Nowadays, most Italian biogas produces electricity even though recent political incentives are promoting biomethane from biogas by “upgrading” it. The aim of this paper is to focus on the regulatory framework for producing biomethane from new or already-existent anaerobic digestion plants. The complexity and lack of knowledge of the regulations on biofuel production and of anaerobic digested biomethane from waste and by-products create difficulties of both interpretation and application. Consequently, the aim of this paper is to analyze the regulations for producing biomethane, underline the critical issues and opportunities, and evaluate whether an electrical plant built in the last 10 years in Italy can really be converted to a biomethane plant, thereby lengthening its lifespan. Three case studies were considered to look more closely into applying Italian biomethane incentives and to simulate the types of incentivization in agriculture with examples based on certain fuel types typica... [more]

Heat storage with thermochemical (TC) materials is a promising technology for solar energy storage. In this paper, a solar-driven desiccant evaporative cooling (DEC) system for air-conditioning is proposed, which converts solar heat energy into cooling with built-in daily storage. The system utilises thermochemical heat storage along with the DEC technology in a unique way. Magnesium Chloride (MgCl2·6H2O) has been used, which serves as both a desiccant and a thermochemical heat storage medium. The system has been designed for the subtropical climate of Lahore, Pakistan, for a bedroom with 8 h of cooling requirements during the night. MATLAB has been employed for modelling the system. The simulation results show that 57 kg of magnesium chloride is sufficient to meet 98.8% of cooling demand for the entire month of July at an elevated cooling requirement. It was found that the cooling output of the system increased with increasing heat exchanger effectiveness. The heat exchangers’ effecti... [more]

The need for deploying fast-charging stations for electric vehicles (EVs) is becoming essential in recent years. This need is justified by the increasing charging demand and supported by new charging technologies making EV chargers more efficient. In this paper, we provide a survey on EV fast-charging models and introduce a data-driven approach with an optimization model for deploying EV fast-chargers for both electric vehicles and heavy trucks traveling through a network of suburban highways. This deployment aims at satisfying EV charging demands while respecting the limits imposed by the electric grid. We also consider the availability of local photovoltaic (PV) farm and integrate its produced power to the proposed charging network. Finally, through a case study on Paris-Saclay area, we provide locations for EV charging stations and analyze the benefits of integrating PV power at different prices, production costs and charging capacities. The obtained results also suggest potential e... [more]

The manuscript presents advanced coupled analysis: Maxwell 3D, Transient Thermal and Fluent CFD, at the time of a rated current occurring on the main busbars in the low-voltage switchgear. The simulations were procured in order to aid the design process of such enclosures. The analysis presented the rated current flow in the switchgear busbars, which allowed determining their temperature values. The main assumption of the simulation was measurements of temperature rise during rated current conditions. Simulating such conditions is a valuable asset in order to design better solutions for energy distribution gear. The simulation model was a precise representation of the actual prototype of the switchgear. Simulations results were validated by experimental research. The heat dissipation in busbars and switchgear housing through air convection was presented. The temperature distribution for the insulators in the rail bridge made of fireproof material was considered: halogen-free polyester.... [more]

This study evaluated the potential of artificial neural networks (ANNs) to predict the system-level performance of a thermoelectric generator (TEG), whose performance depends on various variables including engine load, engine rotation speed, and external load resistance. Therefore, a Python code was developed to determine an optimal ANN structure by tracking the training/prediction errors of the ANN as a function of the number of hidden layers and nodes of hidden layers. The optimal ANN was trained using 484 output current (I)−load resistance (R) datasets obtained under three different engine rotation speeds and five different engine loads. The prediction accuracy of the ANN was validated by comparing 88 I−R datasets reproduced by the ANN using experimental data that were not used for training. In the validation procedure, differences of only 3.49% and 2.59% were observed in the experimental and ANN-predicted output power obtained for the 1000 rpm−0.8 MPa brake mean effective pressure... [more]

Interfacial electron injection from a photoexcited surface-immobilized dye to a semiconductor substrate is a key reaction for dye-sensitized photocatalysts. We previously reported that the molecular orientation of heteroleptic Ir(III) photosensitizer on the TiO2 nanoparticle surface was important for efficient interfacial electron injection. In this work, to overcome the weak light absorption ability of heteroleptic Ir(III) photosensitizer and to improve the photoinduced charge-separation efficiency at the dye−semiconductor interface, we synthesized two heteroleptic Ir(III) complexes with different coumarin dyes, [Ir(C6)2(H4CPbpy)]Cl and [Ir(C30)2(H4CPbpy)]Cl [Ir-CX; X = 6 or 30; HC6 = 3-(2-enzothiazolyl)-7-(diethylamino)coumarin, HC30 = 3-(2-N-methylbenzimidazolyl)-7-N,N-diethylaminocoumarin, H4CPbpy = 4,4′-bis(methylphosphonic acid)-2,2′-bipyridine], as the cyclometalated ligands and immobilized them on the surface of Pt-cocatalyst-loaded TiO2 nanoparticles. Ultraviolet-visible absor... [more]

Biogas plants may support the transformation towards renewable-based and integrated energy systems by providing dispatchable co-generation as well as opportunities for biogas upgrading or power-to-X conversion. In this paper, a simulation model that comprises the main dynamics of the internal processes of a biogas plant is developed. Based on first-order kinetics of the anaerobic digestion process, the biogas production of an input feeding schedule of raw material can be estimated. The output of the plant in terms of electrical and thermal energy is validated against empirical data from a 3-MW biogas plant on the Danish island of Bornholm. The results show that the model provides an accurate representation of the processes within a biogas plant. The paper further provides insights on the functioning of the biogas plant on Bornholm as well as discusses upgrading potentials of biogas to biomethane at the plant from an energy perspective.

Repairing materials are well-known to play an important role in rehabilitating and extending the service life for hydraulic concrete structures. However, current underwater repairing materials possess several problems, including insufficient bond tensile strength, inconsistency with the deformation of the old substrate, and insufficient underwater self-sealing ability. In the present paper, an experimental study was carried out to evaluate the influence of silica nanoparticles (SNs) on the properties of underwater composite-repairing materials. The underwater deformation, impermeability, bond tensile strength, and compressive strength of the SN-modified underwater composite-repairing materials were used as the properties’ evaluation indices. The results show that, within a certain range, the performance of the repairing material increase with increased SN percent. The deformability, impermeability grade, underwater bond tensile strength, and compressive strength of the SN-modified comp... [more]

This paper describes experimental investigations of single-phase and two-phase gas−liquid flow through channels with a diameter of 20 mm and length of 2690 mm, filled with metal foams. Three types of aluminium foams with pore densities of 20, 30 and 40 PPI and porosities ranging from 29.9% to 94.3% were used. Air, water and oil were pumped through the foams. The tests covered laminar, transitional and turbulent flow. We demonstrated that the Reynolds number, in which the hydraulic dimension should be defined based on foam porosity and pore diameter de = ϕdp/(1 − ϕ), can be used as a flow regime assessment criterion. It has been found that fluid pressure drops when flowing through metal foams significantly depends on the cell size and porosity of the foam, as well as the shape of the foam skeleton. The flow patterns had a significant influence on the pressure drop. Among other things, we observed a smaller pressure drop when plug flow changed to stratified flow. We developed a model to... [more]

It is known that keeping the power balance between generation and demand is crucial in containing the system frequency within acceptable limits. This is especially important for renewable based distributed hybrid microgrid (DHμG) systems where deviations are more likely to occur. In order to address these issues, this article develops a prominent dual-level “proportional-integral-one plus double derivative {PI−(1 + DD)} controller” as a new controller for frequency control (FC) of DHμG system. The proposed control approach has been tested in DHμG system that consists of wind, tide and biodiesel generators as well as hybrid plug-in electric vehicle and an electric heater. The performance of the modified controller is tested by comparing it with standard proportional-integral (PI) and classical PID (CPID) controllers considering two test scenarios. Further, a recently developed mine blast technique (MBA) is utilized to optimize the parameters of the newly designed {PI − (1 + DD)} control... [more]

Meeting biorefineries’ demands for lignocellulosic biomass will require sourcing feedstock without affecting the food or animal-feed supply. A decision-aid model can assess the dual use of switchgrass (Panicum virgatum L.) to maintain animal production while providing biomass. We simulated a mixed-farm operation with 156 ha of hay+pasture, 96 beef cows (Bos spp.), and poultry (Gallus gallus L.) production wherein the hay land was converted to switchgrass for dual use as biomass and forage. The cow-calf simulator tracked changes in forage and cattle production, economic returns, and net greenhouse gas (GHG) emissions. Dual use of switchgrass consisted of harvesting the first cutting (mid-June) for hay and the second cutting (October-November) for biomass. Dual use required a modest increase in fertilizer application and supplementing cows with corn grain to meet nutritional requirements. Converting hay land to dual-use switchgrass produced 122 Mg of switchgrass, reduced net GHG emission... [more]

Ventilated windows have the potential to contribute to both indoor air quality and energy efficiency in cold climates. A typical ventilated window functions as a solar collector under inward air flow direction and incident solar radiation. The ventilated window is a modification of the multiple pane windows in which air is drawn in from outside and is heated through conduction, convection, and radiation in the cavity. In this study, a detailed parametric analysis was conducted to investigate the thermal performance of ventilated windows and their capacity to preheat ventilation air. High-resolution 3D steady RANS computational fluid dynamic (CFD) simulations were performed for six ventilated window geometries. Model results were compared with measurements. The following geometric characteristics were evaluated in detail: (i) The height of the window, (ii) the width of the cavity, (iii) the location of double-layered glazing, and (iv) the width of the supply air opening. The results sug... [more]

This article presents the problems of powering wireless sensor networks operating in the structures of the Internet of Things (IoT). This issue was discussed on the example of a universal end node in IoT technology containing RFID (Radio Frequency Identification) tags. The basic methods of signal transmission in these types of networks are discussed and their impact on the basic requirements such as range, transmission speed, low energy consumption, and the maximum number of devices that can simultaneously operate in the network. The issue of low power consumption of devices used in IoT solutions is one of the main research objects. The analysis of possible communication protocols has shown that there is a possibility of effective optimization in this area. The wide range of power sources available on the market, used in nodes of wireless sensor networks, was compared. The alternative possibilities of powering the network nodes from Energy Harvesting (EH) generators are presented.

The energy efficiency requirements of most energy-consuming sectors have increased recently in response to climate change. For buildings, this means targeting both facility managers and building users with the aim of identifying potential energy savings and encouraging more energy-responsible behaviors. The Information and Communication Technology (ICT) platform developed in Horizon 2020 FEEdBACk project intends to fulfill these goals by enabling the optimization of energy consumption, generation, and storage and control of flexible devices without compromising comfort levels and indoor air quality parameters. This work aims to demonstrate the real-world implementation and functionality of the ICT platform composed of Load Disaggregation, Net Load Forecast, Occupancy Forecast, Automation Manager, and Behavior Predictor applications. Particularly, the results obtained by individual applications during the test phase are presented alongside the specific metrics used to evaluate their per... [more]

The interest of supplying lignocellulosic materials for producing fermentable sugars has recently emerged in order to diminish the negative environmental effects of fossil fuels. In this study, the Ulmus minor clone Ademuz, characterized for its tolerance to Dutch elm disease and its rapid growth, was evaluated as a source of fermentable sugars. For that, different pretreatments, comprising autohydrolysis, dilute acid hydrolysis, acid catalyzed organosolv, and alkaline extraction, were evaluated at two levels of severity (pretreatment temperatures at 160 °C and 180 °C, except for alkaline extraction at 80 °C and 160 °C); and the resulting pretreated materials were enzymatically hydrolyzed for fermentable sugars production. The major extraction of lignin and hemicellulose was achieved during organosolv (48.9%, lignin; 77.9%, hemicellulose) and acid hydrolysis (39.2%, lignin; 95.0%, hemicellulose) at 180 °C, resulting in the major enzymatic digestibility (67.7%, organosolv; 53.5% acid hy... [more]

This paper introduces a novel design of an electric vehicle (EV) fast charging station, consisting of a battery energy storage system (BESS) with reconfigurable cell topology. The BESS comprises two battery strings that decouple the power flow between EV and grid, to enable charging powers above the grid capacity. The reconfigurable design is achieved by equipping the battery cells with semiconductor switches and serves two main purposes. First, it aims at solving cell unbalance issues to increase safety, reliability, and lifetime of the battery. Second, it enables the BESS to actively control the EV charging process by changing its cell configuration in a real-time fashion, making a DC-DC converter redundant. The paper presents a modelling approach that captures the reconfigurable design including the controlling algorithm used for cell engagement. The simulation results show that the BESS is able to fulfil the EV request with sufficient accuracy for most of the fast charging process.... [more]

Industries account for about 30% of total final energy consumption worldwide and about 20% of global CO2 emissions. While transitions towards renewable energy have occurred in many parts of the world in the energy sectors, the industrial sectors have been lagging behind. Decarbonising the energy-intensive industrial sectors is however important for mitigating emissions leading to climate change. This paper analyses various technological trajectories and key policies for decarbonising energy-intensive industries: steel, mining and minerals, cement, pulp and paper and refinery. Electrification, fuel switching to low carbon fuels together with technological breakthroughs such as fossil-free steel production and CCS are required to bring emissions from energy-intensive industry down to net-zero. A long-term credible carbon price, support for technological development in various parts of the innovation chain, policies for creating markets for low-carbon materials and the right condition for... [more]

Drinking water distribution networks (DWDNs) have a huge potential for cold thermal energy recovery (TED). TED can provide cooling for buildings and spaces with high cooling requirements as an alternative for traditional cooling, reduce usage of electricity or fossil fuel, and thus TED helps reduce greenhouse gas (GHG) emissions. There is no research on the environmental assessment of TED systems, and no standards are available for the maximum temperature limit (Tmax) after recovery of cold. During cold recovery, the water temperature increases, and water at the customer’s tap may be warmer as a result. Previous research showed that increasing Tmax up to 30 °C is safe in terms of microbiological risks. The present research was carried out to determine what raising Tmax would entail in terms of energy savings, GHG emission reduction and water temperature dynamics during transport. For this purpose, a full-scale TED system in Amsterdam was used as a benchmark, where Tmax is currently set... [more]

Development of a transition metal based catalyst aiming at concomitant high activity and stability attributed to distinguished catalytic characteristics is considered as the bottleneck for dry reforming of methane (DRM). This work highlights the role of modifying zirconia (ZrO2) and alumina (Al2O3) supported nickel based catalysts using lanthanum oxide (La2O3) varying from 0 to 20 wt% during dry reforming of methane. The mesoporous catalysts with improved BET surface areas, improved dispersion, relatively lower reduction temperatures and enhanced surface basicity are identified after La2O3 doping. These factors have influenced the catalytic activity and higher hydrogen yields are found for La2O3 modified catalysts as compared to base catalysts (5 wt% Ni-ZrO2 and 5 wt% Ni-Al2O3). Post-reaction characterizations such as TGA have showed less coke formation over La2O3 modified samples. Raman spectra indicates decreased graphitization for La2O3 catalysts. The 5Ni-10La2O3-ZrO2 catalyst produ... [more]

Electric trams are one of the standard forms of public transport. They are characterized by large amounts of electric current and electric current gradient from the power grid, especially during acceleration. For this reason, a regenerative braking system is considered with the aim of reducing electric current peaks and increasing energy efficiency by reducing the total energy consumption of the power grid. A supercapacitor module is used as a storage device for storing and utilizing the braking energy. The supercapacitor module and the power grid constitute a hybrid energy system, for which a control algorithm has been developed. The control algorithm takes into account the influence of the elevation profile and the slope of the vehicle route in storing and using the braking energy. The operation of the algorithm was simulated and analyzed using the MATLAB/Simulink software package for tram lines with different elevation profiles.

In this research, Zinc Oxide-Ethylene @ glycol distilled water based nanofluid was synthesized using the sonochemical method. The convective heat transfer properties of as synthesized nanofluid were observed for a closed single circular tube pipe in turbulent flow regimes. The prepared nanofluids were characterized by ultra violet spectroscopy (UV−VIS), UV−VIS absorbance, X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and stability analysis. Five calibrated k-type thermocouples were mounted on the surface of the test section. Analytical data related to heat transfer properties of the synthesized nanofluid for the heat exchanger, incorporated with the closed circular tube test section were collected. The addition of ZnO solid nanoparticles in the EG@DW mixture enhanced the value of thermal conductivity and other thermophysical characteristics of the nanofluids. Maximum thermal conductivity was observed at 45 °C for using 0... [more]

Heat transfer analysis of the pulsatile flow of a hybrid nanofluid through a constricted channel under the impact of a magnetic field and thermal radiation is presented. Hybrid nanofluids form a new class of nanofluids, distinguished by the thermal properties and functional utilities for improving the heat transfer rate. The behaviors of a water-based copper nanofluid and water-based copper plus a single-wall carbon nanotube, i.e., (Cu−SWCNT/water), hybrid nanofluid over each of velocity, wall shear stress, and temperature profiles, are visualized graphically. The time-dependent governing equations of the incompressible fluid flow are transformed to the vorticity-stream function formulation and solved numerically using the finite difference method. The laminar flow simulations are carried out in 2D for simplicity as the flow profiles are assumed to vary only in the 2D plane represented by the 2D Cartesian geometry. The streamlines and vorticity contours are also shown to demonstrate th... [more]

The Atacama Desert receives the highest levels of solar irradiance in the world with an annual average of 2500 kWh/m2 for the global horizontal irradiance and 3500 kWh/m2 for the direct normal irradiance. One of the challenges is the large portion of ultraviolet light. This part of the spectrum be detrimental for the encapsulant materials, reducing their lifetime. To develop a module adapted to the Atacama Desert conditions, it is imperative to have standardized information from first-hand about the typical faults experienced by photovoltaic modules operating in the desert. This work reports on the design and implementation of the Inspection Data Collection Tool to evaluate crystalline silicon-based moules operating in desert climates. The tool brings together novel features of compatibility with current standards, efficient mobile-type instrumentation (equipment and tools), clear procedures/protocols for non-expert users and low development costs. A total of 95 modules were inspected... [more]

This article reports an investigation into ferrite and nanocrystalline materials for the medium-frequency transformer of a dual active bridge DC-DC converter, which plays a key role in the converter’s efficiency and power density. E65 MnZn ferrite cores and toroidal and cut nanocrystalline cores are selected for the construction of 20-kHz transformers. Transformer performance is evaluated with a 1.1-kW (42−54 V)/400 V dual active bridge DC-DC converter with single-phase shift and extended phase shift modulations. The experimental results indicate that the toroidal nanocrystalline transformer had the best performance with an efficiency range of 98.5−99.2% and power density of 12 W/cm3, whereas the cut-core nanocrystalline transformer had an efficiency range of 98.4−99.1% with a power density of 9 W/cm3, and the ferrite transformer had an efficiency range of 97.6−98.8% with a power density of 6 W/cm3. A small mismatch in the circuit parameters is found to cause saturation in the nanocrys... [more]

An essential line of worldwide research towards a sustainable energy future is the materials and processes for carbon dioxide capture and storage. Energy from fossil fuels combustion always generates carbon dioxide, leading to a considerable environmental concern with the values of CO2 produced in the world. The increase in emissions leads to a significant challenge in reducing the quantity of this gas in the atmosphere. Many research areas are involved solving this problem, such as process engineering, materials science, chemistry, waste management, and politics and public engagement. To decrease this problem, green and efficient solutions have been extensively studied, such as Carbon Capture Utilization and Storage (CCUS) processes. In 2015, the Paris Agreement was established, wherein the global temperature increase limit of 1.5 °C above pre-industrial levels was defined as maximum. To achieve this goal, a global balance between anthropogenic emissions and capture of greenhouse gase... [more]