• Energy Research

Electrostrictive polymers have been investigated as electroactive materials for electromechanical energy harvesting. This kind of material is isotope, i.e. there is no permanent polarization compared with piezoelectric material, so in order to ensure its polarization and scavenging energy, the electrostrictive polymers need necessarily an application of a static field. To avoid this problem, we used the hybridization of electrostrictive polymer with electret. The present work aims an analytical modeling for predicting the power convert when the material was mechanically excited. The study was carried out on polyurethane and terpolymer [P(VDF–TrFE–CFE)] films, either without filler or filled with carbon nanopowder. Experimental measurements of the harvested power showed a good agreement with the theoretical behavior predicted by the proposed model. It was also shown that the incorporation of nanofillers increased the power harvested from 5.22 · 10−2 to 1.498 · 10−1 μW cm−3 and from 6.87 · 10−1 to 1.76 μW cm−3 in polyurethane and in the terpolymer, respectively. Copyright © 2015 John Wiley & Sons, Ltd.

Piezoelectric composites of PU/PZT with 0–3 connectivity were prepared in the film form. Homogeneous dispersion of the ceramic PZT in polyurethane matrix has been obtained and has been verified by SEM analysis. Dielectric properties reveal that under an electrical field of 1000 V the remnant polarization increased from 1.9 to 4 µC/cm−2 when the volume fraction of PZT increased from 50 to 80 %. Modeling and vibratory energy harvesting tests has been realized. At very low frequency and deformation, and without application of any static electric field, 1.15 µW of power has been obtained. The results obtained in this work contribute to demonstrate the ability of the incorporation of PZT particles in the polymer matrix to improve the conversion efficiency of the vibratory energy into electrical energy for the development of µ-generators.

Nowadays, population growth and increasing urbanization imply a growing demand for energy, which must be achieved while limiting polluting emissions. To meet this dual challenge, the use of renewable energy resources and energy generators is essential. Thermoelectric generators (TEGs) have demonstrated their ability to directly transform thermal energy into electrical energy through the Seebeck effect. Due to their unique advantages, thermoelectric systems have emerged in the last decade as a promising alternative among other green energy generation technologies. In this regard, the study focuses on a design of a Photovoltaic-Thermo-Electric (PV-TE) Hybrid System for thermal energy harvesting in low power collectors. The power harvested by TEG increases with the temperature and an interesting value close to 7mW is achieved with a maximum temperature of 52 °C of the hot face the thermoelectric system.

This research addresses the challenge of elevated temperatures impacting the performance of photovoltaic (PV) panels, considering both the dimensions of the cooling tube and the flow of water. A comprehensive analysis of various water flow rates is conducted using three tubes (tube 1, tube 2, and tube 3) with cross-sections of 100.27, 148.27, and 202.27 mm2 and 15, 11, and 9 loops, respectively. The numerical results reveal a significant 41.66% reduction in PV cell temperature, decreasing from 60 °C to 35 °C using tube 3 at a flow rate of 7.5 L/min, reflecting high electrical performance and efficiency. Meanwhile, at a flow rate of 1.5 L/min, tube 1 delivers optimum hot water at the outlet with a temperature of 55.6 °C. The proposed design significantly contributes to PV cell efficiency, emphasizing the impact of cooling tube dimensions on the overall efficiency of the PV/T system. This study introduces an innovative approach using a flat oval tube to minimize temperature elevation and simultaneously generate hot water. The innovative PV/T system demonstrates potential advancements in thermal management and lays the foundations for future sustainable energy applications.

Marine energies are a strategic channel for renewable energies to diversify and complement the global energy mix. From this perspective, several researches have seen the light in order to allow the maximum exploitation possible of the energy estimated at 80,000 TWh/year, presenting multiple vacant possibilities concerning energy not yet exploited on a large scale. The purpose of this paper is the use of ocean vibratory energy coupling with a smart composite material in order to harvest the maximum power. This study will be devoted to the design, modeling, and simulation of a floating harvester energy system that combines the mechanical strength and flexibility of polymer with the high piezo and pyroelectric activities of ceramic. The harvester system is composed of a mass-spring system used to transfer wave movements to mechanical vibrations, and two piezoelectric lever devices will be used to amplify and convert the harvested mechanical vibration into electrical power. With this flexible device, the maximum power harvested is 56.45 μW/mm², using PU/PZT composite with the optimal resistance of 108 MΩ. Considering these results, this system can be used in very different ways in marine applications.

Abstract The harvesting of energy from ambient environments is an emerging technology with potential for numerous applications, including portable electronic devices for renewable energy. Most of the current research activities refer to classical piezoelectric ceramic materials but more recently the development of electrostrictive polymers has generated novel opportunities for high-strain actuators. At present, the investigation of using electrostrictive polymers for energy harvesting (a conversion of mechanical to electrical energy) is beginning to show potential for this application. Basically, the relative energy gain depends on the current induced by the mechanical strain and frequency. The aim of this work was to determine the optimum operating range for improved electro-mechanical conversion efficiency of electrostrictive polymer composite by the effect of mechanical parameters (mechanical frequency and the amplitude strain) that leads to an increase in the generated current and improve the output power in relation to the injected power. It was also found that the trend of the experimental data is in good accordance with that of the theoretical prediction. Finally, the results indicated that the frequency and the amplitude of mechanical excitation were the critical parameters for the best electromechanical conversion.

In this work we investigate the diffusion of Ag dimer on Cu(110) surface by molecular dynamics simulation based on semi-empirical many-body potentials derived from the embedded atom method. The dissociation-reassociation process is predicted to be dominant in static regime and this is confirmed by the dynamic investigation. A good agreement is found between static activation barrier and dynamic potential barrier.

Abstract In this paper we investigated the diffusion of Ag adatom by computing the energy barriers for many elementary diffusive processes which are likely to happen near to the step edge on Cu (110). The barriers are calculated by means of molecular dynamics simulation by using embedded atom potentials. The proximity to steps alters these barriers considerably, and very different results may be expected. In fact, our numerical calculations show that the diffusion via jump process along step edge is predominant for Ag/Cu(110) and the diffusion over the step occurs sometimes, but only via exchange mechanisms. The adatom diffusion across channels is difficult due to the high value of activation energy required (around 1 eV). Furthermore, we found the Ehrlich–Schwoebel barrier for diffusion around 120 meV in order to descend via exchange process and of the order of 170 meV via hopping mode. This aspect may have a strong influence on the growth character. In general our results suggest that, for our metal system, diffusion mechanism may be important for mass transport across the steps. Implications of these findings are discussed.