Flexible Source Research Articles

The quantity-quality transition in the value of expanding wind and solar power generation

SummaryWind and solar photovoltaic generators are projected to play important roles in achieving a net-zero-carbon electricity system that meets current and future energy needs. Here, we show potential advantages of long-term site planning of wind and solar power plants in deeply decarbonized electricity systems using a macro-scale energy model. With weak carbon emission constraints and substantial amounts of flexible electricity sources on the grid (e.g., dispatchable power), relatively high value is placed on sites with high capacity factors because the added wind or solar capacity can efficiently substitute for running natural gas power plants. With strict carbon emission constraints, relatively high value is placed on sites with high correlation with residual demand because resource complementarity can efficiently compensate for lower system flexibility. Our results suggest that decisions regarding long-term wind and solar farm siting may benefit from consideration of the spatial and temporal evolution of mismatches in electricity demand and generation capacity.

Solution-Processed Electron-Transport Layer-free Organic Photovoltaics with Liquid Metal Cathodes

Flexible, lightweight, and large-area solar cells provide new power supply opportunities in the renewable energy field and facilitate the supply of power to internet-of-things devices and wearable devices. The choice of printing process technologies is a key parameter for such flexible power sources because of their energy-saving process technology and high throughput rate. In addition to selecting the appropriate printing method for the active and charge transport layers, the development of printed electrodes is critical. Numerous printable materials have been developed to replace conventional evaporated top electrodes. However, achieving fully solution-processed organic photovoltaics (OPVs) with power conversion efficiency (PCE) comparable to OPVs with vacuum-deposited transparent and top electrodes is challenging. This is because of the difficulty of forming a uniform interface between the top solution-processed electrode and the active layers while preventing deterioration. In this study, an electron transport layer-free, eutectic gallium-indium (EGaIn) top-cathode strategy was developed and a record PCE of 12.7% in fully solution-processed, flexible OPVs was achieved. Direct coating of EGaIn on the active layer, in a nitrogen atmosphere, is conducive for energy band matching and obtaining physically perfect interfaces without any penetrations or voids. An average PCE of 14.1% and enhanced operating stability, comparable to conventional OPVs, were achieved with indium tin oxide transparent electrodes by eliminating the electron-transport layer. The fully solution-processed flexible OPVs fabricated with the embedded silver nanowire strategy in ultrathin transparent polyimide, achieved an average PCE of 12.7%, representing a promising technique to meet green and high-throughput energy demands.

Autonomous Energy Management by Applying Deep Q-Learning to Enhance Sustainability in Smart Tourism Cities

Autonomous energy management is becoming a significant mechanism for attaining sustainability in energy management. This resulted in this research paper, which aimed to apply deep reinforcement learning algorithms for an autonomous energy management system of a microgrid. This paper proposed a novel microgrid model that consisted of a combustion set of a household load, renewable energy, an energy storage system, and a generator, which were connected to the main grid. The proposed autonomous energy management system was designed to cooperate with the various flexible sources and loads by defining the priority resources, loads, and electricity prices. The system was implemented by using deep reinforcement learning algorithms that worked effectively in order to control the power storage, solar panels, generator, and main grid. The system model could achieve the optimal performance with near-optimal policies. As a result, this method could save 13.19% in the cost compared to conducting manual control of energy management. In this study, there was a focus on applying Q-learning for the microgrid in the tourism industry in remote areas which can produce and store energy. Therefore, we proposed an autonomous energy management system for effective energy management. In future work, the system could be improved by applying deep learning to use energy price data to predict the future energy price, when the system could produce more energy than the demand and store it for selling at the most appropriate price; this would make the autonomous energy management system smarter and provide better benefits for the tourism industry. This proposed autonomous energy management could be applied to other industries, for example businesses or factories which need effective energy management to maintain microgrid stability and also save energy.

V2 O3 /MnS Arrays as Bifunctional Air Electrode for Long-Lasting and Flexible Rechargeable Zn-Air Batteries.

Exploring highly efficient, stable, and cost-effective bifunctional electrocatalysts is crucial for the wide commercialization of rechargeable Zn-air batteries. Herein, a vanadium-oxide-based hybrid air electrode comprising a heterostructure of V2 O3 and MnS (V2 O3 /MnS) is reported. The V2 O3 /MnS catalyst shows a decent catalytic activity that is comparable to Pt/C toward the oxygen reduction reaction and acceptable toward oxygen evolution. The extraordinary stability as well as the low cost set the V2 O3 /MnS among the best bifunctional oxygen electrocatalysts. In a demonstration of an assembled liquid-state Zn-air battery using V2 O3 /MnS as cathode, high power density (118mW cm-2 ), specific capacity (808 mAh gZn -1 ), and energy density (970Wh kgZn -1 ), as well as the outstanding rechargeability and durability for 4000 cycles (>1333 h, i.e., >55days) are enabled. The V2 O3 /MnS is also integrated into an all-solid-state Zn-air battery to demonstrate its great potential as a flexible power source for next-generation electronics. Density functional theory calculations further elucidate the origin of the intrinsic activity and stability of the V2 O3 /MnS heterostructure.

Carbon Nanofibers Based on Potassium Citrate/Polyacrylonitrile for Supercapacitors.

Wearable supercapacitors based on carbon materials have been emerging as an advanced technology for next-generation portable electronic devices with high performance. However, the application of these devices cannot be realized unless suitable flexible power sources are developed. Here, an effective electrospinning method was used to prepare the one-dimensional (1D) and nano-scale carbon fiber membrane based on potassium citrate/polyacrylonitrile (PAN), which exhibited potential applications in supercapacitors. The chemical and physical properties of carbon nanofibers were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and the Brunnauer–Emmett–Teller method. The fabricated carbon nanofiber membrane illustrates a high specific capacitance of 404 F/g at a current density of 1 A/g. The good electrochemical properties could be attributed to the small diameter and large specific surface area, which promoted a high capacity.

Perceived Acceptability and Experiences of a Digital Psychoeducation and Peer Support Intervention (COPe-support): Interview Study With Carers Supporting Individuals With Psychosis.

BackgroundWeb-based mental health interventions offer a novel, accessible, and self-paced approach to care delivery to family carers (ie, relatives and close friends who support a loved one with psychosis). We coproduced COPe-support (Carers fOr People with Psychosis e-support), a psychoeducational intervention delivered via an enriched web-based learning environment with network support from professionals and peers. In addition to the rigorous investigation of the effectiveness of COPe-support on the well-being of carers and mental health outcomes, it is imperative to understand the experiences of using the web-based intervention by carers and its associated web-based implementation and facilitation strategies.ObjectiveThis study aims to explore the experiences of carers and perceived acceptability of COPe-support and its different components, how carers found engagement with COPe-support affected their own well-being and caregiving, and the ideas of carers for improving COPe-support and its delivery to inform any future wider implementation.MethodsWe conducted a qualitative study, individually interviewing 35 carers, following their use of COPe-support for 8 months through a web-based, randomized controlled trial across England. A semistructured guide with open-ended questions was used to explore the experiences of carers and perceived acceptability of the intervention and their ideas to improve the provision. All interviews were conducted remotely through mobile phones or internet communication media, audio recorded and transcribed verbatim. We used a thematic analysis framework to analyze the data.ResultsThree key themes were identified: remote, flexible, and personalized support; impacts on well-being and outlook on caregiving; and future implementation and integration with existing services. Overall, carers found COPe-support a flexible source of knowledge and support from professionals and peers that they could personalize to suit their own needs and convenience. Participants described gaining self-confidence, hope, and a sense of connectivity with others in a similar situation, which helped ameliorate isolation and perceived stigma. Most importantly, COPe-support promoted self-care among the carers themselves. Participants’ experiences, use, and activity on COPe-support varied greatly and differed among carers of various ages and levels of computer literacy.ConclusionsNearly all participants had a positive experience with COPe-support and supported its wider implementation as a beneficial adjunctive support resource for carers in the future. Any future scale-up of such an intervention needs to consider feedback from carers and suggestions for further improvement. These included having more graphics and audiovisual content materials, improving the navigation, and building in more interactional and customization options to suit various user styles, such as emoji reactions, live web-based chat, opting in and out of updates, and choosing the frequency of reminders. To ensure successful implementation, we should also consider factors pertinent to reaching more carers and integrating the web-based resources with other conventional services.Trial RegistrationInternational Standard Randomized Controlled Trial Number (ISRCTN) 89563420; https://www.isrctn.com/ISRCTN89563420International Registered Report Identifier (IRRID)RR2-10.1186/s12888-020-02528-w

A Flexible Triboelectric Nanogenerator Based on Cellulose‐Reinforced MXene Composite Film

AbstractA flexible triboelectric nanogenerator (TENG) is an indispensable part in future flexible self‐powered system. However, it is still a great challenge to establish a balance among the robust mechanical property, strong triboelectrification effect, and high conductivity of electrode materials. A flexible and enhanced‐performance TENG based on cellulose nanofibrils (CNFs)/transition metal carbides and nitrides (MXene) composite films is developed here for harvesting human movement energy. By introducing CNFs, the mechanical strength, flexibility of the composite film, and sensitive to the temperature change and strain are improved. The effect of CNFs concentration, working force, and frequency on the output performance of TENG is also demonstrated. At the optimized CNFs/MXene ratio of 2/5, the transferred charges and output voltage reach the maximum value of 7.4 nC and 24.9 V, respectively. The maximum instantaneous output power density of the as‐prepared TENG is 1.2 mW m−2. Moreover, a self‐powered flexible display system is demonstrated by integrating the TENG with a flexible alternating current electroluminescence. The flexible TENG based on cellulose nanofibrils‐reinforced MXene composite film is promising as a flexible energy source for self‐powered system.

Ti3C2Tx/aramid film electrode with high capacitance and good mechanical strength and the assembled wide temperature all-solid-state symmetrical supercapacitor

Using large Ti3C2Tx nanosheets (L-Ti3C2Tx) and aramid nanofibers as the assembled units and functional additive, the L-Ti3C2Tx nanosheets/E-ANF film electrode (T/E-A-10) with high capacitive performance of 332 F g−1 in 3 M H2SO4 electrolyte and good mechanical strength of 153 MPa was prepared. Also PVA/Ti3C2Tx nanosheet flexible hydrogel electrolyte with excellent antifreezing, long-lasting moisture, high ion conductivity and wide temperature working range was developed. A wide-temperature flexible all-solid-state T/E-A-10 film symmetrical supercapacitor (T/E-A-10 FSSC) was assembled by using T/E-A-10 flexible film as electrodes, and PVA/Ti3C2Tx membrane as hydrogel electrolyte and separator. The assembled devices not only showed a specific capacitance of 83 F g−1 at a current density of 0.5 A g−1, 92% of the initial capacitance after 4000 cycles, and a maximum energy density of 11.8 Wh kg−1, but also maintained good flexibility in a wide temperature range of −40–60 °C, it showed a promising flexible power source in the field of portable/wearable electronic devices.

Optimal Deployment of SRv6 to Enable Network Interconnection Service

Many organizations nowadays have multiple sites at different geographic locations. Typically, transmitting massive data among these sites relies on the interconnection service offered by ISPs. Segment Routing over IPv6 (SRv6) is a new simple and flexible source routing solution which could be leveraged to enhance interconnection services. Compared to traditional technologies, e.g., physical leased lines and MPLS-VPN, SRv6 can easily enable quick-launched interconnection services and significantly benefit from traffic engineering with SRv6-TE. To parse the SRv6 packet headers, however, hardware support and upgrade are needed for the conventional routers of ISP. In this paper, we study the problem of SRv6 incremental deployment to provide a more balanced interconnection service from a traffic engineering view. We formally formulate the problem as an SRID problem with integer programming. After transforming the SRID problem into a graph model, we propose two greedy methods considering short-term and long-term impacts with reinforcement learning, namely GSI and GLI. The experiment results using a public dataset demonstrate that both GSI and GLI can significantly reduce the maximum link utilization, where GLI achieves a saving of 59.1% against the default method.

A Flexible Ionic Polymer for “Soft Machines” – Where is the Low Temperature Limit?

AbstractSoft wearable robotics, electronic skins, exoskeletons, implantable drug delivery, medical sensors, fitness trackers as well as flexible power sources (batteries, capacitors, fuel cells) are emerging technologies that require significant innovation to succeed. Conducting hydrogels are one of the promising flexible platforms that can adopt a modular specification of wearable electronics. However, a common difficulty arises from incorporation of water that serves as main facilitator of ionic conductivity for these materials. This results in severe loss of performance when need to operate below freezing point of water. This work shows that the hydrogel with 50 vol % of glycerol with respect to water content can nominally support a modest weight at room temperature (360 g), and a significantly higher weight (1.5 kg) when cooled to −60 °C. Unlike other formulations, this hydrogel remained transparent at extremely low temperatures and thus could be useful in flexible optical devices. At −20 °C, conductivity of hydrogel without anti‐freeze drops below 2×10−4 S cm−1, with 25–50 vol % of glycerol ranging at ∼0.5 to 4×10−3 S cm−1. Furthermore, at −40 °C the hydrogel without glycerol becomes an insulator (∼2×10−6 S cm−1), and the one with 50 vol % glycerol shows ionic conductivity in the range of 1–4 ×10−4 S cm−1. Altogether, we define the operational temperature limit at −40 °C with respect to the ionic conductivity and at −60 °C in terms of sufficient mechanical strength for the hydrogel containing 50 vol % glycerol.

Vector Soliton Molecules Manipulation Using Projected Super-Position Technique

Soliton manipulation is considered as an effective way to generate complicated and controllable vector soliton molecules (VSMs). With the help of projected super-position technique, we have successfully obtained a series of novel and stable VSMs from fundamental 1-1-2 VSMs to more complex 2-2-4 VSMs. Moreover, we have investigated that vector soliton separation is the key parameter that determines the formation of obtained VSMs. These results would be significant complementation for soliton dynamics as well as a flexible and useful soliton light source for various practical applications.

ГИБРИДНЫЕ НАКОПИТЕЛИ ЭНЕРГИИ: ПРОБЛЕМЫ И ПЕРСПЕКТИВЫ ТЕХНОЛОГИЙ ХРАНЕНИЯ ЭНЕРГИИ

The ever-increasing trend of renewable energy sources (RES) in energy systems of various levels has increased uncertainty in their operation and management. The vulnerability of RES to unforeseen changes in meteorological conditions requires additional resources to support, which are energy storage systems (ESS). However, existing ETSs have limited capacity to meet all the requirements of a modern enterprise energy system. Thus, the hybridization of multiple ETSs to form a composite ETS is a potential solution to this problem. As a flexible energy source, energy storage has many potential applications for integration into renewable energy generation, transmission and distribution networks. This paper analyzes the prospects for hybrid energy storage applications and summarizes the latest experience in terms of the maturity of these technologies, efficiency, scale, lifetime, cost and applications, taking into account their impact on the entire power system, including generation, transmission, distribution and utilization. The challenges of large-scale applications of energy storage in power systems are presented in terms of technical and economic considerations.

Flexible self-charging lithium battery for storing low-frequency mechanical energy

Flexible self-charging power source, with admirable capability to harvest/store the energy generated by human motion, is considered as the most suitable power supply for next generation of wearable electronic devices. Herein, we demonstrated a flexible self-charging lithium battery for storing low-frequency tiny motion energy. The electrospinning polyvinylidene fluoride-trifluoro ethylene (P(VDF-TrFE)) porous membranes was adopted as a piezoelectric separator and a supporting layer of the electrode to fabricate a novel flexible self-charging power cell (SCPC). The flexible SCPC could be effectively charged by directly collecting movement energy through mechanical deformation. The SCPC sealed in flexible case could be charged via periodic tapping (6 N, 1 Hz), indicating a storage capacity of 0.092 μA h in 330 s. Compared with traditional self-charging batteries, the flexible SCPC can work effectively at lower frequency and pressure, and collect the tiny motion energy of human body to power wearable electronic devices. This work may provide an innovative way to develop new self-charging wearable electronic devices.

Conceptual design of the Hybrid Ring with superconducting linac.

The Hybrid Ring with a superconducting-linac injector as a highly flexible synchrotron radiation source to enable new experimental techniques and enhance many existing ones is proposed. It is designed to be operated with the coexistence of the storage (SR) bunches characterized by the performance of the storage ring, and the single-pass (SP) bunches characterized by the performance of the superconducting linac. Unique experiments can be performed by simultaneous use of the SR and SP beams, in addition to research with various experimental techniques utilizing the versatile SR beam and research in the field of ultrafast dynamics utilizing the ultrashort pulse of the SP beam. The extendability of the Hybrid Ring will allow it to be developed into a synchrotron radiation complex.

Synthesis and plasma treatment of nitrogen-doped graphene fibers for high-performance supercapacitors

Graphene fiber-based supercapacitor has aroused great interest as a flexible power source in future wearable electronics. However, the low electrochemical performance of graphene fibers (GFs) usually causes the serious limitation of use in practical applications due to the material stacking, hydrophobicity and fabrication process complexity. In this work, a facile and effective plasma-assisted strategy is put forward to increase specific surface area, tune hierarchically porous structure and promote wettability of nitrogen-doped graphene fibers (NGFs), resulting in the improvement of electrochemical performance. The supercapacitor assembled from plasma-treated NGFs shows superior capacitance (878 mF/cm 2 at 0.1 mA/cm 2 current density) and high energy density (19.5 μW h/cm 2 at 40 mW/cm 2 power density), which is 23.7% and 131.4% higher than that of NGFs and GFs, respectively. Additionally, the fiber-based supercapacitor based on plasma-treated NGFs exhibits high rate capability of 59.8% and excellent cyclic performance (95.8% retention over 10,000 cycles). These plasma-treated NGFs can be promising candidates for high-performance and flexible power sources in future wearable electronics.

Lessons learned – lessons enacted? Opportunities for supply chain improvements coming out of the pandemic

The COVID19 pandemic triggered a flurry of research about pandemic risks in supply chains and how to navigate through and out of the pandemic. Because change in supply chains takes time this work is far from complete. This paper reflects upon opportunities for structural improvement in supply chains coming out of the pandemic. These include (1) the need to move away from over-reliance on unidimensional strategies and consider nearshoring and reshoring, (2) lean and just in time inventory management have not lost all of its value and the need to ensure multiple flexible sources, (3) disruption provides a step up, not a step away from sustainability. We reflect upon these opportunities and the risks of partial enactment of these opportunities in an effort to inspire progress in supply chain management research and practice.

A Method for Assessment of Sub‐Daily Flow Alterations Using Wavelet Analysis for Regulated Rivers

AbstractNew tools are needed to evaluate the impacts of short‐term hydropower regulation practices on downstream river systems and to progress towards sustainable river‐flow management. As hydropower is increasingly being used to balance the energy load deficit caused by other less flexible sources, sub‐daily flow conditions across many regulated river (RR) systems are changing. To address this, we used wavelet analyses to quantify the discharge variability in RRs and categorized the level of variability based on the conditions in natural free‐flowing rivers. The presented framework used the definition of fluvial connectivity (Grill et al., 2019) to identify free‐flowing rivers used in the study. We tested the developed framework in 12 different RRs in Finland and found higher overall averaged subdaily variations, with up to 20 times larger variability than natural conditions. A large, highly regulated Finnish river system was found to have the highest sub‐daily variations in winter, while smaller RRs with lower levels of regulation the highest variations in summer. The proposed framework offers a novel tool for sustainable river management and can be easily applied to various rivers and regions globally. It had flexibility to analyze sub‐daily variations in desired seasonal or other ecologically sensitive periods.

Flexible hydrogen production source for fuel cell vehicle to reduce emission pollution and costs under the multi-objective optimization framework

As countries strive to meet their targets for reducing the effects of global climate change, the de-carbonization of energy systems becomes a hot topic in the worldwide energy business. In the meantime, Fuel-cell vehicles (FCVs) play an influential role in integrating more renewable sources and reducing urban pollution as a suitable replacement for diesel vehicles. However, emission pollution from the preparation of the primary fuel for hydrogen-based transportation cannot be neglected. This paper presents a multi-objective approach to operating FCVs along with wind and solar sources and power-to-gas (P2G) storage to reduce operating costs and pollution emissions in a hybrid power-gas-hydrogen system. One of the main concerns in the performance of FCVs is the stable supply of hydrogen as the primary fuel. In this paper, P2G is coupled with FCVs as a high-efficiency technology to convert excess electrical energy into hydrogen and natural gas to play an influential role in carbon capturing while maintaining its stable performance. The proposed hybrid system participates in the electricity and gas markets while supplying the hydrogen needed for FCV and selling hydrogen to hydrogen-based industries. Considering the uncertainty related to renewable sources and prices, the problem is modeled as a multi-objective probabilistic model, and the weighted sum approach based on fuzzy decision-making is used to solve it. After comprehensively analyzing FCV's performance, results show an 8.04% and 9.8% reduction in the cost and emission pollution, respectively, under the comprehensive operation approach of FCV and P2G technology.

Flexible plasma multi-jet source operated in radial discharge configuration.

Following up on a recent study describing a flexible plasma source operated in planar geometry, the performance of a cold atmospheric plasma jet (CAPJ) matrix emanating radially from a soft cylindrical surface in the open air is presented. The plasma device, which has a set of small outlets produced in its side surface, has a length of 12cm and an outer diameter of 5.4cm. The dielectric barrier discharge (DBD) sustaining the plasma jets is generated in helium flowing between two coaxial electrodes, which are separated by both an insulating tape and a cylindrical wall made of polymer foam. Two operation modes are considered: four equidistant CAPJs at the same axial position (round brush mode) and three aligned CAPJs at constant azimuthal angle (comb mode). All discharges, excited by 15 kHz-AC voltages at 3.8kV in amplitude, have resulted in uniform lengths and intensities of the jets. Consumed discharge powers of between 0.1 and 1.5W have been estimated from current-voltage measurements. Optical emission spectroscopy has shown the preponderance of hydroxyl groups, nitrogen molecules, and helium atoms in the active DBD region and the jet afterglow zone. This new designof CAPJ anticipates promising applications for treating the inner surface of hollow and delicate components for activation or healing purposes.

Development path of China's gas power industry under the background of low-carbon transformation

The natural gas power generation (hereinafter referred to as gas power) industry is an important force in the development process of clean energy in China, and it not only plays an important role, but also faces many challenges in the process of transformation to low-carbon energy. In order to explore the sustainable development path of China's gas power industry in the process of low-carbon transformation, this paper studies the carbon emission intensity of gas power unit in different scenarios by taking GE's three mainstream types of gas turbine units (6F.03, 9F.03 and 9HA.01) as examples, and then compares it with that of coal power unit in the same scenario based on industrial status and development trend. On this basis, the development path of gas power industry in the period of low-carbon transformation is proposed. And the following research results are obtained. First, the proposal of the time limit of carbon peak and carbon neutrality points out the goal and path of future low-carbon transformation in China. As a kind of low-carbon clean energy, natural gas will play a more important role in the process of energy transformation in China. Second, compared with coal-fired power generation, gas power is much more advantageous in emission reduction, so the orderly development of gas-based cogeneration has good direct emission reduction effects. Third, as a kind of flexible power source, gas power provides good guarantee and promotion for the development of renewable energy sources and the active development of gas-powered peak-shaving power stations has a good effect of collaborative emission reduction. Fourth, moderately increasing the proportion of natural gas and gas power in energy consumption before carbon neutrality can effectively exert their collaborative emission reduction effects and generate collaborative emission reduction benefits, so as to optimize energy resource allocation and maximize social welfare. In conclusion, gas power is one of the important ways to utilize natural gas.