Electrical Energy Input Research Articles

Thermo-osmosis-Coupled Thermally Regenerative Electrochemical Cycle for Efficient Lithium Extraction.

Lithium (Li) production based on the soda evaporation process is time-consuming and unsustainable. The emerging electrochemical Li extraction is time-efficient but requires high-concentration Li sources and significant electrical energy input. Here, we demonstrate a fast, energy-saving, and environment-friendly Li production process by coupling a thermally regenerative electrochemical cycle (TREC) using lithium manganese oxide (LMO) and nickel hexacyanoferrate (NiHCF) electrodes with poly(vinylidene fluoride) membrane-based thermo-osmosis (denoted as TO-TREC). The characterization of LMO and NiHCF electrodes confirmed that the relatively high temperature of TO-TREC has negligible adverse effects on the ion intercalation in LMO and NiHCF electrodes. The LMO/NiHCF pair has a positive temperature coefficient of 0.843 mV K-1. In the TO-TREC process, Li ions are selectively extracted from a Li-containing brine warmed by low-grade heat and then released into a room-temperature recovery solution such as LiCl with a production rate of 50-60 mmol Li+ m-2 h-1. Li source solutions are concentrated by thermo-osmosis simultaneously, making it possible to utilize previously unusable Li-containing sources, such as concentrated brines from desalination plants and industrial effluents. Besides, the TREC harvests thermal energy from the heated brine, saving >20% of electrical energy compared to conventional electrochemical methods. The new process shows the potential to meet the growing global Li demands for many applications.

Effect of Using a Copper Insert on Stability and Energy Balance in an Aluminum Production Cell

Roughly half of the electrical energy input to a modern Hall–Heroult cell for the aluminum (Al) production is lost as heat. Naturally, significant efforts are currently directed toward increasing the thermal efficiency of the cell by a variety of means. In this work, a slice thermoelectric model of a Hall–Heroult cell was developed for a conventional base model (insert-free collector bar) as well as for a copper (Cu) insert model (cylindrical copper inserts in the steel collector bar). Finite element method-based simulations were carried out to determine the components of voltage drops, steady-state ledge profile, cell stability and the overall heat balance. Comparison of the specific energy consumption (SEC) and the cell current in all cases highlighted the advantages of copper insert collector bar assembly over the insert-free, base case. The use of a Cu insert can increase the plant productivity by over 5% at the same SEC as in the base case. Moreover, with the introduction of an insert, an increase in productivity with a concomitant decrease in the SEC could be achieved.

Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst

The development of low-cost and sustainable hydrogen production is of primary importance for a future transition to sustainable energy. In this work, the selective and simultaneous production of pure hydrogen and chemicals from renewable alcohols is achieved using an anion exchange membrane electrolysis cell (electrochemical reforming) employing a nanostructured Pd-CeO2/C anode. The catalyst exhibits high activity for alcohol electrooxidation (e.g. 474 mA cm−2 with EtOH at 60 °C) and the electrolysis cell produces high volumes of hydrogen (1.73 l min−1 m−2) at low electrical energy input (Ecost = 6 kWh kgH2−1 with formate as substrate). A complete analysis of the alcohol oxidation products from several alcohols (methanol, ethanol, 1,2-propandiol, ethylene glycol, glycerol and 1,4-butanediol) shows high selectivity in the formation of valuable chemicals such as acetate from ethanol (100%) and lactate from 1,2-propandiol (84%). Importantly for industrial application, in batch experiments the Pd-CeO2/C catalyst achieves conversion efficiencies above 80% for both formate and methanol, and 95% for ethanol.

The Prototype of Non-thermal Plasma After treatment System for Simultaneous Reduction of Nitrogen Oxide Emission in Flue Gas

Nowadays, global warming is the main environmental problems all over the world. The air pollutants mainly from the burning of fossil fuels and coal in power plants, transportation, and automobiles. There are release major point emission of the atmosphere. The nitrogen oxides are the most relevant for air pollution that contribute to the formation of photochemical smog and acid rain. Numerous methods have been studied to eliminate the nitrogen oxides such as the use low-nitrogen fuels technology, the selective catalytic reduction (SCR), wet scrubbing. The aim of this research is investigated non-thermal plasma (NTP) techniques offer an innovation to eliminate both nitrogen oxide (NOx) and soot emissions from combustion. This study is used to selectively transfer input electrical energy to electrons without expending this in heating the entire gas flow which creates free radicals in the flue gases. The simulated flue gas from combustion process is applied to the system. The results showed that the prototype of nonthermal plasma system is shown the highly efficient of NOx removal was achieved. However, the optimised of NTP operating conditions are required to enhance the NOx reduction activities.

Study of the Formation Conditions of Aluminum Oxide Nanoparticles in an Overstressed Nanosecond Discharge Between Aluminum Electrodes in a Mixture of Nitrogen and Oxygen

The results of the study of oscillograms of voltage, current, pulsed electric power and energy input into the plasma of an overstressed nanosecond discharge between aluminum electrodes in argon and mixtures of nitrogen with oxygen (100-1) at pressures in the range of 13.3-103.3 kPa are presented, the emission plasma spectra are studied. It is shown that in mixtures of nitrogen with oxygen at atmospheric pressure, nanoparticles of aluminum oxide (Al2O3) are formed, the luminescence of which manifests itself in the spectral range of 200-600 nm and which is associated with the formation of F-, F + - centers and more complex aggregate formations based on oxygen vacancies. Calculations of the electron-kinetic coefficients of plasma, transport characteristics, such as mean electron energies in the range 5.116-13.41 eV, are given. The electron concentration was 1.6 ∙ 1020 m-3 - 1.1 ∙ 1020 m-3 at a current density of 5.1 ∙ 106 A / m2 and l. 02 ∙ 107 A / m2 on the surface of the electrode of the radiation source (0.196 · 10-4 m2 ). Also drift velocities, temperatures and concentrations of electrons, specific losses of the discharge power for elastic and inelastic processes of collisions of electrons per unit of the total concentration of the mixture from the reduced electric field strength (E / N) for a mixture of aluminum, nitrogen, oxygen, rate constants of collisions of electrons with aluminum atoms on the E / N parameter in plasma on a mixture of aluminum vapor, oxygen and nitrogen = 30: 1000: 100000 Pa at a total mixture pressure of P = 101030 Pa are given.

A Review of Cocoa Drying Technologies and the Effect on Bean Quality Parameters.

Considering drying as a key farm-based, quality determining unit operation in the cocoa processing chain, this paper reviews recent studies in the drying methods and quality parameters of cocoa beans. Open sun, solar, oven, microwave, and freeze drying methods have been investigated at various levels in the drying of cocoa beans with objectives to improve the drying properties and final quality of cocoa beans. While an open sun dryer employs natural passive mechanisms, the solar drying methods can employ a combination of passive and active mechanisms. The oven, microwave, and freeze drying methods are fully active requiring electrical energy inputs. To improve drying rates in the open sun method, dryer materials and location of drying trays are the parameters optimized since the drying temperature depends on solar intensity. For solar dryers, materials, angles of elevation, heaters, and fans are manipulated to optimize energy absorption and drying parameters. For the oven and microwave methods, drying air properties are directly controlled by electronic systems. Moisture content, mouldiness, bean colour, pH, titratable acidity, fat content, and acetic acid concentration are the most widely evaluated bean quality parameters.

A novel approach of high-voltage low-current electric energy input to synthesise cost-effective ultra-strong ductile material

ABSTRACT Adopting a unique electrical circuit design, here we treat a significant low-cost engineering material (eutectoid steel not containing costly alloying elements) with a high-voltage (100 kV) low-current (150 mA) energy input (energy level exceeding cohesive energy). A distinctive structural evolution is ascertained with treatment duration of only 5 min as an outcome of lamellar fragmentation and matrix supersaturation. This envisages an origin of dispersed nano-sized hard cementite spheroids embedded in nano-thick martensite crystals of stratified-tile-morphology along with distributed α-ferrite regions containing sub-microscopic cementite particles of various shapes. Apart from the conjoint effect of nano-scale dispersion strengthening and martensitic strengthening overhauling the effect of conventional lamellar strengthening on a gross scale; high dislocation density and systematically arranged dislocations of similar sign at incoherent cementite particle-matrix interface provides a unique combination of ultra-high strength (UTS ∼ 1.5 GPa), significantly high specific strength (188 MPa/g cm−3) and large ductility (%Elongation = 20). Therefore, in terms of the adopted synthesis route, structural evolution and mechanical property achieved, a new dimension is hereby added to the next-generation material development so as to meet the ever increasing demand for low-cost structural application. In turn, we elucidate a fundamental conceptualization for the first time which exemplifies disproportionate atomic migration at highly incoherent nano-sized cementite particle-martensite matrix interface in steel under high-voltage low-current energy input, resulting in accumulation of dislocations of similar sign so as to significantly enhance strength along with retention of substantial ductility.

Comparative exergy analysis between rotary hearth furnace-electric arc furnace and blast furnace-basic oxygen furnace steelmaking routes

Resource fuel used in integrated steelmaking processes are different based on fuel availability consideration. A fuel-based comparative energy utilisation efficiency in integrated steel plants as obtained through exergy analysis for two steelmaking routes, namely, rotary hearth furnace-electric arc furnace (RHF-EAF) and blast furnace-basic oxygen furnace (BF-BOF) is presented with additional consideration of electrical energy input replacing fuel energy in EAF for RHF-EAF route. Initially, exergy flow models of sub-systems (BF, BOF, RHF and EAF) are established separately. These sub-system models are coupled together to analyse the exergy flows, exergy losses and exergy efficiencies of the two integrated steelmaking systems. Gas-based exergy efficiency based on input exergy of RHF-EAF steelmaking process is always found to be better than conventional BF-BOF process as well as BF-Tenova Flexible Modular Furnace system (a modified BF-BOF process having electric arc facility in BOF to increase the scrap percentage in BOF charge). However, BF-BOF processes are found to be superior to RHF-EAF process when metal-based exergy efficiencies are compared. Combined metal plus gas-based exergy efficiencies of RHF-EAF steelmaking process are marginally better than BF-BOF route. Efficiency of scrap reycle for both steelmaking routes has also been analysed through exergy efficiency parameters. It was found that exergy utlisation efficiency of RHF-EAF steelmaking process based on both products steel and total by-product fuel gas for hot charging of direct reduced iron (DRI) above 600°C is superior to BF-BOF steelmaking process for all levels of scrap charging in steel making. For hot charged DRI at 600°C in RHF-EAF steelmaking process, the combined exergetic efficiency based on metal and by-product fuel gas is around 75% compared to 67% of BF-BOF and modified BF-BOF steelmaking systems, indicating more efficient input fuel utlisation than both variants of BF-BOF route.

Modeling of electromagnetic radiation-induced from a magnetostrictive/piezoelectric laminated composite

Magnetoelectric (ME) materials can realize the conversions between electric and magnetic energy. Different from the previous studies, the electromagnetic (EM) radiation of ME materials has been adequately considered in this work. The electrical energy input can be converted into the dynamic magnetization oscillation by converse magnetoelectric (CME) effect. The antennas operate at their acoustic resonance frequency, which provides a new idea for antenna miniaturization. We analyze the CME effect and EM radiation from a vibrating ME laminated composite. The results show that the ME heterostructure resembles an ideal magnetic dipole in terms of radiating EM waves. This structure reduces the antenna size by several orders of magnitude, suggesting vast superiority of controlling magnetizations to generate EM radiation at a micro-scale.

Biobased bitumen analogue formation during hydrothermal treatment of microalgae residues, part 1: Influence of reaction enthalpy on the process

The hydrothermal conversion process of industrial Spirulina sp. residues into bitumen analogue is studied with an instrumented reactor heated at 260 °C under autogenous pressure. During hydrothermal conversion experiments, an exothermic reaction starts during the heating ramp above 200 °C and perturbs the thermal regulation of the process. The end of the reaction is detected from recorded pressure and temperature signals. Thermal insulation of the reactor and monitoring of the electrical energy input for thermal regulation allows estimating a total reaction enthalpy ΔHr ≈ - 1.7 MJ/kg of dry biomass by performing two successive heating-isotherm experiments: First with biomass until complete reaction and again with reaction products after cooling. This second run is used as a reference for energy balance calculations.

Reinforcement Learning-Based Minimum Energy Position Control of Dielectric Elastomer Actuators

This article deals with the closed-loop optimal control of mechatronic devices based on dielectric elastomer membranes. The goal is to minimize the input electrical energy required to achieve a given position regulation task. The actuator is modeled based on a free-energy framework, which provides a thermodynamically consistent characterization of the losses that occur during actuation. Due to the strongly nonlinear behavior of both system model and dissipation function, traditional techniques based on the analytical solution of the Hamilton-Jacobi-Bellman (HJB) equation cannot be applied. Therefore, a reinforcement learning-based algorithm is here proposed as a tool to solve, offline, the HJB equation related to the energy minimization problem. After discussing the theory, experimental results are presented to validate the effectiveness of the proposed approach for different positioning tasks.

Hypothetical Efficiency of Electrical to Mechanical Energy Transfer during Individual Stochastic Molecular Switching Events.

There are now many examples of single molecule rotors, motors, and switches in the literature that, when driven by photons, electrons, or chemical reactions, exhibit well-defined motions. As a step toward using these single molecule devices to perform useful functions, one must understand how they interact with their environment and quantify their ability to perform work on it. Using a single molecule rotary switch, we examine the transfer of electrical energy, delivered via electron tunneling, to mechanical motion and measure the forces the switch experiences with a noncontact q-plus atomic force microscope. Action spectra reveal that the molecular switch has two stable states and can be excited resonantly between them at a bias of 100 mV via a one-electron inelastic tunneling process which corresponds to an energy input of 16 zJ. While the electrically induced switching events are stochastic and no net work is done on the cantilever, by measuring the forces between the molecular switch and the AFM cantilever, we can derive the maximum hypothetical work the switch could perform during a single switching event, which is ∼55 meV, equal to 8.9 zJ, which translates to a hypothetical efficiency of ∼55% per individual inelastic tunneling electron-induced switching event. When considering the total electrical energy input, this drops to 1 × 10-7% due to elastic tunneling events that dominate the tunneling current. However, this approach constitutes a general method for quantifying and comparing the energy input and output of molecular-mechanical devices.

Hybrid Inorganic-Biological Systems: Faradaic and Quantum Efficiency, Necessary but Not Sufficient

Adam J. Rieth is a postdoctoral scholar in the Nocera group at Harvard University. He completed his undergraduate studies at the University of North Carolina at Chapel Hill, in his hometown. He then earned his Ph.D. in the laboratory of Prof. Mircea Dincă at the Massachusetts Institute of Technology, where he designed metal-organic frameworks for water harvesting. For the past year in the Nocera group, he has investigated the mechanisms and kinetics of photochemical processes that activate strong bonds. Daniel G. Nocera is the Patterson Rockwood Professor of Energy at Harvard University. He created the field of proton-coupled electron transfer (PCET) at a mechanistic level with the first kinetics measurements and theory of PCET. From this platform, he invented the Artificial Leaf and Bionic Leaf for the solar-driven fixation of carbon dioxide from air in the form of biomass and liquid fuels at energy efficiencies that are 10× greater than natural photosynthesis. He has since elaborated the Bionic Leaf for the solar-driven fixation of nitrogen from air for distributed and carbon-negative ammonia (and fertilizer) synthesis.

A Review on Synthesis of Methane as a Pathway for Renewable Energy Storage With a Focus on Solid Oxide Electrolytic Cell-Based Processes

Environmental issues related to global warming are constantly pushing the fossil fuel-based energy sector toward an efficient and economically viable utilization of renewable energy. However, challenges related to renewable energy call for alternative routes of its conversion to fuels and chemicals by an emerging Power-to-X approach. Methane is one such high-valued fuel that can be produced through renewables-powered electrolytic routes. Such routes employ alkaline electrolyzers, proton exchange membrane electrolyzers, and solid oxide electrolyzers, commonly known as solid oxide electrolysis cells (SOECs). SOECs have the potential to utilize the waste heat generated from exothermic methanation reactions to reduce the expensive electrical energy input required for electrolysis. A further advantage of an SOEC lies in its capacity to co-electrolyze both steam and carbon dioxide as opposed to only water, and this inherent capability of an SOEC can be harnessed for in situ synthesis of methane within a single reactor. However, the concept of in situ methanation in SOECs is still at a nascent stage and requires significant advancements in SOEC materials, particularly in developing a cathode electrocatalyst that demonstrates activity toward both steam electrolysis and methanation reactions. Equally important is the appropriate reactor design along with optimization of cell operating conditions (temperature, pressure, and applied potential). This review elucidates those developments along with research and development opportunities in this space. Also presented here is an efficiency comparison of different routes of synthetic methane production using SOECs in various modes, that is, as a source of hydrogen, syngas, and hydrogen/carbon dioxide mixture, and for in situ methane synthesis.

Energy consumption and conversion efficiency for a micromotor under DC voltage

A water droplet works as a novel kind of micromotor exhibiting back-and-forth motion between two needle-shaped electrodes in an oil phase under a stationary direct-current voltage. In the present study, a quantification method was adapted to estimate the kinetic energy output of back-and-forth motion of a water droplet, together with the electric energy input to this system. It was observed that the volume of the droplet gradually decreased accompanied by the periodic motion, which is attributed to electrolysis. Energy consumption owe to the electrolysis vs. the generation of kinetic energy of the moving droplet experimentally evaluated. The kinetic energy was deduced based on Stokes’ drag equation. Electric current was measured at the pA level. Then, the energy conversion efficiency of this micromotor system was able to be calculated. As far as we aware, this is the first report on the conversion efficiency for the autonomous motion under stationary DC voltage. Until now, various kinds of micromotor systems have been individually developed by different study group, and the comparison was difficult due to the lack of universal reliable index of the efficiency. The quantification method reported here evaluates micromotor system on its energy conversion efficiency, irrespective of experiment conditions. This quantification method can be a universal tool for micromotor system comparison, and is expected to play the role as the guidelines for future developments.

A new fast response cryogenic evaporative calorimeter.

We present the principle and implementation of a new type of fast response evaporative calorimeter designed to work at cryogenic temperatures and above-ambient pressures. It is capable of measuring input energy from an electric pulse and the thermal output energy by measuring the evaporation of liquid nitrogen through a mass flow meter. This system may be used to measure either the steady heat output from the system submersed under the cryogen or the heat output that results from a fast square-wave profile electrical pulse of duration from 10 µs or longer. The energy output of metal capillary-wire composite systems has been measured calorimetrically. A four-wire measurement was used to monitor the input electric energy with an uncertainty less than 5% for a typical pulse. Mass flow meters and pressure regulation systems were used to monitor the rate of evaporation of liquid nitrogen with a typical precision of 2 std.-ml/min. For a typical pulse, the integrated mass flow of nitrogen could be determined with an uncertainty less than 3%. The pressure controllers and ballast compliance volumes allow the system to return to a steady state of mass flow in less than 2 min following an electric pulse. The system is capable of housing and measuring four separate wire-capillary systems in a single Dewar. On average, a calibration resulted in 3.9 std. ml evaporated per joule of input energy. This corresponds to a 97% efficiency for this calorimeter.

Power supply efficiency in dual magnetron large area sputter coatings

In large area sputter coating of glass, the consumption of electric power is one of the major cost drivers. This applies especially to dielectric transparent coatings which are relatively thick and for which sputter yields and rates can be rather low. These materials are usually sputtered from dual magnetrons using medium frequency (sine wave) or bipolar (square wave) power supplies at frequencies up to 100 kHz. Frequencies at 50 kHz or higher are beneficial for suppressing arcing on the target surface, and the power required to achieve viable sputter rates is often high, making the power consumption a significant cost contribution. In this study we look at the effect of the power supply technology and frequency on the sputter rate and the sputtered layer thickness per electrical energy input. The tests were carried out with aluminum dual planar targets and with TiOx dual rotary targets. At low frequencies around 20 kHz, the bipolar generator can yield about 10% higher sputtering rates at the same input power. At about 40 kHz, which is often chosen to minimize arcing, the rates from the two power supplies are about equal.

Hydrogen production by methane decomposition: Analysis of thermodynamic carbon properties and process evaluation

Methane decomposition is a promising approach to reduce the carbon footprint of hydrogen production. Solid carbon is one of the products and can improve the economics as a valuable byproduct or it is to be stored. The morphology of the produced carbon affects not only its economic value, but thermodynamic properties as well. Thermodynamic properties of graphite are usually used for modelling and simulation tasks for methane decomposition. In this study, the impact of the produced carbon type on the decomposition of methane is analyzed. Based on experimental data from literature for e.g. amorphous carbon, carbides, carbon filaments and nanotubes, the equilibrium of the methane decomposition reaction in dependence of temperature and carbon type is evaluated. The highest equilibrium methane conversion is observed for multiwall carbon nanotubes and the lowest for coke as carbon product. If another carbon morphology than graphite occurs, the reaction enthalpy is, in average, increased by 17.6%. To evaluate the potential influence on a production process, a methane decomposition process based on an electrically heated moving bed reactor is simulated. The specific electrical energy input and the methane consumption is calculated in dependence of the main process parameters and the produced carbon type. In a base case simulation the specific electrical energy input is 1.13kWh/NmH23. About 60% of the electrical power is required for heating the reactor. The energy input is highly affected by the amount of recycled bed material, the effectiveness of heat transfer, the methane conversion and by the carbon type. In the simulated temperature range of between 800 and 1300 K, the specific electrical energy input for a produced carbon type that differs from graphite is in average increased by 14.2% and by 58% in maximum. Further research on thermodynamic properties of different carbon types and their relevance for different methane pyrolysis processes is required.

IGDT-Based Robust Optimization for Multicarrier Energy System Management

In this paper, the information-gap decision theory (IGDT)-based robust problem model for multicarrier energy system (MES) management is presented. It is noted that in the proposed problem, electrical and gas energies are inputs of MES or energy hub, and electrical and heating energies are outputs of MES. The output electrical energy of hub provided by renewable energy sources (RESs), storage system, combined heat and power (CHP) system is managed by hub manager, and they do not participate in the market and input electrical energy. Also, it is considered that input electrical energy is bought from the PoolCo and bilateral contract markets. Moreover, the CHP is only connecting element for different energies. Therefore, the deterministic problem model expresses in the first step, where its objective function is minimized of hubs energy cost. Also, the constraints of problem are power flow equations and indexes limit in electrical, natural gas and district heating networks, PoolCo and bilateral contract market models, RES, storage system and CHP equations. This problem is as mixed integer nonlinear programming, where in the next step, the equivalent mixed integer linear programming model is presented because this new model can obtain the global optimal solution with low calculation error and time. In addition, the different loads, energy price in PoolCo market and RESs output power are uncertain parameters. Hence, this paper for considering uncertainty parameters presents the IGDT-based robust optimization for proposed problem. Finally, this problem is applied to standard test network with GAMS software, and thus the capability of the proposed problem investigates.

Development of an adaptive static-dynamic electrical model based on input electrical energy for PEM water electrolysis

Compared to alkaline electrolyzers, PEM electrolyzers offer high current densities and can be coupled to renewable energy sources because of their fast responses to dynamics. The modeling of PEM electrolyzers is a challenging issue to reproduce its behavior and to design properly power electronics and its control without damaging a real electrolyzer. The input current may have an impact on the dynamics of the electrolyzer and must be taken into consideration to make a model more reliable. In this work, an equivalent electrical circuit to replicate accurately the dynamic behavior of the PEM electrolyzer subject to fast current change is investigated. Based on the input current, the parameters of the model can not be considered as constant. Hence, to improve the accuracy of the model, an adaptive static-dynamic electrical model is proposed and takes into consideration the change of input current. This model is validated by using a commercial-400 W PEM electrolyzer. The obtained results demonstrate the effectiveness of the model to predict the PEM stack voltage.