Nuclear fusion is the gateway to a whole new paradigm of energy and is a strong candidate for the decarbonization of electricity generation on a global scale. With recent developments in high-temperature super-conducting magnets, the race is on to develop sub-systems which will support a commercially viable fusion reactor for use as a thermal power plant. The fusion of lighter elements creates an enormous amount of heat which must be transferred away from the reactor core. These intense conditions require novel approaches to efficiently transfer very high heat loads into useable thermal energy without compromising the structural integrity of the reactor core and the surrounding components. This report outlines the concept of a fundamental approach to solve the heat transfer problem as proposed by Commonwealth Fusion System’s design for a fusion reactor. A literature review was conducted for other applications that could serve as inspirations, as well as material properties and machinin... [more]

Conventional and cyclic unloading tests with different unloading rates were conducted to study the influences of unloading patterns and rates on the deformation characteristics and mechanical properties of tectonic coal. The results demonstrate that, under continuous unloading, a lower unloading rate promotes an increase in the circumferential strain but inhibits increases in axial strain. A lower unloading rate was found to be able to promote volume expansion under the cyclic unloading path, and the axial, circumferential, and volume strains increased stepwise with the unloading levels, but the increment of the strains decreased with the number of cycles in the same unloading level. It was easier for tectonic coal to reach the elastic limit by a low speed unloading rate when the unloading level was small, and volume dilatation was promoted when the unloading level was large. In both unloading patterns, the tangential modulus and the Poisson ratio were proportional to the unloading rat... [more]

The penetration of electric vehicles is becoming more and more widespread and recently electric buses and trains are fetching the attention of researchers and developers. In this review, we examine the charging systems applied to the fast charging of electric vehicles and buses as well as the charging strategies, mainly applied to electric buses. We also briefly delve into power topologies for a more electrified railway system where we discuss their different supply systems as well as their motor drive systems. Problems and charge challenges for electric buses and trains are discussed too.

The new perspectives of the water−energy nexus, water-for-energy and energy-for-water, emphasize the current and future need to find ways to produce as much energy with as low an amount of water as possible and to obtain as much water with as little energy as possible. In order to promote and implement the concept of sustainable development, the understanding of the dynamic and complex relationship between water and energy is crucial, especially in the context of energy transition. This paper presents a comprehensive analysis of the recent approaches regarding water and energy and the interlink during implementation, operation and servicing of various water and energy production systems. This endeavor is placed in the context of current energy transition from fossil fuels to renewable energy sources. A qualitative and quantitative analysis is performed with various literature solutions from water-for-energy and energy-for-water perspectives for a broader view of the impact of implement... [more]

Solar energy utilization for covering and offsetting the heating loads of buildings, is a sustainable way to reduce energy consumption (electricity, gas, etc.) for space heating. As such, a Trombe wall technology is a classic passive solar heating system used in buildings, that can be modified and applied to cold climate regions. This work presents a case study on a Trombe wall’s application in relation to its thermal energy output for space heating purposes at a factory building in central Latvia. The solar radiation and temperature measurements were carried out throughout the months of June to October. The results show that the examined wall has a monthly energy yield of 120 to 290 kWh, suggesting that Trombe wall systems are applicable as a secondary space heating source in cold climate regions such as northern Europe, however, a number of design and structural aspects have to be thoroughly considered.

In order to give full play to the frequency regulation ability of multiple types of resources such as wind power, energy storage, and controllable load in a microgrid, this paper proposes a hierarchical cooperative frequency regulation control strategy of wind-storage-load in a microgrid based on model prediction. Firstly, according to the operation characteristics of each resource in the microgrid, a hierarchical cooperative frequency regulation architecture of wind-storage-load is constructed. On this basis, the frequency regulation control models of wind power, energy storage, and controllable load are established, respectively, and the calculation method of the characteristic index of the system frequency response is proposed. Then, taking the maximum frequency deviation as the stratification index, a hierarchical cooperative frequency regulation control strategy of wind-storage-load based on model prediction is proposed, and a power compensation strategy for connecting the wind tu... [more]

The annual target reliability level for structural components is given as β = 3.3 in the main design standard for wind turbines IEC 61400-1 ed. 4. However, since the same safety factors are used for a range of load cases and limit states, deviations in the obtained reliability level can be expected, and it should be considered how to handle this in relation to the development of the IEC TS 61400-9 on probabilistic design measures. In this paper, structural reliability analyses were performed for components designed using safety factors for a range of extreme load cases, and by using the correlation between limit states for different years, the development of the reliability level over time was calculated. A relative risk-based assessment was applied to assess the optimal target reliability level and safety factors. The risk-based assessment explicitly includes the uncertainties, benefits, and costs and can motivate differentiation of the annual reliability level between load cases. Ann... [more]

This paper describes an energy management strategy for a DC microgrid that utilizes a hybrid renewable energy system (HRES) composed of a photovoltaic (PV) module, a wind turbine based on a permanent magnetic synchronous generator (PMSG), and a battery energy storage system (BESS). The strategy is designed to provide a flexible and reliable system architecture that ensures continuous power supply to loads under all conditions. The control scheme is based on the generation of reference source currents and the management of power flux. To optimize the supply−demand balance and ensure optimal power sharing, the strategy employs artificial intelligence algorithms that use previous data, constantly updated forecasts (such as weather forecasts and local production data), and other factors to control all system components in an optimal manner. A double-input single-output DC−DC converter is used to extract the maximum power point tracking (MPPT) from each source. This allows the converter to... [more]

As tidal current and marine hydro-kinetic energy converters start to be deployed in pre-commercial arrays, it is critical that the design conditions are properly characterised. Turbulence is known to influence fatigue loads and power production, so developers use turbulence models to generate unsteady flows in order to simulate device performance. Most such models construct a synthetic flow field using a combination of measured parameters and theoretical assumptions. The majority in use today are based on atmospheric flow conditions and may have limited applicability in tidal environments. In the present work, we compare key turbulence model assumptions (which are recommended by the tidal turbine standards and are used in design software) to turbulence measurements from two tidal test sites in Scotland and Canada. Here, we show that the two sites have different levels of conformity to theoretical models, with significant variability within nearby locations at the same site. The agreeme... [more]

Geothermal energy is a type of renewable energy that has rich reserves, is clean, environmentally friendly and has been widely used in the heating industry. The single-well closed-loop geothermal system is a technology with the characteristics of “taking heat without taking water” and is mainly used for geothermal energy heating. Although the heating requirements in the cold region of Northeast China are urgent, the traditional heating mode not only has high economic costs but also causes serious damage to the environment. Therefore, it is of important practical significance to change the heating structure and develop and utilize geothermal energy for heating according to local conditions. In this study, the actual operating single-well geothermal system in the Songyuan area of Jilin Province is used as a case study, and a numerical model is established based on the T2WELL simulation program. The flow production temperature and heat extraction response law of the single-well system in... [more]

The concern with the best energy performance of buildings is a current theme, and construction materials that bring improvements to the performance of buildings and their surroundings are in demand. Façades play a crucial role in regulating the temperature within buildings by permitting or obstructing the transfer of heat and also affect the ambient temperature. Light-colored façades help maintain environments with milder temperatures, but pollution, rain, and other degrading agents darken the colors of the façades, reducing their capacity of sunlight reflection. In this scenario, the present study analyzed the addition of different types of titanium dioxide, anatase and rutile, in cement tiles for building façades, combining the ease and speed of assembly with the self-cleaning effects of photocatalysis. The 1 cm thick tiles were produced with a 1:3 mortar ratio (cement:sand/dry aggregate) with a 0.5 water:cement ratio and the addition of 0.3% polypropylene fiber. Different admixture... [more]

In the present paper a new multi-objective optimisation procedure for the design of a shell-and-tube Latent Heat Thermal Energy Storage (LHTES) is proposed. A simple arrangement of a cylindrical shell with multiple vertical tubes has been examined. The optimisation considers, as design variables, the number of tubes, the tube internal radius and the device height-to-diameter ratio, H/D, while the storage volume is kept constant. This analysis aims to detect the set of solutions which optimises the LHTES performances evaluated in terms of charging and discharging times and overall thermal energy capacity. To accomplish the multi-objectives optimal thermal storage design, a simplified mathematical model of the LHTES has been employed. This model can evaluate the prescribed performances for a given set of design variables. The proposed optimisation procedure evaluates new solutions along the most promising directions in the design variables domain, leading to a significant improvement in... [more]

A bottom-up cost analysis for delivering utility-scale PV-generated electricity as hydrogen through pipelines and as electricity through power is undertaken. Techno-economic, generation, and demand data for California are used to calculate the levelized cost of transmitting (LCOT) energy and the levelized cost of electricity (LCOE) prior to distribution. High-voltage levels of 230 kV and 500 kV and 24-inch and 36-inch pipelines for 100 to 700 miles of transmission are considered. At 100 miles of transmission, the cost of transmission between each medium is comparable. At longer distances, the pipeline scenarios become increasingly cheaper at low utilization levels. The all-electric pathways utilizing battery energy storage systems can meet 95% of the load for as low as 356 USD/MWh, whereas when meeting 100% of load with the hydrogen gas turbine and fuel cell pathways, the costs are 278 and 322 USD/MWh, respectively.

Nanostructured materials have gained much attention in recent engineering and material- science research due to their unique structural makeup, which stands them out from their bulk counterparts. Their novel properties of tiny-size structural elements (molecules or crystallites, clusters) of nanoscale dimensions (1 to 100 nm) make them a perfect material for energy applications. The recent keen interest in nanostructured materials research by academia and industrial experts arises from the unique variable characteristics of increased electrical and thermal conductivity. This occurs as nanostructured materials undergo a transient process from infinite-extended solid to a particle of ascertainable numbers of atoms. The commercial and energy sectors are very interested in developing and expanding simple synthetic pathways for nanostructured-electrocatalysts materials to aid in optimizing the number of active regions. Over the decades, various techniques have been put forward to design and... [more]

To study the influence of the axial installation deviation of the runner on the hydraulic axial force of the 1000 MW Francis turbine unit, geometric models of the full flow passage of the Francis turbine with the runner sinking in the axial direction by 0, 0.5, 1, 1.5, 2.5, 4, and 5.5 mm were established. The geometric models of the upper crown clearance, lower band clearance, and pressure balance pipes were also built. The SST turbulence model was used in the CFD setup to numerically simulate the flow in the Francis turbine with different runner installation sinking values. The results show that the hydraulic axial force on the inner surface of the runner remains stable when the runner is lowered. The hydraulic axial force on the entire runner surface and the outer surface of the lower band decreases, and the hydraulic axial force on the outer surface of the upper crown clearance increases. All of these hydraulic axial forces gradually tend to stabilize as the amount descending from t... [more]

Modern power systems are structurally complex and are vulnerable to undesirable events like faults. In the event of faults in transmission line, accurate fault location improves restoration process, thereby enhancing the reliability of the overall system. Fault location methods (FLMs) are tools which assist in identifying fault locations quickly. However, the accuracy of these FLMs gets affected in the presence of flexible alternating current transmission system (FACTS) devices. Therefore, in this work, the performance of four different signal decomposition techniques aided traveling wave aided FLMs are qualitatively compared in the context of fault localization in FACTS-compensated systems. FLMs based on intrinsic time decomposition (ITD), empirical mode decomposition (EMD), S-transform (ST), and estimation of signal parameters via rotational invariance technique (ESPRIT) are investigated. The accuracy of FLMs is tested for different cases of series, shunt, and series-shunt FACTS-comp... [more]

The present review describes the current achievements in the applications of a planar laser-induced fluorescence (PLIF) method for the diagnostics of liquid films, bubbles, individual droplets, and sprays. Such flows are related with strongly curved interphases, which often results in additional high errors during the PLIF data quantification because of laser light reflection, refraction, and absorption. The present review demonstrates that a two-color PLIF approach and a PLIF modification for regularly structured illumination resolves the reflection- and refraction-caused errors. The latter modification ensures proper phase separation in the measurement cross-section and visualization of the interface dynamics. The former approach provides the accurate evaluation of the local temperature and concentration both in liquid and gaseous phases even in the case of strong variations of the laser sheet intensity. With intensified cameras, the PLIF method is used for multi-parameter diagnostic... [more]

This study focuses on the development and testing under lab-controlled conditions of a hybrid sensible−latent thermal energy storage (TES) system for domestic hot water (DHW) provision in residential buildings. The TES system’s design is based, for the first time in the literature, on a commercial tank-in-tank architecture integrating a macro-encapsulated commercial phase change material (PCM) inside the external tank to guarantee the safe provision of DHW and increase overall energy storage density at a reasonable cost. The PCM is a salt hydrate with a nominal melting temperature of 58 °C. The overall tank-in-tank TES volume is about 540 dm3. Almost one tenth of this volume is occupied by the PCM macro-capsules. The developed TES system was comparatively tested against the same configuration operated as a sensible TES. The obtained results showed the ability of the PCM to increase the thermal inertia inside the external tank, thus guaranteeing the quite stable provision of heat to the... [more]

Energy poverty vulnerability constitutes a significant concern in Portugal, with 17.5% of the population being unable to keep their home adequately warm. Furthermore, there is evidence that a substantial number of children live in unhealthy homes. This study aims to comprehensively characterise a sample of 101 Portuguese families with children and their homes in order to identify opportunities for actions for promoting long-lasting energy efficiency and environment health-promoting behavioural changes. To accomplish this aim, two tools—a building survey checklist and a questionnaire to participants—were developed and implemented to collect harmonised data on building-specific characteristics and on participants’ socioeconomic status and behaviour. The home visits for recruitment and data collection were conducted from July 2021 to April 2022. The results suggest that, for the population under study, the main opportunities for improvement include: (i) replacing low energy-efficient tech... [more]

This work aims to study the dynamic characteristics of an entire aero-engine casing by experiments using a new type of rotating exciter. New vibration sensor layout rules are proposed according to experimental results and vibration transmission characteristics. The vibration response of the aero-engine casing is carried out, and the vibration response of different casing measuring points is also studied. The finite element model of the engine casing’s structure is established to obtain the natural frequency of the whole aero-engine casing, which agrees well with the experimental measurement. We find that the vibration acceleration transmission value of the radial measuring point of bearing No. 1, but not the fan sensor, is more suitable for detecting the running state of the fan rotor. In addition, the sensor in the intermediate casing can detect the vibration of the high-pressure rotor. Bolt loosening of the flange has little effect on the vibration transmission characteristics of the... [more]

Energy poverty is a phenomenon that is affecting an increasing number of EU citizens. It occurs when people are unable to buy enough energy to meet their needs at a socially acceptable level. Despite the many efforts and measures taken to prevent this negative phenomenon, the looming energy crisis could exacerbate it. On the one hand, efforts towards energy transition are intended to prevent this phenomenon, but on the other hand, inadequate restraint on the energy market may lead to its escalation. Various scenarios need to be analysed to ensure that the risks associated with energy shortages do not lead to even greater levels of energy poverty, with negative consequences for societies, economies, and the environment. Using a scenario approach and expert research, as well as mathematical−statistical tools, the article presents possible scenarios related to the implementation of measures affecting energy transformation and the transition to renewable energy sources in economies. These... [more]

The main goal of this paper is to assess the life cycle environmental impacts of a multifunctional smart window luminescent solar concentrator (SW−LSC) prototype through the application of the Life Cycle Assessment methodology. To the authors’ knowledge, this is one of the first studies on the topic. The analysis followed a cradle to gate approach, considering the assembly and maintenance phase as well as the end of life, examined separately through a recycling/landfill scenario. A comparison of the impacts of LSC modules with those of some building-integrated photovoltaic technologies was carried out. Results showed that the global warming potential (100 years) for SW−LSC was 5.91 × 103 kg CO2eq and the manufacturing phase had the greatest impact (about 96%). The recycling/landfill scenario results showed the possibility to reduce impacts by an average of 45%. A dominance analysis of SW−LSC components showed that the aluminum frame was the main hotspot (about 60% contribution), follow... [more]

This study describes the implementation of an energy sector community to examine the practice of cybersecurity for operational technology environments and their supply chains. Evaluating cybersecurity from the perspectives of different actors participating in the energy sector, the progress and challenges of operators and suppliers in delivering cybersecurity for the sector are explored. While regulatory frameworks incentivize individual organizations to improve their cybersecurity, operational services contain contributions from many organizations, and this supply chain of activity needs to be influenced and managed to achieve desired security and resilience outcomes. Through collaborations and systems engineering approaches, a reference model is created to facilitate improvements in managing the cybersecurity of supply chains for different actors, including service operators, maintainers, manufacturers, and systems integrators. This study provides an illustration of implementing a co... [more]

Daily electricity peak load forecasting is important for electricity generation capacity planning. Accurate forecasting leads to saving on excessive electricity generating capacity, while maintaining the stability of the power system. The main challenging tasks in this research field include improving forecasting accuracy and reducing computational time. This paper proposes a hybrid model involving variational mode decomposition (VMD), empirical mode decomposition (EMD), fast Fourier transform (FFT), stepwise regression, similar days selection (SD) method, and artificial neural network (ANN) for daily electricity peak load forecasting. Stepwise regression and similar days selection method are used for input variable selection. VMD and FFT are applied for data decomposition and seasonality capturing, while EMD is employed for determining an appropriate decomposition level for VMD. The hybrid model is constructed to effectively forecast special holidays, which have different patterns fro... [more]

As the utilization of DC systems increases worldwide, the importance of DC cutoff technology is increasing. We proposed a hybrid DC cutoff technology combining an SFCL (superconducting fault-current-limiter) and a mechanical DC circuit breaker. This model can perform a fault-current-limiting operation through the quenching of the SFCL and a breaking operation through an artificial cutoff zero point of a mechanical DC circuit breaker. In particular, the SFCL is responsible for the growth of the initial fault current according to the DC characteristics. As the DC system’s supply and demand increase, the DC system’s capacity also increases. Therefore, the fault-current-limiting capability of the SFCL should be increased according to the increasing DC system breaking capacity. The fault-current-limiting capability can be increased by increasing the superconducting wires used in the SFCL. Current commercially available SFCLs use bifilar-helical-type and bifilar-spiral-type winding methods.... [more]