The present investigation concerns the potentiality of Rhodopseudomonas sp. cells to produce clean energy such as molecular hydrogen (H2). The abovementioned goal could be reached by improving the capability of purple non-sulfur bacteria to produce H2 via a photofermentative process through the enzyme nitrogenase. Rhodopseudomonas sp. cells were immobilized in calcium alginate gel beads and cultured in a cylindrical photobioreactor at a working volume of 0.22 L. The semi-continuous process, which lasted for 11 days, was interspersed with the washing of the beads with the aim of increasing the H2 production rate. The maximum H2 production rate reached 5.25 ± 0.93 mL/h with a total output of 505 mL. The productivity was 40.9 μL (of H2)/mg (of cells)/h or 10.2 mL (of H2)/L (of culture)/h with a light conversion efficiency of 1.20%.

This work aims at investigating the kinetic mechanisms of the reduction/oxidation (redox) reactions of iron oxide/iron pellets under different operating conditions. The reaction principle is the basis of a thermochemical hydrogen storage system. To simulate the charging phase, a single pellet consisting of iron oxide (90% Fe2O3, 10% stabilising cement) is reduced with different hydrogen (H2) concentrations at temperatures between 600 and 800 °C. The discharge phase is initiated by the oxidation of the previously reduced pellet by water vapour (H2O) at different concentrations in the same temperature range. In both reactions, nitrogen (N2) is used as a carrier gas. The redox reactions have been experimentally measured in a thermogravimetric analyser (TGA) at a flow rate of 250 mL/min. An extensive literature review has been conducted on the existing reactions’ kinetic mechanisms along with their applicability to describe the obtained results. It turned out that the measured ki... [more]

The organic flash cycle (OFC) is a novel power cycle with small exergy loss in the endothermic process. However, the low-pressure throttle valve in the cycle has a large throttling loss. Aiming to reduce the cycle exergy loss and improve the system performance, this study constructs a new configuration named the organic flash Rankine cycle (OFRC). Using the R600/R245fa mixture as the circulating working fluid and 200 °C geothermal water as the heat source, the effects of the change in working fluid composition on the thermal properties of the OFRC were studied based on the first and second laws of thermodynamics. Then, the economic performance of the proposed OFRC was investigated and then compared with that of the conventional OFC. The results show that the OFRC system has a significant improvement in thermal performance and economy compared with the OFC system. When the mole composition of the R600/R245fa mixture is 0.5/0.5, the net output work, thermal efficiency, and exergy efficie... [more]

Introducing a cathode modification layer is an effective method to obtaining highly efficient organic solar cells (OSCs) and improving their stability. Herein, we innovatively introduced a double cathode modification layer (SnO2/ZnO) into a non-fullerene OSCs based on PM7:IT-4F and explored the mechanisms. The effects of SnO2/ZnO film on charge carriers transfer in OSCs are studied via a variety of electrical testing methods including Photo-CELIV measurements. As a result, a cathode buffer layer with low recombination rate and high carrier mobility could be introduced, which is beneficial to electron transport and collection. The champion device based on the double cathode modification layer acquires an efficiency of 12.91%, obviously higher than that of the single cathode modification layer (SnO2 or ZnO) device. Moreover, The SnO2/ZnO double layer is demonstrated to be of great help in the improvement of device stability, and our work could provide a new inspiration for the preparatio... [more]

Converting CO2 into fuels via solar-driven thermochemical cycles of metal oxides is promising to address global climate change and energy crisis challenges simultaneously. However, it suffers from low energy conversion efficiency (ηen) due to high sensible heat losses when swinging between reduction and oxidation cycles, and a single product of fuels can hardly meet multiple kinds of energy demands. Here, we propose an alternative way to upsurge energy conversion efficiency by integrating solar thermochemical CO2 splitting with a supercritical CO2 thermodynamic cycle. When gas phase heat recovery (εgg) is equal to 0.9, the highest energy conversion efficiency of 20.4% is obtained at the optimal cycle high pressure of 260 bar. In stark contrast, the highest energy conversion efficiency is only 9.8% for conventional solar thermochemical CO2 splitting without including a supercritical CO2 cycle. The superior performance is attributed to efficient harvesting of waste heat and synergy of CO... [more]

Energy efficiency is becoming one of the key research topics in the energy field and has, therefore, attracted extensive attention in recent research [...]

The seismic sensors used for automatic seismic trip systems (ASTS) of nuclear power plants (NPPs) are mainly arranged on the raft foundation of reactor buildings; however, the arrangement principle of seismic sensors is not clear. In order to analyze the seismic response sensitivity of the raft foundation of reactor building in NPPs, this paper carried out the seismic response sensitivity research at seven positions on the raft foundation of a reactor building under three site conditions, with two sets of time histories as input. The results show that (1) the peak acceleration of the outer ring point of the raft foundation was the largest, and the peak acceleration of the center point was the smallest; (2) the peak value of the floor response spectrum at the outer ring point of the raft foundation was the largest, and the peak value at the center point was the smallest. In an earthquake, the outer ring point of the raft foundation of the reactor building was the most sensitive. It was... [more]

The aim of this analysis is to identify the possibility of treating eco-innovation in micro and small enterprises as a factor influencing the energy efficiency of the economy. In order to obtain an answer to such a research question, quantitative research was carried out among Polish enterprises from the SME sector (N = 400). Accordingly, the CATI technique was applied. The selection of enterprises was random and took place in the non-returnable drawing process. The criterion for selecting the sample was the size of enterprises, but in order to ensure the possibility of drawing conclusions based on a sufficiently large research sample, its structure (300 micro and 100 small enterprises) assumed the study of small enterprises in a proportion greater than their actual share in the population of enterprises. As a result of this research, the existence of a relationship between the improvement of the company’s competitive position and its activity in the field of eco-innovation implementat... [more]

Currently, woodchips and logging residues form the greatest share of biomass fuels used to generate heat in combined heat and power plants. They are supplied from various regions of the EU. The calorific values of the wood species used as biomass may vary significantly depending on the moisture and composition of the fuel, harvest seasonality, location, and other factors. This article presents the main resources of forest biomass and its characteristic features, as well as the calorific value of woodchips depending on the moisture content. Our research is based on the source data of forest resources from the State Forests National Forest Holding (PGLLP) in Poland. The research conducted by the main forestry enterprise in Poland covered a period of four years. The data on the harvesting of woodchips and logging residues converted into the calorific values of biomass were based on our research and a review of reference publications. Standard methods were used in the research, which inclu... [more]

This article was aimed to answer the question of whether local energy communities have a sufficient energy surplus for storage purposes, including hydrogen production. The article presents an innovative approach to current research and a discussion of the concepts of the collective prosumer and virtual prosumer that have been implemented in the legal order and further amended in the law. From this perspective, it was of utmost importance to analyze the model of functioning of an energy cluster consisting of energy consumers, energy producers, and hydrogen storage, whose goal is to maximize the obtained benefits, assuming the coopetitive nature of the relationship. The announced and clear perspective of the planned benefits will provide the cluster members a measurable basis for participation in such an energy community. However, the catalogue of benefits will be conditioned by the fulfillment of several requirements related to both the scale of covering energy demand from own sources a... [more]

Future grid refers to the next generation of the electrical grid, which will enable smart integration of conventional, renewable, and distributed power generation, energy storage, transmission and distribution, and demand management [...]

The properties of GaAsSbN and GaAsSb layers grown by liquid-phase epitaxy on n-GaAs substrates were investigated in a comparative plan with a view of their possible application in multi-junction solar cells. To avoid non-uniformity effects in the composition of these compounds with two or three different group-V volatile elements, the crystallization was carried out from finite melt with a thickness of 0.5 mm at low (<560 °C) temperatures. X-ray microanalysis and X-ray diffraction were used to determine the composition, lattice mismatch, and crystalline quality of the epitaxial layers. The morphology and surface roughness were examined by atomic force microscopy. Surface photovoltage (SPV) spectroscopy at room temperature was applied to study the optical absorption properties and the photocarrier transport in the samples. The long-wavelength photosensitivity of the GaAsSbN and GaAsSb layers, determined from their SPV spectra, is extended down to 1.2 eV. Although GaAsSb has a slightl... [more]

The resilience of energy systems is gaining more importance under the threat of pandemics, extreme weather, natural disasters, military conflicts, trade wars, energy supply shortages, rising energy demand, etc. [...]

This paper presents a two-stage DC/DC converter with high efficiency utilized in an electronic power conditioner (EPC), which is widely applicable in satellite communications, etc. The galvanically isolated converter contains two cascaded converters: a buck converter, which is a pre-regulator operating under a closed-loop condition, and a push−pull converter, which is intended to boost the input voltage, operating under an open-loop condition. In the push−pull converter, the power switches, including the main switches and the rectifier diodes, operate under zero-voltage switching (ZVS) and zero-current switching (ZCS) at both switch off and switch on, which minimizes the switching loss. Furthermore, all of the parasitic parameters, such as the parasitic capacitance, leakage inductance, and magnetizing inductance of the main transformer, are fully utilized. Therefore, the presented topology benefits from fewer semiconductors but higher efficiency. The proposed topology produces less EMI... [more]

In this article, a theoretical mathematical model of gas flow through a duct in the case of local mass and momentum sources and sinks is presented. The continuity equation and motion equation with one-dimensional, density-stable gas flows were used to create this model. The size of sources and sinks and their locations have an effect on the size of gas stream flows in the duct, gas energy losses, and the parameters of the mechanical source energy that is causing the flow. In the traditional approach to describing the gas flow in the duct, the concept of resistivity and the equivalent resistance of the conduit is used. In the case of flow in the duct with local mass and momentum sources and sinks, the transport resistance depends on a bigger number of parameters than the concept of specific resistance usage. The location and size of the source flux or mass and momentum sinks and the fan work (suction, blowing) were taken into account in the presented model. The model gives the opportuni... [more]

The article deals with the issue of electromagnetic disturbances caused by electromechanical relays. Electromagnetic compatibility (EMC) is important for the reliable work of electrical and electronic devices. Our research focused on the low-voltage relay, which is the source of electrical fast transients (EFT)/burst disturbances. The voltage and current waveforms were tested on the constructed stand while opening the relays’ contacts. We investigated one-circuit topology with varied element parameters in order to observe their influence on the burst phenomenon. The new technologies in the measurement equipment allow us to observe many detailed aspects of the burst phenomenon, which were not reported up to now. In order to analyze the disturbances, they have been fragmented into restoration, ignition and arc times. The number of disturbance cycles differs depending on the value of the circuit capacitance on the load side. The effect of capacity on times of restoration, ignition and bur... [more]

Hydrogen adsorption measurements were taken by the weighting method using the Sartorius low-pressure microbalance. Experiments were conducted at two temperatures: 77.5 and 300 K; the adsorbent used was active carbon obtained from wood and modified with potassium hydroxide. The porous structure of the carbon prior to and after modification was evaluated based on the nitrogen adsorption and desorption data. Thus, the densimetric characteristic of active carbon was modified; porous structures were developed in the range of micro-, meso- and macropores and the volume of hydrogen adsorbed at 77.5 K showed an almost four-fold increase. Modified active carbons are found to be suitable for applications in hydrogen storage systems.

To solve the problem of rising energy use and CO2 emissions, China issued the 14th Five-Year Plan in 2020, emphasizing the need to reduce its carbon intensity and achieve a carbon emission peak before 2030. In order to estimate the future path of carbon peak in China, a novel dataset was constructed to analyze 30 provinces in China, and found that the realization of carbon peaking in 2025 requires a reduction of 1.072 million tons of carbon emissions in 2025, at which point peak carbon emissions will be 11,008.4 million tons. Due to this energy gap caused by carbon emission reduction the total amount of clean electricity has reached 3600 billion kWh. In carbon emission allowance trading, provinces with large carbon emissions, like Jiangsu and Guangdong, prefer to buy carbon allowances, while those with small carbon emissions like Shanxi and Inner Mongolia prefer to sell carbon allowances. In the energy trading market, the overall situation meets the 14th Five-Year Plan of west-east and... [more]

Due to the high acid, oxygen and water contents of fast pyrolysis oil, it requires the improvement of its fuel properties by further upgrading, such as catalytic hydrodeoxygenation (HDO). In this study, Nb2O5 was evaluated as a support of Pd-based catalysts for HDO of fast pyrolysis oil. A Pd/SiO2 catalyst was used as a reference. Additionally, the impact of iron as a promoter in two different loadings was investigated. The activity of the synthesized catalysts was evaluated in terms of H2 uptake and composition of the upgraded products (gas phase, upgraded oil and aqueous phase) through elemental analysis, Karl Fischer titration, GC-MS/FID and 1H-NMR. In comparison to SiO2, due to its acid sites, Nb2O5 enhanced the catalyst activity towards hydrogenolysis and hydrogenation, confirmed by the increased water formation during HDO and a higher content of hydrogen and aliphatic protons in the upgraded oil. Consequently, the upgraded oil with Nb2O5 had a lower average molecular weight and w... [more]

In this study, 3D premixed turbulent ammonia-hydrogen flames in air were studied using DNS. Mixtures with 75%, 50% and 25% ammonia (by mole fraction in the fuel mixture) and equivalence ratios of 0.8, 1.0 and 1.2 were studied. The studies were conducted in a decaying turbulence field with an initial Karlovitz number of 10. The flame structure and the influence of ammonia and the equivalence ratio were first studied. It was observed that the increase in equivalence ratio smoothened out the small scale wrinkles while leading to strongly curved leading edges. Increasing the amount of hydrogen in the fuel mixtures also led to increasingly distorted flames. These effects are attributed to local increases in the equivalence ratio due to the preferential diffusion effects of hydrogen. The effects of curvature on the flame chemistry were studied by looking at fuel consumption rates and key reactions. It was observed that the highly mobile H2 and H species were responsible for differential rate... [more]

This work investigated the influence of the reaction time and catalyst-to-residual fat ratio by catalytic upgrading from pyrolysis vapors of residual fat at 400 °C and 1.0 atmosphere, on the yields of reaction products, physicochemical properties (density, kinematic viscosity, and acid value) and chemical composition of bio-oils, over a catalyst fixed-bed reactor of activated carbon pellets impregnated with 10.0 M NaOH, in semi-pilot scale. The experiments were carried out at 400 °C and 1.0 atmosphere, using a process schema consisting of a thermal cracking reactor of 2.0 L coupled to a catalyst fixed-bed reactor of 53 mL, without catalyst and using 5.0%, 7.5%, and 10.0% (wt.) activated carbon pellets impregnated with 10.0 M NaOH, in batch mode. Results show yields of bio-oil decreasing with increasing catalyst-to-tallow ratio. The GC-MS of liquid reaction products identified the presence of hydrocarbons (alkanes, alkenes, ring-containing alkanes, ring-containing alkenes, and aromatics... [more]

In the context of smart electricity consumption, demand response is an important way to solve the problem of power supply and demand balance. Users participate in grid dispatching to obtain additional benefits, which realises a win-win situation between the grid and users. However, in actual dispatching, community users’ strong willingness to use energy leads to low enthusiasm of users to participate in demand response. Psychological research shows a direct connection between users’ herd mentality (HM) and their decision-making behavior. An optimal dispatching strategy based on user herd mentality is proposed to give full play to the active response-ability of community flexible load to participate in power grid dispatching. Considering that herd mentality is generated by the information interaction between users, by calling on some users to share the experience of successfully participating in demand response in the community information center and using the Nash social welfare functi... [more]

This study analyzed factors that influence the ignition delay characteristics of n-heptane/methane-blended fuel. The effects of chemical species, exhaust gas recirculation rate, compression ratio, cool/hot flames, and combustion chamber conditions (temperature, pressure, and O2 concentration) were determined and analyzed using CHEMKIN Pro. The experiment conditions for verification were 550−1000 K at 15 bar with 50% H2/50% CH4 fuel. The main combustion reactions were confirmed through reactivity analysis and sensitivity analysis on the ignition delay time. The ignition delay time at 14.7% O2 concentration was significantly higher than that at 21% O2 concentration by more than 30%. In addition, a higher ratio of methane in the blended fuel increased the ignition delay time as a result of methane dehydrogenation, delaying the ignition of heptane.

As the cooling requirement and the energy prices are increasing rapidly across the world, the need to develop highly efficient cooling equipment is rising as well. Adiabatic cooling employs evaporation to pre-cool the air flowing through a closed-loop coil. This study examines various adiabatic evaporative cooling pads in terms of their pre-cooling potential and advantages over currently available technological solutions through isolating three cross-sectional metal cooling pad shapes (W, Z and Z1). The results of the study suggest that the correlation between Δt↓ and RH↑ is somewhat close in all three cases; however, a slightly higher temperature drop is observed when using a W-shaped metal sheet. Pressure drop variability was negligible under current cooling pad configurations and experimental boundary conditions. Further studies focusing on measurement continuity, longevity and boundary conditions’ variability are recommended.

A new mathematical model was developed to predict the cylindrical effect of the membrane performance in the pressure retarded osmosis process. The cylindrical membrane transport layers (the draw side boundary and the porous membrane) were divided into very thin sublayers with constant mass transport parameters, among others with a constant radius in every sublayer. The obtained second-order differential mass balance equations were solved analytically, with constant parameters written for every sublayer. The algebraic equation system involving 2N equations was then solved for the determinant solution. It was shown that the membrane properties, water permeability (A), salt permeability (B), structural parameter (S) and the operating conditions (inlet draw side solute concentration and draw side mass transfer coefficient) affect the water flux strongly, and thus the membrane performance, due to the cylindrical effect caused by the variable surface and volume of the sublayers. This effect... [more]