Electrolyzer Stack Research Articles

Investigation of Advanced Components in a High Pressure Single-Cell Electrolyser for the Development of a HP-PEM-ELY Stack as Part of a Regenerative Fuel Cell System

The objective of the presented work, done under current ESA activity (Contract No. 4000109578/13/NL/SC), is the performance and tolerance evaluation of selected components and materials for the development of a High Pressure, Polymer Electrolyte Membrane (PEM) Electrolyser (HP-PEM-ELY) Stack, aiming to operate at 80 bar with a performance output of 0.3 A/cm 2 at 1.6 V. An extensive study was performed on a single-cell high pressure PEM electrolyser manifold, leading to a list of materials with suitable properties and engineering solutions towards operation in space environment. This investigation provided the necessary feedback for the design of a HP-PEM-ELY stack, which is also discussed. The ultimate target of the current ESA activity is to implement research findings, develop and operate a complete regenerative fuel cell system, comprising of a High Temperature Fuel Cell Stack and the HP-PEM-ELY stack. System aspects are briefly discussed.

Mechanical and Durable Properties of Ni-YSZ Electrode Under High Temperature for Solid Oxide Electrolysis Stack

Many researches based on SOFC development and high temperature electrolysis (HTE) have been reported in the last couple of decades. HTE is one of the most clean and efficient technologies for manufacturing large amounts of hydrogen from water with oxygen. The processing and structure of HTE is closely related to the knowledge and concept of solid oxide fuel cells (SOFCs). Specially, it is very important to evaluate the durability’s properties of oxide electrolysis stacks under high temperature as well as steam environment to apply HTE. Unfortunately, no study has been reported the durable properties of oxide electrolysis stacks at high temperature as well as steam environment. For the reason, the aim of this work is to realize the durable properties (ex, high temperature strength fatigue and creep) at high temperature of 600°C~850°C for oxide electrolysis stacks which consists of 55%NiO-45%YSZ(8mol%Y2O3) composition. NiO-YSZ cathode supports were prepared in the shape of flat tubes by extrusion method. The pre-sintered NiO-YSZ flat tubes were dip-coated in YSZ slurry to secure the interconnector area with a masking fluid and then were sintered at 1400°C for 3h. The creep properties showed decreasing tendency with increasing applied load in range of 40~80MPa and temperature in range of 600°C~800°C. The life time of fatigue at 850°C under Ar-4%H2O environment was decreased with increasing applied load.

Electro-catalytic conversion of ethanol in solid electrolyte cells for distributed hydrogen generation

The global interest in hydrogen/fuel cell systems for distributed power generation and transport applications is rapidly increasing. Many automotive companies are now bringing their pre-commercial fuel cell vehicles in the market, which will need extensive hydrogen generation, distribution and storage infrastructure for fueling of these vehicles. Electrolytic water splitting coupled to renewable sources offers clean on-site hydrogen generation option. However, the process is energy intensive requiring electric energy >4.2kWh for the electrolysis stack and >6kWh for the complete system per m3 of hydrogen produced. This paper investigates using ethanol as a renewable fuel to assist with water electrolysis process to substantially reduce the energy input. A zero-gap cell consisting of polymer electrolyte membrane electrolytic cells with Pt/C and PtSn/C as anode catalysts were employed. Current densities up to 200mAcm−2 at 70°C were achieved at less than 0.75V corresponding to an energy consumption of about 1.62kWhm−3 compared with >4.2kWhm−3 required for conventional water electrolysis. Thus, this approach for hydrogen generation has the potential to substantially reduce the electric energy input to less than 40% with the remaining energy provided by ethanol. However, due to performance degradation over time, the energy consumption increased and partial oxidation of ethanol led to lower conversion efficiency. A plausible ethanol electro-oxidation mechanism has been proposed based on the Faradaic conversion of ethanol and mass balance of the by-products identified and quantified using 1H nuclear magnetic resonance spectroscopy and gas chromatography.

Mathematical modeling and dynamic Simulink simulation of high-pressure PEM electrolyzer system

PEM electrolysis based hydrogen generator system model is developed by using Simulink in MATLAB. The model covers the following system components: PEM electrolyzer stack, water pump, cooling fan, storage tank, water tank, power supply, control unit and sensors. In simulation, PEM electrolyzer stack model is the most complex component and consists of four parts; anode and cathode modules, membrane and finally voltage calculations module. Efficiency drops and voltage losses in the PEM electrolysis stack are estimated. The overpotentials are investigated as anode and cathode activation, electronic and ionic ohmic resistances. In addition, the loss of the other components is considered. The model is tested against the dynamic changes and it responded with quick outputs. The cell and stack behavior under different conditions (i.e. ranging of temperature and pressure) are examined. The loss of each system component at different current densities is added to the simulation. The study shows that the loss of stack dominates the losses of other components at higher current densities. The simulation counts that the stack and system model can run with different cases and scenarios. It is run for the scenario that it consumes constant power for a high pressure operation. Results show that current drawn by the stack decreases as the voltage increases because of the increasing pressure.The model is also compared with the experimental results and the model is found to be consistent with the experimental data.

Evaluation of polarization and hydrogen production efficiency of solid oxide electrolysis stack with La0.6Sr0.4Co0.2Fe0.8O3−δ- Ce0.9Gd0.1O1.95 oxygen electrode

The 30-cell (10 × 10 cm2) LSCF-GDC (La0.6Sr0.4Co0.2Fe0.8O3−δ − Ce0.9Gd0.1O1.95) oxygen electrode supported planar solid oxide electrolyzer cell (SOEC) stack module is manufactured and tested at different operation conditions (operating temperature, steam content, gas flow rate et al.) in steam electrolysis mode for hydrogen production. The i–v curves of each electrolysis are recorded and fitted according to the electrochemical models, the influences of operation conditions on the polarization loss of high temperature water electrolysis are analyzed, and the electrolysis efficiencies are calculated. High operating temperature gives the reduction of Ohmic and activation polarization, and high steam content results in significantly lowered activation polarization. The flow rates of the gas onto the hydrogen electrode and oxygen electrode have great impact on concentration and activation polarization. The electrolysis efficiency can reach the maximal value of 80.8% (electrolysis voltage 1.273 V) when the system operating at 800 °C, with 6 L min−1 90% humidified hydrogen mixed gas, and the rate of resultant hydrogen is 4.57 L min−1.

Protective coatings on stainless steel bipolar plates for proton exchange membrane (PEM) electrolysers

Proton exchange membrane (PEM) electrolysis is a promising technology for large H2 production from surplus electricity from renewable sources. However, the electrolyser stack is costly due to the manufacture of bipolar plates (BPP). Stainless steel can be used as an alternative, but it must be coated. Herein, dense titanium coatings are produced on stainless steel substrates by vacuum plasma spraying (VPS). Further surface modification of the Ti coating with Pt (8 wt% Pt/Ti) deposited by physical vapour deposition (PVD) magnetron sputtering reduces the interfacial contact resistance (ICR). The Ti and Pt/Ti coatings are characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). Subsequently, the coatings are evaluated in simulated and real PEM electrolyser environments, and they managed to fully protect the stainless steel substrate. In contrast, the absence of the thermally sprayed Ti layer between Pt and stainless steel leads to pitting corrosion. The Pt/Ti coating is tested in a PEM electrolyser cell for almost 200 h, exhibiting an average degradation rate of 26.5 μV h−1. The results reported here demonstrate the possibility of using stainless steel as a base material for the stack of a PEM electrolyser.

Bipolarly stacked electrolyser for energy and space efficient fabrication of supercapacitor electrodes

Stacked electrolysers with titanium bipolar plates are constructed for electrodeposition of polypyrrole electrodes for supercapacitors. The cathode side of the bipolar Ti plates are pre-coated with activated carbon. In this new design, half electrolysis occurs which significantly lowers the deposition voltage. The deposited electrodes are tested in a symmetrical unit cell supercapacitor and an asymmetrical supercapacitor stack. Both devices show excellent energy storage performances and the capacitance values are very close to the design value, suggesting a very high current efficiency during the electrodeposition. The electrolyser stack offers multi-fold benefits for preparation of conducting polymer electrodes, i.e. low energy consumption, facile control of the electrode capacitance and simultaneous preparation of a number of identical electrodes. Therefore, the stacked bipolar electrolyser is a technology advance that offers an engineering solution for mass production of electrodeposited conducting polymer electrodes for supercapacitors.

Coated Stainless Steel Bipolar Plates for Proton Exchange Membrane Electrolyzers

Given its rapid response to fluctuating currents and wide operation range, proton exchange membrane (PEM) water electrolysis is utmost suitable for generation of hydrogen from renewable power. However, it is still hindered by the high cost of the stack components compared to those used in the alkaline technology. In particular, the titanium bipolar plates (BPP) are an issue and the replacement of this metal by stainless steel is a challenge, due to the highly corrosive environment inside PEM electrolyzer stack. Herein, we coat stainless steel BPPs with 50–60 μm Ti and 1.5 μm Pt coatings by vacuum plasma spraying (VPS) and magnetron sputtering physical vapor deposition (PVD), respectively. The BPPs are evaluated at constant 1 A cm−2 for more than 1000 h. The thermally sprayed Ti coatings fully protect the stainless steel substrate during this period of time, and the Pt surface modification allows achieving a cell performance comparable to the baseline.

Co-electrolysis of water and CO2in a solid oxide electrolyzer (SOE) stack

Summary Solid oxide electrolyzer (SOE) can operate in co-electrolysis mode of H2O and CO2 because of the high operating temperature and the nickel-based fuel electrode material. In this configuration, the fuel electrode is fed with a mix of steam and carbon dioxide that is converted through electrolysis reactions into a syngas that can be further upgraded to other carbon fuels. This technology can lead to interesting scenarios in the field of energy storage and CO2 reuse. SOE performance in terms of syngas quality and chemical equilibrium is presented in this study. An experimental test on a four-cell stack was performed to evaluate which are the effects of inlet gas composition and current density on the output syngas composition and on the thermal balance of the stack. Results were analyzed with the support of a thermodynamic model that aims to demonstrate that equilibrium condition is reached within the stack for all the involved reactions including reverse water shift. Also, we show that there is a direct relation between inlet and outlet compositions. For each composition, current density for thermoneutral condition was calculated obtaining values in the range of 377–493 mA/cm2 depending on the composition. Such results permit to study SOE integration in a complete process for energy and CO2 storage. Copyright © 2015 John Wiley & Sons, Ltd.

Integration of Solid Oxide Electrolyzer and Fischer-Tropsch: A sustainable pathway for synthetic fuel

Because of their easy and widespread distribution and safe handling, liquid fuels are used in everyday life, to power vehicles, aircrafts, ships, etc. The use of fuels from conventional fossil sources is now called for a more sustainable alternative. Hence, chemical energy storage of electricity generated by renewable sources into synthetic fuels represents an interesting solution, solving also other typical problems with renewables, such as grid stabilization.Within this framework, the present study deals with the production of synthetic green fuels by means of the Fischer-Tropsch process, downstream a previous electricity-to-gas conversion achieved operating a Solid Oxide Electrolyzer (SOE) stack in co-electrolysis. With reference to the state of the art, this study developed the concept of integrating an SOE and a Fischer-Tropsch process in a small plant size, which is compatible with renewables power density. To this aim, fuel upgrading is supposed to be performed separately.Based on experimental results on a Solid Oxide Cells stack operated in co-electrolysis, three system-level models were developed, evaluating the most performing option. Thus, considering a plant capacity of 1bbl/day of liquid fuel, in the best scheme, the electricity-to-liquid efficiency was estimated to be 57.2%. Materials introduced into the system are simply water (33,701ton/MJ) and carbon dioxide (79,795ton/MJ). While hydrogen is necessary to feed the SOE, net consumption is zero because it is recovered from Fischer-Tropsch product lighter fraction.

Computational Modelling of the Flow Field of An Electrolyzer System using CFD

A bipolar plate is one of the primary components in a Polymer Electrolyte Membrane (PEM) electrolyzer which contributes to its hydrogen production efficiency. Its primary function is to distribute the flow of a fluid, in this case water, evenly over the active area of an electrolyzer cell. A well designed and optimized bipolar plate is required to produce an efficient and cost effective PEM electrolyzer stack. In this paper optimal flow plate design and computer models of several available flow plate designs were constructed, and then run through a numerical simulation to evaluate both the hydrodynamic properties they exhibited, the velocity field and pressure gradients. Results indicate that under the specified conditions, the pressure gradient decreases diagonally along the bipolar plate, from the inlet to the outlet. However, the sharpness, or evenness of the pressure gradient varies depending on the design of the bipolar plate. The velocity fields also follow the same general trend, only that they increase in magnitude as they approach the outlet rather than decrease. However, the magnitude of their velocity in the middle of the plates, especially in some of the designs, such as in the multi-pass serpentine designs, varies randomly within a certain range rather than decreasing or increasing evenly, it is only at the outlet that the velocity gradient becomes more consistent. However, of all the designs evaluated the parallel flow field stands out as a very suitable design for use, due to its ability to maintain operational pressures above 1MPa through its entire flow field and also, due to its ability to maintain a stable flow velocity between 3-5m/s, both characteristics which were not displayed by the other two designs. In addition, the parallel flow field design was also able to maintain a average Reynolds number close to the critical value or RE=4000, thus minimizing its internal turbulence.

Solar hydrogen power system for isolated passive house

Solar hydrogen power system for supplying isolated passive house with utility power energy and hydrogen fuel for personal transport has been established and discussed. Commercially available components such as photovoltaic module, proton exchange membrane fuel cell stack and electrolyzer stack were acquired. Appropriate control logic was developed. MATLAB/Simulink software has been used to simulate control logic and system components. The proof of the control logic and components models has been performed by simulations predefined scenarios, i.e. with and without solar irradiance and with given energy demands by the user. All of that can be used as valuable tool for any autonomous solar hydrogen system design of passive house.

Micro/small wind turbine power control for electrolysis applications

This paper compares the efficiency of three power converter and maximum power point tracking (MPPT) systems for connecting a micro/small wind turbine to an electrolyser stack: a conventional DC–DC voltage converter with hill-climb search (HCS); a novel variable electrolyser cell load controller where the number of series cells varies to allow MPPT; a novel hybrid DC–DC voltage converter integrated with direct-connect circuitry, variable cell control and lookup-based MPPT. The variable cell and hybrid converters demonstrated superior performance, averaging efficiencies 2–4% higher than the conventional converter, reaching near ideal at a wind speed of 7.7 ms−1 due to direct connection. MPPT function measured electrolyser current as a power reference. HCS performed MPPT at approx. 98% of ideal but requiring very advanced function including variable step size and intelligent perturbation to achieve this during dynamic conditions. The variable cell and hybrid converters produced superior MPPT (based on lookup data) to HCS. This demonstrates alternative novel power control and MPPT approaches for low-cost and efficient hydrogen production from micro/small wind-electrolysis systems.

Efficiency analysis of a solar photovoltaic array coupled with an electrolyser power unit: a case study

ABSTRACTHydrogen as an energy carrier is one of the most potential candidates for clean energy and can be produced by water electrolysis. The use of 10 kW photovoltaic arrays for supplying a 5 kW electrolyser which consists of 10 series-connected electrolyser stacks and a 28% alkaline (KOH) solution electrolyte has been investigated at the Taleghan renewable energies site in Iran. The hydrogen produced by the electrolyser provides energy for the 1 kW polymer electrolyte membrane fuel cell, which meets the load when the solar energy is insufficient. Variations of the solar radiation intensity, the hydrogen production rate, the solar hydrogen efficiency and the overall efficiency of the solar hydrogen energy unit were monitored in detail. The overall energy efficiency was found to range from 0.93% to 5.01%. The obtained results demonstrate the great potential of such a power system for producing and storing energy in a solar-belt country like Iran.

Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit consisted of two solid oxide electrolysis stacks electrically connected in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A cm−2 was used for the long-term operating at a constant current mode, resulting in a theoretical hydrogen production rate about 23 slpm. A demonstration of 830 h stable operation was achieved with a degradation rate of 3.1% per 1000 h. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.

Synthetic natural gas via integrated high-temperature electrolysis and methanation: Part II—Economic analysis

This part II work is built on the energy performance results of part I and focuses on the cost of producing synthetic natural gas and sensitivity scenarios around main economic variables.Capital costs for each plant section have been evaluated taking into account operational parameters such as pressure and temperature of the SOEC. The costing and financial methodology is based on a discounted cash flow analysis that was used to calculate the specific cost of synthetic natural gas (SNG) which ensures economic profitability of the investment.The co-electrolysis case has higher capital, operating and maintenance costs; however it shows a weaker dependence on the electricity cost due to its higher plant efficiency. The impact of key parameters such as electrolysis stack cost, cell degradation rate and carbon dioxide feedstock cost were further investigated. Both “state-of-the-art” and “target” scenarios were defined to account for the expected enhanced technological maturity of the SOEC technology that is expected to occur in the following decade.For the co-electrolysis case, break-even electricity prices (i.e., costs that yield an SNG cost comparable to that of fossil natural gas) of 8 $/MWh and 67 $/MWh were calculated for “state-of-the-art” and “target” scenarios, respectively.

New Low to Medium Temperature Electrolyte Separation Method and System for Alkaline Water Electrolysis

The a novel electrolysis technology was developed by Advanced Hydrogen Products is a patented method of maintaining separation of product gases (hydrogen and oxygen) by using fluid flow through porous electrodes rather than a gas impermeable membrane. This eliminates the need for any type of membrane. Eliminating the need for a membrane in alkaline electrolysis allows the device to operate at temperatures above 120 °C, where most ion conducting membranes would degrade and fail. Operating at higher temperatures reduces the anode and cathode overpotentials substantially. The reduction in overpotentials allows non-platinum group metals to be used, while increasing the electrical efficiency at comparable current densities. In addition, the device is operated at high pressure for electrochemical compression of the product gas. The method by which separation occurs is by flow of the alkaline electrolyte solution through the porous cathode and anode electrodes where hydrogen and oxygen gases are generated. The product gases are then separated from the electrolyte that is re-circulated back into the electrolyzer stack. The new method has advantages over traditional methods. By not having a membrane it is able to operate at a much higher temperature than current membrane separators allow. Not having a membrane is also beneficial since the membranes are costly and more prone to failure than other parts. Figure 1 A conceptual illustration of the electrode compared to standard electrode designs Immobilized electrolytes are able to operate at higher temperatures, but have a higher resistance than the new method. At higher temperatures with higher catalytic activity, Ohmic resistances become more important. In comparison, for low temperature cells, which typically use platinum group metals, the incredibly thin polymer type membranes offer a lower resistance. The newmethod takes advantage of both higher catalytic activity at high temperatures, and lower Ohmic resistance than immobilized electrolytes. The new electrolyzer method also reduces the Ohmic losses due to bubbles. Note that additionally, the electrolyte conductivity is also increased by not having a membrane. The pure electrolyte has a conductivity of at least 3 times greater than most immobilized electrolytes. The initial tests at low temperatures have been shown that gas crossover was low enough that the oxygen product side failed to ignite when given an ignition source and that hydrogen was produced due to ignition of the hydrogen product side. Based on the increase in exchange current density, resulting from the increased temperature, the hydrogen production method should achieve a current density of 1A/cm2 at 1.5V and 2A/cm2 at 1. 75 V[1]. A high temperature bipolar plate model is currently being built. The current state of the art in electrolysis is limited by the catalysts and operating temperature of the membrane. Alkaline electrolysis has a long history, and as such is generally the most cost effective of electrolysis methods. Although it has lower current density, it has much lower material costs, making it the most effective choice in water electrolysis. In the area of renewable energy integration and grid-stabilization, low capital cost is very important for cost effective hydrogen production. Most current separation membranes are unable to operate above 100 °C. Investigation into higher temperature membranes has been the subject of research since the 1970’s (Fig. 2). As of yet, no membrane has been developed that is cost effective above 100 °C. This results in choice between using a larger amount of lower cost materials such as nickel, or a smaller amount of higher cost materials such as platinum. By eliminating the membrane, the operating temperature can be increased and dramatically improve the efficiency of the system. An increase in the operating temperature from 80 °C to 240 °C results in the exchange current density of nickel that is comparable to platinum. Significant savings will result from efficiently producing high current-densities utilizing non-precious metals. [1] Miles et al. “Effect of Temperature on Electrode Kinetic Parameters for Hydrogen and Oxygen Evolution Reactions on Nickel Electrodes in Alkaline Solutions”, J. Electrochem. Soc.123, 332-336 (1976). Figure 1

PEM Electrolysis: Ready for Impact

The need for energy storage has never been so pressing; due to their increasing proliferation and the intermittent nature of wind and solar power sources, many regional grids can no longer accept more of these sources. Electrolysis of water using polymer electrolyte membranes (PEMs) has long held the promise of large-scale energy storage, needing only the simplest of reactants, water. More importantly it is perfectly suited for storing excess energy from these sources as they can handle tremendously high ramp rates as well as many start-stop cycles. The adoption of PEM electrolyzers has been impeded due to the headwinds of high capital cost, (including expensive high precious metal content), poor efficiency, and the empty promises made by the hydrogen economy from many years. Numerous incremental improvements, and increasing economies of scale over the past 10 years have led to very large decreases in the cost of PEM electrolysis. The complexity of the electrolyzer stack and precious metal content have been decreased, while simultaneously increasing lifetime. Increasing operating temperature has had the largest impact on efficiency and output, while improved membrane supports have allowed for higher differential pressures; reducing the need and cost of ancillary systems (see Figure 1). These advances have had the combined effect of reducing the cost of hydrogen from PEM electrolysis by nearly an order of magnitude, allowing it to approach the cost of pumped hydro, the standard in large-scale energy storage. Subsequently, whereas only a few years ago there were no commercial PEM electrolyzer stacks in the 1 MW range, today no fewer than five companies are at or near launch of MW electrolyzer systems. Figure 1. Total cost of hydrogen as a function of plant size and operating current Figure 1

Large Active Area PEM Electrolysis Stack Test Bed - Design, Data and Development

In a growing number of regions around the world, solar and wind generated electricity is a large percentage of the overall supply. In times of low demand and high renewable electricity production energy storage can be deployed to shift the environmentally preferred energy to times of the day/week/month when it is needed most. Additionally, energy storage enables even higher penetrations of naturally varying renewable electricity sources to provide the increasing demand of the planet. Historically, polymer electrolyte membrane (PEM) electrolysis systems have been limited to small active areas, current density in the range of 1500 mA/cm2 and stack power levels in the 10's of kilowatts. Today, PEM stack active area and current density are both increasing to enable smaller footprints than their alkaline counterparts. Both of these changes are helping to decrease the cost of PEM electrolyzer systems.The National Renewable Energy Laboratory (NREL) has shown that both PEM and alkaline electrolyzer systems can ramp power up and down very quickly to accommodate the needs of grids with high penetration of renewable electricity installed. In addition, their ability to ramp quickly enables these electrolyzer systems to participate in grid ancillary services aimed at assuring a safe and reliability electrical grid. The 99.99+% purity levels of the hydrogen product from these electrolyzer systems can be used in a number of industries including; fuel cell electric vehicle refueling, stored for use in stationary fuel cell applications, material handling refueling (e.g., forklifts) and can be reacted with carbon dioxide to produce renewable hydrocarbon chains (e.g., methane), which can then take advantage of existing infrastructure. In a project with DOE, NREL has designed, built and now operates a large active area stack test bed (STB) to support water electrolyzer industry partners. The STB provides a flexible and open platform to allow the quick exchange and testing of stacks, sub-systems and components. The goal of the modular system design is to provide industry a place to develop and validate hardware, process software and sub-system control algorithms to improve electrolyzer system efficiency, response, safety and capital costs. The electrolyzer stack test bed was commissioned at NREL's Energy Systems Integration Facility (Golden, CO) in third quarter 2014 and then immediately provided factory acceptance testing of three 150 kW PEM electrolyzer stacks built by Giner, Inc. in November. The STB is providing a testing platform for a novel hydrogen drying technique, developed at NREL, to reduce the amount of hydrogen product wasted when the stack is being powered with variable power. In 2015 and 2016, research, development and demonstration work conducted with the STB will focus on improving system efficiency by optimizing balance of plant power requirements, power conversion optimization, grid integration and providing gas for hydrogen infrastructure component validation and 700 bar refueling demand.

Electrochemical reforming of alcohols on nanostructured platinum-tin catalyst-electrodes

Abstract This study reports the feasibility of high purity H2 production by means of the electrochemical reforming of biomass derived organic alcohols (methanol, ethanol and ethylene glycol)-water solutions in a proton exchange membrane (PEM) electrolysis cell. For that purpose, a nanostructured bimetallic carbon-supported Pt–Sn catalyst, with nominal Pt/Sn atomic ratios of 70/30, was synthesized by a modified polyol reduction method and characterized by means of TEM, XRD and XPS analysis. The resulting Pt7–Sn3/C catalyst consists of a bi-phase Pt/SnOx structure and presents a narrow particle size distribution with size predominantly in the order of 4.5 nm, showing high dispersion on carbon support (20 wt.% metal loading). During electrochemical reforming tests, the influence of reaction temperature and the electrocatalytic stability of the system were verified for mild working operation times. Synthesized 20 wt.% Pt7–Sn3/C anodic catalyst provided a promising electro-catalytic activity, comparable to that of commercial 60 wt.% Pt–Ru/C and required lower amounts of Pt in order to produce the same amount of hydrogen. Proposed system allowed to produce H2 with a lower electrical energy requirement (26 kWh kg H 2 − 1 even after deactivation), in comparison with commercial PEM water electrolyser stacks (50 kWh kg H 2 − 1 ). In addition, obtained H2 purity was very high (99.938%) and only few ppm of CO and CO2 were detected at the cathode chamber. These results demonstrated the potential interest of Pt7–Sn3/C anodic catalyst, synthesized via the polyol method, for production of pure hydrogen from biomass-derived compounds via electrochemical reforming at low temperatures.