Microbial lipids produced from lignocellulosic biomass are sustainable alternative feedstock for biodiesel production. In this study, corn cobs were used as a carbon source for lipid production and growth of oleaginous yeast Trichosporon oleaginosus. Lignocellulosic biomass was subjected to alkali and acid pretreatment using sulfuric acid and sodium hydroxide under different temperatures, catalyst concentrations and treatment times. Pretreatment of corn cobs was followed by cellulase hydrolysis. Hydrolysis of alkali pretreated (2% NaOH at 50 °C for 6 h, 1% NaOH at 50 °C for 16 h, 2% NaOH at 121 °C for 1 h, 1% NaOH at 121 °C for 2 h) and acid pretreated (1% H2SO4 120 °C for 20 min, and 2% H2SO4 120 °C for 10 min) corn cobs resulted in more than 80% of the theoretical yield of glucose. The effect of substrate (5, 10, 15 and 20%, g g−1) and cellulase loading (15 and 30 Filter Paper Units per gram of glucan, FPU g−1) on fermentable sugar yield was also studied. The maximal glucose concentr... [more]

The high energy-consuming building sector needs to meet both electricity and heat demands. In a nearly zero energy building scenario, most of the consumed energy would be generated locally by means of renewable solutions that nowadays seem not to provide an attractive performance or cost-competitiveness. Solar-based technologies tend to be the most promising ones, but for high densely populated areas, the usual photovoltaic or thermal single approaches may not be efficient enough. The current work is focused on the analysis of the dual use of the solar resource by means of hybrid PVT collectors and their smart combination with direct expansion heat pumps through predictive control strategies. To that end, a system was developed, installed in a real-use single-family house at a continental climate for domestic hot water application, operated and monitored for one entire year. The average day indicator results show 83% renewable energy share, 220% self-sufficiency ratio, 41% heat pump se... [more]

In this work, the optimal participation of heterogeneous, Renewable Energy Source (RES)-based Virtual Power Plant (VPP) in Day-Ahead Market (DAM) and Intra-Day Market (IDM) is studied. For this purpose, a detailed model of the RES-based VPP and of the market operation is needed. The VPP includes both dispatchable and non-dispatchable RESs and flexible demand assets. This paper presents an improved, linear solar thermal plant model to consider its non-linear efficiency curve. A novel demand model with two flexibility levels that are associated with the different market sessions is also proposed. The market operation allows for updates of energy offers and this is used by the VPP to submit DAM auctions and to participate subsequently in IDM to correct for deviations. Finally, the optimal participation of the VPP in energy markets is assessed under different weather conditions.

The cubic garnet Li7La3Zr2O12 (c-LLZO) is one of the most promising solid electrolytes due to its high ionic conductivity and large electrochemical window. However, the critical issue of Li2CO3 formation on the c-LLZO surface when exposed to air is problematic, which is detrimental to the ionic conductivity and storage. Herein, comparative studies were carried out on the air stability of Al-doped Li7La3Zr2O12 (Al-LLZO), Al-Ta-doped Li7La3Zr2O12 (Al-LLZTO), and Al-Nb-doped Li7La3Zr2O12 (Al-LLZNO). It was found that Al-LLZTO and Al-LLZNO are less reactive with air than Al-LLZO. The morphology of Li2CO3 on Al-LLZTO micro-sized powders after air exposure was island-like with ~1.5 μm in thickness. The interfacial resistance of Li/Al-LLZTO was also a factor of ~3 smaller than that of Li/Al-LLZO, leading to the improved cycle stability of Li/Al-LLZTO/Li symmetric cells. The first-principles calculations based on density functional theory (DFT) verified that the decomposition energy of Al-LLZT... [more]

Energy generation from conventional energy sources, such as oil, coal, and gas, produces adverse environmental pollutants, e [...]

Electric Vehicles (EVs) are gaining acceptance due to the advantages they offer in the reduction of nitrogen oxide and carbon dioxide emissions. The need for emission reduction and the potential of EVs for these reductions is reflected in the current sustainable mobility policies of the EU as well as the German government. Increasing the penetration of EVs in the grid requires an expansion of EV charging infrastructure, which in turn requires either grid reinforcement or solutions for more efficient use of existing infrastructure to avoid or postpone grid reinforcement. Distribution transformers face increased loading due to EV charging and need to be protected from overloading during peak load periods to ensure continuity of service. Therefore, transformers are one of the components that are upgraded or replaced as a part of grid reinforcement. In this paper, we propose the connection of a Solid-State Transformers (SST) between two buses operating at the same-voltage level as an alter... [more]

Tailpipe emissions from vehicles consist of CO2 and other greenhouse gases, which contribute immensely to the rise in global temperatures. Green hydrogen produced from the gasification of biomass can reduce the amount of CO2 emissions to zero. This study aims to provide a modelling framework to optimize the production of hydrogen from biomass waste obtained from different cities, for use in the road transport sector in Nigeria. A gasification model with post-treatment shift conversion and CO2 removal by adsorption is proposed. In this study, six cities are simulated based on technical and environmental considerations, using the Aspen Plus software package. The results revealed that Kaduna has the highest hydrogen generation potential of 0.148 million metric tons per year, which could reduce CO2 emissions to 1.60 and 1.524 million metric tons by the displacement of an equivalent volume of gasoline and diesel. This amounts to cost savings of NGN 116 and 161.8 billion for gasoline and die... [more]

Adsorption equations are important to analyze the pore size distribution (PSD) of shale and the adsorption behavior on it. However, the accurate description of nitrogen adsorption on shale by current adsorption equations is difficult to achieve due to the heterogeneous pore structure of shale. In our study, new adsorption isotherms that can properly depict the adsorbed amount of nitrogen were built for shale rocks considering both the processes of nitrogen adsorption and the cylindrical pore shape property of shale. When performing a regression analysis on five sets of experimental adsorption data using the developed adsorption equations, the R-square ranged from 0.739 to 0.987. Based on the pore shape determined by adsorption−desorption curves, the distinct R-square indicated that our equation is not valid for shale samples with ink-bottle pores and pores formed by schistose materials, but that it is suitable for shale samples with cylindrical pores and slit pores. Meanwhile, we preci... [more]

Different mechanisms for balancing power between parallel connected modules have been presented in recent years. They have been broadly classified into active and passive methods. The high output impedance of topologies, including active clamp networks, suggests that they can achieve output current sharing passively when they are connected in parallel. However, some parasitic elements, such as stray capacitances and leakage inductances, have not been considered in the theoretical analyses. Moreover, these need to be taken into account when a high step-up ratio is required because they modify the behavior and output impedance of a module, which changes the current balance. This paper presents a detailed analysis of the influence of parasitic capacitances on active clamp flyback converters that were parallel connected, using the output impedance as a current self-balance method. The proposed solution to alleviate the negative effects on current balance was also studied and validated as a... [more]

In fault detection and the diagnosis of large industrial systems, whose chemical processes usually exhibit complex, high-dimensional, time-varying and non-Gaussian characteristics, the classification accuracy of traditional methods is low. In this paper, a kernel limit learning machine (KELM) based on an adaptive variation sparrow search algorithm (AVSSA) is proposed. Firstly, the dataset is optimized by removing redundant features using the eXtreme Gradient Boosting (XGBOOST) model. Secondly, a new optimization algorithm, AVSSA, is proposed to automatically adjust the network hyperparameters of KELM to improve the performance of the fault classifier. Finally, the optimized feature sequences are fed into the proposed classifier to obtain the final diagnosis results. The Tennessee Eastman (TE) chemical process is used to verify the effectiveness of the proposed method through multidimensional diagnostic metrics. The results show that our proposed diagnosis method can significantly impro... [more]

The flyback converter with its active cell balancing topology for charging lithium-based batteries in Electrical Vehicles (EV) have been adopted recently into the industry. Electrical Vehicle battery charging requires high current operation in continuous current mode and hence, the power loss on the Schottky diode rectifier on the secondary side determines the power conversion efficiency. The depletion mode (D-mode) GaN HEMT synchronous rectifier proposed in this paper has been used to replace the Schottky diode on the secondary side of the flyback converter in order to improve the power conversion efficiency. This synchronous rectifier regulates the forward voltage drop of an external switch to about 100 mV per ampere of current flow with no concern to threshold voltage. The first challenge of converting the D-mode GaN HEMT as a synchronous rectifier is that the normally-on device must be off when the primary side inductor of the flyback converter is initially charging the magnetic en... [more]

The power quality delivered by the distribution companies to consumers has always been a relevant issue, especially to industrial consumers, where power quality is directly related to productivity [...]

The authors wish to make the following correction to their paper [...]

Floating storage and regasification units (FSRU) provide a flexible and competitive energy distribution option when it comes to the regasification of liquefied natural gas (LNG). FSRU projects have become more and more popular, attracting the interest of investors, energy authorities, and governments; therefore, the project feasibility in terms of risks and profitability are a major concern. This paper deals with the appraisal of a greenfield LNG infrastructure project, where usually, decision complexity deals with the high number and different expectation of stakeholders, the capital-intensive financing nature, and the business risks in the project life cycle. Conventional wisdom is to provide a coherent, compact, and well-structured appraisal modelling framework, adjusted to FSRU technical, structural, and operational features on one hand; and business risks, long-term life cycle, and investment attractiveness on the other. Appraisal modelling structure and outputs are considered to... [more]

One of the major challenges in implementing the equivalent fuel consumption minimisation strategy in hybrid electric vehicles is the adaptation of the equivalence factor to real-world driving. In this paper, a novel adaptive equivalent fuel consumption minimisation strategy (A-ECMS) has been developed for a hybrid two-wheeler to further improve fuel savings by predicting the drive cycles and thereby estimating and adapting the equivalence factor online for the ECMS energy management control. A learning vector quantitative neural network (LVQNN)-based classifier was first proposed to recognise the real-world driving cycle based on a fixed time window of past driving information. Along with standardised drive cycles, real-world driving data were used in the learning process to increase the robustness of the learning. The A-ECMS is then capable of regulating its equivalence factors online based on the LVQNN controller output. Numerical simulation results indicated that there was considera... [more]

The advanced thermal-hydraulic test loop for accident simulation (ATLAS) was developed and operated at The Korea Atomic Energy Research Institute. The ATLAS is operated to simulate accidents in pressurized water reactors (PWRs). A domestic standard problem (DSP) using the ATLAS was proposed for transferring the database of the integral effect test to Korean nuclear researchers and developing the safety analysis methodology of PWRs. The fourth DSP (DSP-04) exercise was performed during 2015−2017 with 15 participants (13 organizations), that are universities, government, and nuclear industries. In DSP-04, a top-slot break at the cold leg was chosen as the target scenario to resolve an issue about the effect of loop seal clearing and the reformation on the peak cladding temperature during the cold leg top-slot break LOCA for APR1400. The participants performed a code calculation for the experimental simulation and sensitivity studies for the enhancement of the code. This paper includes br... [more]

High-temperature superconductor (HTS) bulks have shown very promising potential for industrial applications due to the ability to trap much higher magnetic fields compared to traditional permanent magnets. In rotating electrical machines, the magnetic field is a combination of alternating and rotating fields. On the contrary, all studies on electromagnetic characterization of HTS presented in the literature so far have only focused on alternating AC magnetic fields and alternating AC loss due to the unavailability of robust experimental techniques and analytical models. This paper presents a numerical investigation on the characterization of HTS bulks subjected to rotating magnetic fields showing AC loss, current density distribution in three-dimensional axes, and trapped field analysis. A three-dimensional numerical model has been developed using H-formulation based on finite element analysis. An HTS cubic sample is magnetized and demagnetized with two-dimensional magnetic flux densit... [more]

Due to environmental concerns, governments around the world are taking measures to decarbonise railway transport by replacing diesel traction systems with cleaner alternatives. While the electrification of railway systems is spreading rapidly, it is unlikely that all routes will be electrified as the volume of passengers will not justify the high infrastructure costs. Therefore, it is expected that, for several lines, a combination of hydrogen and electric traction will be used, with the latter partly provided by fixed infrastructure and partly by batteries. Railway traction drives will then need to change to accommodate these new types of power supply. A detailed review of the available traction motors and drives is provided with this review, given application to the new hybrid-electric systems. In particular, permanent magnet synchronous motors with multiphase windings are evaluated in comparison with traditional three-phase machines. Additionally, low and medium-voltage multisource... [more]

The Huainan Coalfield is a typical multi-coal seam coalfield. In order to systematically investigate the distribution, occurrence, and integration of arsenic (As) in Shanxi coal, 26 coal samples and three rock samples were collected in the No. 1 coal seam of Huainan coalfield. The minerals, major element oxides, and As were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), polarized light microscopy, X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS). The results indicated that the coals of Shanxi Formation were characterized by very low ash yields and low total sulfur contents. The identified minerals by XRD in the studied coals are dominated by kaolinite, quartz, calcite, and a lesser amount of pyrite. The As content ranges from 10.33 mg/kg to 95.03 mg/kg, with an average of 44.74 mg/kg. Compared with world coals, the studied coals have higher contents of As, which are characterized by enrichment. Based on statistica... [more]

To ensure safe and reliable operation, the ability to ride through various disturbances is vital for a microgrid with multi-inverters. As the voltage and frequency support comes from the power-electronic-based inverters, it is necessary to find a proper control strategy to improve the rejection ability of the DG inverter against disturbances. In this regard, this paper proposes a new distributed secondary frequency control approach for islanded microgrids, in which the main purpose is to remove the frequency deviation under droop control method with better disturbance rejection performance. Unlike many traditional approaches which rely on a detailed control model, the proposed one needs little model information thanks to the model-independent characteristic of active disturbance rejection control (ADRC) technique. A linear extended state observer is introduced to estimate the useless model dynamics (including unknown disturbances, unmodeled dynamics and nonlinear dynamics) which are th... [more]

A novel method characterizing the air backflow of the underhood in order to improve the thermal efficiency of the air conditioning system (ACS) and reduce the energy consumption of PHEV is proposed in this paper. In addition, a 1D model for analyzing air backflow occurring in the underhood is established and a CFD method for calculating air backflow rate and distribution is proposed. It is found that the decrease in the air backflow rate of the underhood helps to improve the refrigeration capacity of the ACS, and when the backflow ratio cannot be reduced below 10%, the air backflow should be distributed as evenly as possible at the front end of the condenser. Moreover, in order to eliminate the impact of backflow on the underhood of PHEV, the gap between the radiator and the bracket is sealed and the gap around the air guide is reduced. Compared with the original structure, the backflow rate of the optimized structure is reduced from 32.7% to 9.3% and the cabin temperature can be reduc... [more]

Nowadays, the ever-growing energy demands, the associated greenhouse gas emissions, and the exhaustible nature of fossil fuels are the biggest challenges of our industrial world [...]

The coalbed methane (CBM) geology in Guizhou is characterized by a high gas content, pressure and resource abundance, indicating superior CBM resource potential. However, there are also many unfavorable factors, such as complex structure geology, significant regional differences in CBM geology, the widespread development of tectonically deformed coal, and the unclear understanding of the configuration of geological factors for CBM enrichment and high yield, which restrict the increase in CBM production and a large-scale development. Taking the Dahebian Block in Liupanshui coal field and the Dafang Block in Qianbei coal field as examples, this study presented the CBM geological differences between middle- and high-rank coals; their origins were analyzed and the effect of depth on gas content and permeability was discussed. A CBM enrichment and high-yield model was illustrated, and the geologic fitness-related exploration and development methods for Guizhou CBM were finally proposed. The... [more]

The ongoing COVID-19 pandemic has disrupted global economic activity in all sectors, including forest industries. Changes in demand for forest products in North America over the course of the pandemic have affected both primary processors and downstream industries reliant on residues, including wood pellet producers. Wood pellets have become an internationally traded good, mostly as a substitute for coal in electricity generation, with a significant proportion of the global supply coming from Canadian producers. To determine the effect of the COVID-19 pandemic on the Canadian wood pellet industry, economic and market data were evaluated, in parallel with a survey of Canadian manufacturers on their experiences during the first three waves of the pandemic (March 2020 to September 2021). Overall, the impact of the pandemic on the Canadian wood pellet industry was relatively small, as prices, exports, and production remained stable. Survey respondents noted some negative impacts, mostly in... [more]

Offshore wind turbine drive train technology is evolving as developers increase size, aim to maximise availability and adapt to changing electricity grid requirements. This work first of all explores offshore technology market trends observed in Europe, providing a comprehensive overview of installed and planned capacity, showing a clear shift from smaller high-speed geared machines to larger direct-drive machines. To examine the implications of this shift in technology on reliability, stop rates for direct-drive and gear-driven turbines are compared between 39 farms across Europe and South America. This showed several key similarities between configurations, with the electrical system contributing to largest amount of turbine downtime in either case. When considering overall downtime across all components, the direct-drive machine had the highest value, which could be mainly attributed to comparatively higher downtime associated with the electrical, generator and control systems. For... [more]