External Power Research Articles

Reliability and economic evaluation of energy storage as backup and load regulation power supply in data centers

AbstractThe battery energy storage system (BESS) combines backup and load regulation functions, making it a potential alternative to the diesel generator (DG) as the backup power source for data centers. Some studies have been conducted on the reliability and cost–benefit of equipping data centers with BESS, but the impact of the reliability of external utility power and the expected outage losses have not been considered. Therefore, this study established a power supply reliability model that included the external utility power reliability and the electrical equipment reliability, and a cost–benefit model that took into account the BESS construction and replacement cost, the outage loss reduction, and the load regulation benefits. A case study was conducted on a data center in Beijing. The results indicate that: (a) the reliability and cost–benefit of BESS significantly vary with the reliability of the external utility power; (b) based on the 2022 utility power reliability data from various regions in China, in over 48% of the regions, the objective function value of BESS, the annual net income considering power outage losses, and the investment payback period are all superior to those of DG; and in over 27% of regions, the BESS–DG parallel system can serve as a suboptimal alternative to DG; (c) in regions with reliable utility power, BESS exhibits the potential as a feasible substitute for DG in providing backup and load regulation power to data centers.

Energy and exergy analysis of a novel solar-powered passive multi-stage osmosis desalination system for sustainable water production

Climate change and population growth constantly exacerbate global water scarcity, and seawater desalination technology is crucial to addressing this crisis. Conventional fossil-fuel desalination poses environmental and economic challenges, especially in remote, water-scarce regions. Renewable energy offers sustainable options for seawater desalination; however, most related technologies face challenges in flexible deployment. Among passive technologies, interfacial evaporation still confronts issues of salt accumulation impacting desalination efficiency. Therefore, this study investigates a novel solar-powered passive multi-stage osmosis device that emulates mangroves’ transpiration and natural osmosis processes. Harnessing solar energy, it employs hydrophilic nanoporous membranes for water movement and evaporation and an osmosis membrane for solute retention, aiming for efficient seawater desalination without external power and pressure. Energy and exergy analyses reveal key efficiency factors. Results reveal significant pressure gradients across the osmosis membrane as a challenge. Optimizing salinity and adjusting the area ratio of the nanoporous membrane to the osmosis membrane is vital for stability and performance. Moreover, potential increases in water production from 0.97 kg/m2/h to 3.53 kg/m2/h with a five-stage setup, though benefits diminish with additional stages due to heat/exergy losses. The exergy efficiency increases from 0.14 % for a five-stage device to 0.18 % for a ten-stage system. This study demonstrates the solar-powered passive multi-stage osmosis device’s dependence on solar flux and highlights the importance of optimizing the air gap thickness and insulation to boost efficiency.

Cholesteric Liquid Crystal Mirror-Based Smart Window Controlled with Ambient Temperature

In this paper, the authors demonstrate a small prototype of a smart window based on the thermo-optical properties of cholesterol liquid crystals. Due to its polymer-free design, the manufactured smart window is transparent and can reflect certain portions of visible or infrared light without requiring an external power source, and thus is easier to install and operate. The proposed smart window technology based on a cholesteric liquid crystal mirror will reduce energy consumption costs by reflecting excess sunlight and heat transfer, increasing comfort for residents of buildings and structures.

A novel pulse liquid immersion cooling strategy for Lithium-ion battery pack

Ensuring the lithium-ion batteries’ safety and performance poses a major challenge for electric vehicles. To address this challenge, a liquid immersion battery thermal management system utilizing a novel multi-inlet collaborative pulse control strategy is developed. Moreover, different cooling methods (cooling structures, immersion coolants and pulse control method) are numerically investigated to assess their impact. Compared with other structural schemes, the battery module using baffles with fish-like perforations for the 5-in and 5-out scheme demonstrates superior cooling capability while reducing external power consumption. Furthermore, the utilization of FC-3283 exhibits better comprehensive performance compared to AC-100 and mineral oil. Notably, in terms of pulse cooling, when the output ratio reaches 50 %, the battery pack temperature can not only be maintained within a reasonable range, but also the time-averaged pump power consumption decreases by 87.6 % compared to the bottom inlet and top outlet scheme. At the same average flow rate, the liquid immersion battery thermal management system with output ratio of 25 % is the optimal choice for the trade-off between cooling performance and flow resistance, and compared with the bottom inlet and top outlet scheme, the maximum temperature and maximum temperature difference decrease by 23.7 % and 13.9 %, respectively.

An Innovative Water Splitting Process for a Sustainable In Situ Hydrogen Generation–Reduction of Nitrobenzenes Catalyzed by a New Bimetallic Nanocatalyst

ABSTRACTIn this research, bimetallic CdNi nanoparticles encapsulated in a magnetic spent coffee ground (Fe3O4@COFF/CdNi) was synthesized as a new nanocatalyst. The structural and chemical characteristics of Fe3O4@COFF/CdNi were comprehensively investigated using various techniques, including FT‐IR, XRD, XPS, TEM, VSM, EDS, TGA, BET, and ICP. Through XRD, XPS analysis, TEM images, and EDS mapping, the presence of CdNi nanoalloys was conclusively established. Fe3O4@COFF/CdNi exhibited remarkable catalytic activity for the hydrogen generation from water using iso‐propanol as a clean sacrificial agent. The high catalytic performance of Fe3O4@COFF/CdNi was attributed to the synergistic cooperative effect of Cd and Ni within CdNi nanoalloys. Interestingly, this process was performed for the in situ generated hydrogen from water to reduce a range of nitrobenzenes simultaneously into the corresponding anilines in high yields (93%–98%). The magnetic and hydrophilic characteristics of Fe3O4@COFF/CdNi facilitated its reusability over five runs. Using water as the most abundant hydrogen source, for the first time for in situ hydrogen generation–reduction of nitrobenzenes without demanding on external light sources or power supplies can be mentioned as a significant milestone of this field of study.

Study on the Improvement of the Degradation Efficiency of Methylene Blue Using Pulsed Direct-Current Self-Power Supply.

Effective treatment of dye wastewater is currently a great concern and a research hotspot. Electrocatalysis has unique advantages in treating toxic and harmful refractory dye wastewater; however, it requires an external power supply, which increases energy consumption and cost. As a new energy collection technology, triboelectric nanogenerators (TENGs) have gained considerable attention. In this study, an origami multilayer spherical friction nanogenerator (Q-TENG) was developed for the removal of methylene blue (MB) from dye wastewater. The current and voltage output performances of Q-TENG were explored, and the removal and degradation mechanisms of MB were discussed. Results indicated that when the water wave acceleration a = 3 m/s2, the open-circuit voltage and short-circuit current reached the maximum values of 179 V and 9.4 μA, respectively. The self-powered catalytic degradation of MB using Q-TENG can produce more •OH and SO4-•, and the free radicals increase with increasing action time of Q-TENG, thus increasing the degradation efficiency of MB. This study provides a new strategy for solving the problem of high energy consumption during electrochemical reactions in wastewater treatment.

Miniature and cost‐effective self‐powered triboelectric sensing system toward rapid detection of puerarin concentration

AbstractThe detection of puerarin concentration is an essential capability to study the functional role of the Pueraria root as a natural medicine and dietary source in the treatment of cardiovascular diseases and liver protection. Current methods to detect and measure puerarin concentration, such as ultraviolet–visible spectrophotometry (UV), are bulky, require an external power supply, and are inconvenient to use. Here, we propose a triboelectric puerarin‐detecting sensor (TPDS) which is based on liquid–solid contact electrification, in which liquid–solid interactions generate rapid electrical signals in only 0.4 ms to enable real‐time detection of puerarin concentration in water droplets. The electrical signal of the TPDS decreases with an increase of puerarin concentration, and the sensitivity of the approach is 520 V·(μg/mL)−1. The TPDS represents a miniature and cost‐effective sensor that is 0.2% of the size and 0.01% of the cost of a UV spectrophotometer. Our theoretical analysis verified that the puerarin concentration in droplets can effectively regulate the electronic structure, where higher concentrations of puerarin lead to a narrower energy bandgap, which allows the TPDS to detect puerarin concentration without the need for an external power supply. The TPDS therefore provides a route for the development of a portable and self‐powered method to measure the concentration of an active ingredient in droplets through the conversion of natural energy.image

Using TiO2 to capture hot electrons for self-powered position-sensitive photodetection.

As environmental issues arise, the demand for self-powered position-sensitive detectors (PSDs) is increasing because of their advantages in miniaturization and low power consumption. Finding higher efficiency schemes for energy conversion is paramount for realizing high-performance self-powered PSDs. Here, a surface plasmon-based approach was used to improve the energy conversion efficiency, and a plasmon-enhanced lateral photovoltaic effect (LPE) was observed in PSD with TiO2/Au nanorods (NRs)/Si structure. The Au NRs convert absorbed light energy into electricity by generating hot electrons, which are efficiently captured by the TiO2 layer, and the PSD is capable of generating position sensitivity as high as 251.75 mV/mm when illuminated by a 780 nm laser without any external power supply, i.e. about five times higher than similar sensors in previous studies. In addition, the position sensitivity can be tailored by the thickness of TiO2 films. The enhancement mechanism is investigated by a localized surface plasmon (LSP)-driven carrier diffusion model. These findings reveal an important strategy for high sensitivity and low energy cost PSDs while opening up new avenues for energy harvesting self-powered position sensors.

Reconfigurable metasurface design via coplanar self-biasing structure

Reconfigurable metasurface enriches the functional integrated design into the originally limited space. Electrical control, through the external power supply to control the electromagnetic response control, is a common and simple control method. However, current methods of electrical control require external biasing circuits and even metallized through-holes to power the metasurface, thus leading the design and machining of the metasurface more complicated. In order to address this problem, we propose a coplanar self-biasing structure with feeder-structure multiplexing. Metasurface design is generated under connectivity control, and the electromagnetic responses under different voltage states are searched. The designed metasurface is fabricated and verified by measurement, which can prove that the metasurface can control one-dimensional far-field scattering beams. Moreover, the deicing function of the metasurface with integrated biasing line is verified by infrared measurement. All the measured results are consistent well with the expected targets, which shows the effectiveness of our ideas. Importantly, our design opens up a new way to simplify the reconfigurable metasurfaces design, which has a wide application value in the dynamic control of metasurfaces.

Electricity Generation at Gas Distribution Stations from Gas Surplus Pressure Energy

At gas distribution stations (GDSs), the process of throttling (pressure reduction) of natural gas occurs on gas pressure regulators without generating useful energy. If the gas expansion process is created in a turbine, to the shaft where an electric generator is connected, then electricity can be obtained. At the same time, the recycling of secondary energy resources is provided, which is an important component in the efficient use of natural resources. The obtained electric power can be supplied to the external power grid and/or used for the GDS’s own needs. The process of generating electricity at the GDS from gas overpressure energy is an environmentally friendly, energy-saving technology that ensures an uninterrupted, autonomous operation of the GDS in the absence of an external energy supply. The power needs of a GDS with regard to electricity are relatively small (5 ÷ 20 kW). Expansion in throttling devices or turbine flow paths leads to gas cooling with a possible hydrate formation. It is prevented via gas preheating or vortex expansion equipment that keeps the further gas temperature at a necessary level. Turbogenerators can be created on the basis of vortex expansion turbomachines, which have many advantages compared to turbomachines of other types. This article studies how gas pressure (outlet: gas distribution station) and gas preheating (inlet: vortex expansion machine) influence turbogenerator parameters. Nine turbogenerator variants for the power needs of gas distribution stations have been assessed.

Integration of biofuel-induced electricity generators (BEGs) with wearable biosensing devices

This review article explores the potential revolutionary uses of biofuel-induced electricity generators (BEGs) integrated into portable biosensing devices. It describes the workings, and benefits of BEGs-based biosensors while highlighting the complementary nature of energy production and biosensing. The article delves into the ways BEGs transform biosensing capabilities in wearable technology, highlighting their ability to sustain themselves, compatibility with living organisms, and ongoing power production. BEGs eliminate the need for external power sources by enabling independent and uninterrupted operation through the metabolic activity of microorganisms. Their compatibility with the human body guarantees a secure and pleasant on-body experience. Wearables that incorporate BEGs allow for the continuous tracking of ambient variables, physiological data, and biomarkers. The review highlights the exciting possibilities of BEGs based-biosensors in healthcare, environmental monitoring, and other fields, paving the way for autonomous, continuous monitoring in the future to enhance health management and raise environmental consciousness.

An organic cathode integrating carbonyl and imino groups for high-performance aqueous zinc-ion battery with air self-charging ability

Air-self-charging aqueous zinc-ion batteries (AZIBs) are a promising system applied in some special occasions, where no external power source can be provided to recharge the battery. Here, a new π-conjugated aromatic compound 2,7,12-tri(4H-1,2,4-triazol-4-yl)-1H-pyrrolo [3,4-b]pyrrolo[3′,4′:5,6]pyrazino[2,3f]pyrrolo[3′,4′:5,6]pyrazi-no[2,3−h]quinoxaline-1,3,6,8,11,13(2H,7H,12H)-hexaone (THQH) is reported. Because THQH contains multiple redox-active groups (CN and CO) and its insolubility in 2 M ZnSO4, as the cathode material of flexible/coin-type AZIBs, it owns outstanding discharge specific capacity, higher-rate performance and longer cycle life. Various ex-situ experiments and theoretical calculation revealed H+ and Zn2+ participated in the THQH cathode reaction. Notably, as the discharged flexible Zn//THQH battery is exposed to air, it can be self-recharged via the redox reaction between oxygen in air and the discharged THQH cathode, along with H+ ions removal. The flexible Zn//THQH battery can deliver a discharge capacity of up to 566 mA h g−1 at 0.5 A g−1, a higher-rate capability and an excellent self-charging cycle stability (31 cycles) after exposed to air for 28 h, displaying an excellent reusability. This work paves a way for the development of high-performance flexible air self-charging AZIBs.

Self‐Powered Electrochemiluminescence for Imaging the Corrosion of Protective Coating of Metal and Quantitative Analysis

AbstractIn almost all electrochemical systems for electrochemiluminescence (ECL) analysis, electrodes are connected with an external power source, either directly or via wireless energy transfer circuit. That is inconvenient and makes some applications impossible. Herein, we use galvanized iron with two different metals as both power source and electrodes to achieve a self‐powered ECL and exploit ECL for the imaging of the corrosion of protective coating of widely used metal (e.g. galvanized iron) for the first time. The self‐powered ECL enables the visualization of the deterioration of galvanic coating on iron using a smartphone and the detection of ascorbic acid with a linear range of 0.5–100 μM and a limit of detection of 0.31 μM. The devices based on self‐powered approach do not require external power supply, thus effectively reducing their volume and cost. The self‐powered ECL holds great promise for metal corrosion imaging and analytical applications.

Enhanced Peltier refrigerator using an innovative hot-side heat-rejection mechanism; Experimental study under both transient and steady-state conditions

Peltier refrigerators are an environmentally friendly cooling method, as they require no refrigerants and have no moving parts. However, effective cooling requires optimal-strong heat rejection from the hot side of the Peltier module. This research proposes and tests a self-capillary ultra-thin (0.1 mm) water-attracting coated PVC membrane (SCCP) as an innovative effective heat rejection mechanism. The SCCP cools the hot side of the Peltier module to temperatures even lower than ambient air, without external power. The cooling effect is achieved through the evaporation of a thin water film on the hot surface, driven by capillary action, which releases latent heat. This process can occur under natural or forced convection, both of which are investigated under various voltage and temperature conditions. The SCCP method was compared to traditional heatsinks and showed superior performance, with the hot side temperature being not only cooler than that in heatsink mode but also cooler than the ambient temperature in most cases. Additionally, the SCCP method demonstrated reduced sensitivity to ambient temperature changes, with only a 2–3° increase in the hot side temperature when the ambient temperature was raised by 10°. The findings suggest that SCCP is a promising technique, with further results discussed.

Optimization clearing strategy for multi-region electricity-heat market considering shared energy storage and integrated demand response

As a new type of energy storage, shared energy storage (SES) can help promote the consumption of renewable energy and reduce the energy cost of users. To this end, an optimization clearing strategy for a multi-region electricity-heat joint market is proposed with consideration of SES and integrated demand response (DR). Firstly, the concept of shared energy storage station (SESS) is proposed, its business operation model is analyzed and its advantages over traditional energy storage are compared. Secondly, to exploit the potential for user flexibility, an integrated DR model that includes shiftable, transferable, interruptible electricity and heat load is constructed. Then, a multi-region electricity-heat joint market clearing model is constructed considering SESS and integrated DR. Finally, a three-region electricity-heat joint market connecting the external power grid, gas grid, and the SESS is used as an example. A comparison is made between the configuration of independent energy storage in each region and the configuration of SESS, which concludes that the introduction of the SESS and integrated DR can reduce the energy cost of users and improve the utilization rate of the energy storage facilities.

Low-emissions hydrogen from MCH dehydrogenation: Integration with LNG regasification

Methylcyclohexane (MCH) is a promising organic hydride carrier for hydrogen transport and storage. Recovering hydrogen from MCH is an energy intensive process. An innovative idea of integrating this process with liquified natural gas (LNG) regasification is proposed in this study and demonstrated via modelling and simulation to substantially reduce external energy use. The synergistic benefits are twofold. In addition to providing a cold energy source for an effective high recovery cryogenic flash separation, the organic Rankine cycle based electrical power generation potential from LNG cold energy is fully exploited to reduce/eliminate external electricity demand for hydrogen compression to the high (end use) pressure. The results is a major reduction in carbon dioxide emissions. The proposed design for an integrated LNG-H2terminal can supply (1) 99.99 mol% pure hydrogen to a Combined Cycle Gas Turbine (CCGT) power plant and (2) commercial-grade natural gas to a gas-grid, both at the desired pressures and temperatures. Subsequently, rigorous simulation-based optimization was performed to minimize external energy inputs.A case study with 100 tph MCH and 100 tph LNG showed that integrating regasification with dehydrogenation produced 6.2 tph of hydrogen while gasifying LNG with a net power generation of 310 kW and a hydrogen recovery cost of 0.282 $/kg H2. Up to 7.3 tonnes of hydrogen can be produced per 100 tonnes of LNG without the use of external power. On the other hand, using external power, up to 11.3 tonnes of hydrogen can be produced per 100 tonnes of LNG without any external refrigeration. Overall, the superstructure proposed in this manuscript provides a generic initial approach for future MCH hydrogen supply chain projects, when considering integrations with LNG regasification plants.

Thermoelectric generator efficiency: An experimental and computational approach to analysing thermoelectric generator performance

TEGs are devices that convert heat directly into electricity through the Seebeck effect, offering a promising solution for waste heat recovery in various industries. In this research, COMSOL Multiphysics 6.0 was used to conduct a comprehensive 3-dimensional computational study of TEGs. Integrating thermal and electrical models in COMSOL facilitates a detailed understanding of the thermoelectric phenomenon. Applying six distinct temperature gradients, temperature and electrical distribution, power output, and efficiency of the TEG was thoroughly analysed. Experimental validation confirms strong agreement between simulation and experimental data, emphasizing accuracy. The average efficiency for the TEG at 1 Ω load is 3.12 %, increasing to 3.62 % for a 2 Ω load. The relative error between the computational model and the experimental model was 5 % for open circuit, 12.56 % for closed circuit at 1 Ω, and 12.14 % for closed circuit at 2 Ω, affirming the accuracy of the computational approach. Therefore, the computational model is validated by experimental results.Moreover, the findings highlight the relationship between external load resistance and power output, revealing that the maximum output power was achieved when the external load resistance matched the internal load resistance at 2 Ω. This work also significantly contributes to advancing the computational modelling of TEGs, validated through rigorous experimental analysis.

Biaxially stretchable metamaterial absorber with a four-dimensional printed shape-memory actuator

Among the various methods for strain sensing, the metamaterial absorbers (MMAs) stand out due to their dual capabilities. Specifically, MMAs facilitate the wireless detection of deformations in the target and operate independently of any external power source. However, conventional research has a limitation in that stretchable strain sensors are unable to deform themselves autonomously, which puts constraints on being efficiently utilised in special environments where human intervention is difficult. Herein, we propose a wireless, power-independent, biaxial strain sensor equipped with self-shape and frequency recovery capability that addresses the limitations of existing wireless strain sensors through the unprecedented integration of a 4D-printed shape memory actuator and a biaxially stretchable MMA. The novel integration with the shape memory actuator enables the stretchable MMA to autonomously recover to its original shape and absorption frequency after being heated to 70 °C for a few minutes. This smart functionality enables the resulting wireless strain sensor based on the proposed idea to revert to the original state when sensing a new target without requiring human intervention. The highly sensitive biaxial sensing capability is as follows. When stretched horizontally from 0 % to 30 %, the absorption frequency of the proposed biaxially stretchable MMA demonstrates a linear change from 9.75 GHz to 7.94 GHz, exhibiting a high sensitivity of 4.3 × 10^7 Hz/%. Similarly, when stretched vertically from 0 % to 30 %, the absorption frequency linearly changes from 7.35 GHz to 6.01 GHz, indicating a sensitivity of 5.9 × 10^7 Hz/%. Accordingly, the wireless biaxial sensing capability of the proposed stretchable MMA, as well as its shape-recovery functionality facilitated by the 4D-printed actuator are highly effective for remote strain measurement in environments where direct human involvement is impractical.

Self-powered strain sensing devices with wireless transmission: DIW-printed conductive hydrogel electrodes featuring stretchable and self-healing properties

With rapid advancements in health and human–computer interaction, wearable electronic skins (e-skins) designed for application on the human body provide a platform for real-time detection of physiological signals. Wearable strain sensors, integral functional units within e-skins, can be integrated with Internet of Things (IoT) technology to broaden the applications for human body monitoring. A significant challenge lies in the reliance of most existing wearable strain sensors on rigid external power supplies, limiting their practical flexibility. In this study, we present an innovative strategy to fabricate glutaraldehyde (GA)-poly(vinyl alcohol) (PVA)/cellulose nanocrystals (CNC)/Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) conductive hydrogels through multiple hydrogen bonding systems. Combining the advantageous rheological properties of the precursor solution and the high specific surface area after freeze–thaw cycling, we have created a self-powered sensing system prepared by large-area printing using direct ink writing (DIW) printing. The resulting conductive hydrogel exhibits commendable mechanical properties (411 KPa), impressive stretchability (580 %), and robust self-healing capabilities (>98.3 %). The strain sensor, derived from the conductive hydrogel, demonstrates a gauge factor (GF) of 2.5 within a stretching range of 0–580 %. Additionally, the resultant supercapacitor displays a peak energy density of 0.131 mWh/cm3 at a power density of 3.6 mW/cm3. Benefiting from its elevated strain response and remarkable power density features, this self-powered strain sensing system enables the real-time monitoring of human joint motion. The incorporation of a 5G transmission module enhances its capabilities for remote data monitoring, thereby contributing to the progress of wireless tracking technologies for self-powered electronic skin.

A Mechanochemically-Triggered, Self-Powered Flash Heating Synthesis of Phosphorous/Caron Composites for Li-Ion Batteries.

"Flash heating" that transiently generates high temperatures above 1000°C has great potential in synthesizing new materials with unprecedently properties. Up to now, the realization of "flash heating" still relies on the external power, which requires sophisticated setups for vast energy input. In this study, a mechanochemically triggered, self-powered flash heating approach is proposed by harnessing the enthalpy from chemical reactions themselves. Through a model reaction between Mg3N2/carbon and P2O5, it is demonstrated that this self-powered flash heating is controllable and compatible with conventional devices. Benefit from the self-powered flash heating, the resulting product has a nanoporous structure with a uniform distribution of phosphorus (P) nanoparticles in carbon (C) nanobowls with strong P─-C bonds. Consequently, the P/C composite demonstrates remarkable energy storage performance in lithium-ion batteries, including high capacity (1417mAhg-1 at 0.2Ag-1), robust cyclic stability (935mAhg-1 at 2Ag-1 after 800 cycles, 91.6% retention), high-rate capability (739mAhg-1 at 20Ag-1), high loading performance (3.6mAhcm-2 after 100 cycles), and full cell cyclic stability (90% retention after 100 cycles). This work broadens the flash heating concept and can potentially find application in various fields.