This study examined the feasibility of green hydrogen as a transport fuel for the very heavy vehicle (VHV) fleet in New Zealand. Green hydrogen is assumed to be produced through water electrolysis using purely renewable energy (RE) as an electricity source. This study chose very heavy vehicles as a potential market for green hydrogen, because it is considered “low-hanging fruit” for hydrogen fuel in a sector where battery electrification is less feasible. The study assumed a large-scale, decentralized, embedded (dedicated) grid-connected hydrogen system of production using polymer electrolytic membrane (PEM) electrolysers. The analysis comprised three steps. First, the hydrogen demand was calculated. Second, the additional RE requirement was determined and compared with consented, but unbuilt, capacity. Finally, the hydrogen production cost was calculated using the concept of levelized cost. Sensitivity analysis and cost reduction scenarios were also undertaken. The results indicate an... [more]

During the fast-filling of a high-pressure hydrogen tank, the temperature of hydrogen would rise significantly and may lead to failure of the tank. In addition, the temperature rise also reduces hydrogen density in the tank, which causes mass decrement into the tank. Therefore, it is of practical significance to study the temperature rise and the amount of charging of hydrogen for hydrogen safety. In this paper, the change of hydrogen temperature in the tank according to the pressure rise during the process of charging the high-pressure tank in the process of a 82-MPa hydrogen filling system, the final temperature, the amount of filling of hydrogen gas, and the change of pressure of hydrogen through the pressure reducing valve, and the performance of heat exchanger for cooling high-temperature hydrogen were analyzed by theoretical and numerical methods. When high-pressure filling began in the initial vacuum state, the condition was called the “First cycle”. When the high-pressure charg... [more]

Currently, Lithium-ion batteries (LiB) are widely applied in energy storage devices in smart grids and electric vehicles. The state of charge (SOC) is an indication of the available battery capacity, and is one of the most important factors that should be monitored to optimize LiB’s performance and improve its lifetime. However, because the SOC relies on many nonlinear factors, it is difficult to estimate accurately. This paper presented the design of an effective SOC estimation method for a LiB pack Battery Management System (BMS) based on Kalman Filter (KF) and Artificial Neural Network (ANN). First, considering the configuration and specifications of the BMS and LiB pack, an ANN was constructed for the SOC estimation, and then the ANN was trained and tested using the Google TensorFlow open-source library. An SOC estimation model based on the extended KF (EKF) and a Thevenin battery model was developed. Then, we proposed a combined mode EKF-ANN that integrates the estimation of the E... [more]

To meet the stated climate change targets and to ensure the capability of meeting the current and future energy demands, there is an urgent need to develop renewable energy sources, such as geothermal systems. If geothermal systems are to be cost-efficient and are to enjoy public confidence, it is essential that they are designed and installed in accordance with the prevailing site-specific conditions. A thorough understanding of the thermal behaviour of the surrounding ground is, therefore, critical. In this work, we investigated temperature and its evolution in the vicinity of a shallow geothermal helix-shaped borehole heat exchanger (BHE). To measure the temperature close to the actual geothermal system, an additional U-tube probe was installed at the edge of the same borehole. A thermal load was then applied to the BHE, and the temperature was detected in the nearby U-tube. The temperature measurements were made with a GEOSniff monitoring device. To understand these localised tempe... [more]

To meet rising energy demands, power plant operations will expand, influencing the interactions between the water−energy nexus and society. However, a major challenge is integration of social dimensions within electricity generation. To address this, we generate a baseline dataset using US public data (2014−2019) from the Energy Information Administration and US Bureau of Labor Statistics. We identify the rate of energy consumed, CO2, SO2 and NOx emissions generated, and water used per MWh net electricity as well as employee wellbeing per unit MW capacity during electricity generation. Rates of energy consumption (MMBtu/MWh) decreased 4.9%, but water consumption and withdrawal (m3/MWh) both increased 0.93% and 0.31%, respectively. Emissions of CO2, SO2 and NOx decreased 22.64%, 75% and 25% MT/MWh, respectively. Thermoelectric cooling withdrawal and consumption is led by natural gas (50.07%, 38.31%), coal (29.61%, 25.07%), and nuclear energies (13.55%, 18.99%). Electric power generation... [more]

The tightened approach of the European Commission to the issue of meeting the levels of pollutant emissions to the environment, inextricably connected with the level of technology used, is a serious financial challenge for many European coke producers, therefore the main aim of the article is to develop an algorithm of conduct that allows a selection of the best available emission abatement techniques from the coking plant in conditions with multiple emission sources, taking into account technological, environmental, and economic criteria. This algorithm can be used as a universal tool supporting production managers in planning investments limiting the environmental impact of the coking plant in the most economically advantageous way, while using BAT techniques. In the development of the algorithm, a multi-criteria analysis and a scenario method were used, as well as a number of typical methods for measuring and reducing the level of emissions in the coke production process. Its demons... [more]

Renewable Energy Sources (RES) have drawn significant attention in the past years to make the transition towards low carbon emissions. On the one hand, the intermittent nature of RES, resulting in variable power generation, hinders their high-level penetration in the power system. On the other hand, RES can aid not only to supply much more eco-friendly energy but also it allows the power system to enhance its stability by ancillary service provision. This article reviews the challenges related to the most intermittent RES utilised in Belgium, that is, wind energy and solar energy. Additionally, wind speed and solar irradiance variations, which are the cause of wind and solar intermittency, are studied. Then, recent techniques to forecast their changes, and approaches to accommodate or mitigate their impacts on the power system, are discussed. Finally, the latest statistics and future situation of RES in the Belgian power system are evaluated.

This work aims at developing a methodology for the assessment of district heating (DH) potential through the mapping of energy demand and waste heat sources. The presented method is then applied to the Metropolitan City of Milano as a case study in order to investigate the current and, especially, the future sustainability of DH with the foreseen building refurbishment and consequent heat demand reduction. The first step is the identification of the areas the most interesting from a heat density and an economic point of view through a clustering algorithm, in which lies the main novelty of the work. The potential is then assessed by investigating their synergy with the available heat sources, which are mapped and analyzed in terms of recoverable thermal energy and costs. In future scenarios with foreseen heat demand reduction, low-temperature networks and excess heat sources are considered, such as metro stations and datacenters, together with the conventional sources, such as thermoel... [more]

Computed X-ray tomography (CT), together with pulse and pressure decay permeability methods were used to evaluate a formula for absolute reservoir permeability. For this reason, 62 core samples representing geological material of tight, gas-bearing sandstones, mudstones, limestones, and dolostones were studied. Samples were divided into two groups with lower and higher permeability values. Images of the pore space were processed and interpreted to obtain geometrical parameters of the objects (pores, microfractures) with 0.5 × 0.5 × 0.5 µm3 voxel size. Statistical methods, which included basic statistical analysis, linear regression, and multiple linear regression analysis, were combined to evaluate the formula for absolute permeability. It appeared that the following parameters: Feret Breadth/Volume, Flatness/Anisotropy, Feret Max/Flatness, moments of inertia around middle principal axis I2/around longest principal axis I3, Anisotropy/Flatness, Flatness/Anisotropy provided the best res... [more]

The growth of renewable energy in the last two decades has led to the development of new power electronic converters. The DC microgrid can operate in standalone mode, or it can be grid-connected. A DC microgrid consists of various distributed generation (DG) units like solar PV arrays, fuel cells, ultracapacitors, and microturbines. The DC-DC converter plays an important role in boosting the output voltage in DC microgrids. DC-DC converters are needed to boost the output voltage so that a common voltage from different sources is available at the DC link. A conventional boost converter (CBC) suffers from the problem of limited voltage gain, and the stress across the switch is usually equal to the output voltage. The output from DG sources is low and requires high-gain boost converters to enhance the output voltage. In this paper, a new high-gain DC-DC converter with quadratic voltage gain and reduced voltage stress across switching devices was proposed. The proposed converter was an imp... [more]

This paper presents the effect of cavity-based injection in an axisymmetric supersonic combustor using numerical investigation. An axisymmetric cavity-based angled and transverse injections in a circular scramjet combustor are studied. A three-dimensional Reynolds-averaged Navier−Stokes (RANS) equation along with the k-ω shear-stress transport (SST) turbulence model and species transport equations are considered for the reacting flow studies. The numerical results of the non-reacting flow studies are validated with the available experimental data and are in good agreement with it. The performance of the injection system is analyzed based on the parameters like wall pressures, combustion efficiency, and total pressure loss of the scramjet combustor. The transverse injection upstream of the cavity and at the bottom wall of the cavity in a supersonic flow field creates a strong shock train in the cavity region that enhances complete combustion of hydrogen-air in the cavity region compared... [more]

This study optimizes pyrolysis conditions that will maximize energy recovery from the Beauty Leaf Tree (BLT; Calophyllum inophyllum L.) oil seed press cake. Response surface methodology (RSM) was used to determine the behavior of pyrolysis coproducts (solid, liquid and gas) at various temperatures and residence times. One significant discovery was that 61.7% of the energy (of the whole BLT oil seed) was still retained in the BLT oil seed cake after oil extraction. Controlled pyrolysis produced various proportions of biochar, bio-oil and syngas coproducts. Predictive models were developed to estimate both the mass and energy yields of the coproducts. In all experimental runs, the biochar component had the highest mass yield and energy content. Biochar mass yields were high at the lowest operating temperature used, but the energy yields based on a high heating value (HHV) of products were optimal at higher operating temperatures. From the RSM models, energy from the biochar is optimized... [more]

Recently, the interest in the plant factory-based crop production technologies is rising following the application of the smart farm technology to the agricultural arena. A lettuce production system platform is proposed in this study considering the effects of indoor environmental conditions and artificial light sources. The spectral characteristics of a visible ray according to growth performances were analyzed first to develop a control algorithm that can stimulate the plant’s growth for the proposal. Secondly, an imaging system was designed to analyze the plant’s growth characteristics based on the images and set up the system configuration. Lastly, a crop production system was proposed by using an experimental crop production group for environmental control and monitoring.

The paper focuses on the development of a thermal protection and energy requirements in relation to the issue of prefab residential housing buildings and prefab housing estates while emphasizing the need for a conceptual approach and environmental considerations. The development is recapitulated with examples of compositional sets of prefab residential housing on selected sites in the Czech Republic. Based on the comparison of archival documents and results of a long-term observation of the prefab residential housing resources, it outlines the direction of further expected development of prefab housing estates within a social context. The comparison also takes into account the impact of the European Union energy strategy and the implementation of directives into the legal rules and standards of the member states. The aim of the paper is to show the negatives and positives of current political and social strategies in relation to the thermal protection of buildings, the energy managemen... [more]

The global spread of the COVID-19 virus has led to difficulties in many branches of the economy, including significant effects on the urban transport industry. Thus, countries around the world have introduced different mobility policies during the pandemic. Due to government restrictions and the changed behaviors of transport users, companies providing modern urban mobility solutions were forced to introduce new business practices to their services. These practices are also apparent in the context of the electric shared mobility industry. Although many aspects and problems of electric shared mobility have been addressed in scientific research, pandemic scenarios have not been taken into account. Noticing this research gap, we aimed to update a previously developed model of factors that influence the operation of electric shared mobility by incorporating aspects related to the COVID-19 pandemic and its impact on this industry. This article aims to identify the main factors influencing t... [more]

Thermal Energy Storage (TES) materials, such as Phase Change Materials (PCMs) are proven to enhance the energy efficiency in many fields, such as automotive and building sectors, which correspond to the most energy intensive ones. Shape-stabilized PCM and cascade PCM are procedures to overcome the most important barriers when PCMs are applied since PCMs need to be encapsulated for their technical use: the leakage of the liquid phase, corrosion, low heat transfer and narrow temperature of application. In the present study, a novel shape stabilized PCM with cascade performance (cascade shape stabilized phase change material, CSS-PCM) is synthesized via dissolution, which allows up to 60 wt.% of a paraffin-PCM in the final composition. The novel CSS-PCM is based on a biopolymer, the polycaprolactone (PCL), a low melting temperature polyester as polymeric matrix and RT27 and Micronal DS 5040 acting as PCM. To evaluate the performance of the new TES materials developed, several techniques h... [more]

The Egyptian irrigation system depends mainly on canals that take water from the River Nile; nevertheless, the arid climate that dominates most of the country influences the high rate of water losses, mainly through evaporation. Thus, the main objective of this study is to develop a practical approach that helps to accommodate solar photovoltaic (PV) panels over irrigation canals to reduce the water evaporation rate. Meanwhile, a solar PV panel can contribute effectively and economically to an on-grid system by generating a considerable amount of electricity. A hybrid system includes a solar PV panel and a diesel generator. Several factors such as the levelized cost of energy (LCOE), total net present cost, loss of power supply probability, and greenhouse gas emissions should be considered while developing a technoeconomically feasible grid-connected renewable integrated system. A mathematical formulation for the water loss was introduced and the evaporation loss was monthly estimated.... [more]

We examine energy efficiency in the European Union (EU) using an integrated model that connects labor and capital as production factors with energy consumption to produce GDP with a limited amount of environmental emissions. The model is a linear output-oriented BCC data envelopment analysis (DEA) that employs variables with non-negative values to calculate efficiency scores for a sample of 28 EU member states in the period 2010−2018. We assume variable returns to scale (VRS) considering the natural inclination of countries to adopt technologies that allow them to produce higher outputs over extended periods of time, which we observed through the trends of increasing labor productivity and decreasing energy intensity over the analyzed period. The average EU inefficiency margin in the sample period is 16.0%, with old member states being significantly more efficient (4.2%) than new member states (29.5%). Energy efficiency management does not improve over time, especially in new member st... [more]

Among the many different applications of geothermal energy, its use for agricultural production purposes is noteworthy. The use of geothermal water in greenhouse cultivation is the most modern form of production; it enables the implementation of the production cycle throughout the year while reducing energy costs. In this paper, based on basic heat transfer relations, the heat demand of modern greenhouse constructions was determined. The monthly and year-round heat demand was determined for facilities with diversified heights of the side walls. Depending on the type of unit of greenhouse area analysed (1 ha), the calculated annual heat demand ranged from 11.05 to 12.46 TJ. Based on data on the geothermal energy potential in Poland, investment costs and payback periods were determined for the analysed locations. The locations of the facilities were selected based on traditions of plant cultivation in the greenhouse facilities and the availability of geothermal energy. The analysis showe... [more]

The fossil-based energy system is transitioning towards a renewable energy system. One important aspect is the spatial and temporal mismatch between intermitted supply and continuous demand. To ensure a reliable and affordable energy system, we propose an integrated system approach that integrates electricity production, mobility, heating of buildings and water management with a major role for storage and conversion. The minimization of energy transport in such an integrated system indicates the need for local optimization. This study focuses on a comparison between different novel system designs for neighborhood energy and water systems with varying modes of system integration, including all-electric, power-to-heat and power-to-hydrogen. A simulation model is developed to determine the energy and water balance and carry out economic analysis to calculate the system costs of various scenarios. We show that system costs are the lowest in a scenario that combines a hydrogen boiler and he... [more]

This paper presents a method that has been developed to reduce the torque ripples under healthy and open-circuit fault-tolerant (OCFT) conditions for a multiphase permanent magnet (PM) machine. For smooth torque, both the phase current and the back electromotive force (back-EMF) should be purely sinusoidal. To improve the torque in a multiphase machine, higher-order current harmonics are injected, which are related to the harmonics in the back-EMF. For this reason, generally, multiphase machines are designed with higher-order back-EMF harmonics. However, these harmonics produce ripples in the torque. In light of this, a torque ripple cancellation method has been developed that first determines an additional current component from the harmonic content of the back-EMF and then injects these additional components to cancel the torque ripple. It has been found that this new torque ripple cancellation method works for both faultless and faulty conditions in a five-phase PM machine. The meth... [more]

For corrugated pipes with a square groove, it is known that there is no interaction between the main flow and groove flow when the aspect ratio is less than four. When the groove length and height are different, the interaction occurs in the pipe. In previous studies, it was investigated whether this interaction is dependent on groove length. However, when changing the groove height, the shape of the vortex generated inside the groove changes, which may cause the interaction to occur. Therefore, in this paper the interaction between the main and groove flow of corrugated pipes is investigated when changing both groove height as well as groove pitch, corresponding to an aspect ratio of less than four. For the groove height, the flow out of the groove after impingement changes with the shape of the secondary vortex in the groove. This flow deforms the velocity distribution in the main flow, and thus the friction factor is different. For the groove pitch, there is no difference in v-veloc... [more]

The rotor wake aerodynamic characterization is a fundamental aspect for the development and optimization of future rotary-wing aircraft. The paper is aimed at experimentally and numerically characterizing the blade tip vortices of a small-scale four-bladed isolated rotor in hover conditions. The investigation of the vortex decay process during the downstream convection of the wake is addressed. Two-component PIV measurements were carried out below the rotor disk down to a distance of one rotor radius. The numerical simulations were aimed at assessing the modelling capabilities and the accuracy of a free-wake Boundary Element Methodology (BEM). The experimental and numerical results were investigated by the Γ2 criterion to detect the vortex location. The rotor wake mean velocity field and the instantaneous vortex characteristics were investigated. The experimental/numerical comparisons show a reasonable agreement in the estimation of the mean velocity inside the rotor wake, whereas the... [more]

The problem of low accuracy and low convenience in the existing state of health (SOH) estimation method for vehicle lithium-ion batteries has become one of the important problems in the electric vehicle field. This paper proposes an improved cuckoo search particle filter (ICS-PF) algorithm based on a charging time segment from equal voltage data to estimate battery health status. Appropriate voltage ranges of charging time segments are selected according to the battery charging law, and in the meantime, the charging time segments are collected as a health indicator to establish the corresponding relationship with battery capacity attenuation value. An improved cuckoo search particle filter algorithm based on the traditional particle filter (PF) and cuckoo search (CS) algorithm is proposed by enhancing the search step size and discovery probability to estimate the capacity attenuation. The estimation result shows that this method is superior to the traditional particle filter and cuckoo... [more]

Rock yielding may well take place during hydraulic fracturing in deep reservoirs. The prevailing models based on the linear elastic fracture mechanics (LEFM) are incapable of describing the evolution process of hydraulic fractures accurately. In this paper, a hydro-elasto-plastic model is proposed to investigate the hydraulic fracture propagation in deep reservoirs. The Drucker−Prager plasticity model, Darcy’s law, cubic law and cohesive zone model are employed to describe the plastic deformation, matrix flow, fracture flow and evolution of hydraulic fractures, respectively. Combining the embedded discrete fracture model (EDFM), extended finite element method (XFEM) and finite volume method, a hybrid numerical scheme is presented to carry out simulations. A dual-layer iterative procedure is developed based on the fixed-stress split method, Picard iterative method and Newton−Raphson iterative method. The iterative procedure is used to deal with the coupling between nonlinear deformation... [more]