Results 21 - 30 of 1068
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[en] This project's mission was to achieve significant advances in the practical application of bulk high-temperature superconductor (HTS) materials to energy-storage systems. The ultimate product was planned as an operational prototype of a flywheel system on an HTS suspension. While the final prototype flywheel did not complete the final offsite demonstration phase of the program, invaluable lessons learned were captured on the laboratory demonstration units that will lead to the successful deployment of a future HTS-stabilized, composite-flywheel energy-storage system (FESS)
[en] Used as low-cost anode in the majority of lithium ion batteries, layered graphite has got critical issues. Owing to its low voltage operation, they reduce electrolyte by stealing lithium from cathode to form an SET (Solid Electrolyte Interphase), and pose fire risk from dendrite based short-circuit likely at times of fast charging or erroneous over-lithiation towards end of discharge. In this talk we are addressing this problems
[en] Highlights: • The theoretical capacity of non-aqueous lithium-air batteries is predicted. • Key battery design parameters are defined and considered. • The theoretical battery capacity is about 10% of the lithium capacity. • The battery mass and volume changes after discharge are also studied. - Abstract: In attempt to realistically assess the high-capacity feature of emerging lithium-air batteries, a model is developed for predicting the theoretical capacity of non-aqueous lithium-air batteries. Unlike previous models that were formulated by assuming that the active materials and electrolyte are perfectly balanced according to the electrochemical reaction, the present model takes account of the fraction of the reaction products (Li2O2 and Li2O), the utilization of the onboard lithium metal, the utilization of the void volume of the porous cathode, and the onboard excess electrolyte. Results show that the gravimetric capacity increases from 1033 to 1334 mA h/g when the reaction product varies from pure Li2O2 to pure Li2O. It is further demonstrated that the capacity declines drastically from 1080 to 307 mA h/g when the case of full utilization of the onboard lithium is altered to that only 10% of the metal is utilized. Similarly, the capacity declines from 1080 to 144 mA h/g when the case of full occupation of the cathode void volume by the reaction products is varied to that only 10% of the void volume is occupied. In general, the theoretical gravimetric capacity of typical non-aqueous lithium-air batteries falls in the range of 380–450 mA h/g, which is about 10–12% of the gravimetric capacity calculated based on the energy density of the lithium metal. The present model also facilitates the study of the effects of different parameters on the mass and volume change of non-aqueous lithium-air batteries
[en] This paper gives a brief overview of battery packaging concepts, their specific advantages and drawbacks, as well as the importance of packaging for performance and cost. Production processes, scaling and automation are discussed in detail to reveal opportunities for cost reduction. Module standardization as an additional path to drive down cost is introduced. A comparison to electronics and photovoltaics production shows 'lessons learned' in those related industries and how they can accelerate learning curves in battery production
[en] What existed first, the energy problem or the energy transition? For the clarification of this question the author gives a survey about the actual situation of our energy demand and the means and ways to its satisfaction. The reader learns to know the function of numerous energy transformers, from the wind mill via the automobile motor until the solar cell. The advantages and disadvantages of the different transformers are explained, just so their efficiencies and cost as well as the physical natural laws, which they must obey. A perpetuum mobile doesn't exist, but indeed an almost inexhaustible energy source, the sun, which can meet many thousandfold our demand, if we use it intelligently. Who has read this book can go confidently in each discussion about the energy problem and the energy transition.
[en] Highlights: ► Electrospun binary fatty acid eutectics/PET ultrafine composite fibers were prepared. ► Fatty acid eutectics had appropriate phase transition temperature and heat enthalpy. ► Their morphological structures and thermal properties were different from each other. ► Composite fibers could be innovative form-stable PCMs for thermal energy storage. - Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements suggested that the heat enthalpies of melting and crystallization of the ultrafine composite fibers increased gradually with increasing fatty acid eutectics amounts, but their phase transition temperatures had almost no obvious variation as relative to the corresponding fatty acid eutectics. Meanwhile, the characteristic temperatures and heat enthalpies of the ultrafine composite fibers varied with the different types of binary fatty acid eutectics. TGA results indicated that the degradation of electrospun binary fatty acid eutectics/PET ultrafine composite fibers with representative mass ratio of 100/100 had two steps and corresponded respectively to the degradations of binary fatty acid eutectics and PET polymer chains; and the charred residue at 700 °C of the composite fibers was lower than that of the neat PET fibers. It could be envisioned that the electrospun binary fatty acid eutectics/PET composite fibers would be extensively used for latent heat storage in the field of building energy conservation.
[en] Highlights: • Maximum braking energy recovery potentials of various cycles are reported. • Braking strategies are proposed for performance, comfort and energy recovery. • Braking force distributions and wheel slip ratios of different strategies are demonstrated. • The performance of ‘Eco’ strategy is experimentally validated in HWFET and NEDC. • The economic benefit of energy recovering is summarized, regarding to the fuel and maintenance cost saving. - Abstract: As motor-supplied braking torque is applied to the wheels in an entirely different way to hydraulic friction braking systems and it is usually only connected to one axle complicated effects such as wheel slip and locking, vehicle body bounce and braking distance variation will inevitability impact on the performance and safety of braking. The potential for braking energy recovery in typical driving cycles is presented to show its benefit in this study. A general predictive model is designed to analysis the economic and dynamic performance of blended braking systems, satisfying the relevant regulations/laws and critical limitations. Braking strategies for different purposes are proposed to achieve a balance between braking performance, driving comfort and energy recovery rate. Special measures are taken to avoid any effects of motor failure. All strategies are analyzed in detail for various braking events. Advanced driver assistance systems (ADAS), such as ABS and EBD, are properly integrated to work with the regenerative braking system (RBS) harmoniously. Different switching plans during braking are discussed. The braking energy recovery rates and brake force distribution details for different driving cycles are simulated. Results for two of the cycles in an ‘Eco’ mode are measured on a drive train test rig and found to agree with the simulated results to within approximately 10%. Reliable conclusions can thus be gained on the economic benefit and dynamic braking performance. The strategies proposed in this paper are shown to not only achieve comfortable and safe braking during all driving conditions, but also to significantly reduce cost in both the short and long term.
[en] The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; and thermal management and pack designs to accommodate the higher operating voltage.
[en] Highlights: • HOMER optimisation analysis to plan smart Island energy systems. • Comparison between different storage solutions and power-to transport strategies. • Hydrogen potential use in insular public transport sector. • Comparison between fuel cell electric buses and enriched natural gas fuelled buses. - Abstract: Energy costs, carbon dioxide emissions, security of supply and system stability are common challenges in small islands. Many European islands have become pilot sites of energy innovation, but this green transition goes slowly in other ones usually not connected to the national grid. This study investigates the economic and environmental sustainability related to the integration of hydrogen and batteries storage in small islands, considering at the same time the use of the stored hydrogen for fuelling Fuel Cell Electric Vehicles and Hydrogen Compressed Natural Gas vehicles to meet electricity and public transportation demand of islands, so as to increase the Renewable Energy Sources penetration level. Selecting the island of Favignana (Italy) as case study, HOMER software has been used to carry out the energy analysis of different scenarios, in order to identify the most effective energy solution from both technological and economical point of views. Using economic and environmental indicators, the outcomes show that the implementation of a hybrid storage system with batteries and electrolyser can be an adequate and reliable option for increasing energy independency of small island and decarbonizing transport sector optimizing economic and environmental sustainability.