results showed that carbon dioxide was the main component in the produced gas, and the maximum gas concentration was 63.6% at 300°C for T₁. The higher temperature and longer residence time increased the syngas (CO + H₂) composition for both T₁ and T₂ treatments. Nevertheless, the produced biochar had a high carbon content and retained a high calorific value, indicating slow pyrolysis is the ideal utilization route of wheat straw pellet biomass for biochar.

In this study, two novel control methods are theoretically introduced as direct slip angle control (DSAC) and model predictive direct slip angle control (MPDSAC) for rotor side converter (RSC) of the standalone Doubly-Fed Induction Generator (DFIG)-DC system (S-DFIG-DC). The numerical analysis of the proposed methods demonstrated that the proposed DSAC method could reduce torque ripple and current harmonics, decrease the output DC voltage drop in fast changes of load condition, and have faster dynamic response. Also, the MPDSAC method could further diminish torque and flux ripple, current harmonics, and output DC voltage drop in sharp changes of load condition compared with the presented DSAC and direct torque control (DTC) methods. The sensitivity analysis of the proposed control methods is investigated at different operating conditions. The performance and usefulness of the DSAC and MPDSAC schemes are verified by various experiments and compared with the conventional DTC method.

To study the seepage law and sectional morphological characteristics in splitting sandstones of different grain sizes, three-dimensional morphological scanning tests and seepage characteristics tests are conducted on the splitting rock samples of siltstone, fine-, medium- and coarse-grained sandstone, and the differences in morphological characteristics and seepage law in different grain size sandstones are compared and analyzed. The test results show that the sections of siltstone and fine-grained sandstone have the overall morphological characteristics of “one high and one low” with large undulation, while the sections of medium- and coarse-grained sandstone have a more uniform distribution and less undulation. In the relationship between pressure gradient and flow velocity, siltstone and fine-grained sandstone are precisely characterized by the Forchheimer formula, and medium- and coarse-grained sandstone are well characterized by the Izbash formula, and the fitting effect is good. The results of the study are of great reference significance for improving the cross-sectional morphological characteristics and seepage law of the splitting rock samples.

The accurate prediction of photovoltaic (PV) power is crucial for planning, constructing, and scheduling high-penetration distributed PV power systems. Traditional point prediction methods suffer from instability and lack reliability, which can be effectively addressed through interval prediction. This study proposes a short-term PV power interval prediction method based on the framework of sparrow search algorithm (SSA)-variational mode decomposition (VMD)-convolutional neural network (CNN)-gate recurrent unit (GRU). First, PV data undergo similar day clustering based on permutation entropy and VMD is applied to solar radiation signals with high correlation. Then, the hyperparameters of GRU are optimized by SSA according to the comprehensive evaluation indicator of interval prediction proposed in this study. Subsequently, quantile prediction results are obtained based on CNN-GRU using the optimal parameters from SSA optimization. Finally, the prediction interval is composed of multiple quantile prediction results. A MATLAB R2022b program is developed to compare different prediction methods. The results demonstrate that compared to single neural network methods, the proposed method effectively improves the coverage width-based criterion. In the interval prediction of sunny and rainy similar days, the comprehensive evaluation indicators of the proposed method are only 54.3% and 37.4% of the single GRU, respectively, indicating significantly improved interval prediction accuracy.

The paper proposes a new stochastic multiobjective technoeconomic model for integrating photovoltaic (PV) and wind energy resources in electricity price (EP)-driven distribution systems. The primary goal of this paper is to determine the optimal location and capacity for renewable energy-based distributed generation, specifically PV and wind resources, while considering weather and system uncertainties. These uncertainties include stochastic variations in PV illumination intensity, wind speed, EP, and load fluctuations. To address these uncertainties, the paper employs scenario modeling techniques named as Latin hypercube sampling with Cholesky decomposition. This technique generates multiple correlated scenarios that represent uncertain variables. Subsequently, a scenario reduction technique is applied to identify the scenario with the highest probability. Later, a mathematical model is developed to minimize an objective function that encompasses various factors like system losses, node voltage deviations, the cost of purchasing power from the grid; and simultaneously maximize the total annual energy savings. The objective is to find optimal solutions that strike a balance between different objectives. To obtain an efficient optimum solution, this paper employs an effective meta-heuristic technique named as JAYA algorithm. The results obtained by the JAYA algorithm are juxtaposed with those obtained using particle swarm optimization and genetic algorithm techniques. The proposed method is evaluated using Institute of Electrical and Electronics Engineers (IEEE) 33-node and IEEE 69-node test feeders to validate its feasibility and effectiveness. However, the effectiveness of the proposed method is not limited to any size of test systems.