Long-Term Stability of Ferroelectret Energy Harvesters

Cellular polypropylene (PP) has been recently used in energy harvesting applications. In this work, we investigate its viability and long-term stability under various operating conditions. Specifically, the effect of constant stress and stress cycling on output power and long-term stability of ferroelectret energy harvesters is analyzed. Our findings show that after 112 days constant stress significantly increases the piezoelectric charge constant d 33 and output power from 0.51 μW for a stress-free harvester to 2.71 μW. It also increases the harvester center frequency from 450 to 700 Hz and decreases its optimal resistance from 7 to 5.5 M Ω .

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TM LDH Meets Birnessite: A 2D‐2D Hybrid Catalyst with Long‐term Stability for Water Oxidation at Industrial Operating Conditions

Angewandte Chemie International Edition ◽

10.1002/anie.202016064 ◽

2021 ◽

Author(s):

Xia Long ◽

Zhuwen Chen ◽

Min Ju ◽

Mingzi Sun ◽

Li Jin ◽

...

Keyword(s):

Water Oxidation ◽

Operating Conditions ◽

Hybrid Catalyst ◽

Term Stability ◽

Long Term Stability

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Accelerated Degradation for Hardware in the Loop Simulation of Fuel Cell-Gas Turbine Hybrid

ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2014-6522 ◽

2014 ◽

Cited By ~ 1

Author(s):

Maria Abreu-Sepulveda ◽

David Tucker ◽

Nor Farida Harun ◽

Gregory Hackett ◽

Anke Hagen

Keyword(s):

Fuel Cell ◽

Real Time ◽

Gas Turbine ◽

Degradation Rate ◽

Operating Conditions ◽

Hardware In The Loop ◽

Electrochemical Degradation ◽

Term Stability ◽

Long Term Stability

Solid oxide fuel cells (SOFCs) are a promising technology for clean power generation, however their implementation has been limited by several degradation mechanisms, which significantly reduce its lifetime under constant output power and inhibits the technology for commercialization in the near future. With the purpose of harnessing the capabilities offered by SOFCs, the U.S. DOE-National Energy Technology Laboratory (NETL) in Morgantown, WV has developed the Hybrid Performance (HyPer) project in which a SOFC 1D, real-time operating model is coupled to a gas turbine hardware system by utilizing hardware-in-the-loop simulation (HiLS). More recently, in order to assess the long-term stability of the SOFC part of the system, electrochemical degradation due to operating conditions such as current density and fuel utilization have been incorporated into the SOFC model and successfully recreated in real time for standalone and hybrid operation. The mathematical expression for degradation rate was obtained through the analysis of empirical voltage versus time plots for different current densities and fuel utilizations at 750, 800, and 850°C. Simulation results well reflected the behavior of SOFC degradation rates from which the long-term stability of the cell under various conditions was assessed. Distributed fuel cell parameters are presented for both standalone and hybrid configurations. The incorporation of the electrochemical degradation rate into the SOFC model provides a framework to study more realistically Fuel Cell-hybrid systems and set forth a mechanism to improve the long-term stability of SOFCs through the hybridization of such technology.

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Long-term stability of the final slopes of the mining waste dumps from Oltenia

MATEC Web of Conferences ◽

10.1051/matecconf/202134203005 ◽

2021 ◽

Vol 342 ◽

pp. 03005

Author(s):

Maria Lazar ◽

Florin Faur ◽

Izabela-Maria Apostu ◽

Constantin Rada

Keyword(s):

Operating Conditions ◽

Strength Characteristics ◽

Design Stage ◽

Term Stability ◽

Long Term Stability ◽

Influence Area ◽

Waste Dumps ◽

The Stability ◽

The Moment

The waste dumps resulted from the lignite exploitation activities from Oltenia are constructions that reach, in most cases, impressive dimensions and store large volumes of sterile rocks. Usually, the dumps are arranged and ecologically restored, but between the moment of their release from technological tasks and the beginning of the arrangement works, periods of time, measured even in years, can pass. The calculations regarding the geometry of the waste dumps are performed in the design stage, taking into account the mechanical strength characteristics of the mixture of sterile material that forms them, so as to ensure a sufficient stability reserve during the construction period and when the projected storage capacity is achieved. If the arrangement and ecological restoration works do not start immediately after the depositing activity is stopped, the exposure of loose and disaggregated material to the influence of external factors (especially erosion and rainfall infiltration) can lead to landslides with disastrous consequences on natural and anthropogenic objectives located in the influence area. This paper analyzes the stability elements of waste dumps under normal operating conditions, the modification of the strength characteristics over time and the geometry required in the final phase so as to ensure their long-term stability.

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Enzymatic Biofuel Cells: A Review on Flow Designs

Energies ◽

10.3390/en14040910 ◽

2021 ◽

Vol 14 (4) ◽

pp. 910

Author(s):

Linda Barelli ◽

Gianni Bidini ◽

Dario Pelosi ◽

Elena Sisani

Keyword(s):

Power Output ◽

Wearable Devices ◽

Operating Conditions ◽

Biofuel Cells ◽

Term Stability ◽

Long Term Stability ◽

Stage Of Development ◽

Enzymatic Biofuel Cells ◽

Wide Range

Because of environmental concerns, there is a growing interest in new ways to produce green energy. Among the several studied applications, enzymatic biofuel cells can be considered as a promising solution to generate electricity from biological catalytic reactions. Indeed, enzymes show very good results as biocatalysts thanks to their excellent intrinsic properties, such as specificity toward substrate, high catalytic activity with low overvoltage for substrate conversion, mild operating conditions like ambient temperature and near-neutral pH. Furthermore, enzymes present low cost, renewability and biodegradability. The wide range of applications moves from miniaturized portable electronic equipment and sensors to integrated lab-on-chip power supplies, advanced in vivo diagnostic medical devices to wearable devices. Nevertheless, enzymatic biofuel cells show great concerns in terms of long-term stability and high power output nowadays, highlighting that this particular technology is still at early stage of development. The main aim of this review concerns the performance assessment of enzymatic biofuel cells based on flow designs, considered to be of great interest for powering biosensors and wearable devices. Different enzymatic flow cell designs are presented and analyzed highlighting the achieved performances in terms of power output and long-term stability and emphasizing new promising fabrication methods both for electrodes and cells.

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