Proton Exchange Membrane System Research Articles

A Feasibility Study of Photovoltaic-Electrolysis-PEM Hybrid System Integrated Into the Electric Grid System Over the Korean Peninsula.

A photovoltaic–electrolysis–PEM hybrid model was developed for a feasibility study, and simulations of several scenarios in Korea were performed. The solar irradiance was derived from the University of Arizona solar irradiance based on satellite–Korea Institute of Energy Research model which provides the satellite imagery over the Korean peninsula every 15 min. In Korea, the annual average solar irradiance is 1,310 kWh m−2 with a maximum of 1,440 kWh m−2 in 2017. Electricity load and solar irradiance information were used to test the performance model of the photovoltaic–electrolysis–PEM hybrid system for baseload and several peak load shave runs. When the baseload was set at 4200 MW, the total capacity of the Photovoltaic plants was 58.5 GWp. In contrast, the hybrid system reduced the peak load more efficiently during daytime. In particular, the capacity factor of the Proton Exchange Membrane system increased in winter because the solar irradiance is relatively weak in that season. These results provide useful insights for the development of control logic models for the PV–electrolysis–PEM system in micro-grid setups.

Hydrogen Separation and Purification from Various Gas Mixtures by Means of Electrochemical Membrane Technology in the Temperature Range 100-160 °C.

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H2/CO2, H2/CH4, and H2/NH3 gas mixtures were determined in the temperature range of 100–160 °C. The effects of both the impurity concentration and cell temperature on the separation performance of the cell and membrane were further examined. The electrochemical properties and performance of the cell were determined by means of polarization curves, limiting current density, open-circuit voltage, hydrogen permeability, hydrogen selectivity, hydrogen purity, and cell efficiencies (current, voltage, and power efficiencies) as performance parameters. High purity hydrogen (>99.9%) was obtained from a low purity feed (20% H2) after hydrogen was separated from H2/CH4 mixtures. Hydrogen purities of 98–99.5% and 96–99.5% were achieved for 10% and 50% CO2 in the feed, respectively. Moreover, the use of proton exchange membranes for electrochemical hydrogen separation was unsuccessful in separating hydrogen-rich streams containing NH3; the membrane underwent irreversible damage.

Impact of Membrane and Gas Diffusion Layer on AEM Electrolyzer Performance

Electrochemical water splitting enables the use of renewable energy to produce O2 and H2 gas, vital for many energy and industrial applications. The leading commercial systems are based on liquid-alkaline and proton-exchange-membrane (PEM) technology. Liquid-alkaline systems operate at large-scale using inexpensive catalyst materials but use caustic electrolyte and cannot operate under the high differential pressures required for compressed H2 output. PEM systems use a solid-polymer electrolyte to allow for high-differential-pressure operation with pure water but require expensive precious-metal catalysts and corrosion-resistant cell materials. Anion-exchange membrane (AEM) electrolyzers, a promising new technology, combine the benefits of liquid alkaline and PEM systems. However, the technology is premature and needs further development. AEMs are prone to performance losses such as membrane degradation and instability, limited OH- conductivity, and membrane dehydration due to water transportation limitations. This behavior can vary based on membrane structure. Understanding the fundamental processes that lead to these performance losses is essential for AEM development. I will discuss the influences of membrane, ionomer, and gas-diffusion layer (GDL) material interactions on AEM electrolyzer performance as well as the importance of cathode water flow during AEM operation (Fig. 1a). To study these parameters, the performance of five different AEM materials with various gas diffusion layer (GDL) supports were evaluated. Interfacial contact between the membrane and GDL has a more-significant impact on performance than bulk membrane conductivity. Directly coating the catalyst material on the membrane improves interfacial contact between the membrane and GDL, which decreases ionic transport losses (Fig. 1b) Applying the knowledge gained, we demonstrate AEM electrolyzer operation at <2.3 V at 1 A cm-2 in pure water (Fig. 1) using only commercially available materials. Understanding AEM material interactions contributes to both a fundamental understanding of ionic transport in membrane electrolysis and to improving electrolyzer technology. This knowledge will improve AEM materials design and performance, thus facilitating the expansion of global electrolyzer capacity to help meet future renewable hydrogen demands. Figure 1

(Invited) Performance and Stability of Radiation Grafted Based Anion Exchange Membrane Electrolysers

Hydrogen is a promising renewable fuel and energy storage solution, due to its highly efficient conversion with electricity and good energy density in comparison to most batteries. However, 95 % of the produced hydrogen globally is generated from non-renewable sources and only 5% is generated from electrolysis due to high systems cost [1,2]. Around 50% of the cost of the electrolyser system comes from the precious metal catalyst used in proton exchange membrane system [3,4]. Alkaline anion exchange membrane water electrolyser AAEM-WE allow the use of non-precious metals as: effective electro-catalyst and affordable flow fields and bipolar plates, reducing the cost significantly. It is estimated that replacement of PEM electrolysers with AAEM electrolysers could offer a 43% reduction in stack cost [5]. We look here at advantages and limitations of AAEM-WE and their ideal operating range.Higher performances can be achieved using high alkaline feed concentration but this in turn reduces the lifetime of the system due to degradation of AEM membrane/ionomers. Thus, in order to reduce the degradation and improve the lifetime, low alkaline concentration should be used as feed solution for AEMWE i.e. deionised water. We have shown previously [4] that an electrolyser current density of 100 mA cm-2 at 1.65V using NiCo2O4 for Oxygen Evolution Reaction (OER) could be achieved at 60 °C [4]. We present here a binary-catalyst based on manganese oxides MnOx as very efficient electro-catalyst for OER with Tafel slope of 30 mV dec-1. Using low cost LDPE based membranes radiation grafted AEM, a very promising performance electrolyser was obtained of 1.59 V at 100 mA cm-2 and a current density of 1 A cm-2 at a potential of 1.78 V in 0.01 M NaOH at 60 °C. The current highest performance reported for Ni based catalysts (2.7 mg cm-2) in the AEM system is 500 mA cm-2 at a potential of 1.9 V in 1% K2CO3 solution(pH 10-11) at 60 °C [6,7] which is ca. a third of the current density reported here. This performance is comparable to PEM electrolysers performances with the reported operating voltage is in the range of 1.6-1.7 V [8] at 1 A cm-2. However, the long-term stability of these systems remains a challenge. Keywords : AEM, water electrolysis, alkaline, non-precious metal catalyst,

AEM Electrolysis Testing Update and Industrial Device Requirements

Membrane (PEM)-based electrolysis provides an ideal near-term technology to address the growing energy storage demands as intermittent renewable energy becomes more prevalent. While proton exchange membrane (PEM) systems are often viewed as preferred solutions to legacy KOH systems due to the lack of corrosive electrolyte, small footprint, dynamic operating range and ability to generate hydrogen at differential pressure, they still present capital cost challenges. In particular, the platinum group metal catalysts and valve metals for separator and flow field construction required for stability in the acidic environment become a significant cost driver at scale. Alkaline exchange membrane (AEM)-based electrolysis is therefore viewed as a potential replacement to the current PEM systems as a means of driving down the high capital cost. This cost reduction is accomplished by replacing the typical high cost catalyst and materials of cell construction with lower cost metals that would corrode in the acidic PEM environments, but are stable in the alkaline chemistries. In theory, this approach is highly promising, but testing of the current state-of the art has shown the technology gaps between the two platforms in terms of stability, durability, and operating electrical efficiency. Modeling has shown that savings realized in capital cost are typically off-set by an increase in operating expense resulting from the lower activity of the non-PGM catalysts and poor conductivity of the AEM. Additionally, thermal instability of the AEMs require stacks to be operated at lower temperatures than a typical PEM system, impacting conductivity further and slowing kinetics. Recent activities have looked at improving the mechanical properties, through the addition of mechanical reinforcements, to support pressurized operation, while operating temperature and varied concentrations of liquid electrolyte to the water feed have been explored to operationally evaluate the impact on performance and durability. The latter of these operating parameters have been shown by some groups to be effective in reducing cell operating potentials and providing overall voltage stability. However, this solution adds management and additional maintenance of handling the caustics typically used. Efforts at Proton continue to show improvements in short duration operational tests under milder conditions and potential pathways to achieve targets required to compete with incumbent technology. In this talk, some of the advancements achieved and how these have impacted the cost of the hydrogen will be discussed, as well as the longer-term targets that need to be reached in order to be a viable commercial application. Additionally, cost models will be compared along with sensitivity analysis to show how the impact of operating parameters, with regard to the capital and operational expense for the AEM electrolysis technology cost, show the critical areas to focus on to establish equivalence with current PEM systems and what is required to go beyond. Figure 1

Evaluation on Thermo-Electrical Characteristics of Sio2 Nanofluids for Fuel Cell Cooling Application in Automobiles

Effective thermal management is critical requirement in fuel cell technologies to avoid the performance degradation during operation. Nanofluids offer the potential to address this cooling challenge in fuel cells better than pure fluids. However, due to the electrochemical changes associated with the proton exchange membrane system, a strict limit on thermal and electrical properties of coolant needs to comply. In this study, the thermal and electrical conductivities of silicon dioxide (SiO2) dispersion of ethylene glycol (EG), glycerol (G), and 40:60 by mass ethylene glycol-glycerol (EG/G) was investigated experimentally. Measurements were carried for particle volume concentrations of 0.25–2.0% at a temperature of 30 °C. The thermal and electrical conductivity of the nanofluids significantly increases with SiO2 loading. Maximum enhancements of ∼4.0% and ∼198% at a volume concentration of 2.0% were obtained with SiO2-EG/G, respectively. Further, analysis of the results reveals that SiO2/G exhibited the greatest thermo-electrical performance, followed by SiO2-EG/G and EG. Therefore, SiO2-EG/G nanofluid is best-suited coolant for PEM fuel cell thermal applications.

AEM Electrolysis Progress and Impact on the Cost of Hydrogen

Membrane (PEM)-based electrolysis provides an ideal near-term technology to address the growing energy storage demands as intermittent renewable energy becomes more prevalent. While proton exchange membrane (PEM) systems are often viewed as preferred solutions to legacy KOH systems due to the lack of corrosive electrolyte, small footprint, and dynamic operating range due to the ability of the PEM systems to generate hydrogen at differential pressure, they still present capital cost challenges. In particular, the platinum group metal catalysts and valve metals for separator and flow field construction required for stability in the acidic environment become a significant cost driver at scale. Alkaline exchange membrane (AEM)-based electrolysis is therefore viewed as a potential replacement to the current PEM systems as a means of driving down the high capital cost. This cost reduction is accomplished by replacing the typical high cost catalyst and materials of cell construction with lower cost metals that would corrode in the acidic PEM environments, but are stable in the alkaline chemistries. In theory, this approach is highly promising, but testing of the current state-of the art has shown the technology gaps between the two platforms in terms of stability, durability, and operating electrical efficiency. Modeling has shown that savings realized in capital cost are typically off-set by an increase in operating expense resulting from the lower activity of the non-PGM catalysts and poor conductivity of the AEM. Additionally, thermal instability of the AEMs require stacks to be operated at lower temperatures than a typical PEM system, impacting conductivity further and slowing kinetics. The addition of liquid electrolyte to the water feed has been shown by some groups to be effective in reducing cell operating potentials and providing overall voltage stability. However, this solution adds management and additional maintenance of handling the caustics typically used. Efforts at Proton have shown significant improvements in operation under milder conditions, showing some potential to achieve targets required to compete with incumbent technology. In this talk, some of the advancements achieved and how these have impacted the cost of the hydrogen will be discussed. An example of this improvement is shown in the figure below, where collaborative ionomer research and partnering with a commercial entity for scale-up of catalyst synthesis have translated into an immediate improvement over targets previously established. Additionally, cost models will be compared to show the path needed to establish equivalence with current PEM systems and what is required to go beyond. Figure 1

Effect of Water Cluster Structure on Proton Transport in Proton-Exchange Membranes Using Reactive Molecular Dynamics Simulations

The proton-exchange membrane (PEM) is one of the principal components for polymer electrolyte fuel cells. In the nanoscopic structure of the membrane, proton transport is one of the dominant factors that governs power generation efficiency, which are largely attributed to the nanoscopic structure of PEMs and water aggregations. Therefore, it is critical to understand the proton transport mechanisms through PEM and clarify an important link between the membrane nanostructure and the proton transport properties. As the phase separation is considered one of the primary factors affecting its performance, the morphological properties of PEM have been studied experimentally and been characterized by proposing the cluster models (e.g., the cylinder model and the lamellar model) which reasonably fit the experimental scattering spectra. However, a detailed relationship between the morphological features and proton transport properties is still under debate. Therefore, in this study, reactive molecular dynamics simulations have been performed to study the effects of water cluster structure on proton transport properties by constructing the cluster models in the simulations. The anharmonic two-state empirical valence bond (aTS-EVB) model has been used to incorporate excess proton transport efficiently through the Grotthuss hopping mechanism, providing an accurate estimation of proton transport properties in multiproton environments within the simplicity of the theoretical framework. The proton transport properties have been estimated in terms of diffusion coefficient and proton distributions in the two hydrophilic cluster structures (i.e., the cylinder model and the lamellar model) that are the most typical proposed morphological models in PEMs. The cylindrical systems with radii from 0.5 nm to 1.7 nm and the lamellar systems with the thicknesses from 0.6 nm to 1.6 nm were constructed for the purpose of comparison. The water contents for all of the models were kept at λ = 7, where the parameter λ indicates the ratio of the number of water molecules to that of SO3 -, which is equivalent to ~10 wt %, typical operating conditions in real PEM fuel cells. To construct the desired water cluster models in the PEM system, water domains with the desired geometric shapes were obtained from equilibrated simulations of bulk water. The systems were built by first placing the water domains into an empty box and then growing polymers around the water. The sulfonate groups were arranged so that they were in close contact with the surfaces of the water domains. The simulation cell for each model was then equilibrated while the positions of water molecules and hydronium ions were constrained. In the production run, a carbon atom in the backbone of each monomer was fixed to maintain the proper geometric shape of the water domain, while still allowing reasonable fluctuations of the sulfonate groups. All other atoms in the system were allowed to relax. The diffusion coefficients in each dimension are calculated and correlated with the cluster size and the type of cluster models. It is found that the proton diffusion shows the peaks in the 0.8 nm radius of the cylinder model and in the 0.9 nm thickness of the lamellar model, and decreases with increasing the cluster size. Nevertheless, the proton diffusions at any cluster size calculated in this study show the higher value than that in the random PEM model using the aTS-EVB method (~0.23×10-5 cm2/s), suggesting that the proton can be transferred effectively in the non-random cluster models. In the cylinder model with 0.8 nm radius, where the proton shows the higher diffusion, a comparatively large number of protons that are farther than the radius of the solvation shell are found in the center of cylinder, and thus the protons are freer to explore the free water region. Similarly, the more protons distribute in the surface of the lamellar model at larger thickness because the surface density of the sulfonate groups increases at larger thickness of the lamellar model. In the lamellar model with 0.9 nm thickness protons show the higher distributions in the center of the lamellar model, suggesting that protons are able to cross from interface to interface and are less hindered by the sulfonate groups, resulting in the faster proton diffusion. In the larger size of clusters, the protons are trapped in the interface of the water domains because the surface density of the sulfonate groups becomes higher at larger cluster sizes, resulting in the slower proton diffusion. Our simulation results provide insight into quantitative information about the water cluster structure dependence of the proton transport properties at an atomic level.

(Plenary) Challenges in Going from Laboratory to Megawatt Scale PEM Electrolysis

Renewable hydrogen is becoming an increasingly important component of the transition away from fossil fuel use and towards reduction in carbon dioxide production. Hydrogen is the intermediary between primary energy sources and end products in many chemical processes such as ammonia generation, refining, and biogas processing, and is currently mainly produced by reforming of natural gas. Hydrogen from electrolysis can both make a strong environmental impact on these industries and also improve utilization of intermittent renewable energy sources such as wind and solar by leveraging otherwise stranded resources. Proton exchange membrane (PEM) electrolysis is especially well suited to energy capture because of the dynamic range and ability to quickly ramp up and down from near zero output to full capacity. This paper will discuss the challenges in continued scale up, translating laboratory scale findings to commercial PEM systems as well as some of recent advancements and impact on cost.

Using the hydrogen for sustainable energy storage: Designs, modeling, identification and simulation membrane behavior in PEM system electrolyser

The objective of this paper is Modeling and simulation of electrolyzer model type proton exchange membrane (PEM) that it is connected with solar cells, for to define and identify the factors that influence the production of hydrogen and oxygen. To generate these types of gas, we have used water and a source of electricity generated by solar cells. To perform the simulations results by using MATLAB software. We have used different physical equations defining these types of problems (Nernst-Planck, Nernst −Einstein and Fick's law). The different results shown in this work, that these types of PEM are best suited for desert areas (Adrar) with high temperatures and solar flux. This study shows the influence of temperature on the various parameters (α,i0, D and Q), and it also shows an electrolyzer equipped with a membrane produces a relatively large amount of hydrogen, volume up to 2.25L compared with an electrolyzer cell without membrane, volume of 0.0001L.

(Invited) Challenges and Limitations of Materials for Membrane-Based Water Electrolysis at Megawatt Scale

Hydrogen infrastructure is becoming a major challenge for widespread introduction of fuel cell vehicles. Electrolysis is therefore rapidly gaining international interest, particularly in the context of the penetration level of renewable energy sources on the electrical grid in places such as Europe. Electrolysis technology can cross-link different infrastructures through capture of excess renewable power (solar or wind): the electrical grid, transportation, and chemical processing. Electrolysis based on ion exchange membranes offers several advantages vs. traditional liquid electrolyte systems that use concentrated potassium hydroxide. Proton exchange membrane electrolysis technology is commercially mature, and can provide higher turndown capability, lack of corrosive electrolyte, system simplicity and ease of maintenance. PEM electrolysis is already cost competitive on an equal output capacity basis vs. other sources of hydrogen for industrial applications, but overall lifecycle cost needs to be reduced for energy markets. This talk will focus on the material challenges in PEM systems, from the catalyst and membrane materials and supports to bipolar plates and coatings. In water electrolyzers, the overvoltage of the oxygen evolution catalyst is a key efficiency loss, typically contributing over 300 mV of overpotential in proton exchange membrane systems. In addition, the catalyst loading is very high, in order to maintain activity throughout operating lifetimes surpassing 50,000 hrs, due to the lack of stability of most catalyst supports in acidic environments at electrolysis potentials. While catalyst cost is not currently a key driver in the overall system cost, as other costs are decreased through system scale up and improvement in other processes, catalyst utilization must be improved in order to meet overall cost targets. Therefore, research must focus not only on composition of the catalyst but also electrode structure and application method. Proton has shown that catalyst composition, process conditions, and electrode formulation can all improve performance vs. current commercial baselines. Catalyst loadings also have the potential to be significantly decreased without loss in performance. The membrane is also a large contributor to the efficiency losses, especially for the much thicker membranes typically used currently vs. state of the art fuel cells, as electrolysis membranes must withstand substantial differential pressure, while fully hydrated. However, they do not typically undergo freeze-thaw cycles, or changes in hydration. Conductivity under hot, dry conditions is also not a primary concern. Therefore, the material challenges and solutions are specific to electrolysis, although much of the understanding from fundamental PEM fuel cell research can be applied. With the right combination of material properties tailored for electrolysis, Proton has demonstrated that membrane thicknesses of 50-75 microns are very feasible even at 400 psi differential pressure operation. Finally, the bipolar assembly is the biggest cost driver, exceeding the cost of the membrane electrode assembly, primarily due to the aggressive conditions it is designed to withstand. On the hydrogen side of the cell, the bipolar plate has to be resistant to hydrogen embrittlement, while on the oxygen side of the cell, the plate has to be corrosion resistant at potentials of 2V, in the locally acidic environment of the PEM electrode. These constraints therefore severely limit the selection of suitable materials for this component. Titanium is a common choice, but adds expense not only in the base material but also in the manufacturing, since titanium is typically very difficult to work. Alternate methods of fabrication and coatings have enabled reduction of over half of the metal in the stack over the last several years, in addition to reduction in scrap. This talk will discuss progress in each of these areas and implications in development of megawatt scale electrolysis. Progress in system development will also be discussed.

Effects of Ni2+/3+ Redox Peak Potential on Oxygen Evolution Activity of Mixed-Transition-Metal-Oxides in Alkaline Electrolyte

High-performance, low-cost electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes are vital for the commercialization of water electrolysis systems. Modular water electrolyzers could be the building blocks of a “plug & play” hydrogen highway infrastructure which would allow on-demand hydrogen production for re-fueling fuel-cell electric vehicles. Current state-of-the-art water electrolysis systems are based on proton-exchange-membrane (PEM) technology. The highly acidic environment of these PEM systems requires the use of rare & expensive platinum group metals (PGMs). Recent break-throughs in anion-exchange-membrane (AEM) technology have re-ignited the development of non-PGM catalysts for operation in alkaline electrolytes.1 Recent literature has shown that PGM-free AEM-electolyzers can achieve performance on par with PEM systems.2 However the mass-loading of the catalysts in this proof-of-concept study was quite high. Further increases in HER & OER activity & stability will move these systems closer to commercial deployment. Recent studies have shown that Ni-Fe hydroxides exhibit the highest OER activity of any non-PGM electrocatalysts.3 Our research has investigated binary & ternary Ni-X-(Y) mixed metal oxides. Results indicate that amorphous (non-stoichiometric) oxy-hydroxide surfaces exhibit the greatest OER activity. Ni-Fe-Mo mixed oxide has shown OER activity on par with perovskites.4 We have identified that mixed metal oxide films exhibit shifts in the Ni2+/3+ redox peaks. In-situ XAS studies are correlated with CV data to show how mixing Ni-oxides with Co or Fe can stabilize or inhibit (respectively) formation of Ni in the 3+ oxidation state. These observations indicate that the OER enhancement from Ni-Fe-oxides is a result of charge-transfer from Fe to the Ni active sites, thus providing a lower (non-integer) Ni oxidation state. The resulting Nix+ (2<x<3) surface sites have been shown experimentally to form more amorphous surface structure5 and presumably behave as more reversible active sites. It is likely that the amorphous structure stabilizes the active oxy-hydroxide network, thus stabilizing the OER intermediates and decreasing the OER on-set potential. In addition, the more reversible Nix+ (2<x<3) active sites enable high turn-over-frequencies by decreasing the binding energy of the Ni-O2 adsreaction product. Acknowledgements: Authors acknowledge the financial support from Proton On-Site as part of an ARPA-E grant and use of the National Synchrotron Light Source (NSLS) (beamline X3B), Brookhaven National Lab (BNL).

(Industrial Electrochemistry & Electrochemical Engineering Division New Electrochemical Technology (NET) Award) Development of Large Scale Commercial PEM Electrolysis

Proton Energy Systems (d/b/a Proton OnSite) was founded in 1996, based on the premise that hydrogen generation from proton exchange membrane (PEM)-based electrolysis cells could be made cost competitive versus existing solutions. From small scale laboratory generators, Proton has successfully scaled up products over several design generations. A key advance has been the development of Proton’s C Series, a 30 Nm3/hr or 65 kg/day hydrogen generator based on PEM technology. A building block of this size is more suited for many applications, including common industrial markets and fueling infrastructure for small fleets of cars. This presentation will describe the evolution of Proton’s electrolyzer technology, including improvements in cell stack technology, balance-of-plant scale up, and the strong product platform we have built leading to our next product scale-up effort, for megawatt scale electrolysis applications. Market drivers and applications for various unit capacities, especially the C Series, will also be discussed. Electrolysis based on PEM technology was initially used in space and underwater for life support applications. Reliability is therefore a key characteristic of these systems. Proton has demonstrated over 50,000 hours of continuous operation in house, and has over 2000 systems fielded across product lines, with excellent reliability and up time. An advantage of the PEM systems in general is the ability to generate and electrochemically compress hydrogen at differential pressure, enabling low pressure on the oxygen side of the cell and inexpensive plastic components. The non-corrosive electrolyte also enables low maintenance cost and simpler balance-of-plant. Commercial applications for on-site hydrogen generation are driven by factors such as the desire for low hydrogen inventory, high purity hydrogen requirements, and lack of easily accessible hydrogen delivery infrastructure. Proton’s initial systems were designed to replace helium as the carrier gas in gas chromatographs, or as the lifting gas in weather balloons. The H Series, the precursor to the C Series, was developed specifically to address the electric generator cooling market. Hydrogen is utilized as a cooling fluid for the windings of over 16,000 power plant generators worldwide due to its high heat capacity and low density. Many of these plants are in areas with no reliable hydrogen delivery infrastructure. By 2006, Proton had established a robust cell design leveraging many of the design principles used today. The C Series was developed to serve larger power plants as well as the next level of fueling demonstrations, including small fleets of fuel cell vehicles and fuel cell buses. In addition, it is an appropriate size for heat treating and semiconductor applications. The cell stack, the core technology for the electrochemical system, was originally developed as a replacement for the existing electrolysis stack design for oxygen generation on board submarines. Proton was selected as the preferred developer based on our water electrolysis cell technology knowledge and expertise, leading to the development of a new, larger active area cell stack, including new flow field materials for the hydrogen side of the cell and a thinner cell configuration. This design effort was completed in 18 months, from early 2008 to 2009. Proton is currently under contract to manufacture cell stacks for several submarine platforms. This new cell architecture was then modified for the commercial application, and used as the basis for designing the new C Series system configuration. On the systems side, funding from the U.S. Army / TARDEC led to the development of key balance-of-plant subsystems, such as the implementation of a new gas/water management system, as well as a new high efficiency power supply configuration to drive the cell stacks. Internal investment from Proton paid for the development of system controls, manufacturing processes, and all of the quality documentation and third party agency certification testing required to release this platform as a commercial product. This development effort also spanned about 18 months, from 2009 to early 2011. Currently, Proton is working to translate many of the material advancements from PEM fuel cells to PEM electrolysis cells. While some changes will require modification, there are significant cost savings and efficiency improvements still possible, which Proton has demonstrated to have feasibility. In addition, Proton is performing another scale up effort to launch a megawatt scale product, representing another order of magnitude increase in hydrogen output. These systems will be designed based on requirements for emerging energy markets such as renewable energy capture and biogas methanization, and will also be discussed in this talk. Figure 1

Design and optimization of a proton exchange membrane fuel cell CHP system for residential use

This work deals with the analysis of a micro-cogeneration system for residential use based on a 1kWe proton exchange membrane (PEM) fuel cell. A detailed system analysis of the fuel cell stack operating at an average temperature of 62°C and the surrounding balance-of-plant (BoP) are taken into account. The gas processing section and the heat recovery system were also designed and optimized in term of heat recovery. Low-grade waste heat, mainly recovered from the PEM stack and the burner exhaust, has been found suitable for feeding a low-temperature thermal user such a radiant floor heating system (operating at ∼35–45°C). According to this configuration, the heat-exchanger network has been optimized following the pinch analysis methodology, and the floor heating system has been sized accordingly.The micro-cogeneration system has been modelled in term of mass and energy balances while efficiency maps were obtained for a varying fuel utilization and current density of the stack. The maximum electrical efficiency achieved is around 36% (AC, LHV), with a stack current of 30A and a Fuel Utilization (FU) of 80%. The global efficiency (that includes also heat recovery toward the thermal utility) is above 75% for same stack operating conditions.From the floor heating system sizing, the considered micro-CHP PEM system is able to supply around 22.4% of the heat demand by a 50m2 medium-low efficiency building (class E – EU classification) during the winter season. Nevertheless, taking into account a high efficiency building (class A++ – EU classification), the heat released by the PEM plant can supply the overall required thermal load without requiring an auxiliary boiler.

A new parameter extraction method for accurate modeling of PEM fuel cells

SUMMARY In this paper, a new parameter extraction method for accurate modeling of proton exchange membrane (PEM) fuel cell systems is presented. The main difficulty in obtaining an accurate PEM fuel cell dynamical model is the lack of manufacturer information about the exact values of the parameters needed for the model. In order to obtain a realistic dynamic model of the PEM system, the electrochemical considerations of the system are incorporated into the model. Although many models have been reported in the literature, the parameter extraction issue has been neglected. However, model parameters must be precisely identified in order to obtain accurate simulation results. The main contribution of the present work is the application of the simulated annealing (SA) optimization algorithm as a method for identification of PEM fuel cell model parameter identification. The major advantage of SA is its ability to avoid becoming trapped in local minimum, as well as its flexibility and robustness. The parameter extraction and performance validation are carried out by comparing experimental and simulated results. The good agreement observed confirms the usefulness of the proposed extraction approach together with adopted PEM fuel cell model as an efficient tool to help design of power fuel cell power systems. Copyright r 2009 John Wiley & Sons, Ltd.

Characterisation of mechanical non-linearities in a proton exchange membrane fuel cell using raw data

The implementation of fuel cells in transportation systems requires some better understanding of their mechanical behaviours in vibrating environments. A preliminary study for detecting and classifying non-linearities from simulations led to the creation of a library of non-linearity signatures. The second step is the comparison with experimental results obtained from a proton exchange membrane (PEM) fuel cell tested under dynamic loads. Two experimental benches are designed for this purpose: a bipolar plate system with or without frames and a PEM fuel cell. They are subjected to swept-sine excitations on a vibrating platform. Their mechanical responses are measured with accelerometers placed on the bipolar plate for the first system and on the top centre of the central cell for the PEM system. The raw experimental data are exploited to characterise non-linearities. Methods of detection and classification of non-linearities are described and applied to the raw data. The results are exposed and commented on.

Diesel Steam Reforming for PEM Fuel Cells

Different applications for the decentralized stationary or mobile power supply require the usage of liquid hydrocarbons such as fuel oil, diesel, or gas oil in fuel cell systems. Reducing the sulfur content of conventional liquid fuels such as diesel or gasoline below 10ppm, the usage of these fuels in fuel cell applications becomes increasingly promising. The first process step represents thereby the reforming, which can be carried out in different ways. One of the commonly favored gas process technologies is the steam reforming process, which is state of the art for natural gas applications. Using a proton exchange membrane (PEM) fuel cell requires a complex gas cleanup system. Using a pressurized steam reforming process offers a significant reduction of the whole system size by efficiently compressing the liquid educts. Complete PEM systems with steam reformers tend to have a higher efficiency than, for example, systems using the autothermal reforming process. Advanced diesel steam reformers for industrialization still have to be developed and improved. The Oel-Wärme-Institut gGmbH has successfully carried out research on steam reforming with variations of important parameters using a sulfur free reference fuel and desulfurized diesel. During the experiments, several parameters such as steam to carbon ratio, reformer inlet temperatures, catalysts, and fuels were varied. While running the process, a continuous product gas measurement was taken. The reformer is equipped with several thermocouples. Three of them are moveable to measure the temperature profile of the catalyst. The experiments show that product gas concentrations reach a nearly equilibrium concentration with reformer inlet temperatures ϑ&gt;700°C of a reference fuel∕steam mixture. Hydrogen concentrations over 70% were feasible. Constant inlet temperatures of ϑ=850°C and a variation of the steam to carbon ratio only have a noticeable effect on the water gas shift equilibrium. After all experiments, carbon deposits were found in the steam reformer system and under some circumstances on the catalysts. Experiments with operating times of more than 20h were performed at a steam to carbon ratio of 4.5. The application of continuously desulfurized diesel fuel indicates a degradation of the catalyst after a few hours. For the overall system design of PEM fuel cell applications, an operation mode at a reduced steam to carbon ratio has to be developed.

Experimental Results of a PEM System Operated on Hydrogen and Reformate

The main objective of this study is to evaluate the performance of a proton exchange membrane (PEM) fuel cell generator operating for residential applications. The fuel cell performance has been evaluated using the test bed of the University of Cassino. The experimental activity has been focused to evaluate the performance in different operating conditions: stack temperature, feeding mode, and fuel composition. In order to use PEM fuel cell technology on a large scale, for an electric power distributed generation, it could be necessary to feed fuel cells with conventional fuel, such as natural gas, to generate hydrogen in situ because currently the infrastructure for the distribution of hydrogen is almost nonexistent. Therefore, the fuel cell performance has been evaluated both using pure hydrogen and reformate gas produced by a natural gas reforming system.