Search

Paper crumb (PC) is a type of paper sludge residue from the wastepaper recycling industry. It is a by-product from the various fiber purification stages that is particularly composed of short cellulose fibers, lignin, organic compounds and inorganic filler residues. Despite representing a reject material for the paper recycling sector, this feedstock can be turned into a bioresource to enable cross-sector industrial symbiosis in the form of a more sustainable concrete, hence an opportunity for novel Net Zero supply chains. This study sought to valorise the PC by the sequential anaerobic digestion to produce methane (CH 4) from the organic compounds, followed by utilization of the digestate as a water replacement in concrete. The 21-day digestion of PC yielded 163 ml CH 4 per gram volatile solids and the resulting digestate improved concrete compressive strength up to 50% water replacement grade, meeting the requirements for structural grade (C32/40) applications with substitution grades up to 50% and 25%, with and without the addition of plasticiser respectively. In a minor capacity, the digestate reduced workability of the concrete mix, however we demonstrate this issue can be resolved by the addition of plasticiser or increased water to cement ratios. The admixture addition is important to facilitate pumpability on site and ensure satisfactory compaction. This study highlights the potential of anaerobic digestate as a concrete supplement (additive), which would improve the sustainability of both the construction and the paper sector. [Display omitted] [ABSTRACT FROM AUTHOR]

Combustible construction solid wastes (CCDW) and paper sludge (PMS) are important components of combustible solid waste (CSW), which are also important ingredient in waste-to-energy system. Torrefaction experiments of CCDW, PMS and their blends in equal proportion (C50S50) were conducted in a tubular furnace reactor at torrefaction temperature (T) of 200–400 °C for 30 min. The fuel properties and migration of heavy metals and Cl of torrefied CCDW, PMS and C50S50 were investigated based on proximate analysis, ultimate analysis, caloric value determination, and the measurement of heavy metals and Cl in solid, liquid and gaseous products. Combustion characteristics of CCDW, PMS, C50S50 and their torrefied solid products were evaluated by TG-FTIR analyzer. The obtained results indicated that torrefaction can improve fuel performance of CCDW, PMS and C50S50. The fixed carbon, higher heating value (HHV) of torrefied solid products increased and volatile matter decreased gradually while T < 250 °C; however, the HHV and energy yield of blended torrefied solid products obviously decreased while T > 250 °C. The combustible index (C n) and burnout index (S) of blended torrefied products at 250 °C were the largest, achieving 111.26 × 10−6 and 0.49 × 10−6. Torrefaction can effectively remove Zn, Hg, As in CCDW, PMS and C50S50. More than 50 % of Cl was released from torrefied C50S50 when T > 300 °C. High torrefaction temperature (T > 300 °C) can remove more heavy metals and Cl, but it has an adverse effect on fuel properties of torrefied products, so the suggested torrefaction temperature is 250 °C. [ABSTRACT FROM AUTHOR]

The sustainable management of residual waste streams generated from the pulp and paper industry (PPI) has garnered increasing concerns due to the energy crisis and the pressing environmental threats posed by substantial effluent discharges. Using renewable lignocellulosic waste for resource generation presents a revolutionary approach to achieve environmental sustainability. Integrating the PPI with biorefinery processes allows for diversification beyond paper production and facilitates resource recovery. This review critically evaluates the valorization of waste streams from the PPI, with a pronounced emphasis on expanding into bioenergy and biofuels production, while also fostering the development of innovative biomaterials, such as biochar and activated carbon for applications with high added-value, such as environmental remediation and supercapacitors development, thus ensuring long-term sustainability. The review also emphasizes the significance of adopting a circular economy and its role in achieving environmental sustainability, with a particular emphasis on thermochemical technologies, which hold promise for resource recovery from wastewater. Furthermore, the review identifies critical bottlenecks in the path of waste stream valorization and engages in a forward-looking discussion on future prospects within the PPI. [Display omitted] • Black liquor contains major inhibitors e.g., furfural, 5-hydroxymethylfurfural. • Black liquor is used as a low-cost sugar, to produce e.g., bioethanol, biobutanol. • Paper mill wastewater used e.g., graphene sheet development, biochar, carbon fuel cell. • Porous carbon by black liquor showed capacitances for supercapacitor electrode. • Integrated biorefineries can achieve sustainability by Kraft pulp conversion. [ABSTRACT FROM AUTHOR]

Food waste and waste paper are the two largest components of municipal solid waste, and many previous studies found that their co-digestion improved methane yield. This study investigated the anaerobic co-digestion of 0–100% food waste with paper food packages on lab-scale with feedstock-to-inoculum (F/I) ratios from 0.5 to 6 (based on volatile solids, VS) and total solids contents from 8% to 28%. In addition to methane yield, volumetric productivity and process economics were also used to evaluate the operating parameters. Results showed that the highest cumulative methane yield of around 530 L/kg-VS feed was obtained from 100% food waste at F/I ratios of 0.5, 1, and 2; the highest volumetric methane productivity of 44.2 L/L work was achieved with 25% food waste at an F/I ratio of 6; and the highest annual net profit was obtained from 75% food waste at an F/I ratio of 2, which also achieved the highest internal rate of return (20.7%) and the shortest payback period (5 years). Addition of waste paper packages to food waste could enhance the digester stability, and it is beneficial to allow certain amount of paper packages and tissues to be collected together with food waste during the initial source separation. [Display omitted] [ABSTRACT FROM AUTHOR]

Organic-rich pulp and paper mill sludge (PPMS) has the potential to become a renewable carbon source for producing alternatives to fossil-based product. In this work, PPMS treated by hydrothermal carbonization (HTC) was investigated based on its pyrolysis properties. The pyrolytic mechanism, kinetics data and product of the sample were studied using TG as well as pyrolysis tests in Py-GC/MS and a bench-scale reactor at 450, 550, and 650 °C. The results show that the thermal decomposition of feedstock is a two-stage reaction. The mean activation energy of the pyrolysis of HTC treated PPMS was estimated as 233.08 kJ/mol, which is higher than that of the pyrolysis of paper sludge reported before. The changes in enthalpies, entropies and Gibbs free energies from the reactants to the activated complex were estimated. The concentration of monocyclic aromatic hydrocarbons in the derived organic liquid fraction shows a positive correlation with the pyrolysis temperature. At 550 °C, the organic liquid fraction reached its highest yield at 13.7% with an oxygen level of 10.7 wt% and a higher heating value of 35.9 MJ/kg. The pyrolytic chars show that a molar ratio of O:C is less than 0.2, which shows potential for use as a carbon sink. • Multi-scale study of pyrolysis behaviour of paper sludge. • Δ H ǂ, Δ G ǂ, and Δ S ǂ of pyrolysis reactions are studied on TG. • Detailed components analysis of the pyrolytic vapor on Py-GC/MS. • Comprehensive evaluation of pyrolysis product from bench-scale reactor. [ABSTRACT FROM AUTHOR]

Numerical simulations based on Computational Fluid Dynamic techniques are performed to analyze the possibility of feeding a biomass-derived syngas into the combustion chamber upstream of the hoods for tissue-paper drying, to replace fossil fuels and thus decarbonize the plant. It was observed that, in the context of Favre-Averaged Navier–Stokes equations simulation, syngas requires detailed kinetics and finite-rate approaches, as the fast-chemistry ones, largely employed in the industrial practice for conventional fuels, lead to unreliable results. The actual chamber, originally designed to be fed with liquid petroleum gas, does not operate properly when fueled with syngas, with incomplete oxidation of carbon monoxide. Numerical simulations have proven how very few modifications of the chamber can be devised to permit feeding efficiently the syngas, obtaining low pollutant emissions and meeting the desired requirements in terms of flow and thermal uniformity for the drying process. The solution proposed in the present study, with the effective use of a biomass-derived syngas to feed the drying section of a tissue paper plant, will allow saving approximately 8500 ton/y of CO 2 emissions in comparison with today's fossil fuel carbon footprint. [Display omitted] • Use of syngas from biomass gasification to decarbonize a tissue paper plant. • CFD simulations to comprehend the behavior of chamber and hood fed with bio-syngas. • Need for detailed kinetics to model with CFD the bio-syngas combustion. • Modification of the combustion system needed to limit CO with the bio-syngas. • Reduction of 8500 ton/y of CO 2 emissions in comparison to today's LPG. [ABSTRACT FROM AUTHOR]

A novel batch simultaneous saccharification and juice co-fermentation (SSJcF) process was investigated using mixtures of PHP (phosphoric acid plus hydrogen peroxide) pretreated wood and fruit juice of paper mulberry tree. All the different substrate mixture configurations evaluated under normal gravity SSJcF (total sugar titer of 180 g/L) significantly improved both ethanol concentration and yield compared to sole simultaneous saccharification and fermentation (SSF) of paper mulberry wood. Among the different mixing ratios, the feedstock mixture with equal sugar content from each substrate resulted in maximum ethanol concentration, yield and productivity of 77.1 g/L, 83.9 % and 1.1 g/L/h, respectively. The external additions of mineral nutrients also had no impact on fermentation performance of the mixture. Furthermore, SSJcF was evaluated under different levels of high gravity (HG) and very high gravity (VHG) conditions. The total sugar titer of 350 g/L at equal contributions from each substrate reached very high ethanol concentration of 147.0 g/L, with yield and productivity of 82.3 % and 1.5 g/L/h, respectively. By implication, the PM wood and fruit juice mixture could serve as suitable low-cost and non-food feedstock alternative to the typical use of sugary and/or starchy feedstocks for VHG fermentation. [Display omitted] [ABSTRACT FROM AUTHOR]

Paper mulberry fruit juice, as a sugar-based biomass waste product, was used to make porous carbon by hydrothermal treatment and KOH activation as supercapacitor electrodes. Under different hydrothermal conditions, we investigated the response of hydrochars and the performance of porous carbon as an electrode material. The results showed that the hydrochar obtained at low temperatures and a short duration retained more abundant oxygen-containing functional groups, and had a better surface morphology of well-dispersed carbon microspheres, which facilitated its activation. The maximum specific surface area of porous carbon (AHCT 8 C 180) obtained in this study was 3543.8 m2 g−1 under hydrothermal conditions of 180 °C for 8 h. The corresponding porous carbon, as the material of the electrode in the supercapacitor, achieved a good specific capacitance of 428 F g−1 at a current density of 0.5 A g−1. The symmetric supercapacitor fabricated using AHCT 8 C 180 achieved an energy density of 9.56 Wh kg−1 at a power density of 125 W kg−1, In summary, hydrothermal conditions can optimize the specific surface area (S BET) and pore structure of carbon biomass materials through modulating the structure of hydrochar and the construction of the precursor, guiding the preparation of porous carbon used as an electrode material with superior capacitance. [Display omitted] [ABSTRACT FROM AUTHOR]

As a mainstream power storage and supply device, batteries are continuously upgraded. The microfluidic fuel cell has great development potential, and the paper-based microfluidic fuel cell is the latest achievement of its lightweight, which can be applied in the field of medical and biological detection. In this work, the cell models with various folding forms and unconventional absorption pads are creatively constructed, then the influence mechanism on cell performance is revealed by numerical simulation. Both transient and steady-state simulation methods are employed to monitor the whole process of paper-based microfluidic fuel cell. Conclusions show that the cell performance decreases with the increase of folding angle, the peak power density is as low as 1.71 mW/cm2, and the corresponding fuel utilization is only 2.73%. The changes in the absorbent pad shapes have little improvement on cell performance, thus the most direct way is increasing the absorbent pad volume. Moreover, materials with better water absorption capacity can increase the maximum current density to 28.70 mA/cm2, and the appropriate increase of operating temperature can also increase the peak power density to 2.36 mW/cm2, but the effect on the cell is significantly weakened if the temperature exceeds a certain limit. [ABSTRACT FROM AUTHOR]

Algae-based wastewater bioremediation offers a cost-effective method for sustainably treating wastewater while simultaneously addressing global water scarcity and pollution. This study highlights the benefits of treating primary-treated (PTW) and secondary-treated (STW) paper-pulp industrial wastewaters using the microalga Tetradesmus obliquus (Turpin) Kützing. A batch culture study revealed that 50 % secondary treated wastewater can increase the biomass yield 1.8 fold to 2.51 g L−1 in 15 days with a corresponding lipid yield of 390.2 mg L−1. Upscaling this work in 200 L open raceway ponds with 50 % STW as the growth medium showed areal biomass and lipid productivities of 26.80 and 3.90 g m−2 day−1, respectively, in 15 days at 20 cm culture depth. This translates to a projected high annual biomass productivity of approximately 85.0 tons hectare−1 year−1 based on datasets spanning two consecutive years. Bioremediation efficiencies of 80.0 %, 91.51 %, and 92.10 % were achieved for COD, TOC, and NH 4 + respectively. Biodiesel produced showed a large percentage of saturated and monounsaturated fatty acids (∼90 %) and its fuel properties complied with the global biodiesel standards. This study thus shows that using paper-pulp industrial wastewater for algal growth offers a sustainable solution for energy generation and wastewater treatment, with significant implications for environmental sustainability. [ABSTRACT FROM AUTHOR]

Algae-based wastewater bioremediation offers a cost-effective method for sustainably treating wastewater while simultaneously addressing global water scarcity and pollution. This study highlights the benefits of treating primary-treated (PTW) and secondary-treated (STW) paper-pulp industrial wastewaters using the microalga Tetradesmus obliquus (Turpin) Kützing. A batch culture study revealed that 50 % secondary treated wastewater can increase the biomass yield 1.8 fold to 2.51 g L−1 in 15 days with a corresponding lipid yield of 390.2 mg L−1. Upscaling this work in 200 L open raceway ponds with 50 % STW as the growth medium showed areal biomass and lipid productivities of 26.80 and 3.90 g m−2 day−1, respectively, in 15 days at 20 cm culture depth. This translates to a projected high annual biomass productivity of approximately 85.0 tons hectare−1 year−1 based on datasets spanning two consecutive years. Bioremediation efficiencies of 80.0 %, 91.51 %, and 92.10 % were achieved for COD, TOC, and NH 4 + respectively. Biodiesel produced showed a large percentage of saturated and monounsaturated fatty acids (∼90 %) and its fuel properties complied with the global biodiesel standards. This study thus shows that using paper-pulp industrial wastewater for algal growth offers a sustainable solution for energy generation and wastewater treatment, with significant implications for environmental sustainability. [ABSTRACT FROM AUTHOR]

Molten salt could act as both heat transfer fluid and catalyst in bio-waste pyrolysis. The temperature and composition of anions and cations of molten salts have significantly different effect on the pyrolysis behavior of bio-waste. In this study, three kinds of molten nitrates have been applied to conduct thermal conversion experiments of two kinds of bio-waste (beech and waste paper). The results showed that NO 2 − has a higher reactivity towards the bio-waste than NO 3 −. In detail, a faster reaction rate of biowaste pyrolysis and higher yield of gas products were found in NaNO 3 –KNO 3 –NaNO 2 and NaNO 3 –NaNO 2 than NaNO 3 –KNO 3. From the GC-MS analysis, it can be concluded that K+ inhibited the dehydroxylation process of phenols at 300 °C, while the phenols were completely converted to the aromatic hydrocarbonas the temperature went up. In addition, nitrogenous heterocycle was produced due to the reaction between furans, aldehydes, ketones and NO 2 −/NO 3 −, and the nitration process was found to be enhanced as the temperature rose. Inorganic components contained in bio-waste remaining in molten salt may affect its catalytic properties. Therefore, the effect of KCl–K 2 SO 4 –CaCO 3 on the pyrolysis behavior of bio-waste in molten nitrate was also investigated. The inorganic components increased the weight loss temperature, while the thermal conversion of bio-wastes was promoted after reaching the reaction temperature. The study in this paper provides guidance for the selection of appropriate molten nitrate system and temperature for bio-waste treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Gas diffusion layer (GDL), as an important transmission component of gas, electricity and liquid, is usually composed of carbon paper, which needs hydrophobic treatment before it is applied in fuel cell. In the paper, ultrasonic dispersion technique is added to the traditional method of preparing hydrophobic carbon paper, and the effect of ultrasonic dispersion on the PTFE load in hydrophobic carbon paper is studied. The theoretical study shows that the ultrasonic dispersion increases the movement of the liquid, thus improving the diffusion performance of the liquid molecules. The experimental results show that compared with the hydrophobic performance of the original carbon paper, the hydrophobic carbon paper prepared by ultrasonic method improves the hydrophobic performance by 13.24%. However, there is no obvious relationship between the PTFE content of the carbon paper treated by ultrasonic dispersion and the hydrophobicity of the carbon paper surface. In addition, ultrasonic dispersion also has a great influence on the gas permeability of hydrophobic treated carbon paper, but the effect on the surface conductivity of carbon paper is not obvious. The results can provide a guidance for the preparation of hydrophobic carbon paper for fuel cells. • Properties of hydrophobic carbon paper prepared by ultrasonic method are studied. • The Carbon paper prepared by ultrasonic method has better gas permeability. • Ultrasonic method can significantly improve the content of PTFE in carbon paper. • Ultrasonic method can improve the uniformity of PTFE material distribution. [ABSTRACT FROM AUTHOR]

As a rising star, the fuel cell will be applied very broadly. However, when the fuel cell works at a high current, too much water yield and the redundancy water block the air or oxygen enter the fuel cell, then the power reduces sharply. The gas diffusion layer (GDL) in the fuel cell is the critical component to transfer water and gas. A novel GDL was prepared in this paper to improve transferability. The new GDL consists of one carbon paper and two microporous layers. The microporous layer close to carbon paper is modified by pore-former CaCO 3. The total thickness of the new GDL is 270 μm; then, the samples were pressed to 220, 240, and 260 μm by rolling, respectively. The electrochemical impedance spectroscopy tests at a large current (2.5 A/cm2) show that the fuel cell with 240 μm GDL has relatively small transmission impedance regardless of high or low humidity. The results show that the new GDL can significantly improve the water transferability of the proton exchange membrane fuel cell. [ABSTRACT FROM AUTHOR]

Producing biodiesel via transesterification of waste oils or fats with short-chain alcohol is one of the possible ways to alleviate global energy and environmental issues, and further reducing the cost of transesterification catalyst is the essential strategy to enhance the competitiveness of biodiesel, such as applying industrial solid wastes as the source of catalyst active species. Thus in this work, via one-step pyrolysis of the calcium-rich residue, a byproduct from the hydrothermal treating (140–180 °C for 2–4 h) of paper mill sludge (PMS), a novel walnut-shaped calcium oxide-cancrinite based catalyst was prepared and applied to the transesterification of waste frying oil. The hydrothermal condition (changed from 140 oC-2 h to 180 oC-4 h) of PMS slightly influenced the yield of fatty acid methyl ester (Y FAME), which ranged from 98.87% to 96.95% due to the slight decrease of the total basicity of strong basic sites (TSB β+γ) from 149.6 to 102.9 μmol g−1. On the contrary, the pyrolysis temperature had a much greater effect on the transesterification performance of obtained catalysts. The optimum pyrolysis temperature was 750 °C and when it was increased to 850 °C, the increased bonding tendency of Si with Ca passivated the activity of calcium species and reduced the basic intensity and basicity of PS C -850, thus lowering its transesterification activity. Besides, the key process parameters were optimized and at the conditions of 70 °C, 3 h, 6.0 wt% of catalyst dosage, 10:1 of molar ratio of methanol to oil, over 95% of Y FAME can be reached. The work herein not only provided a feasible way to recycle the inorganic solid residue of PMS but further lowered the cost of preparing biodiesel. [Display omitted] • The consistency analysis model and algorithm of grinding roundness error of workpiece journal are proposed. • The rationality of the proposed model is verified by experiments. • The Influence of roundness error batch consistency of workpiece journal grinding is studied. [ABSTRACT FROM AUTHOR]

Constant electrode (CE) operation of a unitized regenerative fuel cell (URFC) facilitates the optimization of each electrode. In this work, bipolar plates (BPPs) with different flow fields (FFs) are assessed, and a graphite BPP is compared with a titanium BPP in the cathode. Platinum coated titanium felt and carbon cloth and paper gas diffusion layers (GDLs) are tested in the cathode. The carbon BPP and GDLs operated with higher ohmic resistance than the titanium alternatives. However, the titanium GDL caused flooding in FC mode. Carbon GDLs can be applied in the cathode, where carbon paper operated with higher performance than carbon cloth. Titanium GDL is still required in the anode to resist the corrosive environment. A double-serpentine FF in the cathode and a parallel design in the anode were applied. Optimization of the URFC operating conditions under FC mode provided the best results at 80 °C, 2 bar abs , with saturated air and dry hydrogen and stoichiometry ratios of 2 and 8. This resulted in a round-trip efficiency of 56% at 0.1 A cm−2, 48% at 0.3 A cm−2 and 22% at 1 A cm−2. In comparison, 56%, 52% and 37% were obtained with a discrete regenerative fuel cell (DRFC). [ABSTRACT FROM AUTHOR]

This work is carried out in the context of the anion exchange membrane water electrolysis (AEMWE) and pursuits to determine the influence of different cell components on the global electrochemical performance. Ionomer-free electrodes consisting of anodic Ni–Fe and cathodic Ni electrocatalysts deposited by magnetron sputtering in an oblique angle deposition configuration were utilized for this study. In addition to the characteristics and equivalent thickness of the electrocatalysts, other factors affecting the efficiency that have been considered in this study encompass the type of gas diffusion layer (GDLs), including carbon paper and stainless-steel fiber paper supports, and several commercial anion exchange membranes. The electrocatalytic performances in both a three-electrode and complete single cell AEMWE set-ups, together with the physico-chemical characterization of the electrodes before and after operation, have served to select the optimum components for the utilized cell configuration. Thus, current densities of 670 mA cm−2, at polarization voltage of 2.2 V, 1.0 M KOH electrolyte and 40 °C were obtained in a membrane electrode assembly. A seven days chronopotentiometry experiment at a fixed current of 400 mA cm−2 demonstrated a noticeable stability of this type of AEMWE cells incorporating ionomer-free electrodes. [Display omitted] [ABSTRACT FROM AUTHOR]

While studies on horizontal axis tidal turbines are plentiful, those on ducted twin vertical axis alike HydroQuest's turbines are lacking. For such a device, both the relative counter-rotation direction of the rotors and the tripod base geometry upstream are different between ebb and flood tide. Consequently, this paper analyses the effect of the two opposed flow directions on the hydrodynamic performance and on the wake of the turbine. The study is based on experimental measurements at a 1/20th scale in Ifremer's wave and current flume tank. The hydrodynamic performance of the model are characterised over a wide range of operating points with the turbine installed on a tripod and on a monopile base. In addition, the 3D wake of the turbine is thoroughly analysed in the two flow directions using 3-component laser Doppler velocimetry. Overall, the drag and the maximum average power coefficient are not affected by the current direction but the optimal tip speed ratio is 7 % lower during ebb with 1.5 times higher power fluctuations compared to flood tide. Besides, the wake of the two rotor columns interact differently depending on the flow direction, leading to a 30 % faster surface averaged velocity recovery in the flood tide configuration. The observed effect of flow direction provides a better knowledge of twin vertical axis turbine wake interactions and highlights the impact of the gravity base geometry on the development of the overall turbine wake. This paper also provides a wide experimental database for the validation of numerical models applied to ducted twin-vertical axis tidal turbines. • Ebb and flood tides modelled experimentally in a tank by turning the turbine around. • Twin vertical axis turbine (2-VATT) mean power is barely affected by the flow direction. • Gravity based 2-VATT power fluctuation and wake development depend on base geometry. • Rotors wake merging distance and recovery depend on the counter-rotation direction. [ABSTRACT FROM AUTHOR]

This paper investigates the impacts of economic (in)stability on carbon emissions and the role of renewable energy in these effects at the crossroads of accelerated climate change and rising global economic instability. The paper hypothesizes that these implications should be examined not by direct impacts across variables, but rather via indirect effects serially mediated by renewable energy consumption and economic growth. This paper analyzes the United States from January 1980 and April 2022 using manifest structural equation modeling. The paper reaches two major conclusions. First, there are clear distinctions between (i) the direct and indirect effects of economic stability, surrogated by inflation and policy interest rate, on carbon emissions, (ii) the symmetric and asymmetric indirect effects, and (iii) the roles of aggregate renewable energy and its components, such as biomass and hydropower energy use, in mediating these symmetric and asymmetric indirect effects. Second, renewable energy significantly reduces the carbon-increasing effects of inflation and interest rates. The paper contains proper policy suggestions based on the findings. [ABSTRACT FROM AUTHOR]

With further penetration of low-carbon energy conversion, microgrids (MGs) have become a necessary tool for expanding the consumption of renewable energies. In this paper, an optimal operation model for a microgrid-based multi-agent system is proposed. The goal is to save the total energy cost, which is expressed as a sum of locally observable convex functions. Therefore, improving the operational efficiency of microgrids is the key to promoting renewable energy development. This paper develops a three-layer multi-agent system model considering energy storage system and power thermal load demand response to solve the energy management problem of microgrids. In order to investigate the effect of energy storage system and demand response in microgrids, this paper designs three simulation cases, namely infrastructure case, energy storage case and demand response case. In order to prove the effectiveness of the proposed method, this paper uses the proposed method to solve three cases and compare the result with other meta-heuristic algorithms. The comparison results show that: (1) the multi-agent system model can realize the joint optimization of "resource, network, load and storage". (2) The introduction of energy storage and demand response system in microgrids can stabilize the output. Renewable energy units promote the use of renewable energy and reduce the overall operating cost of microgrids. Moreover, the results clearly demonstrate that the proposed algorithm has far better performance than other optimization methods. Also, the analysis obtained from the results shows that the cost is reduced by 1.82%. PV and WT output increased by 14.54% and 2.42%. In addition, their standard deviation decreases after ESS participation. The proposed approach is very effective through a simulation case study, which shows high potential for applications. [ABSTRACT FROM AUTHOR]

Renewable Portfolio Standards (RPS) and carbon emission trading (CET) system are the top-level system design of China's energy low-carbon transformation, which have great strategic significance for realizing the "carbon peak in 2030 and carbon neutrality in 2060". At present, China's tradable green certificates market and CET market are still in the initial stage. The implementation single system may have diverse trials and errors in its initial stage, and the market activity and transaction frequency are low. Therefore, this paper aims to explore whether the synergistic effect between the two systems can effectively promote China's energy low-carbon transformation. This paper establishes the system dynamic model of the synergistic effect between the RPS and CET in China's electricity market to reveal the influence mechanism and the synergistic effect. The results show that: (1) There is a positive synergistic effect between the RPS and CET, which will change with the institutional parameters. (2) The simultaneous implementation of the RPS and CET can effectively stimulate market vitality and promote the development of the renewable energy industry. (3) Higher quota and lower benchmark price can optimize power source structure, and improve social welfare and institutional performance. [ABSTRACT FROM AUTHOR]

Thermal stratification widely exists in large reservoirs, causing significant inflow-outflow temperature difference (IOTD), which goes against the downstream ecology. Reservoir optimal operation has recently been conducted to regulate the outflow temperature, while its effects for cascade reservoirs urgently needed to be illuminated. Taking the typical Xiluodu-Xiangjiaba cascade reservoirs (XXCR) as study case, this paper had built a multi-objective optimal operation model combing the non-dominated sorting genetic algorithm II (NSGA-II) and a hydrodynamic-temperature model, and the total power generation (TPG) and IOTD were simultaneously considered. The effects of different inflow discharge and global warming scenarios were analyzed. This paper showed the following: (1) The IOTD and TPG of XXCR showed a positively linear relationship with the water level of the superior Xiluodu Reservoir (XLD), instead of the inferior Xiangjiaba Reservoir (XJB). (2) The reservoir with larger water volume and depth (such as XLD) determined the thermal structure and hydropower generation in cascade reservoirs, compared with the inferior reservoir (such as XJB). (3) As the inflow discharge or air temperature increased, the slope between the IOTD and TPG in the Pareto front curve increased. The results of this paper could support the ecological operation for cascade reservoir to regulate the outflow temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

Membraneless microfluidic fuel cell (MMFC) has potential application prospects in micro-devices due to the characteristics of considerable output performance, superior cleanliness and easy miniaturization. Whereas, the performance of MMFC is restricted by the mass transfer of two-phase flow, which manifests as the inefficiency transportation in liquid phase and obstruction of gas phase. This paper proposes a novel sinusoidal corrugated channel (SCC) for MMFC though developing a three-dimensional two-phase model by coupling the multi-physics field to improve the cell performance in mass transfer, and further studies the two-phase flow characteristics of geometric parameters of SCC, including the amplitude A and angular frequency ω. Based on the optimal configuration in A of 0.5 mm and ω of 3 rad s−1, compared with the conventional straight channel, the increase ratios of maximum current density, power density, fuel utilization are 13.69%, 8.39% and 13.72%, respectively. Additionally, the gas volume fraction at the maximum power density decreases by 12.62%. This paper provides new insights and theoretical foundations for the study of MMFC flow field configurations, and furnishes references for the mass transfer intensification. [ABSTRACT FROM AUTHOR]

Global warming has focused attention on how the world produces the energy required to power the planet. It has driven a major need to move away from using fossil fuels for energy production toward cleaner and more sustainable methods of producing renewable energy. The development of offshore windfarms, which harness the power of the wind, is seen as a viable approach to creating renewable energy but they can be difficult to design efficiently. The complexity of their design can benefit significantly from the use of computational optimisation. The windfarm optimisation problem typically consists of two smaller optimisation problems: turbine placement and cable routing, which are generally solved separately. This paper aims to utilise selection hyper-heuristics to optimise both turbine placement and cable routing simultaneously within one optimisation problem. This paper identifies and confirms the feasibility of using selection hyper-heuristics within windfarm optimisation to consider both cabling and turbine positioning within the same single optimisation problem. Key results could not identify a conclusive advantage to combining this into one optimisation problem as opposed to considering both as two sequential optimisation problems. [ABSTRACT FROM AUTHOR]

This paper examines the impact of green finance on environmental performance in developing countries. Using panel cointegration analysis and panel vector error correction model (VECM) to a sample of 76 developing economies from 2010 to 2019, this study confirms that carbon emissions (CO 2) is cointegrated with green finance, real gross domestic product, urbanization, and renewable energy under different specifications and therefore we estimate the long-run relationships among these variables. Specifically, both green finance and renewable energy are found to exert significant and inhibitory effects on CO 2 emissions, reaffirming the necessity to promote green finance and renewable energy. Results from the paper also document the existence of the Environmental Kuznets Curve and the increasing effects of urbanization on CO 2 emissions. Several policy implications and recommendations are drawn from this study. • We examine impact of green finance on environmental performance. • 76 developing economies from 2010 to 2019 are considered. • Green finance and renewable energy exert inhibitory effects on CO 2 emissions. • Results support the existence of the Environmental Kuznets Curve. [ABSTRACT FROM AUTHOR]

The short-term forecast of photovoltaic (PV) power is crucial for the security and economics of power system operations. However, the fluctuation characteristics of the PV power, which are closely related to the meteorological factors, introduce inaccuracies in its forecast. Towards this end, the paper studies the effects of clustering analysis at long time scale and data reconstruction technique at short time scale on capturing PV power fluctuation characteristics. A short-term PV power forecasts method based on multi-scale fluctuation characteristics extraction (MFCE), which employs a path analysis to identify the relevance of meteorological factors with PV power at long time scale and a phase space reconstruction to analyze PV power fluctuation characteristics at short time scale, is proposed in this paper. The proposed MFCE methodology deploys a widely-used extreme gradient boosting (XGBoost) model to output the forecasting results. Both the effectiveness and accuracy of the proposed methodology are verified by using the real data under the conditions of sunny and cloudy days of four seasons compared to traditional methodologies. • The multi-scale fluctuation characteristics are analyzed for PV power forecast. • Identify dominant meteorological factors affecting PV power by path analysis. • The hour-level fluctuation is reduced by using path analysis-based clustering. • The phase space reconstruction is used to reduce the minute-level fluctuation. [ABSTRACT FROM AUTHOR]

Energy process system positively contributes to the energy utilization efficiency, the energy complement, and the construction of a low-carbon sustainable energy system. The multiple energy subsystems are deep interdependent, therefore, significant operational risks exist in the energy process system. To avoid system risk and fulfill operation requirement, we propose the Safety-Index based model predictive control that coordinates the controller design and system safety in this work. The innovation of the method is to integrate the state-space model of process system with advanced controller design while accounting for system safety. Since the state-space model of the energy process system is described by coupled partial differential equations and ordinary differential equations, which leads to difficulties in modeling and solving, the main contribution of this work is to simplify the constrained optimization problem formed by model predictive controller. The paper addresses the compressed air energy storage system as case study. From the numerical simulations of the safety controller performance, it shows that the system safety can be guaranteed by control strategy which realizes the system operation target and reject the system external disturbances, which caused by environmental or operation change. • The paper addresses the modeling and dynamic safety control of compressed air energy storage system. • A control loop for safety operation that consists of controllers, system models, system constraints, and safety index is proposed. [ABSTRACT FROM AUTHOR]

To achieve the carbon peaking and carbon neutrality goals, China promoted county-wide photovoltaic projects (CWPVs) in 2021. A large number of distributed photovoltaic (DPV) installations have expanded the scale of prosumer. It also brings the inequity problem of prosumer, distribution network system operator (DSO) and consumer--DSO and consumer bear the costs such as access cost and depreciation of stock investment caused by DPV access. Combined with China's current electricity tariff system and the promotion of photovoltaic scale development, this paper proposes a standby fee model based on the principle of "beneficiary apportionment". In this model, the standby fee mechanism for self-owned power plants is applied to DPV to reduce the implementation cost of the mechanism, and the principle of "beneficiary apportionment" is adopted to ensure the profitability of DPV. This paper takes the CWPV in Hunan Province, China as an example, calculates the standby fee under various electricity metering methods, and determines the most appropriate standby fee by considering factors such as output uncertainty of DPV. Finally, the difficulties in the implementation of standby fee are sorted out. [ABSTRACT FROM AUTHOR]

The present paper analyses the evolution of renewable energy generation in the European Union through a decomposition analysis based on the Index Decomposition Analysis together with the Logarithmic Mean Divisia Index within the EU27 between 2000 and 2020. A four factors decomposition approach is considered for decomposing the total RES generation and a five factors model is employed to decompose the carbon emissions. Furthermore, a focus on wind and solar photovoltaic generation is introduced through a four factors decomposition calculated in the period 2010–2020. The most influential factors affecting the RES generation trend in the period 2000–2020 are the RES share and energy efficiency wich determined an increase of 1841 TWh and a decrease of 635 TWh respectively. Variations of carbon emissions are mostly affected by the energy intensity, namely the amount of energy necessary to produce one unit of GDP, which determined a reduction of 1040 Mt. Through the decomposition analysis, the paper successfully identifies the specific drivers supporting RES development and controlling carbon emissions, thus adequate policy measures can be designed to reach planned targets. • LMDI methodology is used to study decomposition of RES generation in EU. • Technical and socio-economic factors are highlighted by using 4 or 5 factors identity. • Technical factors have the main impact on the increase in RES generation. [ABSTRACT FROM AUTHOR]

With more and more micro-generation being connected to the low-voltage network, it becomes increasingly difficult for operators to anticipate the loading condition of their networks. Several facts concur with such difficulty, one being the frequent lack of knowledge about the generation component of the measured net load. The generation component is typically more volatile than the natural load and is impossible to predict without reliable information on the grid's renewable installed capacity. In this context, the objective of this paper is to propose a non-intrusive methodology to estimate distributed generation' installed capacity. Relying upon net-load historical data obtained at the secondary substation level and on historical meteorological data, the paper presents algorithms that proved effective in determining an approximation of the renewable embedded capacity. The accuracy and effectiveness of the proposed algorithms are illustrated in the paper with real data, for real use cases in the distribution systems. • New non-intrusive methodology to estimate PV capacity installed in LV distribution grids. • Disaggregation of net load profiles into demand and PV generation. • Use of disaggregated profiles for improved LV net-load forecast. [ABSTRACT FROM AUTHOR]

The valorisation of lignin is being increasingly recognised to improve the economics of pulp and paper making mills. In the present study, an integrated lignin–glycerol valorisation strategy is introduced with an overarching aim for enhancing the process value chains. LignoBoost kraft lignin was subjected to base-catalysed depolymerisation using glycerol as a co-solvent. The generated bio-oil was used as a renewable additive to biodiesel for enhancing its oxygen stability. The influence of three independent parameters including temperature, time and glycerol amount on lignin depolymerisation was investigated. Response surface methodology was applied to design the experiments and to optimise the process for maximising the yield and antioxidant impact of bio-oil. The results showed that glycerol has a positive qualitative and quantitative impact on the produced bio-oil, where an enhancement in the yield (up to 23.8%) and antioxidant activity (up to 99 min induction period) were achieved using the PetroOxy method (EN16091). The addition of 1 wt% bio-oil to biodiesel has led to an improvement in the oxidation stability over a neat sample of up to ∼340%, making it compliant with European standard (EN14214). The proposed process presents a biorefinery paradigm for the integrated utilisation of waste cooking oil, lignin and glycerol. [Display omitted] • Bio-additives from the base-catalysed depolymerisation of LignoBoost kraft lignin. • Effect of reaction variables on bio-oil yield and biodiesel oxidation stability. • Oxidation stability of biodiesel increased up to 340% by adding 1 wt% bio-additive. • An integrated biorefinery concept for valorising lignin and glycerol waste streams. [ABSTRACT FROM AUTHOR]

The development of clean energy has made the green finance market attractive to investors, but existing studies lack an analysis of the impact of uncertain environmental shocks on the volatility of green finance stocks. This paper focuses on the impact of major events on clean energy stock returns by using a mixed-frequency model. Specifically, to identify asymmetric effects and extreme information spillovers, we construct extreme positive returns/positive returns and extreme negative returns/negative returns, respectively. The in-sample findings suggest that asymmetric effects and extreme shocks contain valid information about future clean energy stock price volatility. The out-of-sample analysis shows that the extended model can successfully predict the volatility of clean energy stock markets. More importantly, the extended model can generate predictive gains from both statistical and economic aspects. This study can provide a reference for implementing and adjusting energy policies, which is important for optimizing the energy structure and developing the green energy industry. • This paper investigates the performance of the extended GARCH-MIDAS model. • Extreme shocks have different effects on the clean energy stock markets volatility. • The model with long and short-term extreme shocks has better predictive power. • The predictability of extreme shocks is robust by several robustness checks. [ABSTRACT FROM AUTHOR]

Sigma Energy has performed its foremost prototype tests of a scaled wave energy converter (WEC) in a real sea environment. The prototype was a point absorber with a circular buoy, a mechanical power take-off (PTO) system and a counterweight, moored to the seabed as a tension leg platform with three equal tendons. In these extensive experiments, numerous device characteristics were measured and analysed. The paper presents these sea trials, focusing on the power and efficiency of the device. The power has been calculated from the data recorded at 6 locations along the PTO system. In that way, a decay of capture width ratio (CWR) from the one absorbed from the waves to the one delivered to the electrical network was found and analysed. Also, losses of the main elements of the PTO system were defined, calculated and ranked. Optimal sea and loading conditions were indicated, giving the maximal values of the efficiencies. These optimal conditions are physically explained, and the challenges in their prediction are discussed. In addition to the results of numerous 20-min tests, the paper presents the long-term average values of the efficiencies, covering all the tests performed, and accounting for the probabilities of different sea conditions. [ABSTRACT FROM AUTHOR]

Reliability of blades has a profound impact on both serviceability and safety of offshore wind turbines. Reliability estimation of wind turbine blade is a complex and time-consuming problem with multi-physics coupling and multi-failure modes correlation. Developing physics-of-failure modeling and reliability analysis methods with high efficiency and accuracy is a long-term challenge. In this work, a high availability and cost-effectiveness reliability estimation framework for offshore wind turbine blade by combining transfer learning (TL) and direct probability integral method (DPIM) is proposed. Extensive performance simulation of offshore wind turbine blade is a complex and necessary task, this paper develops a new adaptive sampling strategy to improve the validity of sample selection in the design space; On this basis, a physics-of-failure surrogate modeling approach is proposed by introducing TL method to fuse two kinds of multi-physics coupling analysis data, then the performance of all critical loads can be predicted efficiently in advance to provide a reliable design; Further, this paper provides an efficient reliability estimation method for offshore wind turbine blades by combining DPIM and surrogate model. Finally, the validity of the proposed approach is illustrated by numerical example and offshore wind turbine blade reliability estimation. The proposed framework provides a cost-effective alternative to higher loads simulation efforts and safety factors selection. • A new adaptive sampling strategy for multi-failure modeling is proposed. • A failure modeling method is developed for multi-physics coupling system. • A reliability estimation method is proposed based on Dirac delta function. [ABSTRACT FROM AUTHOR]

CO 2 sequestration is an effective technology for reducing greenhouse gas effect. To ensure the safety, assessment of well applicability should be conducted before CO 2 sequestration. However, current studies mainly focus on identifying which barrier has the highest risk of leakage rather than selecting a target well for injection in specific geological formation. To further investigate, this paper proposes well applicability assessment method combining reservoir and wellbore properties together for CO 2 sequestration. A novel assessment system combing Fuzzy comprehensive evaluation and Analytic hierarchy process has been established. Twenty-nine indexes subjected to seven categories (i.e., formation, well, cement sheath, cementing quality, casing, tubing, and wellhead properties) are taken into consideration. The weighting factors of these seven categories are 0.0673, 0.0552, 0.096, 0.1537, 0.2283, 0.2637 and 0.1369, respectively. Tubing and casing properties have the greatest influence on safety injection. Furthermore, the proposed system has been applied to S gas reservoir, China. Results show that Wells #P1 and #P2 are suitable for injection. Since more comprehensive indicators are considered comparing with previous studies, the results are more accuracy and objective. The findings of this paper could help efficiently and effectively evaluating well applicability for CO 2 sequestration and reducing the risk of CO 2 leakage. [ABSTRACT FROM AUTHOR]

Non-interconnected island systems around the globe present a great variety and substantial particularities regarding the methods applied in generation scheduling, primarily under high renewable energy sources penetration levels. Under such conditions, one of the main challenges in island systems is the coherent treatment of intermittent renewable generation and the implementation of robust unit commitment and economic dispatch methodologies, seeking to achieve high RES absorption rates, least cost scheduling, and system security. In this paper, an extensive and in-depth literature review is undertaken to identify the generation scheduling principles and methods applied in island systems experiencing high renewable penetrations. Principal features of electricity markets in islands are highlighted, state-of-the-art unit commitment and economic dispatch models suitable for such applications are identified, and their advantages and limitations are discussed. The effect of renewables uncertainty on the islands' scheduling is analyzed, especially regarding the classification and quantification of system operating reserves to enhance operational security and system stability. Given the isolated nature and limited inertia of islands, very high RES penetration targets may impact their ability to survive severe contingencies, a topic also addressed in this paper, extending the review to include literature on frequency-related dynamic phenomena for isolated systems. • An overview of generation scheduling principles for island systems is presented. • Techniques available to deal with intermittent RES uncertainty are discussed. • A taxonomy of operating reserves adopted in the literature is performed. • A survey on island systems dynamics under high RES penetrations has been conducted. [ABSTRACT FROM AUTHOR]

This paper probes the effectiveness of competitive industrial performance (CIP) and renewable energy in enhancing load capacity factor in top-10 CIP economies for the period 1990–2018. We run panel econometric techniques that address cross-sectional dependence, endogeneity and heterogeneity to provide policy recommendations with the applications of industry, innovation, and infrastructure (SDG 9), which is linked to affordable and clean energy (SDG 7) and climate action (SDG 13). In the empirical analysis, two different environmental quality indicators such as CO 2 emissions and load capacity factor are used. While cointegration between variables cannot be detected in the emissions model, evidence for the existence of cointegration is presented in the load capacity factor model. The findings in the paper suggest that economic growth and competitive industrial performance adversely impact environmental quality, while renewable energy consumption and human capital can improve load capacity factor. The result shows that human capital and renewable energy consumption can be strong tools for stimulating load capacity factor in top-10 CIP economies. Countries with high competitive industrial performance need to return to a green economy without losing their competitiveness. • SDG-based environmental policies was presented for the top-10 CIP economies. • A battery of second generations methods was employed. • Investigating the impacts of Competitive industrial performance on environmental quality. • Competitive industrial performance has a negative impact on environmental quality. [ABSTRACT FROM AUTHOR]

Tidal currents are renewable and predictable energy sources that could prove fundamental to decrease dependency from fossil fuels. Tidal currents, however, are highly unsteady and non uniform, resulting in undesirable load fluctuations on the blades and the drive train of turbines. A passive morphing blade concept capable to reduce the load fluctuations without affecting the mean loads has recently been formulated and demonstrated with numerical simulations (Pisetta et al., 2022). In this paper, we present the first demonstration of this morphing blade concept, through experimental tests on a 1.2-m diameter turbine. We show that fluctuations in the root-bending moment, thrust and torque are consistently reduced over a broad range of tip-speed ratios. This work also highlights some critical design aspects of morphing blades. For instance, it is showed that the friction resistance can substantially decrease the effectiveness of the system and thus must be minimised by design. Overall this paper demonstrates for the first time the effectiveness of morphing blades for tidal turbines, paving the way to the future development of this technology. • We test a model-scale tidal turbine equipped with a passively pitching blade. • The blade angle of attack decreases with an increase in instantaneous loads. • This does not affect the time-averaged power generated by the tidal turbine. • Torque and thrust fluctuations are reduced by at least 40% at on-design conditions. • Friction on the turbine shaft affects performance and must be minimised. [ABSTRACT FROM AUTHOR]

In order to reveal the role moisture content in the dense molding process of Salix psammophila, a discrete element model was established by PFC3D. Under the conditions of temperature of 100 °C and pressure of 0–180 kN, three groups of uniaxial compression simulation with different moisture content were done, and experiments are used to prove the feasibility of using discrete element to simulate the influence of moisture content on the dense molding of Salix psammophila. The significance of this paper on the influence of moisture content on the densification of salix psammophila is as follows: There are abundant shrub resources in northwest China. Effective control of moisture content is conducive to utilization of shrub biomass resources and improvement of product quality; Many scholars have studied the influence of moisture content on forming fuel from the same perspective, but this paper expounds the influence of moisture content on the dense forming of Salix psammophila from the perspectives of force, fracture, energy, etc., providing a reference for the study of the role of moisture content. [ABSTRACT FROM AUTHOR]

The growing carbon crisis threatens sustainable development. This paper verifies that the rise of green finance contributes to overcoming this challenge. The benchmark results show that green finance can directly drive decarbonization of the economy. High-level openness, government support, human capital and urbanization are prerequisites of this effect, and green finance is more effective in promoting decarbonization in areas with high carbon intensity. Moreover, green finance drives economic decarbonization by promoting economic growth, technical innovation, industrial upgrading, and renewable energy transition. Internet availability, financial level and higher education have moderating roles in boosting this effect. Furthermore, the implementation of green finance policy also contributes to decarbonization. The robustness of the basic result is proven with several methods, thus strengthening the reliability of the basic conclusion in this paper. Based on the above main findings, targeted policy recommendations concerning how to further develop green finance are proposed in this paper. • Green finance can directly drive economic decarbonization. • Some high-level external circumstances are the prerequisite of that effect. • Green finance can drive economic decarbonization through mediating paths. • Moderating paths are Internet availability, financial level and education. • Green finance policy makes contributions to the economic decarbonization. [ABSTRACT FROM AUTHOR]

The primary purpose of this paper is to investigate the effects of two variables, trade openness and the issuance of green bonds, on the consumption of renewable energy in Southeast Asian countries. Quarterly data throughout 2016–2021 in the framework of the panel data method were used for the case of 6 selected countries (Indonesia, Malaysia, Philippines, Singapore, Thailand, and Vietnam). The results confirmed that the issuance of green bonds is an effective green financing tool in the implementation of the development policy of the deployment of renewable energy in the countries of the Southeast Asian region. The degree of trade openness has a driving effect on increasing renewable energy consumption due to the increased possibility of transferring green technologies and increasing interactions with leading countries in the field of sustainable development. The typical standard of green bonds, green scientific network (GSN), the development of e-commerce, and the publication of digital green papers are the recommended practical policies of this research. • Green bond is an effective tool to increase of deployment of renewable energy. • Trade liberalism increases the deployment of renewable energy. • Green R&D is a leading factor in the field of clean energy consumption. [ABSTRACT FROM AUTHOR]

In this paper, a three inputs six-phase Interleaved Boost Converter (IBC) is proposed and designed for Fuel Cell (FC) systems, where the different Polymer Electrolyte Membrane Fuel Cells (PEMFC) systems are employed to validate. Considering that the selected converter is composed of three two-phase IBCs connecting in parallel, it shows many superiorities in topology, such as simple structure, high scalability/flexibility, easy maintenance and good fault-tolerant ability. The whole design process containing the selection of phase numbers, parameters design of the converter's components and steady-state operations analysis is focused in this paper. To further validate the correctness of the designed converter, a test bench is established based on dSPACE1104 , where the issue of the implementation of six-PWM signals from dSPACE1104 is analyzed and a feasible solution is proposed. Last, experimental results are shown by performing the load disturbance rejection, the variable reference voltage and the PEMFC system's failure based on the designed Double-Loop Super-Twisting Sliding Mode (DL-STSM) controller. • Three inputs six-phase interleaved boost converter is designed for fuel cell systems. • The designed converter shows high scalability and good fault-tolerant ability. • A solution is proposed to address the achievement of six-PWM signals in dSPACE1104. • Experimental verification of the designed converter with different fuel cell systems. • Load disturbance rejection, variable reference voltage and FC failure are validated. [ABSTRACT FROM AUTHOR]

This paper collects monthly data for the United States from January 2005 to April 2021 and develops a time-varying parameter vector autoregressive model with stochastic volatility (TVP-SV-VAR) model to investigate the time-varying relationship between climate policy uncertainty, oil prices, and renewable energy consumption. In addition, this paper discusses the dynamic impact of climate policy uncertainty on five types of renewable energy consumption. Our results show that the relationship between them is time-varying. In most periods, climate policy uncertainty positively affects oil prices in the short and medium term, and positively affects total renewable energy consumption in the short and long term. In addition, the impact of climate policy uncertainty on the consumption of the five types of renewable energy is heterogeneous. The results of the robustness tests indicate that our results are robust and our study has important implications for the development of relevant policies. [ABSTRACT FROM AUTHOR]

A relatively simple, optimal, and robust nonlinear Sliding Mode Control (SMC) is developed in this paper for a novel nonlinear Wave Energy Converter (WEC). Giving that deriving an optimal control for a complex system is very cumbersome or nearly impossible, an SMC (purely switching only) is thus implemented with the sliding surface defined in an optimal sense. Despite it is simple, the optimality of this control is proved by using a new equivalent control analysis mathematically and also demonstrated numerically. In addition, the robustness of the control is shown mathematically with Lyapunov analysis and by simulations with uncertainties. The main contributions of this paper are: (1) a novel Sliding Mode Control is developed which is simple, optimal, and robust;(2) the robustness and optimality of the proposed control are both proved mathematically and verified numerically; (3) a weakly nonlinear model is developed for a nonlinear WEC which is utilized to validate the performance of the proposed nonlinear control. The numerical simulations are then conducted on a weakly nonlinear model developed for the nonlinear WEC. The results show the robustness and optimality of the proposed control (compared with a nonlinear damping control) subject to uncertainties and nonlinearities. [ABSTRACT FROM AUTHOR]

Thermochemical processes to convert bio-wastes into valuable products and bioenergy have been extensively studied in the literature. Experimental and, to a lesser extent, rigorous simulation papers concerning these processes have been widely considered and discussed in the literature. Nonetheless, there is still a gap to fill in providing a fast and reliable simulation scheme. In this paper, an efficient simulation strategy, combining the free-software COCO simulator for the bio-waste slow pyrolysis coupled with commercial SimaPro code to carry out the Life Cycle Assessment (LCA), was applied. The pyrolysis product yields at 673, 773, and 873 K were well predicted using mass and energy balances and a proposed reaction scheme from the literature. Simulations were validated using experimental data previously reported. The highest yield was 53.7% for biochar (673 K – stalk of white grape), 32% for bio-oil (773 K - marc of red grape), and 56.3% for gas (873 K - marc of white grape). The results from LCA and cumulative exergy demand (CExD) were useful to detect and reduce environmental impacts in previous stages of the process. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, nano hexagonal boron nitride grafted with silane coupling agent (APTES-hBN) is selected to modify the natural ester, conducts thermal aging tests on the modified natural ester insulating oil and explores the mechanism of the nanoparticles on the improvement of natural ester properties from a microscopic perspective combining with molecular dynamics. The experimental results show that the addition of Nano APTES-hBN inhibited the production of acids in oil-paper insulating, leading to a corresponding decrease in the number of polar molecules in the oil. Compared with crude oil, the acid value and dielectric loss factor in the modified oil are reduced by 8.4% and 43.8%, respectively at the end of aging, and the rate of increase is smaller. Through its mechanism study, it is found that the addition of Nano APTES-hBN results in a tighter interfacial bonding between oil and paper insulation, and the adsorption energy of modified natural ester insulating oil to H 3 O+ is greater. The addition of Nano APTES-hBN introduced a large number of electron traps, providing a medium for the transition of valence electrons. At the same time, there are hydroxyl groups with strong electrostatic potential on Nano APTES-hBN, which have strong adsorption effect on charged particles. In addition, the Nano APTES-hBN is able to form hydrogen bonds with acids, which slows down the promotion of hydrolysis of ester molecules by acids, and thus improves the thermal stability of the modified natural ester insulating oil. [ABSTRACT FROM AUTHOR]

In building integrated PV/T applications, the utilization of linear Fresnel micro-concentrators could promote solar energy harvesting efficiency. For the consideration of low wind load and building aesthetics, the height of the concentrator is invariably kept in a small range, resulting in severe optical blocking between mirrors. In this paper, two offset-axis mirror models are introduced to promote the optical efficiency of the micro-concentrator. The rotating axis of the mirror in the former model is not located on the symmetrical axis of the mirror but is offset to one side of the mirror. The later model is a rod offset-axis mirror with the axis offset to the outside of the mirror by a rod. These offset-axis mirrors allow the mirrors farther away from the receiver to possess a higher position for larger angular rotation, thus reducing the blocking between mirrors. Thereafter, mathematical models were established to obtain the key parameters of each mirror at different axis positions, and the influence of the axis position on the optical performance of the micro-concentrator was analyzed. The results revealed that both kinds of offset-axis mirrors could significantly improve the ground utilization ratio of the micro-concentrator and realize a more compact micro-concentrator design. In comparison with the layout scheme with the conventional central-axis mirrors, the ground utilization ratio of micro-concentrator with a hybrid layout of side-axis mirrors and rod offset-axis mirrors was improved by 28%. The optical simulations based on the Monte Carlo method revealed that a micro-concentrator with a hybrid layout of side-axis mirrors and rod offset-axis mirrors could promote the solar harvesting efficiency by 56.8% compared to the conventional central-axis mirror layout, regardless of direct normal sunlight or large angle inclined sunlight. The concept and calculation methodology of offset-axis mirror presented in this paper could reduce the thickness of linear Fresnel micro-concentrators in the design and improve their concentrating efficiency, which would lay the solid foundation for the wide application of micro-concentrators in the building domain. [ABSTRACT FROM AUTHOR]

In recent decades, the role of green energy in realizing green transition and addressing environmental degradation needs to be brought into full play. To promote green energy development in China, this paper examines the relationship among green economic growth, green finance, and green energy (3G) between 2011 and 2019. The heterogeneous, asymmetric, and mediation impact relationship that exists in the 3G nexus is also explored in this study. Accordingly, the results suggest that: (1) Green economic growth and green finance are positively associated with green energy, and the impact is heterogeneous on different types of green energy and in different regions; (2) the impact of green economic growth on green energy are asymmetric, while that of green finance is consistent; and (3) green innovative technology is an effective mediator between green economic growth and green energy, while the investment effect is not significant. This paper contributes to formulating several reasonable policies for improving the green energy industry and achieving sustainable development. It is essential to give full play to the transformation of green achievements to enhance the role of green economic growth in promoting the green energy industry. • This study explores 3G nexus (green economic growth, finance, and energy (GRE)) in China. • The heterogeneity, asymmetry, and mediating mechanism are further analyzed. • Green economic growth and green finance can significantly promote GRE. • The impacts of green economic growth and green finance on GRE are heterogeneous. • Green technological innovation is an effective mediator in the 3G nexus. [ABSTRACT FROM AUTHOR]

Strengthening environmental regulation (Reg) is an important measure to solve energy and environmental problems, then to realize the profit sustainable growth (Gro). Taking 116 listed renewable energy enterprises in China from 2010 to 2019 as samples, this paper uses FE and SYS-GMM models to examine the moderating effect of three types of Reg in the relationship of factor market distortions (Dist) and the Gro. The conclusions are as follows: For the direct impact, capital and labor market distortions (DistK and DistL) hinder the Gro. Specifically, the absolute value of the coefficient of DistK in state-owned enterprises (SOEs) is greater than that of the DistL, which indicates that the inhibitory effect of DistK in SOEs is more significant. For the indirect impact, the coefficients of economic and supervised environmental regulation (RegE and RegS) are positive and significant, and promote the Gro of SOEs and non-SOEs, while legal environmental regulation (RegL) is the opposite, which shows that Reg has significant "cost effect" and "rebound effect". Moreover, Reg has a positive moderating effect, which is mainly reflected in SOEs, and alleviates the inhibitory effect of DistK and DistL on Gro to a certain extent. Finally, this paper puts forward some targeted policy suggestions. [ABSTRACT FROM AUTHOR]

The integrated phase change materials (PCM) solar wall can store solar energy effectively, which has a broad application prospect. However, the integrated PCM solar wall cannot completely release heat at night. In this paper, the evaporator of the heat pump system is embedded in the integrated PCM solar wall, which can realize the combination of active and passive utilization of solar energy. A numerical study on the thermal storage/release characteristics of the integrated PCM solar wall with an embedded evaporator was carried out in this paper considering its two-dimensional heat transfer. The effect of the thermal release mode, the thermophysical parameters of PCM and the solar radiation intensity on the thermal storage/release characteristics was studied. The simulation results showed that the active thermal release mode increased the released heat by 33.33 kJ/kg, and the proportion of the released heat to the stored heat increases by 30.12%, compared with the passive thermal release mode. Moreover, the increase of the phase transition temperature and the thermal conductivity of PCM can increase the stored heat and released heat, and the latent heat of PCM will increase the stored heat and decrease the released heat. The conclusion can provide a theoretical basis for the research of active and passive solar systems. [ABSTRACT FROM AUTHOR]