Electrolysis Step Research Articles

Dual-objective optimization of solar driven alkaline electrolyzer system for on-site hydrogen production and storage: Current and future scenarios

Achieving cost competitiveness of renewable hydrogen could accelerate the transition to the deeply decarbonized energy system. In this article, we develop and apply a dual-objective optimization model to explore the photovoltaic (PV) hydrogen production pathway and costs development from the present through 2050. The model is applied for optimal capacity allocation of the megawatt-scale off-grid PV-Hydrogen system to achieve maximum production at the minimal levelized cost of hydrogen (LCOH). Methodology includes a smoothing control strategy. Simulation is performed utilizing measured meteorological data for one year with hourly resolution and considering electrolyzer's load flexibility constraint. It has been found that the smoothing control strategy is indispensable for maximizing PV energy utilization, enhancing the electrolyzer's capacity factor and reducing the power curtailments. The analysis shows that the off-grid solar hydrogen in Algeria lacks economic competitiveness currently. Components CAPEX reduction turns out to be the fundamental condition towards the future LCOH decrease. LCOH could decline from 4.2 $/kg in 2025 to 2.24 $/kg in 2050 under central assumptions and to roughly 1.4 $/kg under optimistic assumptions. Alkaline electrolysis step cost could reduce by 0.28 $/kg every decade. Hydrogen storage autonomy could rise the LCOH by 7.1 c$ per day of autonomy in 2050.

Application of Industrial-Scale Lithium Sulphate Electrolysis in Battery Recycling

As the world charges towards electrification and sustainable transportation, it is critical that the entire supply chain is equally sustainable. Industrial processes must be tailored towards circular processes in which emissions and effluents to the environment are minimized, if not eliminated altogether. When it comes to the production of battery grade lithium hydroxide monohydrate, a critical component of lithium ion batteries (LIBs), and the recovery of the lithium in spent LIBs. NORAM Electrolysis Systems Inc (NESI) has developed electrochemical technologies in which effluents are greatly reduced.NESI has developed a flexible, multi-compartment industrial electrolyser for salt splitting (NORSCAND®) applications including electrolysis of lithium sulphate to produce battery-grade lithium hydroxide (LHM). This electrolysis step can be used for the initial production of LHM or for recovering the LHM from recycling LIBs. In either case sulphuric acid is a by-product of the electrolysis process and it can then be recycled for dissolution of black mass in battery recycling processes or for e.g. SX regeneration. In both cases the incorporation of electrolysis in the flowsheet eliminates effluent streams.This presentation will outline the product quality and environmental benefits of electrolysis applied as part of a battery recycling flowsheet. It will outline the approach to electrolyser scale-up and present test and performance data from industrial-scale application. Figure 1

Screening the Optimal Loading of a Pt-Catalyzed Zeolite for Hydrogen Isotope Exchange

The separation of tritiated sources from the exhaust stream of a nuclear fusion system remains a key area of study. While current hydrogen isotope separation technologies are effective at separating gaseous elemental hydrogen, they require additional costly and time-intensive electrolysis steps to be applied toward tritiated water. Previous work has proposed a capture and exchange method, which this work has applied to screen for an optimal weight loading of platinum onto a zeolite molecular sieve. Several samples of various weight loadings were cycled using a series of isotope exchange processes, and it was determined that a weight loading between 0.65 to 0.80 wt% Pt is optimal to separate heavier isotopes of hydrogen from a water waste stream.

Life cycle assessment of the biofuel production from lignocellulosic biomass in a hydrothermal liquefaction – aqueous phase reforming integrated biorefinery

The use of biofuels in the transport sector is one of the strategies for its decarbonization. Here, the LCA methodology was used for the first time to assess the environmental impacts of a biorefinery where hydrothermal liquefaction (HTL) and aqueous phase reforming (APR) were integrated. This novel coupling was proposed to valorize the carbon loss in the HTL-derived aqueous phase, while simultaneously reducing the external H2 demand during biocrude upgrading. Corn stover (residue) and lignin-rich stream (waste) were evaluated as possible lignocellulosic feedstocks. The global warming potential (GWP) was 56.1 and 58.4 g CO2 eq/MJbiofuel, respectively. Most of the GWP was attributable to the electrolysis step in the lignin-rich stream case and to the thermal duty and platinum use in the corn stover case. Other impact categories were investigated, and an uncertainty analysis was also carried out. A sensitivity analysis on biogenic carbon, electricity/thermal energy source and alternative hydrogen supply was conducted to estimate their influence on the GWP. Finally, the two scenarios were compared with the environmental impact of fossil- and other biomass-derived fuels, also considering fuel utilization. HTL-APR allowed a 37% reduction compared to fossil diesel, further reduced to 80% with the lignin-rich stream when green energy was used.

Obtaining ultrafine copper electrolytic dendritic powders

In recent years, ultrafine copper powder has become one of the most promising industrial materials due to its unique physical and chemical properties. For example, the high electrical conductivity of the powder allows to use it as a conductive paste or screen for protection against electromagnetic waves. JSC Uralelectromed is a unique enterprise in Russia with multi-tonnage production of copper electrolytic powder. The particle size of the powders varies depending on the brand in a wide range — from 5 to 250 microns. It is necessary to obtain ultrafine copper powder with an average particle size of 3 to 6 μm. The literature review showed the possibility to obtain ultrapowders by chemical methods and electrolysis from various media. However, the above examples of obtaining ultrafine copper powder differ significantly from the JSC Uralelectromed technology. Therefore, laboratory experiments were performed to optimize the existing electrolysis mode and determine the effect of the electrolyte components concentration and cathode current density on the process of obtaining a powder with a high content of fractions up to 5 μm. Regression equations were compiled, which showed the predominant effect of chloride ions and sulfuric acid, whose growth results in increase in the content of the required fraction. Industrial tests, in addition to the modified electrolysis step, included experiments on the separation of the powder on an air-centrifugal classifier. The range of the optimal specific surface and the average particle size of the initial (before classification) powder was determined. The modes of operation of the air classifier to obtain the required fractional composition of the powder were also determined. The specific surface area of the obtained ultrapowders ranged from 4400 to 5600 cm2/g.

Comparison of oxidative roasting and alkaline leaching for removing chloride and fluoride from brass ashes

A brass ash sample was characterized, presenting a high content of Zn (50.1%) and Cu (18.9%), with zincite, tenorite, quartz, willemite, and metallic Zn and Cu as major phases. It is a heterogeneous material composed of agglomerated particles of different shapes and sizes. Aiming at reaching the requirements for the subsequent Zn electrolysis step in a hydrometallurgical route to recover Zn and Cu, the initial content of Cl (0.14%) and F (0.22%) in the brass ashes was reduced by oxidative roasting and alkaline leaching. In the oxidative roasting method, the increase in roasting temperature from 400 °C to 900 °C favored the removal of Cl and F (nearly 60% average) from the brass ashes; however, a high Zn evaporation efficiency (18.4% average) was observed. The thermodynamics of the reactions involved in Cl and F removal from the brass ashes was evaluated to explain the experimental results. In contrast, remarkable selectivity in removing Cl and F was obtained by leaching the brass ashes with Na2CO3 solutions, and 100% Cl and 89% F were removed with only 0.05% Zn and 0.2% Cu co-extractions using Na2CO3 (14% w/w) after 2 crosscurrent stages, both operated at 90 °C, L/S ratio of 4 mL g−1, for 30 min, and without pH control (pHinitial ≈ pHfinal ≈ 10.8). Practically no Cl and low F contents were found in the Zn/Cu-rich sulfuric leach solution, which proved to be appropriate for the hydrometallurgical treatment of brass ashes when using subsequent operations such as solvent extraction and electrowinning.

Investigations on a platinum catalyzed membrane for electrolysis step of copper‐chlorine thermochemical cycle for hydrogen production

SummaryConsidering the low temperature demand (~550°C maximum) and high efficiency (~43%), Cu–Cl thermochemical water splitting cycle has immense potential as a futuristic scalable hydrogen generation process. CuCl/HCl electrolysis is the crucial hydrogen generation step in the Cu–Cl thermochemical cycle. The efficiency of this electrolysis process is highly dependent on the performance of the membrane electrode assembly (MEA) employed. To explore the suitability of the platinized membrane for this step, in this study, we have investigated a Pt/Nafion‐117 MEA prepared by in‐situ impregnation‐reduction method for CuCl/HCl electrolysis. A single‐cell PEM‐type electrolyser (4 cm2 active area) consisting of serpentine channels (2 cm × 2 cm) grooved in graphite flow field plates was designed and fabricated to carry out the CuCl/HCl electrolysis. Platinum electrocatalyst was deposited on Nafion‐117 membrane on the cathodic side by reduction of hexachloroplatinic acid (H2PtCl6) with sodium borohydride (NaBH4) by the impregnation‐reduction method which served as the MEA. Monodispersed nanocrystalline Pt particles formed a ~30 μm thick electrocatalyst layer on the membrane. Pt/Nafion‐117 MEA was found to be effective for CuCl /HCl electrolysis. In a PEM‐type electrolyser with Ar‐purged 0.2 M CuCl in ~2 M HCl solution as anolyte flowing at ~ 8.8 mLmin−1, a current density of ~100 mA cm−2 was achieved at a cell voltage of 1 V. However, undesired Cu‐crossover could be noticed from anode to cathode side during operation.

Canadian advances in the copper–chlorine thermochemical cycle for clean hydrogen production: A focus on electrolysis

Hydrogen is a clean energy carrier that can help mitigate greenhouse gas (GHG) emissions if it is used to replace fossil fuels for power production. One way to produce hydrogen on a large scale is through the use of water splitting thermochemical cycles such as the hybrid copper chlorine (Cu–Cl) cycle. Canadian Nuclear Laboratories Ltd. (CNL) chose to develop the Cu–Cl cycle because the highest temperature required by this cycle is about 530 °C, compatible with the Canadian Super Critical Water Reactor (SCWR) or some small modular reactors (SMR). The on-going effort at CNL is to demonstrate a fully integrated Cu–Cl cycle at laboratory scale with a hydrogen production rate of 50 L/h. Some recent experimental results of the electrolysis step, one of the main steps of the cycle, are discussed in this paper.The anode reaction of CuCl oxidation was investigated using a three-electrode electrochemical cell. Half-cell experiments found that CuCl oxidation did not require noble metals as catalyst. The CuCl oxidation on carbon was found to be a mass-transfer controlled process. Hence the limiting current density increased with increasing turbulence on the electrode surface. Increasing the CuCl concentration and the solution temperature also resulted in higher limiting current densities. A current density of 0.53 A/cm2 was achieved for a 1.0 M CuCl solution at 80 °C.Single cells with electrode areas up to 100 cm2 were used to establish the operating conditions for the electrolysis step. The effects of flow rate, temperature, and current density on the cell voltage were studied. A hydrogen production rate of 50 L/h was successfully achieved at 0.4 A/cm2 in a 2.0 M CuCl solution at 80 °C. The electrolysis step is fully developed for integration in a laboratory-scale demonstration of the Cu–Cl cycle.

Improvement of electrochemical oxidation efficiency through combination with adsorption processes

In this work, a three-step process (adsorption-desorption-electrolysis) is evaluated as an interesting approach for the removal of organochlorinated compounds (clopyralid, lindane and perchloroethylene) with different physical properties (solubility and vapor pressure) from low concentrated wastewater. First steps are based on the adsorptive capacity of granular active carbon (GAC) particles to retain organics and on the solvent capacity of methanol to extract them to concentrated solution and regenerate GAC. In the last step of electrolysis with conductive diamond electrodes, the degradation of pesticide is projected, as well as the recovery of methanol. Results show that clopyralid, lindane and PCE are efficiently retained in GAC, although adsorption efficiency depend on pollutant/GAC ratio and physicochemical properties of pollutant. Pretreatment allows the concentration of clopyralid and PCE solutions up to 8 times, but worse results are obtained in case of lindane solutions. Electrolysis of concentrated methanol solution seems to be more efficient than electrolysis of diluted aqueous wastes, mainly in the case of clopyralid. In all cases, electrochemical degradation fits a first order kinetics confirming mixed oxidation mechanisms with diffusion control of the direct processes and mediated oxidation. Results obtained in terms of current efficiency and energy consumption of electrolysis step point out the lower operation cost of concentrated liquid wastes and encourage further works on the development of cost-effective combined processes for the treatment of diluted solutions polluted with polar compounds (such as clopyralid).

CO2-to-Fuels Renewable Gasoline and Jet Fuel Can Soon Be Price Competitive with Fossil Fuels

Download : Download high-res image (69KB) Download : Download full-size image Rob McGinnis, PhD, is an inventor and entrepreneur. He is the founder and CEO of Prometheus, a company that is developing technology to remove carbon dioxide from the air and turn it into fuels. He previously founded Mattershift, where he developed large-scale carbon nanotube membranes. Rob was previously founder of Oasys Water, a company focused on developing forward osmosis technologies for water purification. Rob received his PhD in Engineering from Yale University.

Student Deployed Compu-Graphical Methods for Electrochemistry Education

Spreadsheets enhance student acquisition of electrochemical concepts at both undergraduate and graduate levels. The interactive nature of compu-graphical methods allows students more rapid and therefore extensive exploration of electrochemical concepts in thermodynamics, kinetics, and electrochemical methods. Here, several instructional tools are described with focus on the potential axis. Potential Axis - A Spreadsheet for Thermodynamics, Voltammetry, and Electrolysis For reactions A + ne ⇌ B at standard potential EA⁰ and C + me⇌D at EC⁰, calculation of standard cell potential Ecell⁰ = EA⁰ -EC⁰ for net reaction mA + nD ⇌ mB + nC yields thermodynamic information of standard free energy for the reaction ΔGcell⁰ = -nmFEcell⁰. In turn, ΔGcell⁰ identifies spontaneity when ΔGcell⁰ < 0 and equilibrium when ΔGcell⁰ = 0. When more than two reactions are possible or when pH changes for proton dependent reactions or oxygen is present or not, developing chemical intuition about the system and identifying stable species and thermodynamic reaction energies is more complicated. By plotting the reactions on a potential axis, thermodynamic assessment is readily obtained. Under IUPAC conventions with positive potential E to the right, reaction A + ne ⇌ B is plotted as B|A at potential EA⁰ on the potential axis. On addition of a second reaction C + me ⇌ D where EA⁰ < EC⁰, a simplified potential axis is B|A........D|C where potential is positive to the right. When chemical species are on the outside of the E⁰ lines, reaction is spontaneous. For example, if the axis for the A B couple and the C D couple is B|A........D|C , B and C react to form A and D spontaneously. Any other combinations of species are thermodynamically stable (B+A+D and C+D+A). A potential axis is shown below for several copper species at pH = 0. Because Cu and O₂ are outside the E⁰ vertical axes at 0.34 and 1.23 V vs NHE, Cu reacts spontaneously with O₂ based on thermodynamic potentials ECu²⁺|Cu⁰ and EO₂|H₂O⁰. Several other observations about copper electrochemistry are of note. Copper metal Cu is stable in strong acid. Cu⁺ is not observed in water because Cu⁺ is outside the vertical E⁰ lines for Cu⁺|Cu²⁺ and Cu|Cu⁺, so Cu⁺ reacts spontaneously with itself (disproportionation) to form copper metal and cupric cation. Cu is stable in HCl but not oxidizing HNO₃. Nickel metal and Zn metal (Zn|Zn²⁺ not shown at -0.76 V vs NHE) react spontaneously with both HCl and HNO₃. Potential axes are also useful for mapping voltammetry and identifying the sequence of electrolysis steps. Consider a system that contains Cu, Cu²⁺ and Cl⁻ in an aqueous system that is not degassed (contains O₂) at pH = 0. Based on the reactions plotted on the potential axis for copper, the species that are present and can be oxidized will be oxidized in sequence as potential E is swept from negative to positive. Species are oxidized in the sequence Cu then H₂O; because water is the solvent, chloride will not be accessible for oxidation to chlorine. Species that are present and can be reduced, are reduced in ranked in order for E swept from positive to negative as O₂, Cu²⁺, and H⁺. If pH changes, the formal potentials E⁰' for O₂, H⁺, and NO₃⁻ will also shift and the order of reactions can change. Note that as shown, neither concentrations other than standard conditions nor metal ions precipitated as oxides and hydroxides are not included but can be introduced. Several other ideas will be discussed briefly. Compu-graphical finite difference simulations for cyclic voltammetry for use at the undergraduate and graduate levels. (Thanks to Alanah Fitch who first suggested the form for undergraduates.)Useful ideas to convey include: • the concept of flux as number per area per time • electrochemical systems are circuits composed of electron and ion conductors • relationship between measurement rates and kinetic rates • difference between equilibrium (thermodynamics) and steady state (kinetics) • diffusion length ℓ² ≈ Dt (diffusion coefficient and time) and use in characterizing micro- and nano-structures on electrodes ...... Figure 1

Preliminary results of the integrated hydrolysis reactor in the Cu-Cl hydrogen production cycle

This paper presents preliminary results of an integrated hydrolysis reactor at the Clean Energy Research Laboratory (CERL), University of Ontario Institute of Technology. Initial tests have demonstrated a successful reactor design allowing for effective recovery of liquid products. Using our best available performance metrics, the conversion rate of reagents to products ranged from 7% to 10%. Initial experimental runs demonstrated that the reactor was successfully operational with combined H2O and reagent injection in a configuration suitable for integration with the electrolysis step of the Copper-Chlorine loop. In this paper, we discuss the updated hydrolysis reactor design and present data from a number of recent experiments in which our research team recovered solids and chemical products not previously collected in prior studies. Comparisons were made with earlier XRD data taken at the Argonne National Laboratory. The comparisons showed promising results in the chemical composition of the solids produced. We conclude this paper with a discussion of future experiments to increase the conversion rate of reaction based on the observed trends.

Anodic oxidation for the remediation of soils polluted with perchloroethylene

AbstractBACKGROUNDThis work focuses on the removal of perchloroethylene (PCE) from soils spiked with this hazardous chlorinated hydrocarbon and oil by a combination of two technologies: soil washing and anodic oxidation with diamond electrodes. The first attains the transfer of the pollutant from the soil to a soil washing fluid (SWF), from which the organics are then efficiently removed.RESULTSResults show that high concentrations of sodium dodecyl sulphate (SDS) are required in the SWF for an efficient extraction of the chlorinated hydrocarbon and electrolysis has to be applied not only to the clarified liquid, but also to the interphase. The surfactant used interacts strongly with soil not only during the washing, but also during the electrolysis step. This interaction seems to play a protective role against the oxidation of SDS. The initial phase of the electrolysis is rather complex and there are several processes which modify the results importantly.CONCLUSIONSRemoval of PCE by electrolysis from soil is less efficient than its removal from synthetic solutions of this chlorinated pollutant. There are two first‐order kinetic zones, which indicate an important competition for the oxidation of the different organics contained in the SWF during the electrolysis. © 2018 Society of Chemical Industry

PBI-Blended Membrane Evaluated in High Temperature SO2 Electrolyser

It has been shown that hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) process. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4. The proton exchange membrane (PEM) used for this process should have both a high proton conductivity and acid stability. Since the widely used perfluorosulfonic type materials are restricted by their humidification requirements, materials such as polybenzimidazole (PBI) has been found to be promising in blends with partially fluorinated polyaromatic polymers at operating temperatures of 80 and 95 °C within the SO2 electrolyser. Operation at higher temperatures (>100 °C) however holds many advantages such as improved reaction kinetics and simplified water management. For this study a cross-linked partially fluorinated polyaromatic PBI blended membrane was evaluated at 120 °C. Humidified SO2 was supplied to the anode to produce sulfuric acid while hydrogen was formed at the cathode. The SO2:H2O feed was managed at the applied current densities until a constant voltage was obtained, and there after increased accordingly with increasing current density. Polarisation curves (Figure 1) recorded for the blended PBI membrane were comparable with reported s-PBI in literature values in the lower current density region (< 0.5 A/cm2). A maximum current density of 1.1 A/cm2 was reached in comparison to the 0.5 A/cm2 for s-PBI at a temperature of 110 °C. Voltage stability was monitored at a current density of 0.3 and 0.6 A/cm2 for a duration of 6 hours or until the maximum voltage had been reached. The lower current density (0.3 A/cm2) was more constant over the course of the measurement, with a standard deviation of 3 mV, when compared to the higher applied current density. These results are promising for further testing and optimization of the blended PBI membranes for higher temperature SO2 electrolysis. Figure 1

An integrated electrolysis – electrospray – ionization antimicrobial platform using Engineered Water Nanostructures (EWNS) for food safety applications

Engineered water nanostructures (EWNS) synthesized utilizing electrospray and ionization of water, have been, recently, shown to be an effective, green, antimicrobial platform for surface and air disinfection, where reactive oxygen species (ROS), generated and encapsulated within the particles during synthesis, were found to be the main inactivation mechanism. Herein, the antimicrobial potency of the EWNS was further enhanced by integrating electrolysis, electrospray and ionization of de-ionized water in the EWNS synthesis process. Detailed physicochemical characterization of these enhanced EWNS (eEWNS) was performed using state-of-the-art analytical methods and has shown that, while both size and charge remain similar to the EWNS (mean diameter of 13 nm and charge of 13 electrons), they possess a three times higher ROS content. The increase of the ROS content as a result of the addition of the electrolysis step before electrospray and ionization led to an increased antimicrobial ability as verified by E. coli inactivation studies using stainless steel coupons. It was shown that a 45-min exposure to eEWNS resulted in a 4-log reduction as opposed to a 1.9-log reduction when exposed to EWNS. In addition, the eEWNS were assessed for their potency to inactivate natural microbiota (total viable and yeast and mold counts), as well as, inoculated E. coli on the surface of fresh organic blackberries. The results showed a 97% (1.5-log) inactivation of the total viable count, a 99% (2-log) reduction in the yeast and mold count and a 2.5-log reduction of the inoculated E. coli after 45 min of exposure, without any visual changes to the fruit. This enhanced antimicrobial activity further underpins the EWNS platform as an effective, dry and chemical free approach suitable for a variety of food safety applications and could be ideal for delicate fresh produce that cannot withstand the classical, wet disinfection treatments.

Assessment and analysis of hydrogen and electricity production from a Generation IV lead-cooled nuclear reactor integrated with a copper-chlorine thermochemical cycle

Summary An integrated system for compressed hydrogen and electrical power production based on a Generation IV nuclear reactor (a lead-cooled reactor) is proposed. The hydrogen is produced by the integrated system through a hybrid thermochemical and electrical water decomposition cycle. The water decomposition cycle is based on copper and chlorine compounds and decomposes water through four main steps. The electrical power is produced by the Rankine cycle, which also contributes to cooling the compressed hydrogen between the compression stages as well as providing the electrical power required by the electrolysis step in the water decomposition cycle. In the proposed system, a heat recovery network is incorporated within the water decomposition cycle so that only the hydrolysis and the oxygen production reactors in the cycle receive thermal energy from the lead-cooled nuclear reactor. The integrated system is modeled and simulated by using engineering process simulation software (Aspen Plus). The performance of the integrated system is assessed with energy and exergy analyses, and the overall energy and exergy efficiencies are found to be 25.4% and 40.6%, respectively. The integrated system produces 3.45 g/s of compressed hydrogen ready for shipping and 467.2 kW of electrical power.

An origami paper device for complete elimination of interferents in enzymatic electrochemical biosensors

Many efforts have been made to prevent interferences in enzymatic electrochemical biosensors by permselective membranes or mediators with low redox potential. However, it is difficult to completely eliminate interferents without compromised sensitivity by these traditional procedures. We propose here a method based on an origami paper device that separates the electrochemical reactions of interferents and substrates for complete depletion of interferents and precise analysis of substrates. Interferents such as ascorbate, urate and paracetamol were completely consumed by a simple electrolysis step, while substrates were quantitatively analyzed by coulometry. With GOx as a model enzyme, an interference-free and calibration-free coulometric glucose biosensor has been demonstrated successfully. The proposed origami paper device provides a facile and easy-controlled approach to eliminate the electroactive interferents completely for enzymatic electrochemical biosensors.

Sequential solid entrapment and in situ electrolytic alkaline hydrolysis facilitated reagent-free bioelectrochemical treatment of particulate-rich municipal wastewater

We introduce here a novel process for the treatment of particulate-rich wastewater. A two-stage combined treatment process, consisting of an electrolysis filter and a bioelectrochemical system (BES) configuration was designed and evaluated to remove particulate and soluble organic matter from municipal wastewater. The system was designed such that the electrolysis step was used as a filter, enabling physical removal and in situ alkaline hydrolysis of the entrapped particulate matter. The alkaline effluent enriched with the hydrolysed soluble compounds (soluble chemical oxygen demand, SCOD) was subsequently loaded into the BES for removal via bioanodic oxidation. The coupled system was continuously operated with a primary sedimentation tank effluent (suspended solids (SS) ∼200 mg/L) for over 160 days, during which SCOD and total COD (TCOD), SS removal and current production were evaluated. With no sign of clogging the process was able to capture near 100% of the SS loaded. A high Coulombic efficiency (CE) of 93% (based on overall TCOD removed) was achieved. The results also suggest that the SCOD-laden alkaline liquor from the electrolysis step compensated for the acidification in the bioanode and a final effluent containing low COD with neutral pH was achieved. Overall, since the system can effectively entrap, in situ hydrolyse and oxidise organic matter without external dosing of chemicals for pH control, it has desirable features for practical application.

Development and assessment of a novel integrated nuclear plant for electricity and hydrogen production

A novel nuclear-based integrated system for electrical power and compressed hydrogen production is proposed. The hydrogen is produced through the four-step Cu-Cl cycle for water decomposition. A Rankine cycle is used to generate the power, part of which is used for the electrolysis step in the hybrid thermochemical water decomposition cycle and the hydrogen compression system. In the proposed design of the four-step thermochemical and electrical water decomposition cycle, only the hydrolysis and the oxygen production reactors receive thermal energy from the nuclear reactor. The nuclear thermal energy is delivered to the integrated system in the form of a supercritical fluid. The nuclear reactor, which is based on the supercritical water-cooled reactor, is responsible for delivering the thermal energy to the system, which is simulated using Aspen Plus and assessed with energy and exergy analyses. It is determined that the energy and the exergy efficiencies of the proposed system are 31.6% and 56.2% respectively, and that the integrated system is able to produce 2.02kg/s of highly compressed hydrogen and 553MW of electrical power.

Improvement of the selectivity of the electrochemical conversion of CO2 to hydrocarbons using cupreous electrodes with in-situ oxidation by oxygen

It is still a challenge to find catalysts for the selective electrochemical reduction of CO2 to value added products. We present a new method for the in-situ modification of a copper catalyst by adding oxygen to the reactant gas. With an appropriate process procedure consisting of a sequence of electrolysis and purge steps, a Cu2O layer was formed during the purge steps. When it was reduced again during the next electrolysis step, Cu+ species remained stable on the surface and let to a higher faradaic efficiency for C2H4 formation and even a lower onset potential for CO2 reduction in general. This effect was observed for a wide range of O2 content from 10 % to 60 % in the reactant gas. In comparison to electrolysis with pure CO2, formation of methane was largely suppressed.