Electric power, as an efficient and clean energy, has considerable importance in industries and human lives. Electricity price is becoming increasingly crucial for balancing electricity generation ...and consumption. In this study, long short-term memory (LSTM) with the differential evolution (DE) algorithm, denoted as DE–LSTM, is used for electricity price prediction. Several recent studies have adopted LSTM with considerable success in certain applications, such as text recognition and speech recognition. However, problems in the application of LSTM to solving nonlinear regression and time series problems have been encountered. DE, a novel evolutionary algorithm that effectively obtains optimal solutions, is designed to identify suitable hyperparameters for LSTM. Experiments are conducted to verify the performance of the DE–LSTM model under the electricity prices in New South Wales, Germany/Austria, and France. Results indicate that the proposed DE–LSTM model outperforms existing forecasting models in terms of forecasting accuracies.
•Effective Long short-term Memory (LSTM) is proposed for electricity price forecasting.•Differential evolution helps selecting suitable hyper-parameters of LSTM.•The proposed method named DE-LSTM is the best for three cases in terms of accuracy.
Over the past decades, the penetration of renewable energies has been increasing in many countries. Due to the natural intermittency of renewable energy sources, finding the optimal capacity and ...location of these energy resources is the most important issue in smart sustainable cities. In this regard, a mathematical strategy is proposed in this paper to find the optimal capacity and location of wind turbines and photovoltaic panels to minimize the total operation cost of a water and energy nexus. In addition, to increase the system efficiency and maximize the benefit of renewable energy sources, water desalination units have been implemented in the proposed methodology, and both electric and water networks are optimized together. In order to present a comprehensive model, the technical, environmental, and economic aspects of the problem are taken into account as a mixed-integer linear programming, where, a machine learning approach based on long-short term memory networks has been utilized for uncertainty modeling of the stochastic parameters including wind and solar generation power, electricity load demand, water demand, and electricity price. Finally, to evaluate the efficiency of the proposed method three different scenarios on a water and energy nexus have been studied considering Kuwait data. The numerical results show that by optimal planning of renewable energy sources, the total cost has decreased about $11950 that is verified the effectiveness of the proposed method.
•Water and electricity nexus is considered with modeling optimal operation of units.•A techno-economic-environmental effect of different sources has been investigated.•A machine learning based method is proposed for uncertainty modeling.•An optimization framework is proposed to guarantee the global optimum results.
A COVID-19 recovery for climate Rosenbloom, Daniel; Markard, Jochen
Science (American Association for the Advancement of Science),
05/2020, Letnik:
368, Številka:
6490
Journal Article
Recenzirano
Odprti dostop
In response to the coronavirus disease 2019 (COVID-19) pandemic, countries are launching economic recovery programs to mitigate unemployment and stabilize core industries. Although it is ...understandably difficult to contemplate other hazards in the midst of this outbreak, it is important to remember that we face another major crisis that threatens human prosperity—climate change. Leveraging COVID-19 recovery programs to simultaneously advance the climate agenda presents a strategic opportunity to transition toward a more sustainable post–COVID-19 world.
This study aimed to evaluate the performance and effectiveness of two water-soluble transition metal salts, nickel acetate and iron oxalate, in upgrading extra-heavy crude oil from Cuba. The ...experiment involved treating Cuba oil with water and each catalyst in an autoclave reactor under reservoir conditions for 24 h at 300 °C. Various analyses were conducted to assess the catalyst performance in reducing the viscosity of the crude oil, including gas chromatography (GC) of evolved gases, viscosity, and SARA analysis, elemental analysis, and GC analysis of saturated hydrocarbons. The results showed that both catalysts were able to significantly reduce the Cuba oil’s viscosity, with nickel acetate exhibiting a higher reduction of 80% from 16 420 to 3630 mPa·S, compared to iron oxalate, which showed a reduction of 69% from 16 420 to 5200 mPa·S. A significant decrease in asphaltenes was observed after the upgrading process with nickel acetate, with the content decreasing from 20.86 to 12.85%. Furthermore, the study conducted transformation analyses on the catalysts, both before and after the upgrading process, utilizing TG-FTIR analysis, XRD analysis, Mössbauer studies, and SEM-EDX analysis. These analyses revealed that nickel acetate had the advantage of desulfurization through hydrodesulfurization reactions, indicating its capability of reducing the sulfur content of the oil. The SEM-EDX results showed that the sulfur content formed on the nickel metal after the reaction was 16.21%, while the sulfur content formed on the surface of the iron metal constituted only 2.33%. The XRD results also showed large quantities of α-NiS, β-NiS, and Ni3S4 crystals formed after the reaction, in contrast to iron oxalate, which after the reaction formed large quantities of Fe3O4 (magnetite). This finding underscores the importance of nickel acetate in achieving the objectives of the upgrading process. In summary, the study highlights the potential of water-soluble catalysts, such as nickel acetate and iron oxalate, in upgrading heavy crude oil and reducing its viscosity. Moreover, the study emphasizes the importance of understanding the properties of the catalysts and their transformations during the upgrading process.
In this work, the catalytic performance of a synthesized dispersed Ni-based catalyst amorphous catalytic system of Ni(NO3)(OH) in the hydrothermal upgrading of high-sulfur Cuban extra-heavy oil at ...temperatures of 200 and 300 °C for a duration of 24 h was evaluated. The synthesized Ni-catalyst predominantly exhibits an amorphous structure, which is primarily attributed to nickel hydroxonitrate (Ni(OH)(NO3)), as verified through X-ray diffraction and thermogravimetric Fourier transform infrared analyses. The results show that the presence of the synthesized catalyst in the upgrading system improves the physical and chemical properties of the upgraded oil samples compared to non-catalytic aquathermolysis results. The application of the Ni-based catalyst resulted in a reduction of sulfur content by 9.0–17.4%, a decrease in viscosity by 11.4–11.7%, and a lowering of the heavy oil fraction by 6.8–8.3%. Additionally, there was an increment in the production of gases by 0.2–0.3% and an increase in the fraction of hydrocarbons with a carbon number of less than < C20 by 5.4–8.2%. The best upgrading performance was observed during catalytic aquathermolysis at 300 °C. Overall, the findings underscore the synthesized Ni-based catalyst’s potential to significantly enhance the in situ hydrothermal upgrading process of extra-heavy crude oil, offering a promising approach for the treatment of such challenging feedstocks.
This study conducted a seepage experiment of broken shale under cyclic loading and unloading conditions to investigate the permeability characteristics of broken shale with different particle sizes ...under stress disturbance. There were six groups of broken shale samples with different particle sizes, and three cycles of loading and unloading were conducted to test the permeability of broken shale. The influence of the number of cycles and shale particle size on permeability damage was analyzed. Furthermore, the stress-seepage model of broken shale was established to analyze the influence of the number of cycles and shale particle size on the variation of stress sensitivity of broken shale under different loading and unloading stages. The results show that the initial permeability, permeability damage, and stress sensitivity of broken shale are negatively correlated with the number of cycles and that the first cycle has a significant impact on them. As the size of the broken shale particles increases, the rate of change in shale permeability also increases before and after conducting experiments. This results in a greater shale damage permeability. However, the impact of the number of cycles on shale permeability damage decreases. Additionally, the shale’s stress sensitivity becomes stronger. It is also found that the seepage characteristics between the small particle size (G1–G4, 0–6.8 mm) and the large particle size (G5–G6, 7–15 mm) are different in the broken shale samples with six different particle sizes. In addition, the change of the shale particle structure under cyclic loading and unloading conditions is discussed, and the mechanism of the shale permeability change is studied. This study indicates the seepage characteristics of broken shale under cyclic loading and unloading conditions, which has a certain guiding significance for the safe and efficient extraction of shale gas wells.
In the second depressurization test production of marine natural gas hydrates (NGHs) in China, gas was successfully produced from low-permeability clayey silt NGHs through a horizontal ...depressurization well, setting a new record for marine NGHs production. Although significant success has been achieved at the field scale, there is still limited research on its production behavior. In this paper, a layered heterogeneous horizontal well production numerical model was established based on logging data from this field production site. First, the cumulative gas production volume for 30 and 42 days was successfully fitted through numerical simulation, and the short-term production behavior under different irreducible water saturation (S irw) was studied in detail. An increase in S irw during short- and long-term production can increase the flow of free gas toward the production well, thereby increasing gas production. During the long-term production process, a barrier area with high hydrate saturation in the bottom of the hydrate-bearing layer (HBL) hinders the further upward expansion of the decomposition front. Meanwhile, due to the relatively large amount of movable water, the barrier area formed at low S irw is relatively small. Through this study, it is helpful to reveal the hydrate production behavior of the horizontal well under high S irw and a strong sealing effect.
Uniform steam chamber expansion over the whole well length significantly affects the development of steam-assisted gravity drainage (SAGD) in oil reservoirs. Currently, most research is focused on ...optimizing the steam suction profile through the production wells. While uniform steam injection (USI) along horizontal wells is often neglected and studied in only a few reports, it is a critical technique to enhance oil recovery. Herein, a novel type of USI-SAGD process using an injector tube with variable density perforation was developed. The performance of USI-SAGD was evaluated based on a custom-built physical experimental setup and numerical simulation. The experimental findings demonstrate that the USI-SAGD method exhibits a more homogeneous steam injection profile by mitigating the accumulation of wellbore fluids and, thereby, making the steam injection profile more uniform. This resulted in a notable increase of 22.6% in the uniformity of steam chamber development and an 8.02% increase in oil recovery compared with the single-point SAGD method under identical experimental conditions. Numerical simulations indicate that USI-SAGD effectively regulates the outflow profile and mitigates the decrease in steam quality caused by steam overlay along the injector. As a result, the method achieves an even distribution of the pressure and steam quality, which corresponds to an improvement in steam injection uniformity. The perforating point number and distribution were optimized, which indicated an optimal critical value of 30 perforating points per 1000 m wellbore and a 4:6 distribution ratio for improving the uniformity of the steam chamber and enhancing the production performance in the horizontal well. This work proves that USI-SAGD is efficient in improving heavy oil production and has great potential for use in field applications.
The Domanic oil shale, located in the Volga-Ural petroleum basin, has gained significant attention as a prominent source of unconventional oil recovery in Eastern Europe. However, a comprehensive ...understanding of the kerogen conversion processes during Domanic shale oil generation remains limited. This paper presents a detailed investigation into the thermal conversion of Domanic oil shale along with the analysis of the resulting oil and gas products using a combination of physicochemical methods and nuclear magnetic resonance (NMR) spectroscopy. The study reveals that the peak oil and gas generation occurs at 350 °C, while kerogen destruction predominantly takes place at 500 °C, leading to the formation of shale gases. Additionally, the research highlights the progressive increase in condensed aromatics within kerogen with rising temperatures, resulting in the formation of higher molecular compounds in the generated oil. Importantly, a strong correlation is observed among the NMR relaxation technique, saturates aromatics resins asphaltenes analysis, and GC-MS method in evaluating the evolution of Kerogen maturity during hydrothermal conversion. The application of the solid echo sequence demonstrates intense NMR signals, indicating the presence of mobile liquid hydrocarbons within the closed pores of kerogen. This hypothesis is further supported by SEM images and GC-MS analysis of aromatic fractions across different temperatures and various studied samples. Overall, this study significantly enhances our understanding of the complex processes involved in kerogen conversion within the Domanic oil shale.
Hydrate formation and decomposition are major challenges in marine hydrate development drilling. Filtrate reducers are important additives in water-based drilling fluids that reduce methane hydrate ...formation. However, research on the influence of commonly used filtrate reducers in drilling fluids on hydrate formation is limited. Here, we investigated the effects of three filtrate reducers, humic acid potassium (KHm), hydroxypropyl starch (HPS), and hydrolyzed polyacrylonitrile sodium salt (Na-HPAN), on methane hydrate formation kinetics and those of different concentrations under an initial pressure of 6 MPa and different initial pressures (6, 8, 10, and 12 MPa) in the same concentration system. The KHm solution (1–3%) promoted hydrate formation at 4 °C and 6 MPa, the Na-HPAN solution (0.3–1.5%) inhibited hydrate formation, and the HPS solution (0.1–1.5%) inhibited hydrate formation in the first 10 h of reaction but promoted a large amount of hydrate formation after the inhibition failure. At 4 °C, higher initial pressures led to earlier and faster formation of CH4 hydrate in large quantities in the filtrate reducer solution. An extreme gas hydrate conversion value was observed, indicating that the initial pressure is crucial when using a filtrate reducer. These observations provide a crucial basis for flow assurance and water-based drilling fluid design.
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