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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]

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]

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]

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]

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]

Paper wastes form the major biodegradable fraction of the municipal solid waste. One of the best ways to treat paper wastes is using them as a feedstock for biomethane production through anaerobic digestion (AD). However, the AD characteristics, kinetics, and energy potential of different types of paper wastes are not clear. In this study, four kinds of typical paper wastes including corrugated board (CB), office paper (OP), tissue paper (TP), and magazine paper (MP) were used as feedstocks to produce biomethane at different volatile solids (VS) organic loading (OL). TP had a high cellulose content and showed high biomethane potential, while the lowest was obtained by CB, possibly due to its high lignin content. Kinetic analysis showed that Cone and modified Gompertz model could fit the biomethane production process well. Energy potential analysis revealed that biomethane yield, electric generating efficiency, and electricity price were the principal factors accounting for the profitability of biomethane production project treating paper wastes. Overall, paper wastes could be a promising feedstock for biomethane production, because paper wastes not only had high biomethane yield and biodegradability that exceeded many kinds of organic wastes but also could be continuously supplied for AD plants without the influence of seasonal changes. • Anaerobic digestion characteristics of typical paper wastes were investigated. • High cellulose content in tissue paper might account for its high biomethane yield. • Corrugated board with high lignin content showed the lowest biomethane yield. • Energy potential of the anaerobic digestion of paper wastes was evaluated. [ABSTRACT FROM AUTHOR]

Waste office paper (WOP), was used to produce microbial lipids using Cryptococcus curvatus. Pretreatment of WOP with 1% (v/v) sulfuric acid removed the lignin without any inhibitor formation and increased the cellulose content. The optimum conditions for enzymatic hydrolysis of WOP were predicted at 92 h, 50 FPU/g cellulase, 50 CBU/g β-glucosidase, 5% substrate loading, 50 mL working volume and 156 rpm using the central composite design. The maximum sugar yield obtained in the validation experiment was 35.3 g/L. Ammonium chloride and yeast extract combination were more suitable for lipid production by C. curvatus with the carbon to nitrogen ratio of 60. A maximum biomass 11.48 ± 0.09 g/L was obtained at 120 h with a lipid yield of 4.95 ± 0.02 g/L. The lipid profile studies reveal the presence of 11 fatty acid methyl esters. These predominantly comprised of (%, w/w) 50.8% oleic acid, 25.7% palmitoleic acid, 7.1% stearic acid, and 6.5% myristic acid. The characteristic features of the biodiesel, such as cetane number, cold performance, density and iodine value met the requirements of the international standard (EN14214). Thus, the WOP could be a potential renewable feedstock to produce microbial lipids which are essential for the future sustainable production of biodiesel. • Waste office paper was used as a feedstock for microbial lipid production. • Dilute sulfuric acid pretreatment increased the cellulose content of waste paper. • Optimization of enzymatic hydrolysis yielded 35.3 g/L of glucose. • Lipid profiling of obtained FAMEs showed high similarities with vegetable oil. • The produced biodiesel properties are on par with international standards. [ABSTRACT FROM AUTHOR]

Bioethanol production using paper wastes seems a promising approach towards sustainable energy, but mainly hindered by hazardous ink. Therefore, in our experimental plan various methods were applied for the deinking of waste newspapers, laser printed papers and examination papers. A newly designed paper pulper reduced the pulping time from 6 h to 2 h. Cellulase (15 FPU/g) from Aspergillus oryzae MDU-4 was found effective for the deinking of newspapers, whereas laccase isozymes (150 U/g) from Ganoderma lucidum MDU-7 along with 2 mM HOBt was preferred for the ink removal and degradation from the examination papers. Ozonation in the presence of Tween-80 was found to be efficient in the removal of toxic toners used in laser printing papers. The biologically and physically deinked papers, studied with the help of SEM, TEM, FTIR, and XRD analysis revealed significant changes in the chemical and surface structure. Moreover, the saccharification of deinked papers with the help of an enzymatic consortium of Trichoderma citrinoviride MDU-1 resulted in 305 mg/g, 377 mg/g, and 409 mg/g release of sugars from the newspaper, examination paper, and laser printed paper, respectively. Finally, the enzymatic hydrolysates fermented with Saccharomyces cerevisiae NCIM-3640 produced 3.35 g/L ethanol, with 40.85% ethanol yield. Image 1 • Pulping time was reduced from 6 h to 2 h by designing a new pulp maker. • Cellulase and laccase were effective for the deinking of NP and EP, respectively. • Ozonation was found appropriate for the removal of toners from PP. • Optimized deinking methods were comparatively better than chemical process. • Ink free paper hydrolysates resulted in 40.85% ethanol yield using S. cerevisiae. [ABSTRACT FROM AUTHOR]

Biohydrogen and biomethane production via two stage sequencing system from paper mill effluent (PME) was evaluated to enhance its COD reduction. Heat-shock pretreatment of anaerobic sludge at 90 °C for 15 min was chosen to obtain a mixed microbial inoculum for dark fermentative hydrogen production. The effect of initial pH (5, 6 and 7) on the efficiency of hydrogen fermentation at different concentrations of substrate (3, 5 and 7 g-COD/L) was investigated, which the maximum hydrogen yield was obtained at initial pH 5. After that, the effects of substrate concentration (3, 5, 7, 10 and 15 g-COD/L) and fermentation temperature (37 and 55 °C) were investigated on the hydrogen production yield. The efficiency of dark hydrogen fermentation for all substrate concentrations was higher at 55 °C. The hydrogen production was enhanced as substrate concentration increased up to 5 g-COD/L, but then it was reduced, and the optimum hydrogen yield of 38.8 mL H 2 /g-COD initial was obtained at substrate concentration of 5 g-COD/L at 55 °C. The highest hydrogen (35.1 mL H 2 /g-COD initial) was obtained at 5 g-COD/L and 55 °C and the highest methane (553.8 mL CH 4 /g-COD initial) was obtained at 3 g-COD/L and 37 °C. Maximum COD reduction of 88.1% was obtained in two-stage sequencing dark fermentation/anaerobic digestion system at 3 g-COD/L and 37 °C. • BioH 2 and bioCH 4 were generated in expend of COD reduction from PME. • Effects of initial pH, COD loading and temperature were studied. • Primary step dark fermentation showed higher hydrogen yields at 55 °C. • Max COD reduction 88.1% was obtained in 2-stage sequencing system (3 g-COD/L, 37 °C). • 38.8 mL H 2 /g-COD initial at 55 °C and 553.8 mL CH 4 /g-COD initial at 37 °C were obtained. [ABSTRACT FROM AUTHOR]

Biodiesel, as a green fuel, acts as a potential candidate to supplement conventional fossil fuels. This research study targets green environment (using biodiesel) and clean environment (reduce wastewater) by producing biodiesel through oleaginous biomasses (Yarrowia lipolytica , Metschnikowia pulcherrima and Lipomyces starkeyi) grown on pulp and paper industrial wastewater. Batch culture studies were explored for the potential feedstock of the oleaginous organism by the synthesis of single cell oil and fatty acid methyl ester (FAME) yield. Response surface methodology (RSM) was used to design the optimal experimental matrix and identify the optimal process conditions that enhance the FAME yield. To determine the inherent characteristics of the growth of oleaginous biomasses on the industrial wastewater, a data-driven adaptive neuro-fuzzy inference system (ANFIS) is implemented. Y. lipolytica strain cultured shown high biomass concentration of 32.36 g/l with biomass productivity of 5.39 g/l/d was considered for further scale-up for the transesterification process. Results indicated that the maximum yield of 0.48 (g-biodiesel/g-lipid) was obtained under the 2.5 g of lipid dosage with 0.02 g/ml of catalyst concentration by constant stirring at 70 °C. The optimum conditions to achieve maximum FAME yield of 1.154 g/g was obtained at 2.485 g, 70.87 °C and 0.021 g/ml for lipid dosage, temperature and catalyst concentrations, respectively. • Growth of Y. lipolytica, M. pulcherrima and L. starkeyi yeasts on paper and pulp wastewater explored • Bagasse seepage water, bagasse wash water and hardwood wash water were used • FTIR spectroscopical analysis confirmed the presence of prime biodiesel components • Enhanced FAME yield (1.154) was accomplished by response surface methodology optimization • ANFIS demonstrated the intrinsic characteristics of transesterification process for the better prediction of FAME yield [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]

Waste paper, a promising renewable source of cellulose, was successfully prepared into a magnetic carbonaceous solid acid (SMWP) via a facile and integrated impregnation-pyrolysis–sulfonation process. The resultant catalyst was confirmed to possess a porous structure with a high surface area, various oxygen-containing functional groups and contain Fe 3 O 4 components. The SMWP catalyst also exhibited a high catalytic activity in the alcoholysis of furfuryl alcohol with n-butanol, up to 90.6% yield of n-butyl levulinate and 100% conversion of furfuryl alcohol was achieved by optimizing the reaction conditions. In comparison with other solid acids such as HZSM-5 zeolite and Nafion-212 resin, the better performance of SMWP could be explained by its strong acidity and good affinity to furfuryl alcohol, which results from the synergistic effect of SO 3 H, COOH and phenolic OH groups on the carbon surface. Moreover, the catalyst could be easily recycled with an external magnet and reused 7 times without a distinct loss of activity. The findings in this work provided an environmentally friendly manner for waste paper utilization and fuel additive production. Image 1 • A novel magnetic carbon catalyst derived from waste paper (SMWP) was fabricated. • SMWP possessed high surface area, strong acidity and good magnetic separability. • Up to 90.6% yield of n-butyl levulinate was obtained over SMWP via alcoholysis. • 90% of its original activity could be preserved after seven times recycles. [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]

In the present investigation, porous carbon fiber paper as a gas diffusion layer (GDL) of polymer electrolyte membrane fuel cell was modified by nano-structuring. It was modified by incorporating multiwall carbon nanotubes (MWCNTs) in chopped carbon fiber preform by two approaches; first by incorporating in the matrix phase and second by the in-situ growth of MWCNTs on the carbon fiber preform by chemical vapor deposition technique, followed by impregnation of phenolic resin and processed to carbonization at 1000 and 1800 °C.The effect of MWCNTs incorporation was ascertained by characterizing carbon fiber paper by various techniques. It is found that incorporation of MWCNTs reveals an increase in electrical conductivity from 66 S/cm to 175 S/cm and flexural modulus from 5 GPa to 20 GPa. The extent of increase in electrical conductivity was greater in MWCNTs mixed with phenolic resin as compared to MWCNTs grown over the carbon fiber preform. There is a significant improvement in power density from 361 to 594 mW/cm2 of MWCNTs grown based GDL. The BET contact angle increases the hydrophobicity of GDL, reduced the blockage of gas diffusion path. Also, higher value of electrical conductivity, surface area and optimal pore sizes results in the enhancement of I-V performance. • Gas diffusion layer of polymer electrolyte membrane fuel cell was modified by nano-structuring. • The MWCNTs incorporation has improved both mechanical and electrical properties of GDL. • The significant improvement in power density from 361 to 594 mW/cm2 [ABSTRACT FROM AUTHOR]

Paper mulberry, a fast-growing and vigorous plant, is a potential substrate for producing lignocellulosic bioethanol and an important renewable alternative to fossil fuels. In order to improve the economic feasibility of ethanol production from paper mulberry, H 3 PO 4 /H 2 O 2 pretreatment was selected as the most suitable pretreatment method that could produce the highest glucose concentration (131 g/L) compared with other pretreatments (73.2–89.3 g/L) at high solid loading. Whereafter, the final solid loading of H 3 PO 4 /H 2 O 2 pretreatment was significantly increased to 40% (w/v) without any decrease in the final glucose concentration. Finally, a novel Fed-nonisothermal-simultaneous saccharification and fermentation was constructed using H 3 PO 4 /H 2 O 2 pretreated paper mulberry, which bypassed the inhibition caused by paper mulberry solid and high temperature on the traditional simultaneous saccharification and fermentation, improving ethanol concentration (63.9 g/L), ethanol productivity (1.33 g/L/h) and ethanol yield (0.160 g/g-biomass) by 30.4%, 30.4% and 30.1%, respectively, compared to those obtained from SSF (simultaneous saccharification and fermentation) process. Thus, we have opened up a novel way to produce ethanol or other biofuels using the paper mulberry as an outstanding alternative substrate. • We are the first to produce ethanol from paper mulberry. • An extremely high solid loading (40%) was used in the pretreatment process. • A novel Fed-nonisothermal-SSF was developed, improving ethanol yield by 30.1%. [ABSTRACT FROM AUTHOR]

Paper sludge samples collected from recycling mills exhibited high ash content in the range of 54.59%–65.50% and glucose concentrations between 21.97% and 31.11%. Washing the sludge reduced the total ash content to between 10.7% and 19.31% and increased the concentration of glucose, xylose and lignin. Samples were screened for ethanol production and fed-batch simultaneous saccharification and fermentation (SSF) was optimised for the washed samples that resulted in highest and lowest ethanol concentrations. Maximum ethanol concentrations of 57.31 g/L and 47.72 g/L (94.07% and 85.34% of the maximum theoretical yield, respectively) was predicted for high and low fermentative potential samples, respectively, and was experimentally achieved with 1% deviation. A generic set of process conditions were established for the conversion of high ash-containing paper sludge to ethanol. Techno-economic analysis based on three different revenue scenarios, together with Monte Carlo analysis revealed 95% probability of achieving IRR values in excess of 25% at a paper sludge feed rate of 15 t/d. Feed rates of 30 t/d and 50 t/d exhibited a cumulative probability of 100%. This study presents the technical feasibility and economic viability of paper mills expansion towards bioethanol production from paper sludge. [ABSTRACT FROM AUTHOR]

Abstract The effects of paper waste (PW) ratio on biogas production by two-stage thermophilic anaerobic co-digestion (coAD) of food waste (FW) and PW, two main components of organic fraction of municipal solid waste, were evaluated in lab-scale continuously stirred tank systems with semi-continuous feeding. Four PW ratios (0, 20, 40, and 50%) were studied in the test. The experimental results showed the two-stage thermophilic coAD could operate stably after an adjustment period at all PW ratios. Although the increase of PW ratio decreased methane content, production and yield, reaction rates of four AD steps, it could increase the methane production of substrate when the FW was fixed. The pH, total volatile fatty acids, total alkalinity, and total ammonium of the sludge in the second stage of AD, also decreased with the increase of PW ratio in the test. The change of the substrate's organic composition, increase of carbohydrate and decrease of protein and lipid, were the main reason for the decrease of methane content, production and yield and changes of the second stage sludge characteristics. An apposite PW ratio (PW-20%) could enhance the degradation of matters (TS, VS and TCOD). Highlights • Increase of PW ratio decrease the of biogas and methane yield of mixture. • Increase of PW ratio increase the methane production when FW was fixed. • Some characteristics of second stage sludge decreased with increase of PW ratio. • 20% of PW ratio could enhance the degradation of matters (TS, VS and TCOD). • Changes of organic composition were the main reason for experimental result. [ABSTRACT FROM AUTHOR]

A two-stage thermophilic hydrogen fermentation and mesophilic methane production from paper sludge was successfully explored. The maximum hydrogen and methane potential were 0.165 L/g VS and 0.376 L/g COD effluent , respectively with Clostridium thermocellum augmentation. 63 L of hydrogen and 122 L of methane were recovered from 1 kg Paper sludge (PS, dry weight) with an energy yield of 4.5 MJ/kg PS, 50% higher compared to the single-stage anaerobic digestion (94 L CH 4 , 3.0 MJ/kg PS). The bacterial community of second-stage process was dominated by genus Propionispira , Mesotoga and Aminobecterium with stability, whereas the bacterial structure in single-stage process presented dynamic changes where genus Acetivibrio and Fibrobacter played an indispensable role. However, Genus Methanosaeta , Methanosarcina , Methanobacterium and Methanospirillum existed stably and predominantly in the archaeal community of single-stage and second-stage processes. The present study suggests the potential application of the established two-stage process in valorization of low-value waste biomass. Image 1 • C. thermocellum enhanced two-stage H 2 and CH 4 production from PS was established. • 50% more energy recovery was achieved from two-stage than single-stage. • Archaeal community structure of two BMP tests showed no difference. [ABSTRACT FROM AUTHOR]

We demonstrate that fabricating low-cost microbial fuel cells (MFCs) can be done efficiently by using a paper substrate and origami techniques. A 3-D MFC was developed from a 2-D sheet of paper by integrating the anode, reservoir, cation exchange membrane (CEM) and air-cathode. The cell was easily formed by folding the paper along pre-defined creases. The entirely paper-based all-printed MFC developed in this work rapidly generated power with a small amount of bacteria-containing liquid through rapid adsorption and instant attachment of the bacteria cells to the anode. A graphite-polymer composite and graphite ink with activated carbon were readily applicable as novel anodic materials on paper and enhanced performance better than a conventional graphite ink or gold anode. The hydrophobic wax-based CEM was readily built with a commercially available wax printer and using heat to control how deep the wax penetrated the paper. This work will create a novel platform for paper-based power source, stepping toward batch-fabricable flexible papertronics. [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]

Waste paper as a kind of biomass contains a great quantity of cellulose which is a renewable energy resource. However, complex cellulose supramolecular structure restricts the conversion of waste paper in near-critical water. This study aimed to investigate the change characteristics of cellulose supramolecular structure (hydrogen bond models and crystallinity) during hydrolysis and its effects on 5-HMF yield. Waste paper has been treated in near-critical water at 375 °C and 22.5 MPa for a reaction time (160–240 s) and correlation between 5-HMF yield and the supramolecular structure of cellulose residues has been built up. The 5-HMF yield was increased with the increase of intermolecular hydrogen bonds content in cellulose residues and was increased first and then decreased with the increase of crystallinity of cellulose residues. The rate of decrystallization was out of sync with that of depolymerization, which also influenced 5-HMF yield. Reaction time can be a macro method to adjust the supramolecular structure of cellulose during the conversion of waste paper to obtain more 5-HMF. It showed that 5-HMF yield reached maximum 9.41% ± 0.47% when the intermolecular hydrogen bonds content of cellulose in residue was 67.77% and the crystallinity of cellulose in residue was 57.14% at 200 s. [ABSTRACT FROM AUTHOR]

An enormous gap exists between Africa's current electrification rate and the 2030 UN goal to ensure universal access to modern energy. A study by Sanoh et al. published in Renewable Energy in 2014 [1] is a rare example of finding a cost minimal solution for the Africa-wide generation and transmission network. Unfortunately, however, the paper exhibits a number of relatively serious flaws that demand attention given the alarming paucity of such research on Africa. Five issues of the study by Sanoh et al. are identified and discussed in this commentary paper. Specifically, the study does not account for capacity factors when deriving required capacity additions, misses transmission losses when sizing generation capacity, models country-level import constraints incorrectly, introduces a supply option redundancy, and reports optimisation results that can be shown to be mathematically sub-optimal. As a result of some of these issues, the Sanoh et al. significantly underreport the required capacity to meet additional African demand in 2025. In addition to discussing these flaws, this paper provides potential approaches to avoid each of the five issues. [ABSTRACT FROM AUTHOR]

This work focused on the anaerobic digestion performance of pulp and paper mill sludge (PPMS) pretreated with the microbial consortium OEM1, and exposing the mechanism of performance variations as well. It was found that the methane yield was increased 1.4-fold by pretreating feedstocks with the active OEM1, and the maximum methane yield of 429.19 mL/gVS was noted. Moreover, an appropriate pH range of 6.1–7.5 was found in this digester, and no VFA inhibition was observed. A higher level of stability was also detected in this system based on the analysis of ORP, alkalinity and VFA/TA ratio. Also, a higher lignin decomposition rate was determined in the coupled pretreatment - AD process with the active OEM1 addition, and a 5-fold increase of AOX degradation efficiency was found in the pretreatment stage. Hence, a brighter future of developing OEM1 pretreatment for PPMS before AD could be predicted based on the capabilities of selective delignification and effective AOX degradation. [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]

This study concerns the use of conductive carbon material with different content and structure to produce carbon fiber paper for use in proton exchange membrane fuel cells, and investigates how changes in the content and structure of the conductive carbon material influence fuel cell performance. In this study, phenolic resin is used as a conductive carbon material, and is subjected to heat treatment at temperatures of 700 °C, 1000 °C, and 1400 °C, which changes its structure. Before carbon fiber paper is prepared from carbon felt, the felt is treated with phenolic resin solutions with resin content of 5, 10, 15, 20, 25, and 30 wt%. During fuel cell testing, torsion of 40, 60, 80, 100, and 120 kgf-cm is applied. The study found that when the phenolic resin content is 15 wt%, the heat treatment temperature 1400 °C, the test area 25 cm 2 , and the test temperature 65 °C, a fuel cell can achieve a current density of 2020 mA cm −2 at 0.5 V and torque of 120 kgf-cm. [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 paper investigates the impact of combining CO2 capture and storage with alternative systems for biomass-based combined heat and power production (CHP) in Kraft pulp and paper mills. We compare heat, power, and CO2 balances of systems with alternative configurations of the CHP and CO2-capture systems. Because the captured CO2 comes from renewable biomass, the studied systems yield negative CO2 emissions. It is shown that pulp mills and integrated pulp and paper mills have the potential to become net exporters of biomass-based electricity while at the same time removing CO2 from the atmosphere on a net basis. The study shows that that the overall best CO2 abatement is achieved when CO2 capture is carried out within a biomass integrated gasifier with combined cycle where the syngas undergoes a CO-shift reaction. This configuration combines efficient energy conversion with a high CO2 capture efficiency. Furthermore, cost curves are constructed, which show how the cost of CO2 capture and storage in pulp and paper mills depends on system configuration and the CO2 transportation distance. [Copyright &y& Elsevier]

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]

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]

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]

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]

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]

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 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]

The paper entitled “An economic analysis of energy requirements and input costs for tomato production in Turkey” used energy input–output analysis in tomato (industrial type) production and compare it with production costs. The research also pursued to analyze the effect of farm size. As a result of that research, the authors claimed that the better benefit–cost ratio was found on the large farms and it was more successful in economic performance. However, there are some minor and major miscalculations that could, and perhaps should be added to the result section. [ABSTRACT FROM AUTHOR]