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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]

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]

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]

The carbon neutrality goal places greater demands on integrated energy system (IES) in rural areas. In line with this trend, a multi-objective stochastic-robust based selection-allocation-operation cooperative optimization model is established for planning of rural IES in this paper. Firstly, this paper construct three typical IESs at three levels (user, township and user-township interaction) and make economic selection. Secondly, in order to coordinate the objectives of technology-economy-environment and solve the multiple uncertainties existing in the system, a multi-objective stochastic-robust planning model is proposed. In the model, the objective function introduces indicators such as total cost, primary energy resource efficiency and renewable energy consumption rate. Then constructing stochastic hierarchical scenarios to characterize the stochastic uncertainty of parameters in the time dimension. And introducing typical scenarios into the box sets which characterize the supply-demand sides uncertainty. Finally, a sensitivity analysis is performed to discuss the influence of robustness parameters and biogas prices. The annual total cost of the user-township interaction system is 53.8 % and 8.4 % lower than that of the other two systems, respectively. And from the allocation results of selected system, primary energy resource efficiency is 0.57, total cost is 1.81 × 106 USD and renewable energy consumption rate is 99.46 %. In addition, from the operation results, it is analyzed that the output of the equipment is perfectly balanced with the user's load. Finally, it is obtained by sensitivity analysis that uncertainty budget and biogas price have an impact on the selection of discrete equipment, the capacity of continuous equipment and the total cost. And the optimal capacity of the system under different situations is given. [ABSTRACT FROM AUTHOR]

Asia, the continent most vulnerable to climate change, presents policymakers with the dual challenges of significant income inequality and a scarcity of alternative energy sources. This paper investigates the impact of climate change on income inequality, and the role of renewable energy in moderating this impact for a panel data set of 36 Asian countries over the period of 1990–2021. Results from panel data analysis techniques show that climate change exacerbates the income inequality while renewable energy not only reduces income inequality but also lessens the detrimental impact of climate change on income equality through the channels of job creation and access to renewable energy. Remarkably, the role of renewable energy becomes stronger in those countries that are more exposed to climate change. The findings are robust with different estimation methods as well as various proxies of climate change and income inequality. These results highlight the critical role of renewable energy policies in promoting both environmental sustainability and socioeconomic equity. Through this paper, we aim to provide invaluable insights that can aid policymakers in making informed decisions to advance a future marked by sustainability, equity, and resilience. [ABSTRACT FROM AUTHOR]

The microbial fuel cell is a new kind of green power generation technology. In this paper, the graphene oxide was reduced with hydrazine hydrate at a constant temperature. And the composite anode material of reduced graphene oxide and capacitive polyaniline was used to construct the microbial fuel cell, which had the simultaneous function of power generation and energy storage. The experimental results showed that the power density of the microbial fuel cell comprising the carbon felt/reduced graphene oxide/polyaniline anode was 2.19 times higher than that of the carbon felt/polyaniline anode. In the charging 30 min-discharging 30 min test, the stored charge by the carbon felt/reduced graphene oxide/polyaniline anode was 675.44 C/m2, 5.42 times that of the control anode (124.55 C/m2). In the high throughput test, the surface of the carbon felt/reduced graphene oxide/polyaniline modified anode was 1.75 times higher than that of the control anode. The reduced graphene oxide/polyaniline capacitive composite biological anode material prepared here had the advantages to simultaneously generate electricity and store energy. This paper is expected to break through the current performance bottleneck of microbial fuel cells and improve their performance in energy conversion efficiency and stability. Structure diagram of MFC equipped with CF/RGO/PANI anode. [Display omitted] [ABSTRACT FROM AUTHOR]

As a large amount of wind energy is integrated into the grid, the randomness it brings poses a challenge to modern power systems. The application of Flexible AC Transmission Systems (FACTS) in the grid is becoming more and more common, and it is necessary to consider how to choose suitable equipment in the appropriate locations. In this paper, a multi-objective optimal power flow (MOOPF) model with wind farms and FACTS devices is established. The Weibull probability density function is used to establish the wind speed model, and the cost problem brought by wind power is considered. The locations and ratings of thyristor-controlled series compensators, thyristor-controlled phase shifters, and static VAR compensators are added to the system as control variables. In addition, the constraints on the prohibited operating areas of thermal power generators and the valve point effect are also considered. Coevolutionary constrained multi-objective optimization algorithm (CCMO) is an advanced technology, and this paper improves it and names it two-stage coevolutionary constrained multi-objective optimization algorithm (TSCCMO). The proposed algorithm uses the constraint violation value as an additional objective function in the sub-population environmental selection process, and integrates a neighborhood selection strategy into the mating selection process. The population evolution process is divided into two stages, in the first stage the two populations cooperate weakly, and in the second stage the two populations will have strong cooperation. TSCCMO is used to solve this complex constrained MOOPF problem, and its results are compared and analyzed with CCMO, NSGA–II–CDP, C3M, and PPS. The comprehensive performance of TSCCMO is the best among the 6 cases. [ABSTRACT FROM AUTHOR]

In recent years, the use of cold ironing (CI) has effectively reduced the carbon emissions of ships in port areas. However, due to the limitation of port CI quantity and power supply capacity, the power demand of some ships cannot be met. To solve this problem, this paper proposes a multi-ship power sharing strategy based on two-stage robust optimization and improved Shapley value method. Firstly, considering the uncertainty of ship photovoltaic power generation, a multi-ship power sharing model based on two-stage robust optimization is established. This model is a three-level optimization model with mixed integer variables, which is a NP-hard problem. In this paper, the nested column-and-constraint generation algorithm combined with duality theory and big-M method is used to obtain the optimal scheduling strategy of ship shared power, CI power and load demand response power. Secondly, an improved Shapley value method considering berth and remaining berthing time is proposed to realize the cost allocation in the process of ship power sharing. Finally, the effectiveness of the multi-ship power sharing strategy in reducing berthing costs and carbon emissions is verified by simulation. This method is expected to provide a new idea for the development of green ports. • The energy scheduling of ships in port is optimized. • A power sharing strategy for multi-ships in port is proposed. • A cost allocation strategy considering ship mobility is designed. • A two-stage robust optimization algorithm based on NC&CG is developed. • The operation cost and carbon emission of berthing ships are reduced. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of the design, implementation, experimentation, and optimization of a novel evacuated flat-plate solar thermal collector characterized by a vacuum level between the glass cover and the absorber plate. The paper addresses different research themes, primarily focusing on developing a low-cost evacuated solar thermal collector with a high innovation level. Additionally, it introduces a comprehensive approach for the conceptualization, design, fabrication, testing, and optimization of solar thermal collectors. Specifically, this study aims to highlight the characteristics of a vacuum-enhanced solar thermal collector and demonstrate a step-by-step process involved in its design, fabrication, testing, and optimization. The proposed methodology is based on the adoption of two software tools and an extensive experimental analysis: the commercial software ANSYS is utilized for structural analysis, while MatLab is employed to develop a suitable mathematical tool for assessing the energy performance of the system and optimizing it. The outcomes show the reliability of the methodology and the performance of the low-cost evacuated solar thermal collector under different vacuum levels, providing insights into energy, economic, and environmental aspects. This work innovates by presenting a thorough analysis covering all solar thermal collector production phases, from conceptualization to optimization. The conclusions highlight the production of a reliable approach, and proof-of-concept results demonstrate how increasing the vacuum level enhances the thermal efficiency of a solar collector. [ABSTRACT FROM AUTHOR]

CO 2 pipeline can be applied to Enhanced Oil Recovery (EOR) projects and CO 2 geological storage projects, and has high engineering application value. However, pipeline transportation of CO 2 is a high-risk link in CO 2 storage projects. The phase state commonly used to transport CO 2 is a supercritical state with both gaseous and liquid characteristics, and there are also great challenges in the field of pipeline transportation. The existing researches have carried out a lot of exploration and application development in the heat transfer, phase change, transient and special conditions of supercritical CO 2 pipeline operation. In this paper, the modeling and exploration of the commissioning process before the formal operation of the supercritical CO 2 pipeline are carried out, and the boost path of the supercritical CO 2 pipeline in the phase diagram under different working conditions is obtained. The model developed in this paper is based on the sensitivity analysis of the effects of variables such as ground temperature, filling pressure speed, and whether to perform pressure-stabilizing leak detection operations. The step-up path in the phase diagram of the CO 2 pipeline commissioning process and the adjustment control method are obtained. And the critical temperature of each working condition that cannot avoid phase transition, thus contributing to the existing knowledge system in this field. [ABSTRACT FROM AUTHOR]

In this paper, the role of a Battery Energy Storage System (BESS) in the United Kingdom (UK) electricity market is investigated. Such device is selected since research works related to the topic demonstrate that BESSs help facing challenges caused by renewable energy sources increasing penetration in the power systems' field. Indeed, in the next future, BESSs will assume a relevant role thanks to their fast response time. In the present paper, an optimization model is implemented to encode the UK market rules and output the optimal set of offers on day-ahead and intraday markets, dynamic frequency response services and imbalance settlement. The market rules are formalised in a mathematical model considering market temporal sequencing and BESS technical limitations. The tool also models the state of energy management, necessary since BESSs are energy limited assets. Objective function and constraints are linearized to define a Mixed Integer Linear Programming problem to reduce the computational burden and to integrate the model in the Energy Management System previously developed at University of Genoa. Specific tests are performed including and excluding ancillary services to evaluate the related advantages. The obtained outcomes reveal that ancillary services are the most convenient options within all the implemented scenarios. [ABSTRACT FROM AUTHOR]

Concept-bottleneck models (CBMs) are a new paradigm to construct interpretable classifiers. The CBM architecture can be regarded as a neural network with a single hidden layer whose neurons are replaced by binary classifiers. Each of these binary classifiers implements a concept, that is, it attempts to answer a meaningful yes/no question: the presence or absence of a concept in the observation presented to the network. The output layer is usually implemented as a linear stage that combines the concepts into final decisions. This paper presents an application of the CBM paradigm to a problem of Extreme Wind Speed prediction, such that the forecasting properties of the system can be interpreted in terms of different concepts considered for this problem. A significant contribution of this paper is the proposal of an automated concept generation method, with controlled sparsity, in which the concepts are automatically extracted from the branches of decision trees fitted with informative features that capture the dynamics of the wind speed time series. The final forecasting system is able to predict extreme wind speed values in wind farms with good accuracy and interpretable results, as experiments over real wind speed data from a wind farm in Spain show. • Application of Concept Bottleneck Models for Extreme Wind Speed prediction. • Features capturing the dynamics of the wind speed borrowed from finance analysis. • Concepts are automatically extracted from the branches of decision trees. • Results in real data from a Spanish wind farm are discussed. [ABSTRACT FROM AUTHOR]

The global energy sector is currently undergoing a fundamental transformation as it shifts away from fossil fuels towards renewable energy sources. Green hydrogen is one of the most promising energy carriers of the future in the worldwide effort to reduce the carbon footprint of energy systems. The advancement and uptake of green hydrogen technologies depend on various technological, environmental, and economic factors. In this paper, a comprehensive review of recent studies in green hydrogen energy systems (GHES) is conducted, highlighting technoeconomic aspects from the component to the technology and broader system level. Firstly, the technological principles and recent progress of different green hydrogen generation, storage, and utilization technologies are summarized. Subsequently, an in-depth analysis of various technoeconomic modeling and experimental activities focused on integrated GHES is undertaken. By examining applications in the stationary and transport sectors, this review paper offers an assessment of the current state-of-the-art in terms of development and integration options. The technical challenges, key factors, and future research directions of green hydrogen technologies and systems are outlined, demonstrating that an effective, intelligent, and innovative integration of GHES with other technologies will encourage a more efficient use of resources and enhanced energy system flexibility, resilience, and energy security. • Characteristics, components and configurations of green hydrogen systems are presented. • Technoeconomic studies are collected in tabulated form and exhaustively analyzed. • State-of-the-art applications in stationary and transport sectors are discussed. • A critical review is provided to assess green hydrogen economic viability potential. • Challenges and prospects are evaluated, and future research directions are suggested. [ABSTRACT FROM AUTHOR]

Renewable energy communities with members which own electric vehicles (EVs) can benefit financially from the flexibility that EVs provide to distributed energy resources, such as photovoltaic generators. However, in residential environments, this benefit is often lost because during working hours, most EVs are not plugged in at the premises of the community. In this paper, we hypothesize that such communities can regain some of this lost benefit by offering membership to outside EV owners which are interested in charging their vehicles using the community's charging stations during these periods. This paper introduces an optimization model for energy communities consisting of prosumers, electric vehicles, and EV chargers. The model aims to evaluate the potential advantages of integrating external EV owners into an energy community. A hypothetical community representing a multi-apartment building is analyzed, considering scenarios both with and without external members. The analysis focuses on assessing the technical and economic benefits. The findings indicate that the economic benefits for the examined community are relatively small. However, a notable increase in these benefits is observed when the community is incentivized to share energy among members in the form of a flat network charge reduction for shared energy. [ABSTRACT FROM AUTHOR]

Hydropower has played an important role in Europe in recent decades, offering a unique combination of safe, low-cost, and clean power generation. Today, it is still one of the largest renewable energy sources (RES), accounting for about 35 % of RES electricity generation. However, grid stability is threatened by the increasing amount of undispatchable RES. Flexibility and dynamics such as energy storage and rapid response are urgently needed to achieve EU policy goals. In such a context, hydropower can play a key role, not only as a provider of regulated renewable energy but also due to its ability to balance a renewable energy system in the short term and the medium/long term by pumped storage technology. All these aspects underline the new role of hydropower, which aims to strengthen grid stability and power supply resilience and to enable higher penetration of volatile RES. In this context, the aim of this paper is to demonstrate the role of hydropower at the European level as well as the needs and opportunities of modernization to fully exploit its potential. In particular, this study provides, the assessment of the today flexibility offered by hydropower to the power system at the European level by leveraging a database of information collected through the participants to the working groups of the COST Action Pen@Hydropower which includes stakeholders in the hydropower sector of 34 European countries. The study confirms the key role of hydropower in future energy scenarios with 30 % of the flexibility demand at all time scales met by hydropower. Furthermore, the paper presents a review of the digitalization solutions and innovative technologies that support the growth of a new generation of sustainable hydropower together with the modernization opportunities for existing hydropower plants. The results of this work have practical implications for stakeholders in the hydropower sector and policymakers as it provides evidence at the European scale of the role of hydropower technology in balancing the power system and the need to have supportive frameworks and adequate markets to fully exploit the European hydropower potential to achieve the energy transition goals. [ABSTRACT FROM AUTHOR]

This paper presents a dual condensers heat pipe PV/T system with multiple operating modes, including hot water, space heating, and dual-function. To exploiting the system's potential of energy supply, this paper proposes a dynamic model of the system in dual-function mode on the basis of the verified dynamic heat transfer model and condenser distributed parameter model. Several effect factors on the system performance have been analyzed, including water tank capacity, air-cooled condenser area and the dual condensers installation height difference. The simulated results show that the above parameters have little effect on the system's total thermal efficiency but a significant effect on single condenser heat gain distribution. When the water tank capacity increases from 100 L to 200 L, the thermal efficiency of the water-cooled condenser increases from 10.68 % to 17.82 %, while the air-cooled condenser's decreases from 48.12 % to 40.72 %. As the air-cooled condenser area is changed from model 1 to 4, the total efficiency increase from 58.13 % to 71.41 %. The system's thermal efficiency falls from 58.66 % to 47.50 % and its overall efficiency falls from 71.41 % to 60.40 % when the height difference rises from 0 m to 0.7 m. [ABSTRACT FROM AUTHOR]

Large-scale biomass storage for modern bioenergy introduces potential safety concerns due to the intrinsic self-heating of biomass. Despite this, very limited research has been conducted in this area. This project fills a critical gap by developing a comprehensive modelling framework for self-heating in biomass piles and conducting a series of experimental studies to explore the intricate sub-processes within these piles. This paper presents only a small portion of the modelling and testing work. It successfully demonstrates the model's usefulness in predicting self-heating in coal piles, guiding safety measures for coal storage. Among various storage parameters, the pile height, particle size and ambient wind velocity have been identified as having substantial impacts on self-heating and self-ignition within the coal pile. This paper also illustrates the pronounced effects of initial biomass moisture content on microbial reactivity and oxygen consumption rate. An increase in initial moisture content significantly enhances the overall microbial reactivity and oxygen consumption rate. Wheat straw, compared to rice straw, is more prone to self-heating under identical storage conditions, as evidenced by higher heat generation, faster oxygen consumption, and a shorter time to peak temperature. Moreover, microbial activity is found to play a critical role in biomass self-heating, particularly in the temperature range of 0–75 °C, during the initial stages of heat accumulation. For the modelling discussed here, the flow within the porous pile must be considered laminar, despite the highly turbulent flow around the pile. This is based on the Reynolds number, calculated from the in-pile volume average of the velocity and the mean diameter of the fuel particles, which is significantly below the critical threshold ( R e c r = 200). The insights and sub-models to be derived from the relevant sub-processes in biomass pile can be integrated into the model framework. This integration will create a more comprehensive and robust model for predicting self-heating and self-ignition in biomass storage piles, enhancing both theoretical and practical management of these phenomena. [ABSTRACT FROM AUTHOR]

To tune the wave energy converter (WEC) controller parameters such as damping to reduce the line force during extreme wave conditions, future knowledge of the line force is required. To achieve this, the incoming wave and system state should be predicted for a few seconds in the future. It is rather an arduous task to predict the future knowledge of waves and the system's dynamic when dealing with breaking and steep waves, and the system is subject to various nonlinear forces. The classical model-based control strategies often rely on linear assumptions to estimate the WEC dynamics for the sake of simplicity. Unlike the model-based, the data-driven approaches are free from modeling errors and the algorithms are trained over the true and noisy data to predict non-linear system behaviors. Using data-driven approaches, we are able to model nonlinear dynamics. However, new questions emerge on the accuracy of the future wave and system state predictions, and how this uncertainty propagates into the final prediction of the line force. As incorrect damping may lead to excessive line force and detrimental damage to the system, these are the knowledge gaps that need to be addressed. The main purpose of this paper is to answer these questions through a survivability strategy for wave energy converters by providing a realistic perspective on the implementation of the neural network approaches by accounting for the errors in the input data. For this purpose, a series of neural networks is designed that first predicts the surface elevation for 0.36 s ahead, i.e. corresponding to 2 s in the full-scale WEC. This future knowledge of the wave elevation is then used to predict the system state (i.e. power take-off (PTO) translator position) for the same prediction horizon based on the PTO damping. This information is then fed to a convolutional neural network (CNN) that predicts the peak line force 0.36 s ahead. This paper also evaluates the predictive capabilities of neural network (NN) models, comparing them to classical autoregressive (AR) and Kalman filter methods. While the AR model exhibits slightly higher accuracy in fixed PTO system configurations, it falters in providing real-time predictions when system parameters undergo variations. In contrast, the NN prediction model excels by establishing a robust relationship between system configuration and output signals. Especially noteworthy is its ability to outperform classical methods with minimal training on a selective set of system configurations. Then, the sensitivity of the peak line force prediction to the uncertainties in the input data from NN models and the prediction horizon is analyzed. The neural network models are trained over the experimental data subjected to extreme sea states for a point absorber wave energy converter. The results suggest that the accuracy of the surface elevation prediction has an insignificant direct effect on the peak force prediction model. However, these uncertainties are reflected in the PTO translator position prediction, and the model is considerably sensitive to the accuracy of this prediction. This sensitivity nonetheless is less notable for higher PTO damping values. • Predicting wave elevation, PTO position, and mooring force via neural networks. • Finding optimum damping to reduce mooring force in extreme wave conditions. • Predicting the mooring force is sensitive to the PTO position prediction. [ABSTRACT FROM AUTHOR]

Organic municipal waste is a mixture of carbonaceous feedstock and cross-interaction of volatiles in their co-pyrolysis has been well documented, but quantifying their extent of interactions in co-pyrolysis is difficult. In this study, the ratio of char yield from co-pyrolysis to calculated average of pyrolysis of single feedstock was used as an indicator to probe the interaction in co-pyrolysis of every two typical carbonaceous wastes (sawdust, rice, spinach, chicken manure, office paper, corrugated paper, plastic bottles/films, fiber towel) at 550 °C. The results indicated that the co-pyrolysis of sawdust and corrugated paper had the highest degree of interaction (0.44). Sawdust and rice with ash-rich feedstock (spinach, chicken manure and office paper) resulted in dominance of gasification reactions to reduce char production in co-pyrolysis process. In comparison, the organics from the degradation of spinach and corrugated/office paper could react with the derivatives (mostly radicals) of plastic bottle (PET), plastic film (PE) or fiber towel (polyesters) via secondary condensation to generate more char. The chicken manure with high ash content hardly forms char of enhanced yield during its co-pyrolysis with other feedstocks. The enhancing char yield through secondary condensation generally resulted in additional oxygen-containing deposit on char and reduced thermal stability, which was the opposite to the formation of char with dominance of gasification. Co-pyrolysis of varied feedstock also led to change of morphologies of char via filling mechanism or formation of organics. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a combined passive graded metal foam and active mechanical rotation strategy is proposed to simultaneously solve the problem of slow melting rate and non-uniform phase change problem of the latent heat thermal energy storage (LHTES) technology. The enthalpy-porosity method and fixed grid structure are employed to numerically investigate the effects of porosity range, the number of graded layers, and the rotational angular velocity. Moreover, the response surface method (RSM) is further selected to optimize the structural parameters and obtain the function of melting performance and various factors. The result shows that there is an optimal porosity range and the total melting time decreases first and then increases with the increase of porosity range. When the porosity range is 12 % and the graded layer is three, it can shorten the melting time by 35.54 % and increase the thermal energy storage rate (TESR) by 51.57 %. In addition, the melting performance is gradually improved as the number of graded layers increases. The strengthening effect of graded metal foam with just four layers is close to that of the maximum layers considered in this paper. The trend of the influence of rotation speed on the melting performance of the LHTES unit is consistent with the porosity range, indicating the existence of the optimal rotational speed. The RSM optimization structure, with a 14.969 % porosity range, 5-layer graded number, and 2.267 rpm rotational speed, shortens the melting time by 42.42 % and increases the TESR by 62.75 % compared with the stationary case with uniform metal foam. This work verifies the effectiveness of active rotation coupling with passive graded porous structures, which could provide a new strengthening approach to enhance LHTES. • A strengthening strategy combining graded porous and rotation is proposed. • It realizes the synergistic enhancement of natural convection and heat conduction. • The effects of porosity range, graded layer, and rotational speed are considered. • The structural and rotary parameters are further optimized by the RSM. • Compared to the base case, the optimized case reduces melting time by 42.42 %. [ABSTRACT FROM AUTHOR]

This review reports a quantitative analysis across the deterministic photovoltaic (PV) power forecasting approaches. Model accuracy tests from papers passing a set of selection criteria are collected in a database, along with the meta-information necessary to describe the forecast scenarios. The selection criteria ensure a framework for inter-comparison analyses. 66 papers were found that pass the selection stage, constituting an arbitrary sample of the literature in terms of forecast scenario. Therefore, this review generates a reliable picture of the state-of-the-art in the accuracy of deterministic PV power forecasting. Despite the apparent wealth of the forecasting studies, a detailed analysis is foreclosed by the small number of entries into the database for different scenarios. Simple and hybrid Machine Learning models are the most popular choice. Studies performed in Europe, Asia and North America are dominant, with the majority of locations having a temperate climate (46/66). The number of studies in arid (10/66) and tropical (8/66) climates is small, even with the high speed development of the PV sector. Physics-based models are weakly represented. A set of recommendations on reporting the results of deterministic forecasts and metadata is proposed. A detailed description of forecast scenarios, employed accuracy metrics, and all operations applied on the data is crucial for ensuring a realistic inter-comparability of models' performance. • A quantitative analysis across PV power forecasting scenarios is performed. • nRMSE, MAPE and skill score are collected from 66 studies. • Model class, climate and forecast timescales are the most influential factors. • Test set length, metric normalization and other parameters impede inter-comparability. • Numerous gaps and biases found, despite apparent wealth of publications. [ABSTRACT FROM AUTHOR]

Green ammonia, a promising zero-carbon energy storage vector, has never been produced using solely tidal stream energy despite its predictable characteristics. Combining tidal stream sites with a phase difference (tidal phasing) facilitates anticorrelation between these sites' power profiles, enabling a more consistent power output. Green ammonia production benefits from a steady and predictable power input. The objective of this paper is to determine if nearby tidal sites have a large enough phase difference (anticorrelation) to reduce the cost of ammonia production. Moreover, producing green ammonia from underutilized or unutilized remote and grid-constrained tidal stream sites may enable viability of these sites. This paper is the first analysis of green ammonia production using solely tidal stream energy and the first analysis of tidal phasing for green fuel production. Two UK case studies are presented in i) the North Channel of the Irish Sea and ii) Orkney. There are tidal sites in each which have a phase difference (e.g. the Mull of Kintyre/Sound of Islay, and Graemsay/North Ronaldsay with correlation coefficients of 0.17 and −0.02 respectively), utilising this phase difference reduces the levelized cost of ammonia by 8% in the Irish Sea and by 12% in Orkney. [ABSTRACT FROM AUTHOR]

Designing the support structures for floating wind turbines (FWTs) involves a step-by-step process, typically in three phases, i.e., starting from concept selection and determining the overall dimensions for a given configuration, and finally, determining the detailed specifications. The global design of the hull is used to select the floater concept and determine the global dimensions for the subsequent detailed design. This global design process is a crucial part of the entire design cycle because it has a significant impact on the detailed design, which can be computationally expensive. However, because FWTs are still in the infancy stage of development, there is a lack of effective methods and procedures for determining the global dimensions of floaters. Additionally, the global response characteristics of different hull layouts are not yet well understood. To address these limitations, this paper deals with a global design of semi-submersible floaters to support large-scale wind turbines (using a 10-MW turbine as an example). The paper proposes and describes a methodology and procedures for the global design in detail, specifying criteria and values for a case study. Furthermore, a sensitivity study is conducted to determine the global dimensions of the floaters. Then, intact stability is studied to evaluate their safety in operation under wind loads. Subsequently, global aspects of structural design are analyzed based on wave-induced response amplitude operators (RAOs) of cross-sectional forces and moments, taking into account representative environmental conditions for an offshore site. These analyses provide a foundation for the subsequent detailed design. The results indicate that the spacing of the column centerline and the outer column radius are the most critical design variables for the global response of the semi-submersible hull. Moreover, increasing the outer column radius or freeboard can effectively enhance intact stability. In addition, the study highlights the importance of critical wave periods that cause splitting or prying force on the hull columns in the structural design. Finally, the main findings and conclusions are summarized. This study presents a simplified yet innovative methodology for the global design of mainstream semi-submersible hulls for FWTs. It addresses the lack of effective methods for determining global dimensions and provides valuable insights into the structural design considerations. [ABSTRACT FROM AUTHOR]

Chemical Looping Combustion (CLC) is a carbon capture technology that uses an oxygen carrier to transfer the oxidizing agent to the fuel for combustion. This study used different machine learning algorithms, Artificial neural network and Response surface methodology to estimate the surface region process performance and optimize the process condition for the CLC of different solid fuels waste paper, plastic waste, and sugarcane bagasse blends. Based on the combustion efficiency, CO 2 yield and CO 2 capture efficiency responses, A high performance correlation (R2 > 0.8) was obtained for all the combustion parameters analyzed. The perturbation plot derived from the RSM analysis indicated that the most significant input parameters include the steam to fixed carbon, blend ratio and the fuel reaction temperature. The CLC process was optimized using RSM. For blends of SCB/WP, the best operating conditions were found to be 800 °C, a solid flow rate of 197.7 kg/h, an oxygen carrier to fuel ratio of 1.1, a steam to fixed carbon ratio of 2.16, and a blend ratio of 1. Similarly, for blends of SCB/PW, the optimal operating conditions were 800 °C, a solid flow rate of 199.4 kg/h, an oxygen carrier to fuel ratio of 1.3, steam to fixed carbon ratio of 2, and a blend ratio of 0.3. The optimum combustion performance was found to be 0.98, 0.78, and 0.96 for SCB/WP and 0.99, 0.62, and 0.96 for SCB/PW, respectively. • The process performance of the CLC of MSW/biomass blend was compared using ANN and RSM. • The optimal blend ratios for SCB/WP and SCB/PW blends were 1 (25% WP) and 0.3 (42.5% PW). • The combustion performance of the WP improved by 6.2% and 3.5% in terms of combustion efficiency and CO 2 yield, respectively. • The most significant input factors were discovered to be the blend of fuels ratio and the steam to fixed carbon ratio. [ABSTRACT FROM AUTHOR]

Biomass direct-fired power plant integrated with carbon capture system can achieve negative CO 2 emission during the power generation, which provides an important technology pathway for the transformation of energy system towards carbon neutrality. Understanding the economic competitiveness and CO 2 reduction potential of the plant, and identifying the optimal operating mode are the key to fully exert the advantages of the technology. For this reason, this paper develops life cycle economic and CO 2 emission assessment models for the biomass direct-fired circulating fluidized bed boiler power plant (BCFBP) integrated with solvent-based post-combustion carbon capture (PCC) system. The levelized cost and CO 2 emission of energy indexes are then applied to evaluate the performance of the BCFBP-PCC system. Based on the life cycle assessment, a novel economy and CO 2 reduction dual-objective operating optimization approach is proposed for the BCFBP-PCC to find the optimal hourly power generation and CO 2 capture level of the plant under given market conditions. The static investment payback period is employed as a constraint in the optimization to narrow down the range of the solution set and provide clearer guidance for system operation. This paper provides the first work pioneered the economic and negative carbon operation optimization of the BCFBP-PCC system. [ABSTRACT FROM AUTHOR]

To efficiently utilize the abundant wave power in the ocean, it is necessary to deploy a wave farm. This paper considers a wave farm of oscillating water columns (OWCs) integrated into tubular structures. Each OWC device within the wave farm is constructed with a vertical tubular design, incorporating a partially open submerged side that faces the sea. At the top of each device, an air turbine is installed to harness the pneumatic power generated by incoming water waves. To assess the performance of the wave farm, an analytical model is developed using the eigenfunction matching method within the framework of linear potential flow theory. Subsequently, this model is utilized to assess the efficiency of two wave farm setups: a line array with varying numbers of devices and a square array consisting of four devices. When the openings of the OWC devices are deployed on the exterior side of the square array, the majority of the wave power captured by the wave farm is contributed by the windward OWC devices, over a wide range of wave conditions examined. However, when the openings are placed on the interior side of the square array, wave resonance among the OWC devices becomes a significant factor affecting the wave farm's performance. In this case, the leeward devices could capture more wave power compared to the windward ones. Large wave excitation forces acting on the OWC devices can be excited when the near-trapping of waves arises in a wave farm consisting of a circular array of OWC devices. The physical findings in this paper highlight the importance of the array configuration and opening arrangement for optimizing wave power extraction in wave farms. • We consider an array of oscillating water columns integrated into tubular structures. • An analytical model is developed to solve hydrodynamic problems. • We consider a line array of devices and a square array with four devices. • Windward devices capture most wave power in square array with exterior openings. • Wave resonance crucially impacts square array performance with interior openings. [ABSTRACT FROM AUTHOR]

Increasing the demand for water and energy resources as well as the clean energy policies and the need for pollution emission reduction has developed the research on the renewable energy resources. This paper reviews the recent advances in multi-generation units for heat, electricity, and desalinated water production. It tries to investigate the new papers in this arena which were not mentioned in the previous reviews. The main parts of this work introduce the co-generation systems for the production of "water and electricity", "heat and water", and "electricity, water, and heat". The results show that among the solar energy receiving devices, Photovoltaic/Thermal panels (PV/Ts) and parabolic trough solar collectors are the most used in co-generation systems. On the other hand, a combination of solar collectors and power cycles makes them a suitable choice for the establishment of a large-scale co-generation plant. Therefore, solar collector-based electricity and water co-generation systems have at least 10 times more output capacity than PV- or PV/T-based systems. On the other hand, most heat and water co-generation systems can achieve an output temperature of 60 °C or more and produce around 10000 kg/year of freshwater based on system size. Examining the co-generation systems of water, electricity and heat also shows that these systems have a high production capacity compared to other co-generation systems. Systems based on heliostat solar tower can produce maximum powers of more than 18 MW and fresh water of 90 kg/s. • Recent advances in solar multi-generation units are reviewed. • PV/Ts and parabolic trough solar collectors are most used collectors in cogeneration systems. • RO and MED have more applications in solar-based co-generation units. • Using waste heat can increase technical and economic performance of system. [ABSTRACT FROM AUTHOR]

In this paper, an exploratory data analysis method is employed to investigate the impact of different system parameter combinations on the magnitude and stability of power of flow-induced vibration (FIV). Firstly, orthogonal experimental design within exploratory data analysis is used to set up numerical simulations of flow-induced vibration and collect data on FIV power generation characteristics. Then range method is used to select the optimal parameters combination for flow-induced vibration power generation, and the degree of influence of different system parameters on power and stability is quantitatively described by variance and entropy weight methods. Our results reveal that the optimal parameter combination for power corresponds to m* = 1.343, K = 1200 and ζ = 0.08, and the optimal parameter combination for stability is m* = 1.343, K = 1200 and ζ = 0.04. Additionally, the weight relationship of each system parameter affecting power and stability is W K > W ζ > W m* and W ζ > W m* > W K , respectively. These weight relationships allow for the effective adjustment of the parameter levels to quickly achieve the goal of optimizing power and stability. A new parameter P value-stability is proposed to comprehensively evaluate power magnitude and power stability, and optimal parameter combinations in different vibration branches is achieved. This paper provides new ideas and guidance for the design of the FIV energy harvesting device. [ABSTRACT FROM AUTHOR]

Integrating biomass, photovoltaic, and other renewable energy sources for hydrogen production can form a biomass-photovoltaic-hydrogen integrated energy system (BPH-IES). The system features multi-energy storage and joint supply, as well as cascaded utilization, is a promising co-generation way to meet the system's electricity, heat and hydrogen needs, and has significant energy-exergy-economy-environment (4E) performance. Therefore, scientific and effective evaluation of the BPH-IES is an important prerequisite for promoting its development. Firstly, by analyzing the structure of the BPH-IES system, this paper constructs a comprehensive performance evaluation index system of the system from the 4E dimensions. Secondly, a hybrid multi-criterion decision making (MCDM) framework for the 4E comprehensive performance evaluation of the BPH-IES is constructed, in which the anti-entropy weighting method is used to determine the objective weights, the subjective weights are determined by the decision making trial and evaluation laboratory method improved by intuitionistic fuzzy sets, and the final combined weighting results are obtained based on a game-theoretic method that the objective and subjective weights' heterogeneity can be fully minimized. The grey-relation-analysis-based measurement alternatives and ranking according to the compromise solution method is proposed to determine the ranking of alternatives. This paper selected 8 typical BPH-IES cases for 4E evaluation analysis. The results showed that energy performance is the core dimension that reflects the 4E performance of the system, and system's economy indicators such as energy supply income and energy supply cost will also significantly affect the system's 4E performance. Therefore, the 4E performance of BPH-IES can be effectively improved by expanding the system's demand and supply scale and increasing the system's installed proportion of clean energy and hydrogen penetration. Finally, the ranking consistency test, Leave-One-Out analysis and sample separation test demonstrate that the developed hybrid MCDM can ensure robustness meanwhile improve the decision efficiency. [ABSTRACT FROM AUTHOR]

With the increasing demand of users for distributed energy storage (ES) resources and the emerging development of peer to peer (P2P) transaction technology, shared energy storage (SES) has great potential to contribute into new business models of demand-side ES. In order to compromise essential elements like safety, stability and efficiency of P2P trading, as well as to improve the utilization rate of demand-side ES, this paper devotes to construct a P2P transaction framework based on a partially decentralized topology and proposes a two-stage trading optimization strategy of SES in a P2P market, considering the equilibrium state of supply and demand flow. In the first stage, this paper simultaneously balances the interests of buyers and sellers and brings the carbon trading mechanism into the transaction process. The interaction of interests of bilateral parties with consideration of carbon trading mechanism has been investigated, and a SES capacity sharing model is, then, established based on the bargaining game theory. In the second stage, a unique pricing mechanism for SES leasing fee is designed based on a multi-strategy evolutionary game model, considering bounded rational decision-making for SES operators and communities. Finally, numerical simulation verified the feasibility and superiority of the proposed P2P trading strategy of SES. [ABSTRACT FROM AUTHOR]

In recent years, the government has attached great importance to promoting innovation in new energy technologies, particularly in the area of solar power generation. Photovoltaic (PV) power generation has become an essential factor in the promotion of renewable energy due to its inherent safety, environmental sustainability and abundant solar energy resources. The efficiency and stability of PV generation systems are closely related to the accurate prediction of real-time global horizontal irradiance (GHI). However, some existing research methods have made some progress in hourly resolution, but the multi-step prediction accuracy and model generalization ability in high time resolution are still unsatisfactory. Therefore, this paper proposes a novel minutely multi-step irradiance forecasting based on all-sky images using LSTM-InformerStack hybrid model with dual feature enhancement scheme. In this scheme, the advantages of both LSTM and InformerStack models are combined to further enhance the global and local features, which can better capture the short-term time series patterns and long-term dependencies and improve the accuracy of the time series. The experimental validation results show that the performance of this prediction scheme is improved by 11.2%, and 26.0% for nRMSE and R2, respectively, and the 24-step prediction can be improved up to 26.1% vs. the persistent model. Meanwhile, the prediction scheme of this paper is also expected to provide a reference in future multi-step time series accurate prediction with higher resolution. [ABSTRACT FROM AUTHOR]

This paper proposes the use of Artificial Neural Networks (ANNs), specifically Physics-Informed Neural Networks (PINNs), for dynamic surrogate modelling of wind turbines. PINNs offer the flexibility to model complex relationships while incorporating physics-based constraints, enabling accurate representation of wind turbine dynamics. In this paper, a PINN-based surrogate model is developed for the Blade Element Momentum (BEM) aerodynamic model used in state-of-the-art numerical wind turbine simulations. The PINN model replaces the time-consuming root-finding process in BEM with high-dimensional regression, significantly improving computational efficiency. The PINN model is trained using data generated from a numerical model of the IEA-15MW reference wind turbine, and its performance is compared against conventional data-driven Neural Network (DDNN) models. The proposed surrogate model provides more efficient and accurate evaluations of wind turbine responses compared with traditional surrogate modelling approaches. A significant computational advantage is obtained by using the developed surrogate models with a forty-fold speedup demonstrated compared to the BEM model. Replacing the BEM model with the PINN-based surrogate model for load computation in the numerical model used for dynamic analysis results in an overall reduction of 35% in computational time for a complete dynamic simulation. This is a substantial improvement in efficiency without sacrificing accuracy — the maximum Mean Absolute Error (MAE) values for the surrogate models are of the order of 1 0 − 2 , which shows that the surrogate models can predict the angle of attack at any blade node with a discrepancy of less than 0. 5 °. The surrogate models significantly reduce computational time while maintaining high accuracy, making them a promising approach for simulating wind turbine dynamics, especially in fields such as reliability analysis or fatigue estimation where many simulations are necessary. [ABSTRACT FROM AUTHOR]

A rapid-calculation method O (1 0 3) ∼ O (1 0 4) times faster than a typical BEM (Boundary Element Method) model is presented for optimising an array (farm) of dual-purpose wave-energy converters (WECs) that both generate electricity and protect a coast. It is known that fast semi-analytical descriptions of the wave field are available based on the far-field approach for a widely-spaced wave farm involving point-absorber-type WECs of small sizes, for which scattered waves are negligible. However, these approaches are inept at dealing with "non-small" WECs with non-simple shapes, for which scattered waves can be both complicated and non-negligible. For these devices, this paper demonstrates that a fast semi-analytical description based on a "corrected" version of the far-field approach can still be crafted for an isolated device, with the help of a BEM model. This simple description is then used in an interaction theory for an array of devices, which requires no further input from BEM, hence reducing the computation time drastically. In an example, for an array of eight WECs, 1. 6 × 1 0 5 array configurations are calculated using a laptop computer within seven hours (this time included the time required to set up the far-field model for an isolated device), yielding an array featuring the largest "protection factor", which quantifies wave reduction along a given line downwave of the array. The calculated wave fields around the arrays can be validated against BEM results for the same arrays. Note that the time for searching for an optimum layout can further be reduced by two orders of magnitudes when a standard optimisation routine is used, for the wave farms considered in this paper. • A wave farm model based on far-field waves around an individual device. • Far-field waves are corrected by scattering term and involve nonlinear dissipation. • The wave farm model applies to wave energy devices with non-simple geometry. • The wave farm model is 1000–10000 times faster than a conventional simulation. • The fast model is able to optimise wave farms for coastal protection purposes. [ABSTRACT FROM AUTHOR]

As the penetration of distributed renewable energy gradually increases, prosumer groups in high-altitude areas are being expanded. However, the operation of these prosumers in high-altitude areas faces numerous challenges. To address the issue, this paper proposes a double layer energy cooperation framework for high-altitude prosumer groups, considers peer aggregation and shared composite energy storage, aims to adapt to the trend of diversified energy interactions and improve the economic efficiency, maximize social welfare and ensure the continuous growth of the sharing market of prosumers operations in high altitude areas. To meet the diversified energy interaction needs of prosumers, a composite energy storage provider, an energy aggregator, and a two-stage profit clearing scheme are proposed. Furthermore, the overall benefits of the framework and the impact of profit clearing schemes on fairness under various scenarios are studied, and the comprehensive effects of the double layer energy framework are evaluated. The study results show that compared to independent operation by prosumers, under the guidance of shared electricity prices and composite energy storage providers, the economic benefits, evaluation indicators and energy storage utilization efficiency have all been improved. In addition, compared to other profit distribution modes, the two-stage profit clearing scheme proposed in this paper has higher fairness, which greatly encourages the participation of interested entities in energy cooperation. This study provides a feasible framework for energy cooperation among prosumers, and the framework's effectiveness is well-validated. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper aims to study the nonlinear damping characteristic of hydro-turbine governing systems (HTGS) in various frequency bands and improve the reliability of nonlinear damping quantification. Firstly, an HTGS model including multiple hydraulic-mechanical nonlinearities is established using an actual hydropower system as the object. Then, a trajectory quantification method is proposed to enhance the accuracy and stability of the damping calculation. On this basis, the influence of the hydraulic and controller parameters on the HTGS damping in the ultra-low and low frequency band is analyzed. Finally, a deviation indicator is defined to analyze the contribution level of each nonlinear factor to the damping characteristics, and the action mechanism of dominant nonlinearity on damping is further investigated. The results show that increasing the controller parameter and hydraulic parameter decreases the minimum damping of the HTGS. The total deviation of damping under the influence of nonlinearity reaches 1.31 times. Among them, water system nonlinearity and governor delay are two major nonlinearities, and their influence on damping characteristics accounts for 41.4% and 34.4% of the total nonlinear influence, respectively. This paper provides a powerful tool to quantify the damping of nonlinear HTGS and potentially supports the regulation performance enhancement of HTGS. [Display omitted] [ABSTRACT FROM AUTHOR]

The nonlinearity of the hydro-turbine governing system (HTGS) will affect the regulation stability. This paper investigates the stability of HTGS considering the nonlinear coupling of hydro-turbine characteristics (NCTC) under full operating conditions. Firstly, the HTGS models considering the NCTC and power grid conditions are established. Then, the Hopf bifurcation analysis is carried out to comprehensively explain the mechanism of HTGS stability. Finally, the effect regularity of the NCTC on the stability of HTGS is summarized under the full operating conditions. The results indicate that the NCTC includes the coupling of nonlinear speed characteristic and linear head characteristic (NSHC), the coupling of nonlinear head characteristic and linear speed characteristic (NHSC), and the coupling of nonlinear head characteristic and linear opening characteristic (NHOC). The effect of NCTC on stability and dynamic response is mainly realized through the NHOC. The NHOC is favorable for stability under negative load disturbances and unfavorable for stability under positive load disturbances. A smaller unit inertia time constant or a greater flow inertia reduce the effect of NHOC on stable domain. The NHOC has different effects on stability under different operating conditions with a certain regularity. This paper provides potential support for optimizing control parameters of the HTGS. [ABSTRACT FROM AUTHOR]

The expansion of floating offshore wind brings the industry closer to achieving commercial viability. However, the challenging environment characterised by strong winds, waves, and currents, along with the growing size of wind turbines and the dynamic behaviour of floaters, introduces concerns about power production efficiency and system durability due to increased fatigue loads, which subsequently impacts overall costs. In an attempt to mitigate the financial implications coming from alterations made to control strategies and structural elements during the initial design phase, this paper propounds an all-encompassing simulation framework for offshore wind turbines. The current study thoroughly explores the various capabilities of the tool, with a focus on its simulation models. Importantly, the paper highlights the complex interactions between tool models and different controllers. Carefully designed, this tool offers users a variety of functions to enhance system design, fine-tune control strategies, and thoroughly assess performance metrics. The paper elaborates on these aspects, providing an explanation of the tool's capabilities and enhancing the dynamic comparison between the models. [ABSTRACT FROM AUTHOR]

U-bend deep borehole heat exchanger (DBHE) is a new promising kind of ground heat exchanger, but nowadays there are lack of accurate efficient models to simulate U-bend DBHE. This paper has developed a semi-analytical model of U-bend DBHE, which considers the unsteady heat transfer of borehole, heterogenous soil thermal properties and geothermal gradient. A 2D numerical model and an analytical model based on infinite line-source theory are also developed, and the three models are compared with experimental data for different boundary conditions. Based on the soil thermal properties estimated by logging data and rock identification, the three models have large errors when compared with experimental data. Based on a soil thermal conductivity λ s estimated by matching experimental data, the three models match better with experimental data, and it is inferred that λ s should be measured by thermal response test instead of rock identification. The semi-analytical model and 2D numerical model match very well for all the time, but the analytical model has large differences with 2D numerical model, which is because the analytical model ignores borehole heat capacity and time-varying heat flows at the borehole wall. This paper could provide a cost-effective semi-analytical model and some advices for U-bend DBHE. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable energy solutions, the integration of renewable energy sources and hydrogen technologies has emerged as a promising avenue. This paper introduces the Integrated Renewable Energy-Driven Hydrogen System as a holistic approach to achieve energy independence and self-sufficiency. Seamlessly integrating renewable energy sources, hydrogen production, storage, and utilization, this system enables diverse applications across various sectors. By harnessing solar and/or wind energy, the Integrated Renewable Energy-Driven Hydrogen System optimizes energy generation, distribution, and storage. Employing a systematic methodology, the paper thoroughly examines the advantages of this integrated system over other alternatives, emphasizing its zero greenhouse gas emissions, versatility, energy resilience, and potential for large-scale hydrogen production. Thus, the proposed system sets our study apart, offering a distinct and efficient alternative compared to conventional approaches. Recent advancements and challenges in hydrogen energy are also discussed, highlighting increasing public awareness and technological progress. Findings reveal a payback period ranging from 2.8 to 6.7 years, depending on the renewable energy configuration, emphasizing the economic attractiveness and potential return on investment. This research significantly contributes to the ongoing discourse on renewable energy integration and underscores the viability of the Integrated Renewable Energy-Driven Hydrogen System as a transformative solution for achieving energy independence. The employed model is innovative and transferable to other contexts. [Display omitted] • Integrating renewable energy and hydrogen for energy independence. • Advantages of Integrated Renewable Energy-Driven Hydrogen System: Zero emissions, resilient energy. • Economic viability: Payback period of 2.8–6.7 years. • Technological progress in hydrogen energy. • A novel and transferable system dynamics model for sustainable solutions is proposed. [ABSTRACT FROM AUTHOR]

Annular thermoelectric power generator has been increasingly considered in application of ambient energy harvesting owing to the advantages of simple structure and no pollution. To improve thermal stability and energy harvesting performance of this system, the latent heat of phase change materials to improve thermal management and the high thermal conductivity of the heat sink to enhance heat transfer with the ambient are harness to annular thermoelectric power generator. Motivated by this, a phase change material based annular thermoelectric energy harvester (PCM-ATEH) with fins is developed for ambient energy harvesting and its three-dimensional transient model is also built up through jointly with thermo-electric and phase change processes. This paper considers the influence of key parameters such as temperature fluctuation amplitude, temperature fluctuation period, height ratio of PCM and thermoelectric generator (TEG) and melting temperature on liquid fraction, temperature difference, voltage and power density. Moreover, the comparison of PCM-ATEH and PCM based thermoelectric energy harvester (PCM-TEH) with/without fins is further conducted in this study to explore thermal management and energy harvesting performance. The energy harvesting characteristics of PCM-ATEH with fins is developed concerning the combination of power generation of TEG and melting process of PCM. Based on the results, it is found that the temperature difference and power density of PCM-ATEH with fins vary periodically with the sinusoidal temperature boundary, and results show that increasing temperature fluctuation period is not always feasible. Additionally, the comparative results indicate that the peak power density and energy efficiency of PCM-ATEH with fins are increased by 0.126 W/m2 and 0.02 % compared with PCM-TEH with fins, and increased by 0.195 W/m2 and 0.041 % compared with PCM-ATEH without fins. The results of energy harvesting characteristics show that a maximum of 0.77$ per watt can be reached to power generation cost of PCM-ATEH with fins. This paper can provide theoretical guidance for thermal management and energy conversion of energy harvesting system. [ABSTRACT FROM AUTHOR]

The increasing demand for renewable energy sources has led to the development of HRES that combine multiple sources of renewable energy to provide a reliable and efficient energy supply. However, renewable energy sources typically come with higher costs than conventional energy production methods. Hence, the optimal sizing of HRES is essential to prevent the oversizing of the system while ensuring a reliable supply of load demand, accommodating variations in meteorological conditions and changes in power demand. Numerous research papers addressing the optimal sizing problem are available in the literature. However, none of the mentioned studies take into account the power degradation of all renewable sources. The degradation of renewable sources, such as PV and WT, can have a significant impact on the performance of HRES. The degradation of PV panels can result in reduced efficiency and output, leading to a decrease in the overall energy production of the HRES. Similarly, WT may experience wear and tear over time, leading to reduced performance and output. The reduction in the output of renewables in the standalone system causes an increase in the loss of power supply probability (LPSP). This paper analyzes the optimal sizing of the HRES, considering the degradation of the sources. Further, analysis has also been carried out based on the number of BESS to be added to HRES to meet the derived constraints and their impact on the cost of energy as well. [Display omitted] [ABSTRACT FROM AUTHOR]

The expansion of floating offshore wind brings the industry closer to achieving commercial viability. However, the challenging environment characterised by strong winds, waves, and currents, along with the growing size of wind turbines and the dynamic behaviour of floaters, introduces concerns about power production efficiency and system durability due to increased fatigue loads, which subsequently impacts overall costs. In an attempt to mitigate the financial implications coming from alterations made to control strategies and structural elements during the initial design phase, this paper propounds an all-encompassing simulation framework for offshore wind turbines. The current study thoroughly explores the various capabilities of the tool, with a focus on its simulation models. Importantly, the paper highlights the complex interactions between tool models and different controllers. Carefully designed, this tool offers users a variety of functions to enhance system design, fine-tune control strategies, and thoroughly assess performance metrics. The paper elaborates on these aspects, providing an explanation of the tool's capabilities and enhancing the dynamic comparison between the models. [ABSTRACT FROM AUTHOR]

U-bend deep borehole heat exchanger (DBHE) is a new promising kind of ground heat exchanger, but nowadays there are lack of accurate efficient models to simulate U-bend DBHE. This paper has developed a semi-analytical model of U-bend DBHE, which considers the unsteady heat transfer of borehole, heterogenous soil thermal properties and geothermal gradient. A 2D numerical model and an analytical model based on infinite line-source theory are also developed, and the three models are compared with experimental data for different boundary conditions. Based on the soil thermal properties estimated by logging data and rock identification, the three models have large errors when compared with experimental data. Based on a soil thermal conductivity λ s estimated by matching experimental data, the three models match better with experimental data, and it is inferred that λ s should be measured by thermal response test instead of rock identification. The semi-analytical model and 2D numerical model match very well for all the time, but the analytical model has large differences with 2D numerical model, which is because the analytical model ignores borehole heat capacity and time-varying heat flows at the borehole wall. This paper could provide a cost-effective semi-analytical model and some advices for U-bend DBHE. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable energy solutions, the integration of renewable energy sources and hydrogen technologies has emerged as a promising avenue. This paper introduces the Integrated Renewable Energy-Driven Hydrogen System as a holistic approach to achieve energy independence and self-sufficiency. Seamlessly integrating renewable energy sources, hydrogen production, storage, and utilization, this system enables diverse applications across various sectors. By harnessing solar and/or wind energy, the Integrated Renewable Energy-Driven Hydrogen System optimizes energy generation, distribution, and storage. Employing a systematic methodology, the paper thoroughly examines the advantages of this integrated system over other alternatives, emphasizing its zero greenhouse gas emissions, versatility, energy resilience, and potential for large-scale hydrogen production. Thus, the proposed system sets our study apart, offering a distinct and efficient alternative compared to conventional approaches. Recent advancements and challenges in hydrogen energy are also discussed, highlighting increasing public awareness and technological progress. Findings reveal a payback period ranging from 2.8 to 6.7 years, depending on the renewable energy configuration, emphasizing the economic attractiveness and potential return on investment. This research significantly contributes to the ongoing discourse on renewable energy integration and underscores the viability of the Integrated Renewable Energy-Driven Hydrogen System as a transformative solution for achieving energy independence. The employed model is innovative and transferable to other contexts. [Display omitted] • Integrating renewable energy and hydrogen for energy independence. • Advantages of Integrated Renewable Energy-Driven Hydrogen System: Zero emissions, resilient energy. • Economic viability: Payback period of 2.8–6.7 years. • Technological progress in hydrogen energy. • A novel and transferable system dynamics model for sustainable solutions is proposed. [ABSTRACT FROM AUTHOR]

The increasing demand for renewable energy sources has led to the development of HRES that combine multiple sources of renewable energy to provide a reliable and efficient energy supply. However, renewable energy sources typically come with higher costs than conventional energy production methods. Hence, the optimal sizing of HRES is essential to prevent the oversizing of the system while ensuring a reliable supply of load demand, accommodating variations in meteorological conditions and changes in power demand. Numerous research papers addressing the optimal sizing problem are available in the literature. However, none of the mentioned studies take into account the power degradation of all renewable sources. The degradation of renewable sources, such as PV and WT, can have a significant impact on the performance of HRES. The degradation of PV panels can result in reduced efficiency and output, leading to a decrease in the overall energy production of the HRES. Similarly, WT may experience wear and tear over time, leading to reduced performance and output. The reduction in the output of renewables in the standalone system causes an increase in the loss of power supply probability (LPSP). This paper analyzes the optimal sizing of the HRES, considering the degradation of the sources. Further, analysis has also been carried out based on the number of BESS to be added to HRES to meet the derived constraints and their impact on the cost of energy as well. [Display omitted] [ABSTRACT FROM AUTHOR]

Annular thermoelectric power generator has been increasingly considered in application of ambient energy harvesting owing to the advantages of simple structure and no pollution. To improve thermal stability and energy harvesting performance of this system, the latent heat of phase change materials to improve thermal management and the high thermal conductivity of the heat sink to enhance heat transfer with the ambient are harness to annular thermoelectric power generator. Motivated by this, a phase change material based annular thermoelectric energy harvester (PCM-ATEH) with fins is developed for ambient energy harvesting and its three-dimensional transient model is also built up through jointly with thermo-electric and phase change processes. This paper considers the influence of key parameters such as temperature fluctuation amplitude, temperature fluctuation period, height ratio of PCM and thermoelectric generator (TEG) and melting temperature on liquid fraction, temperature difference, voltage and power density. Moreover, the comparison of PCM-ATEH and PCM based thermoelectric energy harvester (PCM-TEH) with/without fins is further conducted in this study to explore thermal management and energy harvesting performance. The energy harvesting characteristics of PCM-ATEH with fins is developed concerning the combination of power generation of TEG and melting process of PCM. Based on the results, it is found that the temperature difference and power density of PCM-ATEH with fins vary periodically with the sinusoidal temperature boundary, and results show that increasing temperature fluctuation period is not always feasible. Additionally, the comparative results indicate that the peak power density and energy efficiency of PCM-ATEH with fins are increased by 0.126 W/m2 and 0.02 % compared with PCM-TEH with fins, and increased by 0.195 W/m2 and 0.041 % compared with PCM-ATEH without fins. The results of energy harvesting characteristics show that a maximum of 0.77$ per watt can be reached to power generation cost of PCM-ATEH with fins. This paper can provide theoretical guidance for thermal management and energy conversion of energy harvesting system. [ABSTRACT FROM AUTHOR]

This paper proposes an energy management system (EMS) for nanogrids to balance the power supply and forecasted demand in consideration of forecasting errors arising from high instantaneous demand. The proposed EMS employs a power-balancing optimization process for forecasted demand and a reference power modulation strategy for forecasting errors. This power-balancing optimization utilizes nanogrid sources, such as photovoltaics, fuel cells, and batteries, to meet forecasted demand and a supercapacitor charging process to overcome issues with a low energy density. The proposed reference power modulation strategy is utilized to allocate power from a hybrid energy storage system consisting of a battery and supercapacitor in order to compensate for forecasting errors. In addition, this proposed strategy considers battery and supercapacitor constraints such as the power changing rate and total power limitations. The power-balancing optimization process also operates at faster sampling rate than the reference power modulation process in order to improve the computational efficiency. The performance of the proposed EMS is evaluated using real data obtained from the Korea Electric Power Exchange. • This paper proposes a cascaded structure energy management system (EMS) for nanogrid to balance power for both forecasted demand and forecast errors including high instantaneous demand. • The proposed EMS comprises a power balancing optimization process for forecasted demand and reference power modulation strategy for the forecast errors. The power balancing optimization utilizes nanogrid sources, such as PV, fuel cell, and battery, to meet forecasted demand as well as a supercapacitor charging process for addressing low energy density characteristics. • The proposed reference power modulation strategy is utilized to allocate power from the HESS comprising a battery and supercapacitor, in order to compensate forecast errors. In addition, this proposed strategy is performed considering battery and supercapacitor constraints such as their power changing rate, total power limitation. [ABSTRACT FROM AUTHOR]