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Implantable medical devices (IMDs) play a crucial role in improving individuals' well-being and ensuring their safety by providing real-time health data monitoring for recovery. The use of energy harvesting (EH) technology has become increasingly popular among researchers because it offers the potential to extend the battery life of IMDs and reduce their weight. This study successfully examined the expansion of EH in the field of IMDs, the distribution of publications across different countries, and the identification of the most influential authors for potential research collaborations. A bibliometric analysis was conducted to evaluate two metrics: performance and science mapping. Data was collected from the Scopus database from the initial publications until October 2023, encompassing 250 articles published in Englishlanguage journals. The titles, keywords, and abstracts of these publications were analyzed and interpreted using VOS Viewer (version 1.6.19). Furthermore, network analysis using VOS Viewer enabled the identification of key research clusters. The findings reveal a continuous increase in EH for research on infectious and parasitic diseases over the 15-year period from 2008 to 2023. The United States and the University of Bern are recognized as the leading contributors to this field, based on their country and institutional contributions, respectively. The author with the most published papers and citations hails from China. Additionally, this study identifies several opportunities for collaboration with countries, institutions, authors, and research hotspots in EH for IMDs that benefit the reader. [ABSTRACT FROM AUTHOR]

The tidal wave in the Qiantang River, Hangzhou City, China is quite different from that of KdV equation, it is a shock-like wave with a finite amplitude. This phenomenon has mathematicians adjusting their solitary wave models on how such waves behave. This paper applies the variational theory to insight into the energy behave of the tidal wave, which can be modelled by the Benny-Luke equation, and the exp-function method is used to figure out the solution structure. This paper provides a new window for designing energy harvesting devices from the shock-like waves. [ABSTRACT FROM AUTHOR]

In today's 5G era, the energy efficiency (EE) of cellular base stations is crucial for sustainable communication. Recognizing this, Mobile Network Operators are actively prioritizing EE for both network maintenance and environmental stewardship in future cellular networks. The paper aims to provide an outline of energy-efficient solutions for base stations of wireless cellular networks. A total of 5722 studies have been figured out by using the search string and after performing the six stages of SLR protocol, 82 studies were finalised that are published in 26 supreme journals and 19 featured conferences. EE solutions have been segregated into five primary categories: base station hardware components, sleep mode strategies, radio transmission mechanisms, network deployment and planning, and energy harvesting. The predominance of sleep mode procedures is evident in the selected survey studies. Notably, China, Korea, and the US are vigorously engaged in this field, specifically related to the 5G network. This review paper identifies the possible potential solutions for reducing the energy consumption of the networks and discusses the challenges so that more accurate and valid measures could be designed for future research. [ABSTRACT FROM AUTHOR]

A smart asphalt mixture holds new capabilities different from the original ones or can react to a stimulus. These capabilities can be categorized based on smartness or function: smartness, mechanical, electrical, optical, energy harvesting, electromagnetic wave/radiation shielding/absorbing, and water related. The most important capabilities applied to asphalt mixtures are the photocatalytic, self-cleaning, self-healing, superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage abilities. This research deals with a bibliometric review of the peer-reviewed journal articles published on the Scopus database, with the strings of terms related to these capabilities and asphalt or bitum in their titles, abstracts, and keywords. The review analysis highlighted the increasing number of accumulated publications, confirming the relevance of this research topic in recent years. The capability most often referred to was self-healing. The study showed that China was the most productive country. Research articles were mostly published in the journal Construction and Building Materials. Several techniques and methods are being developed regarding smart asphalt mixtures; for that reason, this research work aims to evaluate the literature under a bibliometric analysis. [ABSTRACT FROM AUTHOR]

Potato planting area and the total output have been ranked first in the world in recent years. Since the potato can serve as a growth crop under the soil, the harvest process is complex, large labor intensity, time consuming, and high labor costs. Potato harvest mode is still dominated by manual and semi-mechanized harvesting. Mechanized harvest is one of the key links in potato mechanized production. The low rate of mechanization harvest has been the short board for the potato harvest equipment in the field of agricultural machinery at present. The current situation has restricted the development of the Chinese potato industry. This review aims to summarize the planting characteristics, distribution, and mechanized harvest status of potatoes in the main production areas. At the same time, the key technologies of potato mechanization harvest were also reviewed at home and abroad. For example, the potato efficient ridge-like vine killing, potato digging device, potato low-loss and high-efficiency separation, multi-functional walking chassis, as well as human-computer interaction. The potato digging device was elaborated in the drag reduction and soil breaking, bionic digging, vibration digging, anti-blocking and depth limiting, as well as automatic ridge finding technology. The key technologies of potato low loss and high-efficiency separation were described in detail, including potato soil separation, potato vine separation, potato stone separation, flexible protection, and low position container. A summary was also provided for the structure and technical characteristics of typically small and medium-sized potato diggers, potato picking machines, as well as small-, medium-, and large-sized combined harvesting machines. A systematic analysis was made of the potato mechanization harvest. 1) It was difficult to complete the matching of machines and tools, particularly in various planting modes, complex terrain, and wide planting areas in the small plots in the hilly and mountainous areas. 2) There was a large proportion of small-scale planting areas, the high cost of purchasing harvesting equipment, and the weak ability of farmers to resist risks, leading to insufficient purchasing power for harvesting equipment. 3) Some potatoes in vegetable harvest accounted for a large proportion of China, with high requirements on the quality of the mechanized harvest. Farmers shared low trust in the harvesting equipment, and most of them used manual harvesting. 4) There was no perfect leasing service system for agricultural machinery, resulting in the low utilization rate of mechanized harvesting equipment. 5) The low separation effect and high impurity rate were found in the domestic combined harvesting machinery under the condition of large damage and sticky heavy soil. 6) Much attention can be expected to pay agricultural machinery research and development and support. Therefore, the mechanized potato harvest can be the trend of joint development in the step and combined harvest. In addition, the future directions prospected for the low loss and highefficiency separation device, the breakthroughs in the weak technology, deep integration of agricultural machinery and agronomy in the agricultural machinery service system, together with the national policy support. The finding can also provide a strong reference for the development and research of mechanized potato harvesting technology in China. [ABSTRACT FROM AUTHOR]

Not only is the use of waste heat an important way for companies to reduce fuel costs but it is also an important step in achieving the goal of decreasing peak carbon dioxide emissions. Solid fuels still make up a large proportion of China’s energy consumption structures, and the amount of ash generated and the remaining thermal resources are enormous. When considering coal alone, the theoretical recoverable amount of waste heat associated with the ash can be as much as 15.87 Mt of standard coal per year. An analysis of thermal energy utilization of high temperature ash (TEUHA) was conducted. It was found that the existing direct utilization method had a thermal efficiency in the range of 12% to 92%. However, the process is complicated, and the heat carrier is susceptible to contamination. Indirect utilization could avoid pollution issues, but heat loss was severe and maximum thermal efficiency was calculated as only 59%. Combined with the waste heat characteristics of the ash and the heat demand, a "Point-Point" model of TEUHA using phase-change materials as the heat carrier is proposed. This approach not only avoids ash pollution to the thermal environment, but it also increases the energy harvesting efficiency and realizes a high-quality utilization of thermal energy. [ABSTRACT FROM AUTHOR]

In the automotive and transportation sectors, technological advancements and innovations aim to reduce fuel consumption and CO2 emissions of vehicles. In vehicles, a significant portion of fuel energy is wasted in heat, vibrations, and frictional losses. The vibration energy from vehicle suspension systems is always wasted in heat and can be utilized for useful purposes. Many researchers have designed various regenerative shock absorbers (RSA) to transform vibration energy into electrical energy that can charge electric vehicles' batteries and power low-wattage devices. The present work focuses on an in-depth summary of rotary, hydraulic, and linear electromagnetic RSA. Also, the applications of regenerated energy and technical challenges are discussed. In RSA, the maximum energy harvesting, and ride comfort of the vehicle cannot be achieved simultaneously. The weight of RSA may increase due to the integration of some additional components compared with conventional shock absorbers. It is necessary to examine the impact of weight on the vehicle's road handling and ride comfort. The hydraulic RSAs have low energy harvesting efficiency, so they are not suitable for lightweight vehicles despite their higher energy harvestability than rotary and linear RSAs. The bibliometric analysis is conducted using the visualization of similarities (VOS) viewer to visualize the contributing authors and countries and specify the research themes. The articles are collected from the Web of Science using keywords related to energy harvesting from 2000 to 2021. Authors from China are more productive than others, with the highest number of publications related to the energy-harvesting from RSAs in 2019. [ABSTRACT FROM AUTHOR]

• The condensation rate and condensation power in the south, middle and north China with three ideal radiative cooling emitters are elaborately examined. • An optimal emitter can be selected based on the calculated boundary conditions and condensation rate differences. • To realize the ideal emitters, multilayer design has been put forth, and the numerical calculation of the emissivity match well the impedance theory. • As a case study of the 4-infinite multilayer emitter, the average condensation rate throughout the year is 1.956 Lm−2hour−1 for the solar water purification. Radiative cooling, a novel cooling technology for condensation water harvesting without energy input, offers a promising solution to the water scarcity. According to the actual locations and atmospheric conditions, selecting the ideal radiative cooling spectrum is crucial to achieve improved condensation efficiency. In this work, we analyze the condensation rate and condensation power in the southern, middle and northern China with three ideal radiative cooling emitters, namely, 4-infinite, single-window, and double-window emitter. Depending on variations in temperature, relative humidity, or the heat transfer coefficient, an optimal emitter can be selected based on the calculated boundary conditions and differences in condensation rate. Meanwhile, three multilayer design of 4-infinite emitter, double-window emitter and single-window emitter are developed using the memetic algorithm. Their emissivity aligns well with the impedance theory. They are then applied to a case study that assesses condensed water collection in Hangzhou, utilizing real-time atmospheric and environmental data in the whole year. Regarding the all-day dew collection, the average daily water generation per week in Hangzhou can be up to 256.94 mLm−2. For the solar water purification, the average condensation rate throughout the year is 1.956 Lm−2hour−1 with h = 10 W m − 2 K − 1 . Our findings demonstrate that the multilayer design significantly enhances the water harvesting. Hence, our research provides valuable insights for selecting suitable ideal radiative coolers for water harvesting in specific atmospheric conditions and geographical locations. [ABSTRACT FROM AUTHOR]

Additively manufactured nano-MEH systems are widely used to harvest energy from renewable and sustainable energy sources such as wind, ocean, sunlight, raindrops, and ambient vibrations. A comprehensive study focusing on in-depth technology evolution, applications, problems, and future trends of specifically 3D printed nano-MEH systems with an energy point of view is rarely conducted. Therefore, this paper looks into the state-of-the-art technologies, energy harvesting sources/methods, performance, implementations, emerging applications, potential challenges, and future perspectives of additively manufactured nano-mechanical energy harvesting (3DP-NMEH) systems. The prevailing challenges concerning renewable energy harvesting capacities, optimal energy scavenging, power management, material functionalization, sustainable prototyping strategies, new materials, commercialization, and hybridization are discussed. A novel solution is proposed for renewable energy generation and medicinal purposes based on the sustainable utilization of recyclable municipal and medical waste generated during the COVID-19 pandemic. Finally, recommendations for future research are presented concerning the cutting-edge issues hurdling the optimal exploitation of renewable energy resources through NMEHs. China and the USA are the most significant leading forces in enhancing 3DP-NMEH technology, with more than 75% contributions collectively. The reported output energy capacities of additively manufactured nano-MEH systems were 0.5–32 mW, 0.0002–45.6 mW, and 0.3–4.67 mW for electromagnetic, piezoelectric, and triboelectric nanogenerators, respectively. The optimal strategies and techniques to enhance these energy capacities are compiled in this paper. Highlights: The current technology evolution and advancements in 3DP-NMEHs were evaluated. Categorization and comparison of 3DP-NMEHs were performed in terms of inputs and energy conversion. The emerging applications of 3DP-NMEHs were discussed briefly. The potential challenges confronted by 3DP-NMEHs and respective recommendations were summarized. Sustainable use of recyclable waste generated during the COVID-19 pandemic was proposed. [ABSTRACT FROM AUTHOR]

This paper aimed to optimize working quality and reduce energy consumption of the feeding and shearing device of the silage harvester by making a comprehensive analysis and experiment on the longitudinal compressing and shearing properties of the silage corn stalks. The main factors affecting the shearing energy consumption were obtained by compressing and shearing tests on internodes and nodes of silage corn stalk. The results of three-level and three-factor central combination experiments showed that the overall shearing energy consumption for nodes was much higher than that for internodes. Compressing the silage corn stalk to some extent before shearing at the loading direction of 0° and lower shearing speed was beneficial to saving energy. [ABSTRACT FROM AUTHOR]

The harvesting of wind energy from the slipstream generated when a train passes through a tunnel is a new way to produce renewable energy. From the perspective of CFD (Computed fluid dynamics), a three-dimensional URANS (unsteady Reynolds-averaged Navier–Stokes) model was used to study the energy harvesting performance of wind turbines with different design parameters inside the tunnel during the entire process of a train passing through a tunnel. A higher value of offset distance of blades could promote the power efficiency of the wind turbine inside the wind tunnel. The maximum power efficiency with regard to overlap distance was found when an overlap distance is 0 m. The turbine with a negative twist angle yielded a better performance than the turbine with a positive twist angle. The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h. Given the tunnel distribution in China, 4.8 × 1012 J energy will be recovered each day by this way, which is sufficient to supply the emergency power for railway lighting. It can also effectively ease the pressure of daily lighting power in railway tunnels. • Harvesting wind energy from railway tunnels is considered feasible. • DFBI (dynamic fluid body interaction) was used to simulate the response of the turbine. • The power efficiency of turbines with various design parameters was quantitatively evaluated. • The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h. [ABSTRACT FROM AUTHOR]

• A wind-PV system for powering electrical facilities on highways is proposed. • The system is installed in the medians of highways to avoid occupying extra land. • The system is foldable for easy deployment and self-protection. • Estimation results show that the annual generation of the system reaches 356 GWh. In this paper, a portable wind-photovoltaic power generation system (WPPGS) based on the foldable umbrella mechanism is presented. The proposed WPPGS is installed in the medians of highways, and it can simultaneously capture the solar energy and wind energy produced by running vehicles. The studied system mainly consists of three submodules: a solar harvesting module, a wind-energy-harvesting module and an energy storage module. The whole system is foldable for easy deployment and self-protection. The electricity generated by the wind and solar energy harvesting modules is stored in the energy storage module, which can supply power to the electrical facilities on highways. The Chengdu-Chongqing highway is selected for case study. Theoretical and simulation results show that the annual power generation of the solar harvesting sub-module, wind collection sub-module and entire WPPGS system deployed on all highways in Mainland China can be up to 155 GWh, 201 GWh and 356 GWh, respectively. Furthermore, the wind and solar-energy-harvesting subsystems have appropriate complementarity in time, which indicates that the WPPGS has excellent technical performance throughout the entire year. [ABSTRACT FROM AUTHOR]

Noise pollution has become the second major environmental issue after the air pollution. It negatively affects public health,animal and plant growth,that therefore seriously hinders the sustainable development of ecological environment. To obtain detailed noise distribution information,several countries have launched the noise mapping strategic action. This paper first summarizes the development roadmap of environmental noise sensing technologies in China,and discusses its current state. Then,a comprehensive survey of recent developments on acoustic sensor networks is provided in terms of system architecture,low-cost sensor node design,sound taxonomy and classification,as well as energy harvesting and mobile sound sensing. Based on that analysis,four open issues regarding energy-efficient sensing,lightweight sound noise identification,dependable wireless multimedia transmission and node deployment are identified. Finally,some insights for future research directions are presented. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) is a very promising technology in forest engineering, especially for the environment and plant growth monitoring. LoRa Wide Area Network (LoRaWAN) is a prevailing choice for the Forestry IoT owing to its low-power and long-range ability. Real-world deployment and network optimization require accurate path-loss modeling, so the LoRaWAN radio channel in the forest is needed to be intensively studied. However, most of the subsistent propagation models do not involve specific forestry environmental parameters. In this paper, two parameters related with the trees are considered: the leaf area index and the tree trunk diameter. Due to the time-changing characteristics of these two items (from spring to winter), an empirical model has been developed through extensive measurement campaigns: Firstly, the channel measurement platform is designed based on a real scene of mixed forest. Secondly, the fading characteristics of the channel transmission for LoRa nodes are tested, and the corresponding model is presented and evaluated. Lastly, an energy harvesting LoRaWAN is deployed and operated in a sampled forest region of Eastern China for environment monitoring based on our propagation model. The results show that 433 MHz LoRa path loss in the mingled forest could be precisely predicted by our proposed model. Moreover, network coverage and energy consumption optimization of the LoRa nodes could be performed, which enables the perpetual development of reliable forestry evolution monitoring system. [ABSTRACT FROM AUTHOR]

Unmanned surface vehicles (USVs) are playing a significant role in the marine science and engineering field, e.g., they have been widely used in measuring ocean waves and currents. However, their operation time and range are limited by the energy carried by internal batteries, and this challenge needs to be urgently addressed. In this study, a novel USV concept that can harvest vibration energy excited by ocean waves in the heaving and pitching direction is presented, which provides a sustainable and continuous power supply. A fully coupled wave-to-wire model that considers the viscous damping force is developed to investigate the dynamics and electric power performance of this novel device under site-specific realistic wave climates, with the external electric load optimally tuned for each sea state. Besides, the influence of the forward speed, geometric size, mass ratio and end-stop spring is studied. Numerical results show that the proposed USV in a freely floating situation can efficiently capture and convert harvested energy into electricity with a wave-to-wire efficiency of up to 20. 21 %. Additionally, it can generate an annual mean electric power of 29.73 W, under the wave climates of the national wave energy test site in China. • A novel wave-powered unmanned surface vehicle is designed. • A fully coupled wave-to-wire model is developed. • A high wave-to-wire efficiency up to 20.21% is obtained. • An annual mean electric power of 29.73 W is achieved by the USV. [ABSTRACT FROM AUTHOR]

This study aims to develop a prototype for harvesting thermoelectric energy from railway track. By capturing the existing thermal energy in railway tracks, this technology helps power rail-side sensors in off-grid and remote areas without depleting natural resources. In low latitudes such as southern China, the temperature of railway tracks can reach 57 °C due to solar radiation. However, at a relatively shallow depth (200 mm), the substratum below the track foundation (e.g., soils) has a lower temperature (i.e., 15 °C–26 °C). This temperature difference can be used to generate electricity through a thermoelectric generator (TEG). The proposed approach captures thermal energy from the railway track and transfers the energy to the TEG prototype beneath the bottom of rails. Evaluation of the prototype is conducted by finite volume analysis, field test, and laboratory experiment. The results indicate that the TEG prototype can produce 5.8 mW–316.8 mW of power across a resistant load at thermal gradient from 8 °C to 29.2 °C. A DC-DC buck-booster circuit with lithium battery management is developed to charge the batteries by the harvested thermal energy. The system operates at a low startup voltage of 0.9 V and its conversion efficiency is larger than 60%. • Highlights of the paper: • A prototype was developed for harvesting thermoelectric energy from railway track. • One year temperature data of the railway track infrastructure were measured. • A DC-DC converter with lithium battery management was developed. • The system can charge a cellphone at a temperature gradient of 23.5 °C. [ABSTRACT FROM AUTHOR]

Abstract A novel concept of energy harvesting method (PV-RC) based on the conventional photovoltaic (PV) panel, combining diurnal PV conversion and nocturnal radiative cooling (RC) method, was developed to generate electricity and obtain cooling energy. A PV-RC hybrid system was also designed, manufactured, and spectral characterized, which exhibit high solar absorption in PV conversion band (0.3–1.1 μm) and has strong thermal emission within thermal radiation band (4–25 μm). Experimental studies of the hybrid system were carried out in Hefei (117° E, 32° N), China. The measured results demonstrate that the hybrid system has an average electricity output of 75.7 W m−2 with an average electrical efficiency of 12.4% for diurnal PV conversion and exhibits an equilibrium temperature reduction of 12.7 °C below ambient temperature for nocturnal RC process. Parametric studies were also conducted by a validated simulation model, which discuss the effects of different meteorological parameters on the performance of the system. The simulated results imply that dry regions are more suitable for nocturnal RC mechanism. Highlights • PV panel based photovoltaic and radiative cooling (PV-RC) system was proposed. • A PV-RC hybrid system was designed, manufactured, and spectral characterized. • An average electricity output of 75.7 W m−2 was obtained at daytime PV mode. • An average temperature reduction of 12.7 °C was obtained at nighttime RC mode. • Thermal analysis was conducted by validated mathematical model. [ABSTRACT FROM AUTHOR]

Highlights • Literature on energy production from roadways is surveyed. • e-Roads, which produce energy by energy harvesting modes, are proposed. • In addition to power production, e-Roads can support smart infrastructure. • Scaling-up of e-Road concept could potentially supply most of China's power. Abstract Increasing and projected shortages in non-renewable energy sources have directed attention toward the potential for using regenerated energy from road traffic. There are currently three primary techniques for harvesting energy from roadways—piezoelectricity, thermoelectricity and photoelectricity—although, to date very few studies have focussed on the potential for integrating two or more of these, with most examining the application and optimisation of single-mode harvesting. To address this gap, this paper reviews and analyses the body of past research on road energy harvesting with the goal of developing a 'dynamic-heat-light division recommendation' based on the literature. From this research, a new concept of 'e-Roads' is proposed and defined in detail. If full use can be made of roadways as e-Roads under the division recommendation made in this paper, these structures have the potential to serve as one of the largest sources of energy in the near future. In this manner, this study serves as a reference for road construction and road network planning as well as a source of ideas for the development of intelligent traffic systems. [ABSTRACT FROM AUTHOR]

Harvesting solar energy on rooftops can be a promising solution for providing affordable energy. This requires accurately estimating spatio-temporal solar photovoltaic (PV) potential on urban surfaces. However, it is still a challenge to obtain a fast and accurate estimation of rooftop solar PV potential over large urban built-up areas. Thus, this study proposes a parametric-based method to estimate annual rooftop solar irradiation at a fine spatial resolution. Specifically, seven parameters (Digital Surface Model, Sky View Factor, shadow from buildings, shadow from terrain, building volume to façade ratio, slope, and aspect) are determined that having great importance in modeling rooftop solar irradiation. Three machine learning methods (Random Forest (RF), Gradient Boost Regression Tree (GBRT), and AdaBoost) trained by the selected parameters are cross-compared based on R 2 , Mean Absolute Error (MAE), and computation time. As a case study in Hong Kong, China, the RF outperformed GBRT and AdaBoost, with R 2 = 0. 77 and M A E = 22. 83 kWh/m 2 / year. The time for training and prediction of rooftop solar irradiation is within 13 h, achieving a 99.32% reduction in time compared to the physical-based hemispherical viewshed algorithm. These results suggest that the proposed method can provide an accurate and fast estimation of rooftop solar irradiation for large datasets. • The parametric assessment of rooftop solar irradiation was conducted. • Random Forest, Gradient Boost Regression Tree, and AdaBoost models were compared. • The RF model showed superior accuracy (R 2 = 0.77) and fast computation. • A data and model dual-driven approach was used. [ABSTRACT FROM AUTHOR]

• A tumbler-inspired electromagnetic ocean wave generator (T-EMG) is proposed. • The Halbach array is used to improve the low-frequency energy harvesting capacity. • T-EMG can harvest random and low-frequency ocean wave energy in offshore tests. • The maximum voltage is 3 V and the maximum average output power can reach 65 mW. Ocean wave is considered as one of most promising renewable energy sources due to the merits of wide distribution and high energy density. However, the low-frequency and large randomness characteristics make it hard to harvest. Here we report a tumbler-inspired electromagnetic generator (T-EMG) with a Halbach array to improve the low-frequency ocean wave energy harvesting performance. The theoretical model of the T-EMG is established. The amplitude-frequency relationship is derived. The simulations and experimental investigation are carried out. The maximum harvested voltage of 3 V with a lower frequency of 2.6 Hz is obtained, and the maximum average output power can reach 65 mW through adjusting the load and tumbler parameters. More significantly, the offshore tests in the East China sea were carried out and the experimental results showed that T-EMG can work effectively under ultra-low frequency (<1Hz) real ocean wave environments and achieve a maximum peak power of 120 mW, which could meet the requirement of low-power wireless sensors. In addition, the offshore tests also demonstrate the strong frequency adaptability of T-TMG that enables it to harvest random and low-frequency ocean waves efficiently. This work provides an effective solution to harvest low-frequency and random ocean wave energy and can be easily adapted to mechanical or aerospace engineering, etc. [ABSTRACT FROM AUTHOR]

Comprehensive knowledge about wind energy potential is critical for decision-making to achieve carbon neutrality and shape future energy pathways. Wind turbine technology advances (e.g., higher hub-heights, larger rotor diameters and rated power) can better support wind energy harvesting and alter wind energy potential. This study established an integrated model to evaluate the impact of wind turbine technology advances on onshore wind energy potentials under different wind resource conditions by using China as a case study. We found that technological advances of wind turbine can significantly impact wind energy potential. Compared with land-based 1.5-MW turbines, the onshore wind energy potential using newer generation turbines (land-based 2.5-MW turbines) would increase by 43% to 14.8 PWh (i.e., 2.0 times the electricity consumption of China in 2020). Importantly, advances in wind turbine technology can significantly increase capacity factor in poor wind resource regions, and thus enable economically viable generation in more areas. This can significantly increase wind energy potential in poor wind resource regions with large electrical load (e.g., Central, South and East China). Moreover, in contrast to the wind production of 0.46 PWh in 2020, China's wind energy potential is projected to hit 20.1 PWh by 2030 under the assumption of developed turbine technology in line with the trends of the past decade. The corresponding potential CO 2 emission reduction would range from 12.6 Gt in 2020 to 21.7 Gt in 2030. These values are 1.3 and 2.2 times higher than China's CO 2 emissions in 2020, respectively. To enhance wind energy contribution toward China's carbon neutrality goal, we recommend that the conversion of wind turbines to be accelerated, especially in poor wind resource regions with large electrical load. • Onshore wind potential for China is 2.0 times national electricity demand of 2020 • Wind turbine technology has more influence on wind potential in low wind regions • China's wind potential reach 20.1 PWh (equivalent to 21.7 Gt CO 2 emission) by 2030 [ABSTRACT FROM AUTHOR]

Geothermal energy is gaining global attractiveness owing to its abundance and sustainable nature. An in-depth understanding of potential geothermal production provides the energy industry a possibility to diversify the supply portfolio. With the development of artificial intelligence, machine learning offers an efficient alternative to the conventional numerical simulation method in forecasting energy harvesting. However, a comprehensive comparison and an effective algorithm selection are absent from the machine learning applications in forecasting geothermal energy recovery. In this study, four machine learning algorithms based data-driven models are created to determine the optimal choice in predicting geothermal production, including K -Nearest Neighbors (KNN), Support Vector Machine (SVM), Extreme Gradient Boosting (XGBoost) and Artificial Neural Network (ANN). To investigate their application range, two different sizes of data groups are involved to train and test these models, and their performance is comprehensively compared. As the results show, the highest coefficient of determination R 2 of 0.998 is demonstrated in the ANN models showing its promising predictive ability. Besides, the ANN is the most stable with the lowest performance variances between a training set and a validation set. In addition, the ANN is the most adaptable due to its minimal performance differences between different sizes of data groups. By jointly considering the prediction accuracy, stability and adaptability, the ANN is the best choice to substitute numerical simulation for predicting geothermal development. Importantly, the successful implementation of the proposed data-driven model requires 2700 times less computational time compared to numerical simulation, demonstrating a considerable improvement in the prediction efficiency. The results provide a beneficial reference for operators in conducting machine learning to simulate the development of the geothermal system studied, and can be effectively applied in other energy systems. • Proposed numerical models can generate robust datasets to develop data-driven models. • Five variables are determined as inputs for applying machine learning algorithms. • The ANN performs best due to its highest accuracy, stability and adaptability. • Data-driven model significantly improves the prediction efficiency by 2700 times. • Proposed data-driven method shows the feasibility to substitute numerical simulation. [ABSTRACT FROM AUTHOR]

Taking a continuous rigid segmental prefabrication and assembly bridge on Guangzhou Metro No.14 as example, railway vehicle induced vibration energy harvesting and saving was studied in this paper. By modeling multi-body dynamics system of B-type railway vehicle and the wheel-rail interaction relationship, train-track-bridge (TTB) response was calculated accurately. Through dynamic analysis of the TTB system with two different track irregularity conditions, vertical acceleration time histories of the track slab were acquired. Based on this, a new type of electromagnetic vibration energy harvesters (EM-VEHs) is proposed. Utilizing the track slab vibration, the EM-VEHs set adjacent to the track slab are demonstrated to be feasible to supply enough power for strain collection units or GPS data transmission units in bridge health monitoring system. Compared with previous research, the power density of the proposed EM-VEH device is much higher. The application prospect of the proposed EM-VEH on urban mass transit SPA bridges is worthy to be anticipated. [ABSTRACT FROM AUTHOR]

Over the last two decades, a large body of academic scholarship has been generated on wave and tidal energy related topics. It is therefore important to assess and analyse the research direction and development through horizon scanning processes. To synthesise such large-scale literature, this review adopts a bibliometric method and scrutinises over 8000 wave/tidal energy related documents published during 2003–2021. Overall, 98 countries contributed to the literature, with the top ten mainly developed countries plus China produced nearly two-thirds of the research. A thorough analysis on documents marked the emergence of four broad research themes (dominated by wave energy subjects): (A) resource assessment, site selection, and environmental impacts/benefits; (B) wave energy converters, hybrid systems, and hydrodynamic performance; (C) vibration energy harvesting and piezoelectric nanogenerators; and (D) flow dynamics, tidal turbines, and turbine design. Further, nineteen research sub-clusters, corresponding to broader themes, were identified, highlighting the trending research topics. An interesting observation was a recent shift in research focus from solely evaluating energy resources and ideal sites to integrating wave/tidal energy schemes into wider coastal/estuarine management plans by developing multicriteria decision-making frameworks and promoting novel designs and cost-sharing practices. The method and results presented may provide insights into the evolution of wave/tidal energy science and its multiple research topics, thus helping to inform future management decisions. • An analysis on over 8000 wave/tidal energy articles over the last 20 years is provided. • The evolution of literature, network of contribution, and influential entities are scrutinised. • 98 nations contributed to research with 4 major themes and 19 sub-themes emerged. • Recent research integrates energy assessment into wider coastal management plans. • Findings can inform knowledge gaps, policy decisions, and future research efforts. [ABSTRACT FROM AUTHOR]

An S-shaped wave energy converter (SB-WEC) was designed to assist near-zero-energy oceanography. The SB-WEC comprises a non-linear mechanical power take-off (PTO) and a novel S-shaped buoy (SB) for operation in the wave climate of the National Shallow Sea Comprehensive Test Site in China. The PTO used a ball screw-based transmission system to harvest wave energy during upward and downward strokes, and its operational characteristics were validated through simulations and experimental testing. A comparative analysis was performed to select an optimal buoy shape, and tests were conducted in a lab-scale wave flume on the 3D-printed scaled buoys. Using an ultramodern algorithm, buoy scaling was performed to identify the pure shape-change effects on the heave response irrespective of their size. The optimal buoy size was evaluated, and an algorithm was developed in MATLAB Simscape to study its feasibility of running the non-linear PTO in realistic waves. A study on the tunability of the PTO using a rotary motion rectifier (RMR) suggested that the application of the proposed RMR is not suitable in waves below 0.3 Hz. During experimental tests, the PTO generated 13.5W at 0.3 Hz (realistic wave frequency) with an energy conversion efficiency above 50%. The experiments showed that under identical design and test conditions, the S-shaped buoy (SB) could achieve a 34% greater RMS heave response than the cylindrical-hemispherical buoy. A feasibility study based on MATLAB-AQWA showed that the RMS power absorption of the full-scale SB buoy was 17% higher than the input power of the PTO in irregular waves, validating the proposed buoy shape and size. The SB-WEC can reasonably power the sensors in the satellite-respondent buoys. [Display omitted] • An S-shaped point absorber WEC was studied under the wave climate of ShiDao, China. • The mechanical power take-off generated 13.5W under excitations of 0.3 Hz and 80 mm. • The 1:8.33 scaled model of the S-shaped buoy was tested in a lab-scale wave flume. • Buoy feasibility was evaluated to meet PTO power requirements in realistic waves. • The SB-WEC was proposed to power the sensors in the satellite-respondent buoys. [ABSTRACT FROM AUTHOR]

Currently almost all wastewater treatment plants (WWTPs) require a large amount of energy input to process the influent, mostly as electricity, and the associated carbon emissions are in aggregate significant. In order to achieve carbon neutrality, it is important to understand direct and indirect carbon emissions generated by WWTPs. Here, we focused on electricity use in WWTPs as it is a major source of carbon emissions. Specifically, we compared the electricity intensity and associated carbon emissions of WWTPs in four countries: the USA, Germany, China, and South Africa. We found that 100% energy self-sufficient WWTPs are feasible by a combination of increased energy efficiency and energy harvesting from the wastewater. Carbon emissions of WWTPs depend strongly on the electricity fuel mix, wastewater treatment technologies, treatment capacity, and influent and effluent water quality. A few WWTPs operating in developed countries (USA and Germany) have already achieved almost 100% (or higher) electricity self-sufficiency through energy efficiency and harvesting biogas and electricity. In comparison with Germany, WWTPs in the USA are more heterogeneous and the range of unit carbon emission intensity is much wider. In some areas where the organic content in wastewater is lower and less biogas is produced, it is still possible to achieve energy self-sufficiency by using thermal energy from wastewater. Industrial wastewater in China in general consumes more electricity and the carbon intensity of electricity is also higher, resulting in much higher unit carbon emissions as compared with other countries. In megacities such as Shanghai, larger capacity of centralized WWTPs can decrease the unit carbon emissions significantly. These findings provide a global perspective on the state of WWTPs and are helpful to improve the understanding, designing and operating of WWTPs from the perspective of achieving carbon neutrality. [ABSTRACT FROM AUTHOR]

[Display omitted] • A copolymer hydrogel was fabricated to harvest oceanic energy. • Ionic concentration was main driving force for continuous electricity generation. • This device produced a power density of 89.4 µW cm−2 in real seawater. • The series connection of six devices could power commercial electronic devices. Micro/nano fluidic electricity generation systems based on solid–liquid interface interaction to harvest energy from water in nature offer a potential green and clean electricity generation method. However, the performances of electricity generation were limited in salt solutions. In this paper, we prepared an extraordinary-performance hydrogel through ultraviolet polymerization for the access of ion concentration energy in seawater. This copolymer hydrogel made of AAm/AA (acrylamide/acrylic acid) provides a negatively charged three-dimensional transport network with micro/nano porous channels, which exhibits extraordinary ion selectivity in high ion concentration solutions. The experimental results show that this electricity generation device with intrinsic micro/nano pores can generate a continuous open-circuit voltage of 0.37 V, a short-circuit current of 116 μA, and a power density of 89.4 µW/cm2 from seawater (the Yellow Sea in China). The output current and power can be maximally more than 100 times and 50 times higher than the existing results. Through the series connection of six devices, the overall output is sufficient to supply stable power to directly light up small commercial electronic devices. Our study presents a new research idea for the development of low-cost, environmentally friendly, and self-powered devices. [ABSTRACT FROM AUTHOR]

A novel passive thermoelectric system based on radiative cooling and solar heating is designed for continuous power generation during a full 24-hour day - even in winter. An evaluation model is established to determine the temperature difference between the TEG ends and calculate the system output. The seasonal all-day performance and output map of the system in China are presented. Results indicate that the proposed passive TEG system that integrates radiative cooling and solar heating can produce 24-hour continuous and impregnable output with a maximum of 3.29 W·m−2 in China. [Display omitted] • A passive TEG system integrating radiative cooling and solar heating is proposed. • Theoretical model for evaluating the 24-hour system performance is established. • Effects of radiative cooler, solar absorption rate, and cloud cover are studied. • Seasonal performance and the output map of the passive system are presented. • The output power of the passive system can reach 3.29 W·m−2 in China. Harvesting energy from the sun and ultracold outer space for electricity generation is green access to green energy and helps reduce carbon dioxide emissions. However, current work on passive electricity generation is restrained to daytime or nighttime. In this paper, we propose a passive thermoelectric system that produces continuous electric power during a full 24-hour day - even in winter. The thermoelectric output is maintained and amplified by integrating radiative cooling and solar heating. The utterly passive system consists of a thermoelectric generator (TEG), a radiative cooling film, and a greenhouse cavity. Radiative cooling is used to cool the sky-facing end of the TEG below ambient temperature without the need for fuel. Meanwhile, the solar-heating-based greenhouse is used to heat the hot end of the TEG to enhance the temperature difference between the cold and hot ends and, thus, the output. An energy balance model that considers the varying solar radiation is developed to determine the temperature difference between the TEG ends and system output. The accuracy of the evaluation model is first confirmed by the good agreement between the modelled performance of the system and the experimentally measured data. Afterwards, the effects of radiative cooler, solar absorption rate, and cloud cover on the system performance are studied. Finally, the seasonal and locational performance of the system in China is evaluated. Results indicate that the proposed passive TEG system that integrates radiative cooling and solar heating can produce 24-hour continuous and impregnable output. Therefore, the proposed system in this work may help the development of passive electricity generation. [ABSTRACT FROM AUTHOR]

• use wave energy as the power for transportation ships. • A novel wave energy prediction method based on GRU. • The features of the model are assigned different weights. Efficient use of renewable energy is one of the critical measures to achieve carbon neutrality. Countries have introduced policies to put carbon neutrality on the agenda to achieve relatively zero emissions of greenhouse gases and to cope with the crisis brought about by global warming. This work analyzes the wave energy with high energy density and wide distribution based on understanding of various renewable energy sources. This study provides a wave energy prediction model for energy harvesting. At the same time, the Gated Recurrent Unit network (GRU), Bayesian optimization algorithm, and attention mechanism are introduced to improve the model's performance. Bayesian optimization methods are used to optimize hyperparameters throughout the model training, and attention mechanisms are used to assign different weights to features to increase the prediction accuracy. Finally, the 1-hour and 6-hour forecasts are made using the data from China's NJI and BSG observatories, and the system performance is analyzed. The results show that, compared with mainstream prediction algorithms, GRU based on Bayesian optimization and attention mechanism has the highest prediction accuracy, with the lowest MAE of 0.3686 and 0.8204, and the highest R2 of 0.9127 and 0.6436, respectively. Therefore, the prediction model proposed here can provide support and reference for the navigation of ships powered by wave energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • The overall performance of RC and PV roofs are quantitatively compared. • RC roof has poorer energy efficiency but better economy in common buildings. • Global sensitivity analysis is used to explore suitable application scenarios. • RC roof is suitable for long-term heat dissipation and lightweight buildings. • High-resolution applicability maps of RC and PV roofs in China are plotted. Building-integrated radiative cooling (RC) and photovoltaic (PV) systems are promising renewable technologies harvesting energy from outer space and the sun, respectively, and can contribute to carbon neutrality. However, due to the limited building envelope area, it is significant to compare the energy-saving potential and technical economy of these two technologies, which helps to determine the system form under different working conditions. This study establishes the thermal models for rooftop RC and PV systems to simulate their temperature, heat transfer flux, and energy-saving performance. Then the energy-saving and economic indicators for comparative investigation are proposed, in which the cooling load reduction is converted into electricity saving to be compared with PV's electricity generation. The comparison results show that RC roof has a lower energy-saving potential than PV roof during the cooling season in Beijing, China (the energy saving ratio of RC to PV is 0.536). However, the economic cost of equivalent electricity saving during the life cycle is $0.011 and $0.034 per kilowatt-hour for RC and PV systems, respectively, indicating that RC roof is more economical. In addition, applicability analysis indicates that the total cooling capacity of RC roof throughout the cooling season is larger in western and southern China, while the energy-saving potential of PV roof is higher in western and northern China. Moreover, the effects of meteorological parameters, indoor conditions, building roof characteristics, and surface optical properties on RC and PV roofs' performance are thoroughly analyzed. The parametric analysis shows that RC roof is suitable for buildings with high heat dissipation demand and lightweight envelope structures. It is calculated that the energy yield of the RC roof is comparable to that of the PV roof in a telecommunication base station. This study will pave the way for maximizing the energy-saving potential of limited building roofs and contribute to the efficient utilization of renewable energy. [ABSTRACT FROM AUTHOR]

The field burning of agriculture straw residue is a common method to dispose waste after harvesting seasons in China. The burning of agricultural crop residue in open field which has been given little attention up till now represents an important source of CO 2 for global warming concern. According to the CO 2 emission factors of rice, wheat, and corn straws based on laboratory measurements, the amount of CO 2 emission via agricultural crop residue open burning in China between 1996 and 2013 has been calculated. The diverse accounting methods and geographic information system (GIS) are used to map the CO 2 emission of thirty-one provinces. Identifying the spatial distribution, 5-year average variation, and contributions of CO 2 emission by three major agricultural residue open burning, it is found: (i) About 2707.34 Tg of CO 2 is emitted by agriculture residue open burning, occupies 45.09% of the total residential coal consumption from 1996 to 2013 (ii) The total emission from rice, wheat and corn straw burning are concentrated in south and northeast of China, North China and northeast of China, respectively (iii) Shandong Province contributes the largest portion of CO 2 emission, Henan, Jiangsu, Hebei and Hei Longjiang rank the second, third, forth, and fifth, respectively. From different level of CO 2 emission by agricultural crop residue open burning, we can find mitigation potential of greenhouse gas emission and give three suggestions: (i) generalizing straw returning field application (ii) improving the efficiency of straw utilization (iii) commercializing biomass energy. However, the mitigation potential, and varied policies and regulations need to be developed which are related to the local economic and environmental conditions in different China rural places. [ABSTRACT FROM AUTHOR]

The vibration-based electromagnetic energy harvester offers a cost-effective and promising renewable energy approach. With the rapid development of autonomous agricultural production, advanced agricultural machinery equipped with multiple sensors is of significant importance. In the hilly areas of southwest China, the driver of the pennisetum sinese roxb harvester must frequently adjust the height of the stripping header to adapt to the terrain height variation and it leads to high labor intensity. Because of the harness environment of the working condition, the arrangement of wires for sensors is almost impossible. Thus, a self-powered sensor node by profiling mechanism with a vibration energy harvester is proposed. This paper presents theoretical and experimental research on a profiling mechanism using a vibration energy harvester, with which a detailed theoretical model is established to perform the dynamic simulation study. Diverse excitation conditions such as sinusoidal sweeping vibration tests, fixed frequency vibration and stochastic road spectrum tests of agricultural machinery were implemented to verify the power generation capacity. The simulation results agree well with the experimental data. Experimental results show the peak-peak voltage and power of the proposed device reach about 44 V and 113 mW under low frequency and large displacement excitations. The vibration test justifies the feasibility of the proposed profiling mechanism in the application scene for powering the range sensor applied in agricultural production. [Display omitted] • A self-powered sensor node by profiling mechanism is developed. • The dynamic simulation results agree well with the experimental data. • Stochastic road spectrum tests are conducted to evaluate the device performance. • The device and energy conversion circuit form a self-contained system. [ABSTRACT FROM AUTHOR]

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1–40 years), early stage (41–80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methane from fugitive gases captured and enriched to town gas. • Demonstration pilots conducted on a 110 kg scale using pressure swing adsorption. • Methane capture proved to be an efficient way for greenhouse gas reduction and energy harvest. • 3 most-needed areas of future work proposed to promote methane capture. Methane (CH 4) is the second largest contributor to anthropogenic greenhouse gas (GHG) emissions. The separation of CH 4 from nitrogen (N 2) is crucial for the capture of CH 4 from low concentration sources, such as coal seam gas, to reduce GHG emissions. Pressure vacuum swing adsorption (PVSA) provides a flexible and scalable method for CH 4 /N 2 separation. In this work, a novel adsorbent (ILZ) was used in a 112 kg scale PVSA pilot facility to test the feasibility of separating CH 4 from low concentration sources (4.7–44.5%). A product purity of 44.5% CH 4 and a methane recovery of 81% were achieved from a feed gas containing just 4.7% CH 4 via a 3-stage PVSA process. Such a product gas can then be transported using pipelines and used for either power generation or 4T town gases in China. The total energy consumption was 133 kJ per mol CH 4 captured, which is 85% lower than its heating value (~880 kJ/mol). This study demonstrates that the capture of CH 4 from large but low concentration sources incentivises GHG emissions reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • A road-based energy harvester is designed for near-zero-energy toll stations on expressways. • A spatial double V-shaped mechanism is utilized for mechanical motion conversion. • The output energy is stored in supercapacitors to power small electronic components. • The average efficiency of 59.42 % is obtained during the experimental study. • A simple-installation and low-maintenance design is proposed for applied use. To replace traditional energy sources, researchers are exploring renewable energy technologies. With the continued development of cities, the number of expressways and toll stations in China has increased rapidly. Meanwhile, the expressway toll stations have great potential for kinetic energy scavenging for electronic accessories. This paper presents a novel road energy harvesting system (REHS) based on a spatial double V-shaped mechanism for self-powering small electronic accessories in near-zero-energy toll stations on expressways. The proposed system can be installed at the entrances and exits of expressway near-zero-energy toll stations, to convert the wasted kinetic energy of moving vehicles into electric power. The suggested system comprises four modules: speed bump module, transmission module, generator module and power storage module. As the energy input, the speed bump module captures the kinetic energy of moving vehicles. The transmission module contains a spatial double V-shaped mechanism to transform the vertical linear motion into unidirectional rotary motion. In the energy storage module, the supercapacitors are used to store electrical energy. The experimental analyses were performed using mechanical testing and sensing machine (MTS) and a maximum output voltage of 12.64 V was recorded at a square wave based input force of 500 N and 0.1 Hz frequency. The overall potential of power generation/year for all mainline toll stations was estimated and found that China has 219.66 MW h of potential only from road-based toll stations. The prolific findings prove the feasibility and practicality of the proposed REHS for near-zero-energy toll stations on expressways. [ABSTRACT FROM AUTHOR]

Renewable energy resources have enabled the mitigation of global environmental pollution and sustainable energy generation. Due to renewability, cleanliness, and vast sustainability aspects of wind energy, wind power generation (WPG) systems have recently found rapid development. In this study, the sustainability aspects of WPG systems are briefly summarized by comparing the sustainability parameters for various sources of WPG. The techno-socio-economic, aesthetic, and cultural impacts of conventional wind farms and the influence of the COVID-19 pandemic on the accomplishment of new wind energy projects were also discussed. The study aims to visualize the intellectual background, current research status and state-of-the-art knowledge structure of WPG-related literature using CiteSpace based scientometric investigation. The WPG-related original articles, published from 2005 to 2020, were retrieved from the Web of Science core collection. The most prolific publications, countries and journals involved in the flourishment of WPG research were identified. Moreover, visualization methods were employed to determine the highly productive articles, keywords, hotspots, and research frontiers in the WPG domain. Furthermore, the classification of WPG knowledge was performed in the form of clusters and knowledge structure to achieve ten distinct sub-domains. It was revealed that China was the most prominent country among others in the research of WPG, holding 29% of the total publications; the most probable reason is the more assertive funding support policy from the Chinese government and research institutions, compared to other countries. This study can help the researchers to spot the new research frontiers and distinguish among the most critical sub-domains of WPG based knowledge. [Display omitted] • A total of 841 WPG-related articles were collected from SCI and ESCI databases. • The intellectual background of WPG research was visualized using CiteSpace based scientometric analysis. • The most influential articles and most frequently used keywords were highlighted. • Extracted ten sub-domains of WPG through knowledge structuring and identified research frontiers. • Applications and utilization of wind energy harvesting are summarized. [ABSTRACT FROM AUTHOR]

Inter-basin water transfers are intended to have a positive impact on the development of a region, but are always accompanied by huge energy consumption. The feasibility and effectiveness of water transfer projects have not yet been clearly evaluated, especially in the light of their energy consumption and effects on social development. This paper develops a method that combines life cycle approach and system dynamic model to reveal the effectiveness of different water supply alternatives (transferred water, reclaimed wastewater and rainwater harvesting) when they are all constrained to consume equal energy. This approach is applied to the case of Jinan city in Shandong province, China, the main water-receiving city on the Eastern Route of the South-to-North Water Transfer Project (ER-SNWTP). The results show that in normal years, Jinan's reclaimed water and rainwater harvesting supply are effective replacements for transferred water under the constraints of equal energy consumption and capital costs; even in dry years these two alternatives still play an important role. The results of this study indicate the relative effectiveness of reclaimed water and rainwater harvesting in supplying urban water while conserving energy and capital. • Using a new evaluation approach for urban water supply alternatives analysis. • Local water and transferred water have similar supporting role to the receiving city in the east route of SNWTP; • Local water option has less environmental impact and lower financial cost. [ABSTRACT FROM AUTHOR]

Solar energy is a sustainable and inexhaustible renewable energy. Solar-powered PV systems contribute to the cleanest and the most cost-effective electrical energy. However, PV systems are confronted with a nonlinear maximum power point tracking (MPPT) problem caused by partial shading (PS). PS causes the loss of available power. This paper presents a novel Harris hawk optimization (HHO) based MPPT controller to effectively track maximum power under all weather conditions. The effectiveness of the proposed HHO based MPPT is supplemented by a comparative study with perturb and observe algorithm (P&O), dragonfly optimization algorithm (DFOA), particle swarm optimization (PSO), cuckoo search (CS) and grey wolf optimization (GWO). The analytical and statistical analysis is made based on 4 different cases, including fast varying irradiance, PS, complex-PS (CPS), and field atmospheric data of Hefei city of China, to solidify the effectiveness of HHO based MPPT for PV systems in real-world applications. The proposed HHO shows superior performance in tracking maximum power point and faster convergence at the global maximum power point. The improvement of 10–30% in tracking time and more than 90% in random oscillations are effectively achieved by the proposed MPPT technique. Faster maximum power point (MPP) tracking, lower computational burden and higher efficiency are the key contributions of the HHO based MPPT technique. • Novel Harris hawk optimizations (HHO) based MPPT control of PV system is proposed. • HHO is compared with P&O, PSO, GWO, CSA, and DFOA through field atmospheric data and case studies. • HHO outperform competing techniques with 10-30% faster tracking, 4-6% more energy harvest and oscillation reduction 95.45%. • Statistical and quantitative analysis confirms the superior performance of the proposed HHO. [ABSTRACT FROM AUTHOR]

Wind energy plays an important role in the field of renewable energy due to its lower cost and the maturity of its manufacturing technology. During the last few years, there has been an increase in offshore wind turbine (OWT) projects especially in China. Considering the fact that ocean environment where these offshore wind turbines operate usually has a negative impact on their structural health, the demand for investigating the dynamic characteristics of offshore wind turbines based on sea test is increasing. However, current studies are mainly focused on method development, theoretical analysis and numerical simulation, and few attention has been given to the study of the dynamic characteristics of an actual OWT in different operational states based on sea test. To improve the current studies, in September 2016, November 2016 and April 2017 a series of monitoring campaigns of an actual in service OWT and its monopile were conducted at an offshore wind farm in the sea area near Jiangsu Province, China. For the purpose of acquiring high-quality vibration signal, one type of artificial excitation was adopted to excite the OWT vibration. In these monitoring campaigns, with the help of a group of wireless health monitoring sensor nodes developed by Ocean University of China (OUC), we successfully acquired the vibration signal of the wind turbine in parked state and normal operational state and acquired the vibration signal of the monopile in construction, which means no tower was installed. Afterwards, two modal analysis methods, the eigensystem realization algorithm (ERA) and stochastic subspace identification (SSI), were used to obtain the modal parameters of the tested structure using the vibration signal under artificial excitation and random wave excitation, respectively. The results show that the ERA method can successfully identify the first two order modal parameters of the monopile and the first three order modal parameters of the wind turbine in parked or operational state. However, the SSI method failed to identify the third-order modal parameters of the wind turbine, regardless of whether it is in parked state or operational state (only the first two order modal parameters can be identified); meanwhile, SSI failed to identify the modal parameters of the monopile. Concerning the high-level environmental noise in an offshore site, we applied weak-mode identification (WMI) for the first time to obtain the modal parameters of OWT using vibration signal under both artificial excitation and random wave excitation. The results indicated that WMI has achieved the same good performance as the ERA when the vibration signal under artificial excitation is used. When the vibration signal under random wave is used, WMI successfully identified the first order modal parameters of the monopile and the first three order modal parameters of the wind turbine in parked or operational state, which indicated a better ability than that of the SSI method. We can conclude that the modal parameters of the wind turbine can be obtained by the WMI method and ERA method, and the ERA method is the best way to obtain the modal parameters of monopile under artificial excitation. These monitoring campaign of an actual OWT not only provide modal information support for structural maintenance and operation safety assessment, but also provide a real data reference for wind turbine design. • Vibration signals of an offshore wind turbine under artificial and ambient excitations are obtained, respectively. • Three methods are emplyed to obtain the modal parameters of the tested offshore wind turbine. • ERA is effective in identifying modal parameters from vibration signal under artificial excitation. • SSI and weak-mode identification can obtain modal parameters from vibration signal under ambient excitaiton. [ABSTRACT FROM AUTHOR]

Approaches for energy harvesting from rotating vehicle tires have been investigated for years; however, where the harvestable energy is actually generated has not been discussed so far. For the first time, the potentially harvestable energy under vehicle wheels, as a real energy source, is discovered. Estimations show that the global potentially harvestable energy from the vehicle wheels could be 3.26 × 1011 kW, equivalent to 14 500 times the installed capacity of the worldwide largest hydraulic power plant, Three Gorges Dam of China; 36.7% saving of a vehicle's fuel consumption could be achieved if this potential energy could be totally harvested. State‐of‐the‐art energy harvesting techniques can only extract a negligibly small amount of the energy under vehicle wheels, calling for revolutionary new energy harvesting techniques. [ABSTRACT FROM AUTHOR]

In the context of global warming and energy shortage, this paper discusses the techno-economic feasibility of a residential household based on 100% renewable energy in China. The energy storage life, equipment's residual value, system shortage capacity and atmospheric pollution emissions were considered comprehensively. A life cycle evaluation model based on the net present value (NPV) was built. Taking a real household as an example, the levelised cost of energy (LCOE) is 0.146 $/kW and the unmet load is only 0.86%, which has a big economic advantage when compared with diesel generators. If grid-connected, the system can bring $8079 in 25 years when the LCOE is −0.062 $/kW. The effects of the allowed shortage capacity, renewable energy resources, battery price and the allowed depth of discharge on the economy and energy structure were examined. For example, due to the features of the residential load, the influence of wind resource richness is more obvious than the irradiance. The maximum depth of discharge has less impact on the economy. This paper verifies the techno-economic rationality and feasibility of 100% renewable energy for a household. [ABSTRACT FROM AUTHOR]