is a species distributed worldwide. Its seeds are used to produce castor oil, which can be used for the production of biofuels; yield improvement can be achieved with elicitors that are substances of biological origin that can induce increased productivity of primary and secondary metabolism, when applied to plants. Salicylic acid (SA) is a natural constituent of plants, and applied exogenously acts as an elicitor. The aim of this work is to evaluate the oil content of castor bean plants elicitated with 900, 600, 300, and 100 µM of salicylic acid and its emissions derived from biodiesel made with the oil in blends (0, 10 and 20%) with commercial fuel in a 296 cc diesel cycle engine; elicitation was foliar sprayed. The oil content increased 39% when 900 µM SA was applied compared to control, and the evaluation of emissions showed the maximum reduction with 20% of Ricinus communis biodiesel (RCB) in all different RPM rates. Otherwise, the use of SA could be a method to increase oil conte... [more]

An important requirement of the power grid with high penetration of renewable energy sources is the mitigation of potential harmonic interactions between different distributed large grid-tie inverters and the mains. This work presents the harmonic interaction between multiple multilevel photovoltaic (PV) inverters based on the well-known T-type neutral-point-clamped inverter (3L-TNPC). The multiple 3L-TNPC is connected in parallel to a common ac bus by using distribution voltage feeders. The analysis is performed by using the Norton equivalence model of each power circuit, its admittance matrix modeling, and the potential overall impedance resonances with the ac grid. The main contribution of this work is the development of a current harmonic injection model of the system operating under a polluted voltage grid for harmonic analysis, while overall filtering design restrictions due to impedance limits based on current and voltage standards are considered. The proposed impedance Norton m... [more]

This paper presents the results of research on the energetic use of self-combusted hemp pellets and co-firing with pine pellets. The tests were carried out with the use of a boiler equipped with a Lester Projekt Company gasifying burner and an automatic fuel feeding system. The boiler is equipped with an additional heat exchanger that enables the simulation of any heat load. The experimental stand so built guaranteed to obtain results adequate to the real operating conditions. The research material consisted of pellets made of waste biomass of the Futura 75 sowing hemp and pine sawdust pellets. The experiment was carried out in five proportions by mass of mixtures of both fuels (C-hemp, P-pine): 0:100 (P100), 25:75 (C25/P75), 50:50 (C50/P50), 75:25 (C75/P25), 100:0 (C100). For each variant, the following were determined: effective boiler power, boiler energy balance, boiler energy efficiency, the volumetric composition of flue gas (carbon monoxide, carbon dioxide, hydrogen, sulfur diox... [more]

The electric vehicle (EV) industry has made significant progress but, in many markets, there are still barriers holding back its advancement. A key issue is the anxiety caused to the drivers by the limited range of current EV models and the inadequate access to charging stations in long-distance trips, as is the case on highways. We propose an intuitive multi-criteria approach that optimally places EV charging stations on highways that (partially) lack such points. The approach, which is applied in an iterative fashion to dynamically evaluate the alternatives, considers a set of practical criteria related to the traffic intensity and the relative location of the charging stations with interchanges, major cities, and existing stations, thus supporting decisions in a pragmatic way. The optimal locations are determined by taking into consideration constraints about the EV driving range and installation preferences to improve the operation of the highway while ensuring reasonable cost of i... [more]

Excessive regional differences in energy consumption have led to inequality and energy poverty. It is essential to clarify the factors of energy consumption convergence to solve this problem. We use the spatial convergence model to analyze the convergence characteristics and conditions of China’s natural gas consumption from 2005 to 2017. The results of spatial absolute convergence show that there is absolute convergence of natural gas consumption in China, and the economic competition among provinces slightly hinders the convergence. Furthermore, based on the spatial Durbin model and the spatial conditional convergence model, we found that insufficient pipe network construction and the price difference caused by provincial borders are the main factors hindering the flow of natural gas, which also restricts the spatial convergence of natural gas consumption. The development of the tertiary industry and the improvement of purchasing power will help accelerate the convergence of natural... [more]

The use of waste incineration with energy recovery is a matured waste-to-energy (WtE) technology. Waste incineration can reduce the volume and mass of municipal solid waste significantly. However, the generation of high volumes of polluting flue gases is one of the major drawbacks of this technology. Acidic gases are constituents in the flue gas stream which are deemed detrimental to the environment. The wet flue gas desulphurization (FGD) method is widely employed to clean acidic gases from flue gas streams, due to its high efficiency. A major setback of the wet FGD technology is the production of wastewater, which must be treated before reuse or release into the environment. Treating the wastewater from the wet FGD presents challenges owing to the high level of contamination of heavy metals and other constituents. Membrane distillation (MD) offers several advantages in this regard, owing to the capture of low-grade heat to drive the process. In this study the wet FGD method is adopte... [more]

Coke-making technology utilises two systems for charging the coke oven chambers with coal—a stamp-charged system (stamp-charging) and a gravity charged system (top charging). The presented study examines the impact of selected coal properties on the effectivity of the stamping operation by measuring the bulk density of the obtained stamped coal cake. An empirical mathematical model was developed that allows the forecasting of the coal cake density based on the most frequently assessed coal parameters, such as volatile matter, ash, moisture and particle size parameters, as well as the stamping operation parameter—cumulative stamping energy. The obtained results showed that the density of the stamped coal cake increases with the increase in the stamping energy (53.3 kg/m3 increase, for increase in natural logarithm value of 1), RRSB specific coal particle diameter d′ (6.4 kg/m3 increase, for each 0.1 mm increase in d′), ash content (8.9 kg/m3 increase, for 1% point increase) and moisture... [more]

This paper proposes a wind power probabilistic model (WPPM) using the reflection method and multi-kernel function kernel density estimation (KDE). With the increasing penetration of renewable energy sources (RESs) into power systems, several probabilistic approaches have been introduced to assess the impact of RESs on the power system. A probabilistic approach requires a wind power scenario (WPS), and the WPS is generated from the WPPM. Previously, WPPM was generated using a parametric density estimation, and it had limitations in reflecting the characteristics of wind power data (WPD) due to a boundary bias problem. The paper proposes a WPPM generated using the KDE, which is a non-parametric method. Additionally, the paper proposes a reflection method correcting for the boundary bias problem caused by the double-bounded characteristic of the WPD and the multi-kernel function KDE minimizing the effect of tied values. Six bandwidth selectors are used to calculate the bandwidth for the K... [more]

In this paper, the results of an experimental study on hydrogen production at a tungsten discharge electrode with negative polarity in the DC electrolysis of a typical 10 wt% Na2CO3 aqueous solution in three operational regimes (the Faradaic, transition, and plasma-driven solution electrolysis (PDSE)) are presented for the first time. To focus the study on hydrogen production, a flowing inert gas (argon) was used to transport the gas mixture produced at the discharge electrode and prevent any other potential chemical reactions. The results showed that the highest hydrogen production rate of 0.147 g(H2)/h was achieved in the cathodic PDSE regime at the applied DC voltage of 198 V. However, the energy yield of hydrogen production of 0.405 g(H2)/kWh obtained at the applied voltage range of 141−170 V in the PDSE regime was lower than that obtained in the Faradaic regime (0.867 g(H2)/kWh) at 28 V. The energy balance of hydrogen production in the cathodic PDSE regime for the typical aqueous... [more]

Diesel engines are one of the most popular reciprocating engines on the market today owing to their great thermal efficiency and dependability in energy conversion. Growing concerns about the depletion of fossil resources, fluctuating prices in the market, and environmental issues have prompted the search for renewable fuels with higher efficiencies compared with conventional fuels. Fuel derived from vegetable oils and animal fats has comparable characteristics to diesel fuel, but is renewable, despite being manufactured from various feedstocks. Nevertheless, the direct use of these fuels is strictly prohibited because it will result in many issues in the engine, affecting engine performance and durability, as well as emissions. To make biofuels as efficient as fossil fuels, it is essential to alter their characteristics. The use of emulsification techniques to obtain emulsified biofuels is one of the many ways to modify the fuel characteristics. Emulsification techniques allow for a d... [more]

The dynamic viscoelastic theory of soil−pile interaction dominates the initial impedance calculation during the pile dynamic design and analysis. Further, it provides a firm theoretical ground for the wave propagation simulation, which could be the basis of seismic analysis and some geotechnical testing approaches. This review traces the development history and key findings of viscoelastic soil−pile interaction theory and expounds on the advantages and limitations of various theoretical advances in terms of dynamic design and wave propagation modeling. The review consists of three sub-divisions, which are the longitudinal, horizontal, and torsional viscoelastic soil-pile theories. The development and implement of multi-phase soil constitutive equations, multi-dimensional soil−pile interaction modeling methods, pile−soil−pile mutual interactions in pile groups, and the fluid−structure interaction problems in offshore piles are especially remarked and concluded. Finally, the shortcomings... [more]

Climate change has been turning into a climate crisis. Thus, we live in an era in which it is important to carry out the promise of 2050 carbon neutrality worldwide. South Korea is a country with a very large private education market. As the online education market has also recently expanded rapidly, interest in the electricity consumed by educational institutions is growing. One way to reduce the power consumption of private educational institutions, which is expected to gradually increase, is to replace the existing power system with a hybrid energy system based on renewable energy. This study aims to investigate an optimized renewable-energy-based hybrid system to supply adequate power to private educational institutions in Korea. We propose an optimal system using the HOMER (Hybrid Optimization Model for Electric Renewables) program. The result is that when private educational institutions adopt a hybrid renewable energy system, the renewable fraction is negligible in the grid-conn... [more]

Frequency stability is an important factor for the safety and stability of the power system operation. In a traditional power system, the operation stability is ensured by the inertia response, primary frequency modulation, and secondary frequency modulation. In recent years, in order to achieve the goal of carbon neutralization and carbon peaking, China has made great efforts in new energy development. With large-scale new energy connected to the power grid, the proportion of traditional conventional synchronous units has gradually declined. At the same time, a large number of power electronic devices have been used in the power grid, which led to the capability decline of the inertia response and primary frequency modulation. For example, the East China Power Grid has experienced a sharp frequency drop in such an environment. In order to solve the above problems, the operation principle and control mode of various new energy resources are analyzed in this paper. Moreover, the process... [more]

A high-performance and scalable lipase immobilization method using a dipping and jet break-up technique was reported for the production of microcapsule biocatalysts with an entrapped cascade of lipase enzyme. The lipase from Candida antarctica (CALb) recombinant Aspergillus oryzae and from the vegetal of Jatropha curcas L. (var. Sevangel) in Morelos State of Mexico were entrapped by mixing with a sodium alginate biopolymer at different concentrations. The obtained microcapsules were hardened in a CaCl2 solution, aiming at developing Ca2+ alginate microbeads with sizes mostly from 220 to 300 μm. The relationship between the process variables with the shape and size of the alginate drops before and after the gelation was established with aid of optical image analysis. The results showed that a critical Ohnesorge number (Oh) > 0.24 was required to form spherical microencapsulated beads. The biodiesel production via esterification/transesterification reaction was performed using the crude... [more]

The dependence of road transport on fossil fuels and its contribution to greenhouse gas (GHG) and pollutant emissions are main concerns leading to the need for shifting toward alternative energy sources and, namely, electromobility. The current paper aims to identify the key determinants affecting the consumer adoption of electric vehicles (EVs), focusing on private passenger cars. Toward this purpose, a systematic review of recent international literature is conducted in order to identify motivators and barriers, which are then categorized following the PESTLE (Political−Economic−Social−Technological−Legal−Environmental) approach. Based on the review results, main policy implications and recommendations are discussed. A main conclusion is that the recent literature highlights a wide array of determinants, without converging as to which ones are the most influential regarding EV adoption by consumers. Another conclusion is that the environmental aspects are less important for consumers... [more]

The rising share of renewable energy in the energy mix brings with it new challenges such as power curtailment and lack of reliable large-scale energy grid. The forecasting of wind power generation for provision of flexibility, defined as the ability to absorb and manage fluctuations in the demand and supply by storing energy at times of surplus and releasing it when needed, is important. In this study, short-term forecasting models of wind power generation were developed using the conventional time-series method and hybrid models using support vector regression (SVR) based on rolling origin recalibration. For the application of the methodology, the meteorological database from Korea Meteorological Administration and actual operating data of a wind power turbine (2.3 MW) from 1 January to 31 December 2015 were used. The results showed that the proposed SVR model has higher forecasting accuracy than the existing time-series methods. In addition, the conventional time-series model has hi... [more]

The paper presents the experimental research on the thermal management of a 150 W LED lamp with heat sink inside a synthetic jet actuator. The luminous flux was generated by 320 SMD LEDs with a nominal luminous efficacy equal to 200 lm/W mounted on a single PCB. Characteristic temperatures were measured with three different measurement techniques: thermocouples, infrared camera, and an estimation of the junction temperature from its calibrated dependence on the LED forward voltage. The temperature budget between the LED junction and ambient as well as the thermal resistance network was determined and analyzed. The energy balance of the LED lamp is presented along with the values of the heat flow rate and heat transfer coefficient in different regions of the LED lamp surface. For an input power supplied to the SJA equal to 4.50 W, the synthetic jet dissipated approximately 89% of the total heat generated by the LED lamp. The heat from the PCB was transferred through the front and rear s... [more]

Different renewable energy resources and energy demands between parks lead to waste of resources and frequent interactions between the regional distribution grid and the larger grid. Hence, an optimal dispatching scheme of the regional integrated energy system group (RIESG), which combines the power-to-gas (P2G) and inter-park electric energy mutual aid, is proposed in this paper to solve this problem. Firstly, for the park integrated energy system (PIES) with various structures, the coupling matrix is used to describe the input-output relationship and coupling form of multiple energy sources in the energy-hub (EH), which linearizes the complex multi-energy coupled system and is more conducive to the solution of the model. Secondly, the electrical coupling relationship of the system is improved by adding P2G to enhance the system’s ability to consume renewable energy. Moreover, the installation cost of P2G is introduced to comprehensively consider the impact of the economic efficiency... [more]

Sub-synchronous oscillation is one of the most challenging issues in modern power systems with a high proportion of wind power. Interactions among the wind turbines are key factors causing the oscillations. This paper aims to propose a method to quantify the interactions among N permanent-magnet-synchronous-generator (PMSG)-based wind turbines by transfer functions and analyze the influence of the interactions on the system stability. We derived different terms of the self- and en-stabilizing functions to describe different interactions caused by different wind turbines analytically. Meanwhile, the parameter sensitivity of this method is proposed to analyze the impact of the system and control parameters on the interactions and the system stability. Examples and simulations are given to show the effectiveness of this method.

Electric Vehicles (EVs) replace fossil fuel vehicles in effort towards having more sustainable transport systems. The battery of an EV is recharged at a charging point using electricity. While some recharging will be required at locations where vehicles are normally parked, other recharging could be necessary at strategic locations of vehicular travel. Certain locations are suitable for EV charging station deployment, others are not. A multi-stage decision analysis methodology for selecting suitable locations for installing EV charging station is presented. The multi-stage approach makes it possible to select critical criteria with respect to any defined objectives of the EV charging station and techno-physio-socio-economic factors without which the EV charging station could not be deployed or would not serve its designated purpose. In a case, the type of charging station is specified, and a purpose is defined: rapid EV charging stations intended for public use within and across border... [more]

Seaweeds represent a promising and sustainable feedstock for biofuel production which raises increasing research interests. Their high availability, easy fermentable composition, and good degradation potential make them a suitable candidate for alternating fossil fuels as an advantageous energy resource. This comprehensive review aims to summarize and discuss data from the literature on the biochemical composition of seaweeds and its potential for biomethane and biohydrogen production, as well as to investigate the effect of the common pretreatment methods. Satisfactory yields comparable to terrestrial biomass could be obtained through anaerobic digestion; concerning dark fermentation, the challenge remains to better define the operating conditions allowing a stable production of biohydrogen. Finally, we propose a potential energy production scheme with the seaweed found by the Caribbean Islands of Guadeloupe and Martinique, as well as current techno-economic challenges and future pros... [more]

The article presents and compares two different control methods for a permanent magnet synchronous motor (PMSM) for diesel−electric ship propulsion. The main focus of the article is on control optimization, which allows improving energy efficiency by reducing reactive power in the mechatronic propulsion system. The first method consists in modifying the commonly used field-oriented control (FOC) strategy to ensure zero reactive power in the inverter−PMSM system. Since a characteristic of ship propulsion systems, unlike those used on land, is the step load on the propulsion motor, the system’s performance in dynamic states is particularly important. Unfortunately, control strategies based on FOC do not take into account the dynamics of the system, since they apply only to steady states. Therefore, the authors of this paper, based on control theory methods, proposed an approach that also optimizes control in dynamic states, while minimizing reactive power in the steady state. The analyti... [more]

Methanol crossover is an important factor affecting the performance of direct methanol fuel cells (DMFCs). In this work, a novel membrane electrode assembly (MEA) is designed and prepared by adding a layer of graphene aerogel (GA) between the carbon powder microporous layer and the catalytic layer, which optimizes the methanol transport and improves the output performance of DMFC at high methanol concentrations. Compared to conventional carbon powder, the addition of GA increases the tortuosity of the anode in the through-plane direction; hence, methanol is diluted to a suitable concentration when it reaches the catalyst. The maximum power density of the novel MEA can reach 27.4 mW·cm−2 at a condition of 8 M methanol, which is 234% higher than that of the conventional electrode. The test results of electrochemical impedance spectroscopy (EIS) indicate that the addition of GA does not increase the internal resistance of the novel MEA and that the mass transfer resistance at high concent... [more]

This study analysed a novel re-liquefaction system integrated with a fuel supply system (FSS) for an LPG carrier to conventional systems. The re-liquefaction system and FSS were installed independently in a conventional LPG carrier, while those systems were combined in the novel system. The condensed LPG in the re-liquefaction system was directly transferred to the FSS without the cooling and expansion process in the novel system. 84,000 m3 LPG carrier equipped with a 10 MW engine at normal continuous rating (NCR) was selected as a target ship. Aspen HYSYS ver.12.1 was employed for process simulation. The results showed that the energy consumption for the novel system was reduced by 38%. The energy for re-liquefaction was decreased because the flow rate recirculated was decreased, and the energy for FSS was reduced as the temperature of the stream supplied to the FSS was relatively high in the novel system. A sensitivity analysis was conducted to investigate the effect of the parameter... [more]

Energy security and the reduction of greenhouse gases such as carbon dioxide are two major crises facing the world today. Using carbon dioxide to develop unconventional oil and gas resources is a positive way to reduce greenhouse gas emissions, which can significantly alleviate global energy security issues. This study systematically introduces the prerequisites for CO2 to extract crude oil and CO2 to be safely and effectively stored. Under high temperature and high pressure, the rock properties of deep reservoirs are completely different from those of atmospheric conditions in the two-phase porous media environment of crude oil and high salinity formation water. The research progress on the phase behavior, mutual solubility, CO2 storage potential and mechanism between supercritical CO2 and crude oil, formation water and reservoir are reviewed in detail. In addition, CO2 leakage will inevitably occur during long-term geological storage, the proper estimation and evaluation of the risk... [more]