Abstract

With the development of economy, the chemical production from coal is becoming more and more important. Calcium carbide is a typical product from coal in China. There are two ways to produce calcium carbide product. Oxygen-thermal method (OTM) is a potential means of preparing calcium carbide from coal. The reuse of the furnace off-gas is one of the reasons restricting its industrial application. Besides, the CO2 generated during the off-gas reuse process also needs to be captured and utilized. Therefore, this paper proposes two furnace off-gas reuse ways to polygenerate DME and adds Carbon Capture Utilization and Storage (CCUS) system which can be divided into two technologies as Carbon Capture Storage (CCS) and Carbon Capture Utilization (CCU) to reduce carbon emission. First, the Aspen Plus software was used to simulate the whole process of the two production chains, and then the carbon footprint of the production chain was analyzed. Then the CCUS unit was carried out in the system. Finally, the carbon footprint of the production chain before and after the retrofit are compared. CCS system can reduce the total carbon emissions of indirect and direct methods by 41.55% and 60.52%, respectively. As the output of the system increased with the addition of CCU module, the effect of CCU process was evaluated by comparing the different products yield under the same CO2 emission. The result shows that in the direct polygeneration process, the addition of CCS part can increase the product yield by 2.53 times under the same CO2 emission. In the indirect process, the addition of CCS part has the best carbon emission reduction effect, and the output of calcium carbide and dimethyl ether can be increased by 1.71 times under the same CO2 emission. When using CCU technology to transform the polygeneration system, under the same carbon emission, the production of methanol in the direct method is increased to 15.8 times, and the production of dimethyl ether in the indirect method is increased to 2.33 times, which are promising ways to realize carbon reduction in the chemical production.

Abstract

Environmental concerns and low-carbon policies have intensified the carbon emission pressure for integrated energy systems (IES) to optimize their operation strategies. To address that, this paper establishes a bi-objective optimization model of integrated energy system operation with the consideration of total operation cost and carbon emission. A Nash-bargain-based approach is employed to determine a compromise solution between two objectives. Results indicate that the proposed approach can make a reasonable tradeoff between the operation cost and carbon emission.

Abstract

Proton exchange membrane water electrolysis (PEMWE) is a potential method of hydrogen production. The liquid/gas diffusion layer (LGDL) is of great significance for PEMWE performance. In this work, the untreated carbon paper, titanium mesh and titanium fiber paper are adopted as the anode LGDL, respectively. The polarization curves and electrochemical impedance spectroscopy are measured and compared in detail. The results indicate that the carbon paper as the anode LGDL shows the best electrolysis performance with the low ohmic resistance and interface resistance. And the high interface resistance is the dominated factor that affects the electrolysis performance of PEMWE with the titanium mesh and titanium fiber paper.

Abstract

Molten salt can be effectively improved its specific heat capacity doped with nanoparticles.In this paper,the influence of different contents of MgO on the specific heat capacity of Hitec(KNO3-NaNO2-NaNO3) is investigated. MgO-Hitec is synthesized with electromagnetic by heating to rapidly increase the temperature of the nucleation method, MgCl2·6H2O as the magnesium source.The specific heat capacity of the composite molten salt fluid was measured with a differential scanning calorimeter (DSC). X-ray diffraction (XRD), nanoparticle size analyzer and scanning electron microscope (SEM) were used to characterize the MgO-Hitec molten salt synthesized in situ. The results show that the specific heat capacity of 2.5% MgO-Hitec fluid is 1.737 J∙g-1∙K-1, which is 23% higher than the 1.429 J∙g-1∙K-1 of Hitec-based salt. The average grain size of the synthesized MgO is ~40nm, the average particle size is less than 250nm, and there is a certain degree of aggregation of MgO in the newly synthesized composite salt. The heat storage density is the largest up to 9.87×105 kJ∙m-3. The composite molten salt is suitable for solar energy transfer and heat storage materials.

Abstract

This paper makes a review of the literature and provides a pathway for financing green buildings, particularly in developing countries. To reach net-zero carbon emission and other nationally determined contributions, construction, and building sectors have a tremendous role, thereby providing opportunities for investment in construction, buildings, and allied sectors.

Abstract

This study conducted non-catalytic and catalytic co-pyrolysis of empty fruit bunch (EFB) and high-density polyethylene (HDPE) with HDPE-to-EFB mass ratios of 1:0, 0:1, and 1:1 via thermogravimetric analyser (TGA) and the application of Coats-Redfern method for kinetic and thermodynamic analysis. Hydrogen-exchanged zeolite socony mobil-5 (HZSM-5) catalyst was used with a catalyst-to-feedstock mass ratio of 1:1 for all the catalytic samples. From TGA results, the highest amount of volatilized matter in Phase II was obtained from non-catalytic pyrolysis of HDPE (NCP: 98.6 wt%) while the lowest amount of volatilized matter in Phase II was obtained from non-catalytic pyrolysis of EFB (NCB: 67.3 wt%). The activation energy for the pyrolysis of HDPE was highest followed by the co-pyrolysis of EFB and HDPE and pyrolysis of EFB, for both non-catalytic and catalytic runs. The activation energy based on the HDPE-to-EFB mass ratio was obtained in the following order: NCP (353.6 kJ/mol) > CP (214.3 kJ/mol) > NCPB (109.6 kJ/mol) > CPB (64.7 kJ/mol) > NCB (25.8 kJ/mol) > CB (24.4 kJ/mol). For thermodynamic analysis, ΔH and ΔG were positive for all the runs while ΔS, was negative for the non-catalytic and catalytic pyrolysis of EFB and co-pyrolysis of HDPE and EFB (NCB, NCPB, CB and CPB) and positive for the non-catalytic and catalytic pyrolysis of HDPE (NCP and CP).

Abstract

Huff-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs. However, the microscopic mechanism behind this approach is still unclear, which significantly limits the efficient development of tight oil. In order to reveal the oil and water transport law in nano scale during huff-puff by water, the whole process of pressurizing, high-pressure soaking, and depressurizing was studied by molecular simulation technology. The micro mechanism of crude oil transport at each stage was analyzed, and the effects of reservoir temperature, soaking pressure and soaking time on the transport characteristics of crude oil are investigated. The results show that the crude oil in the pore moves along the positive direction of pressure gradient, and the velocity increases first and then decreases in the pressurizing stage. In the soaking stage, the boundary layer oil molecules move along the positive direction of pressure gradient, while the bulk oil moves along the negative direction of pressure gradient under imbibition. In the depressurizing stage, the crude oil velocity increases rapidly first and then gradually flattens; The same direction of huff and puff system (TSDS) is more beneficial to improve tight oil forced imbibition recovery than the opposite direction of huff and puff system (TODS), and the recovery of TSDS is about 4 times that of TODS; Increasing temperature has a significant effect on each stage of forced imbibition, and the recovery increases about 2% for every 20℃ increase in temperature. The pressure increase only has a significant effect on the depressurizing process. For every 10MPa increase in pressure, the recovery increases by 2%; Prolonged soaking time can significantly improve the recovery in the opposite direction of huff and puff system. This work further reveals the micro mechanism of fluid transport in nano-pores during the high-pressure soaking and drainage process of tight oil, providing theoretical guidance for efficiently adjusting the pressurizing, soaking, and depressurizing system to improve tight oil recovery.

Abstract

The Power Sector is undergoing a rapid technological change with respect to implementation of low carbon technologies. The IEA Energy Outlook 2017 shows that the investments in Renewables for the first time are equal to those on the fossil sources. It is likely that the conventional gas turbines and internal combustion engines will need to be integrated in systems employing biofuels and/or CCUS (Carbon Capture Usage and Storage). Also, the European Union is moving rapidly towards low carbon technologies (i.e. Energy Efficiency, Smart Grids, Renewables and CCUS), see the Energy Union Strategy. This paper presents the basic for the design of CLC combustors to be coupled with gas turbines. Based on CFD modeling and detailed kinetics models.

Abstract

This paper explores the impact of the local electricity market (LEM) in a low-voltage distribution network. At first, a LEM model is established in parallel to the retail electricity market (REM), which enables the customers to engage in trading without considering the network constraints. The motivation of the proposed LEM is to minimise the financial transactions associated with the energy exchange with the electricity retailer by boosting local trading. Subsequently, the LEM model is superimposed to the low voltage distribution network (LVDN) model to understand the impact of the local electricity trading on the LVDN operational performances. The proposed LEM reveals a decline of grid supply by 7.32% and thus increase clean energy local consumption. On the contrary, voltage profiles at certain nodes deteriorate as a result of the LEM. Real-life measured data from an energy community in Ireland is considered for the study where all the participating customers are equipped with energy storage and part of them have PV.

Abstract

Due to the importance of hybrid renewable energies for green power plants, strategies are required to make the market competitive and encourage consumers to admit to using such still less available electricity compared to the power generated from fossil fuels. Promotion-based group-buying tariffs are a selling marketing tool that can be adapted for this purpose. Energy producers and consumers can express their preferences regarding hybrid renewable energies through multiple attributes and values in a conditional manner, a lexicographic representation. In this paradigm, “what to buy” and “who else might incline to buy this,” is a challenging issue for a group of consumers to make a single purchase decision. To this end, an HRECS and a PLPSim method are proposed to group consumers having the most similar lexicographic preferences for purchasing the most appropriate supplier tariff. The evaluation results demonstrate that HRECS using PLPSim outperforms the existing PLPDis method regarding Normal Discounted Cumulative Gain (nDCG) as well as intra- and inter-group Davies-Bouldin dispersion.